Docstoc

electric power engineering research laboratory

Document Sample
electric power engineering research laboratory Powered By Docstoc
					ELECTRIC POWER ENGINEERING RESEARCH LABORATORY


                            '$I '%I




                               '&I




                               ''I




                                I
       Introduction of
       Electric Power Engineering Research Laboratory

  Electric Power Engineering Research Laboratory (EPERL) was established in April 2004 as one of eight
new laboratories according to the restructuring of Central Research Institute of Electric Power Industry
(CRIEPI) organization in order to contribute to society through development of new technology. EPERL is
situated on the Yokosuka site on the west coast (Sagami Bay) of the Miura peninsula in Kanagawa
prefecture.
  Main missions of EPERL are development of lifetime estimation methods for aged power apparatus and
cables in transmission and distribution systems, development of insulation design and lightning protection
methods for power apparatus, solution of electromagnetic compatibility (EMC) and electromagnetic field
(EMF) issues, development of appropriate countermeasures for high-current arc, development of next-
generation power technologies, and realization of laser, plasma, and superconductivity applications.




Research Sectors and Facilities

■ High Voltage and Insulation Sector
 This research sector aims to develop lifetime evaluation and diagnostic methods for power apparatus and
cables for transmission and distribution systems, and to propose next-generation gas insulated switch gear
and all-solid insulated substations.

■ Lightning and Electromagnetic Environment Sector
 This research sector aims to develop insulation design and lightning protection methods for electric power
and telecommunication systems, and to solve EMC and EMF issues.


■ Applied High Energy Physics Sector
 This research sector aims to realize laser and plasma applications to enhance the performance of power
transmission equipment and materials, and to ascertain their durability against large-fault current and high
power arc.


■ Electric Power Application Sector
 This research sector aims to realize power electronics and superconductivity applications to enhance the
performance of power transmission equipment, and to develop electromagnetic transient analysis methods
for power systems.



High Power Testing Laboratory
 This laboratory belongs to the EPERL and has been internationally certified by JAB as an independent
organization. This laboratory can issue certification for the durability of power equipment and materials.

Shiobara Testing Yard
 Shiobara testing yard was constructed at Shiobara, Tochigi pref. in 1961 to obtain the data necessary to
design 500kV class AC transmission lines. Now, this testing yard is used for experimental research on
protecting power transmission lines, distribution lines, and ICT equipment from lightning.
      Introduction of
      Electric Power Engineering Research Laboratory

Contents of Research

① Diagnosis and Lifetime Evaluation of Power Apparatus
② Asset Management Support Tools for Electric Power Equipment
③ Fault Current and High Power Arc Technology for Establishment of Secure and Reliable Power
  Equipment
④ Hybrid Gas-Insulation System
⑤ Element Technologies for All-solid Insulated Substation
⑥ Superconducting Power Apparatus
⑦ Preventive Technology against Lightning Damage
⑧ Evaluation Methods of Electromagnetic Environment
⑨ Analytical Tool for Transient Phenomenon and Electromagnetic Field
⑩ Arc Plasma Waste Treatment Technology
⑪ Synthesis of Aluminum Nitride Nano-particles by Arc Plasma
⑫ Applied laser/photon diagnostics
     Diagnosis and Lifetime Evaluation of Power Apparatus

          Background
     We carry on research on various advanced diagnosis technique and lifetime evaluation
   methods based on electrical and thermal degradation for power equipments such as
   transformers, gas-insulated switchgear, hydro-power generator, and XLPE cables (cross linked
   polyethylene insulated power cable) to reduce the maintenance cost of those equipment.

       Principal results
    (1) We verified the deterioration mechanism of aged XLPE cables, and evaluated the remaining
       lifetime of XLPE cables.
    (2) We proposed the easy-installing on-line partial discharge monitoring system for the stator
       windings to establish the deterioration diagnosis technique of hydro-power generators.
    (3) We proposed an estimation method of lifetime of a distribution transformer based on the
       thermal deterioration of insulating paper due to the load current of the transformer.

    Future Developments
      Our future plan is the development of more accurate advanced degradation diagnosis and
    remaining lifetime evaluation technique for power apparatus and XLPE cables.

                                                                                               Water tree




                                                                                                 Insulator
                                                             Insulator
Pre-breakdown phenomena detection          Cross section of XPLE cable               Example of “water tree”
   system for XPLE power cable                     (20kV-class)

   We re-verified that the predominant degradation process of aged XPLE cables is attributed to
   the "water tree“ and its extension in insulators.



             部分放電信号検出用CT
                       風洞                   Hydro-power generator
                                                水車発電
                                                機
                                      Air duct              Stator          Data acquisition
                                          サーチコイル           固定子コイル
                                                           windings               装置本体
                                                                                system




                                                                            温度測定用ケーブル
        Current transformer for                                              Data transmission
                                                                          部分放電測定用ケーブル
       detecting partial discharge   Searching coil (sensor for partial            cable
           and temperature             discharge and temperature)

              Online partial discharge monitoring system for hydro-power generator stator windings
                                  XLPE cable
                                  XLPE cable

                                                                          XPLE cable                                                                                                                        Water-tree deterioration in XLPE cable may
                                                                                                                                                                                                            Water-tree deterioration in XLPE cable may
                                                                       (connection part)
                                                                                                                                                                                                            cause the third harmonic current which flows on
                                                                                                                                                                                                            cause the third harmonic current which flows on
                                                                                                                                                                                                            the conductor superimposed over the load
                                                                                                                                                                                                            the conductor superimposed over the load
                                                                                                                                                                                                            current of power frequency. Based on this
                                                                                                                                                                                                            current of power frequency. Based on this
                                                                                                                                                                                                            principle, we proposed an optical fiber current
                                                                                                                                                                                                            principle, we proposed an optical fiber current
                                                                                                                                                                                                            sensor wound around the cable. This sensor can
                                                                                                                                                                                                            sensor wound around the cable. This sensor can
                                                          optical fiber current sensor                                                                                                                      be applied to online diagnosis system for XPLE
                                                                                                                                                                                                            be applied to online diagnosis system for XPLE
                                                              wound around cable
                                                                                                                                                    Optical signal
                                                                                                                                                                                                            deterioration.
                                                                                                                                                                                                            deterioration.
                                                                                                                                                    detector unit

                                        Deterioration signal sensing system for XLPE
                                          cable using optical fiber current sensor                                                                                                                                                                                      100000




                                                                                                                                                                                                                                               Partial discharge [pC]
                                                                                                                                                                                                                                                                         80000

                Hydro-power generator
                Hydro-power generator



                                                                                                                                                                                                                                                    放電電荷 [pC]
                                                                                                                                                                                                                                                                         60000


                                                                                                                                                                                                                                                                         40000


                      We proposed a diagnostic method based on the
                      We proposed a diagnostic method based on the                                                                                                                                                                                                       20000

                      continuous measurement of partial discharge and
                      continuous measurement of partial discharge and                                                                                                                                                                                                        0
                      temperature for hydro-power generator to evaluate
                      temperature for hydro-power generator to evaluate                                                                                                                                                                                                                                            90                           180                270
                                                                                                                                                                                                                                                                                                          Relative phase angle [deg]
                                                                                                                                                                                                                                                                                                          相対印加電圧位相角 [deg]
                      deterioration of the stator windings.
                      deterioration of the stator windings.


                                  7 0 00 0                                                                                                                                                                                                                                                                                                                                            10 0
    maximum PD charge (qm) [pC]




                                  6 0 00 0
                                                  ●: Partial discharge
                                                      qm
                                                      c oi l   em per at ur
                                                  ▲: Windingttemperaturee




                                                                                                                                                                                                                                                                                                                                                                                             coil temperature [ C]
                                                                                                                                                                                                                                                                                                                                                                                      80




                                                                                                                                                                                                                                                                                                                                                                                             o
                                  5 0 00 0

                                  4 0 00 0                                                                                                                                                                                                                                                                                                                                            60

                                  3 0 00 0                                                                                                                                                                                                                                                                                                                                            40
                                  2 0 00 0
                                                                                                                                                                                                                                                                                                                                                                                      20
                                  1 0 00 0

                                        0                                                                                                                                                                                                                                                                                                                                             0
                                                                                                              1999/05/01




                                                                                                                                                                          1999/08/01




                                                                                                                                                                                                                              1999/11/01




                                                                                                                                                                                                                                                            1999/12/01
                                                     1999/02/01



                                                                       1999/03/01




                                                                                         1999/04/01




                                                                                                                           1999/06/01




                                                                                                                                                        1999/07/01




                                                                                                                                                                                               1999/09/01




                                                                                                                                                                                                             1999/10/01




                                                                                                                                                                                                                                                                                 2000/01/01




                                                                                                                                                                                                                                                                                                                 2000/02/01



                                                                                                                                                                                                                                                                                                                                       2000/03/01




                                                                                                                                                                                                                                                                                                                                                      2000/04/01




                                                                                                                                                                                                                                                                                                                                                                         2000/05/01




                                                                                                                                                                                             date and        ti m e


   Example of on-site partial discharge and temperature records during 1.5 year for hydro-power generator


                           Distribution Transformer
                           Distribution Transformer
                                                                                                                                                                                                                                                                                                                                     Using this method, it is
                                                                                                                                                                                                                                                                                                                                     Using this method, it is
                                                                                                                                                                                                                                                                                                                                     possible to estimate
                                                                                                                                                                                                                                                                                                                                     possible to estimate
                                                                                                                                                                         Measurement
                                                                                                               Effect of
                                                                                                                日射の影響                                                    Calculation 計算値
                                                                                                                                                                                     実測値
                                                                                                                                                                                                                                                                                                                                     the
                                                                                                                                                                                                                                                                                                                                     the       lifetime
                                                                                                                                                                                                                                                                                                                                                lifetime   of
                                                                                                                                                                                                                                                                                                                                                           of
                                                                                                                考慮
                                      V1            V2                 V3                                      sunshine
                                                                                                                                           100
                                                                                                                                          100                             巻線
                                                                                                                                                                                                                                                                                                                                     distribution transformer
                                                                                                                                                                                                                                                                                                                                     distribution transformer
                                                                                                                                                                      Coil                                                                                                                                                           taking the overloaded
                                             R1                   R2                R3
                                                                                                                                                                                                                                                                                                                                     taking the overloaded
                                                                                                                                 Temperature [℃]




                                                                                                                                                                                       Oil
                                                                                                             Effect of
                                                                                                             風の影響
                                                                                                             考慮
                                                                                                              wind
                                                                                                                                                                                        油
                                                                                                                                                                                                                                                                                                                                     condition into account.
                                                                                                                                                                                                                                                                                                                                     condition into account.
                                                                                                                                     温度(℃)




                                                                                                                                                   50
                                                                                                                                                   50                                                                                                                        1000                        10
                                                                                                                                                                                                                                                                                                         10
                                                                                                                                                                           Tank
                                                                                                                                                                         タンク表 面
                                                                                                                                                                                                                                                                                     Sunshine [W/m2] )
                                                                                                                                                                                                                                                                                         日射量 (W/m 2




                                                                                                                                                                                  surface
                                                                                                                                                                                                                                                                                                               Wind velocity [m/s]
                                                                                                                                                                                                                                                                                                         風速 (m / s )




Temperature for
各ノー ドは以下に対応
 V1 :巻線温度
  V1: coil                                                                                                                                                                              Sunshine                                                                日射量
 V2 :絶縁油温度
  V2: oil
 V3 :タンク表面温度
                                                                                                                                                   0
                                                                                                                                                   0
  V3: tank surface                                                                                                                                                                                                         Wind
                                                                                                                                                                                                                          velocity
                                                                                                                                                                                                                            風速


                                                                            6. 6                      0. 9

                                                                                                                                                                                                                                                                                 0
                                                                                                                                                                                                                                                                                 0                       0
                                                                                                                                                                                                                                                                                                         0
                                                                                                                                                                     9/18 12:00
                                                                                                                                                                       9/18 12時                         9/19 12:00
                                                                                                                                                                                                      9/19 12時                              9/20 12:00
                                                                                                                                                                                                                                           9/20 12時
                                                                                                                                                                                                      Date / hour
                                                                                                                                                                                                         時刻

Transient temperature rise calculation                                                                                                                               Comparison between calculated and
program for distribution transformers                                                                                                                                measured daily temperature change
  Asset Management Support Tools
  for Electric Power Equipment

      Background
  In recent difficult circumstances of the electric power industry, it is necessary to reduce
maintenance costs of electric power equipment by rationalizing maintenance strategies of aged
equipment. Therefore, in sections responsible for the maintenance, in addition to the
improvement of diagnosis techniques, there is a great deal of interest in asset management
techniques that incorporate economic indicators. The operating condition data, inspection data
and diagnostic data are being gathered in utility companies, and attempts are being made to
utilize them to support the maintenance strategy. CRIEPI is investigating techniques to support
them. Effective programs for specific power equipment are being pursued.

   Principal results
(1) Support tool for dissolved gas analysis of oil-immersed power transformers
    A support program for the evaluation of dissolved gas analysis (DGA) has been developed. It
  provides comparison with data obtained from the same kind of transformers, and gives criteria
  among them (Fig1).
(2) Decision support tool based on average maintenance cost
    Support programs to evaluate the average annual maintenance cost have been developed.
  These program can provide an optimum overhaul strategy by considering the overhaul effect
  (Fig.2).

Future Developments
  Support programs for maintenance and renewal strategy by considering individual
 characteristics of equipment are being investigated.

                                                                          DGA data analysis and
                                                                           DGA data analysis and
                                                                          comparison program
                                                                           comparison program
                                                                          The
                                                                           The      program
                                                                                    program     can
                                                                                                 can
                                                                          analyze and display the
                                                                           analyze and display the
                                                                          distribution densities of
                                                                           distribution densities of
                                                                          9 gases (and their
                                                                           9 gases (and their
                                                                          accumulation). The raw
                                                                           accumulation). The raw
                                                                          data, a fitted curve with
                                                                           data, a fitted curve with
                                                                          a normal distribution,
                                                                           a normal distribution,
                                                                          and the cumulative
                                                                           and the cumulative
                                                                          normal distribution are
                                                                           normal distribution are
                                                                          plotted. Criteria, such
                                                                           plotted. Criteria, such
                                                                          as the 5% line and 10%
                                                                           as the 5% line and 10%
                                                                          line, are also indicated.
                                                                           line, are also indicated.
                                                                          As evaluation support,
                                                                           As evaluation support,
                                                                          new data are compared
                                                                           new data are compared
                                                                          with these criteria.
                                                                           with these criteria.
                       (An example of display)


                  Fig. 1: Display of Dissolved Gas Analysis data analysis tool
                                                           Concept
                                                            Concept
                                                           The annual repair cost is assumed to
                                                            The annual repair cost is assumed to
                                                           increase proportionally with age, and
                                                            increase proportionally with age, and
                                                           decrease by an overhaul. In this case, the
                                                            decrease by an overhaul. In this case, the
                                                           accumulated repair cost changes with and
                                                            accumulated repair cost changes with and
                                                           without overhaul, as shown in left figure
                                                            without overhaul, as shown in left figure
                                                           (Only repair cost is illustrated; Overhaul
                                                            (Only repair cost is illustrated; Overhaul
                                                           cost is also considered in the program).
                                                            cost is also considered in the program).
                                                           Overhaul strategy is examined by changing
                                                            Overhaul strategy is examined by changing
                                                           its period and scale. Expected failure cost
                                                            its period and scale. Expected failure cost
                                                           increasing by age is also considered in the
                                                            increasing by age is also considered in the
                                                           same way.
                                                            same way.


                                                           Necessary parameters
                                                            Necessary parameters
                                                           Following data are required: ①increasing
                                                            Following data are required: ①increasing
                                                           rate of annual repair cost, ②overhaul
                                                            rate of annual repair cost, ②overhaul
                                                           effect (relation between overhaul cost and
                                                            effect (relation between overhaul cost and
                                                           reduction of annual repair cost), ③mean
                                                            reduction of annual repair cost), ③mean
                                                           lifetime and cost at failure (for evaluating
                                                            lifetime and cost at failure (for evaluating
                                                           expected failure cost according to age), ④
                                                            expected failure cost according to age), ④
                                                           expected operation term (evaluation term).
                                                            expected operation term (evaluation term).
                                                           They should be obtained from actual data,
                                                            They should be obtained from actual data,
                                                           if possible (the objective of this research
                                                            if possible (the objective of this research
                                                           is to provide programs, which equipped
                                                            is to provide programs, which equipped
                                                           input frames for necessary and sufficient
                                                            input frames for necessary and sufficient
                                                           parameters).
                                                            parameters).

              increasing rate of      evaluation term
              annual repair cost      should be deside

input parameters




                                      overhaul effect

                                          low cost areas



                      life and failure cost




                                                              difference of overhaul
                                                              number in the assumued
                                                              evaluation term

                                               2 times                1 time




   Fig. 2: Display of average annual maintenance cost evaluation program
     Fault Current and High Power Arc Technology for
     Establishment of Secure and Reliable Power Equipment

         Background
  When a short-circuit fault occurs in transmission and distribution systems due to lightning strike,
high current, several to dozens of times as load current, flows to the fault point. In case a high
power arc occurs due to the fault current with dielectric breakdown, it is necessary to protect
power equipment and ensure public security.
  CRIEPI has promoted research for limiting and interrupting the fault current to establish secure
and reliable power systems.


                                  Arc
                                                               High power arc (Current : 30 kA)
                                                Various materials around a short-circuit fault point are
                                                decomposed to molecules, atoms, ions, and electrons,
                                                and finally reach a plasma state. High power arc
                                                produces enormous heat, blinding flash and detonating
                                                sound.




     Principal results
(1) Development of technology for limiting fault current immediately
     Arc driven type fault current limiter for 6 kV class distribution lines has been developed
   by joint research with Tohoku Electric Power Co., Inc. and Sankosha Co., Ltd.
(2) Development of arcing horns for interrupting fault current instantaneously
     Fault current interrupting arcing horns for 66/77 kV transmission and 22 kV distribution
   lines have been developed by joint research. A simulation model of the fault current
   interrupting arcing horns applicable to EMTP (Electromagnetic Transients Program) has
   also been developed to analyze power system conditions.

    For 66/77 kV        Maximum interruption current : 10 kArms (Peak current value : 25 kA)
  transmission lines    by Kansai Electric Power Co., Inc., Tokyo Electric Power Co., Inc., Nippon Katan Co., Ltd. and CRIEPI

       For 22 kV        Maximum interruption current : 15 kArms (Peak current value : 37.5 kA)
   distribution lines   by Kansai Electric Power Co., Inc., Nippon Katan Co., Ltd., Nihon Network Support Co., Ltd. and CRIEPI


(3) Elucidation of high power arc phenomena due to fault current in power equipment
     We have elucidated that the temperature of an arc jet due to a high current of 50 kA
   reached around 10,000 K in the vicinity of electrodes.


 Future Developments
 (1) Develop low-cost and effective technology for limiting and interrupting fault current.
 (2) Develop digital short-circuit test tools to compensate full-scale short-circuit tests,
     and promote rational and efficient research for fault current and high power arc technology.
                                                Demonstration of arc-driven fault
                                                Demonstration of arc-driven fault
                                                        current limiter
                                                        current limiter
        Fault current limiter                The figure shows the verification test of
                                              The figure shows the verification test of
                                             an arc-driven fault current limiter on a
                                              an arc-driven fault current limiter on a
                                             6.6 kV distribution system by joint
                                              6.6 kV distribution system by joint
                                             research with Tohoku Electric Power Co.,
                                              research with Tohoku Electric Power Co.,
                                             Inc. and Sankosha Co., Ltd. We have
                                              Inc. and Sankosha Co., Ltd. We have
                                             confirmed that any malfunction did not
                                              confirmed that any malfunction did not
                                             occur.
                                              occur.




   Fault current interrupting arcing horns               Fault current interrupting arcing horns
      for 66/77 kV transmission line                            for 22 kV distribution line




Fault current interrupting arcing horns
Fault current interrupting arcing horns        Fault current interrupting arcing horns
                                               Fault current interrupting arcing horns
   for 66/77 kV transmission lines
    for 66/77 kV transmission lines                  for 22 kV distribution lines
                                                      for 22 kV distribution lines
Maximum interruption current 10 kA,
Maximum interruption current 10 kA,            Maximum interruption current 15 kA,
                                               Maximum interruption current 15 kA,
around 35,000 installations in Japan.
around 35,000 installations in Japan.                under verification test
                                                     under verification test




                                                      Development of simulation model
                                                      Development of simulation model
                                                      of fault current interrupting arcing
                                                      of fault current interrupting arcing
                                                      horns
                                                      horns
                                                      Calculated waveforms using the
                                                       Calculated waveforms using the
                                                      simulation model are accurately
                                                       simulation model are accurately
                                                      consistent with experimental
                                                       consistent with experimental
                                                      waveforms obtained from full-scale
                                                       waveforms obtained from full-scale
                                                      short-circuit test. We could
                                                       short-circuit test. We could
                                                      simulate the entire process from
                                                       simulate the entire process from
                                                      fault occurrence to fault clearing.
                                                       fault occurrence to fault clearing.
    Hybrid Gas-Insulation System

          Background
   SF6 has been identified as a greenhouse gas with a long atmospheric lifetime. Therefore,
recycling guidelines for SF6 in electric power apparatus have been studied, and the reduction in the
amount of SF6 released into the atmosphere has progressed. In the long term, it is preferable to
reduce the amount of SF6 used. Therefore, it may be important to discuss the possibility of using
environmentally friendly gases as an alternative insulation gas for practical gas-insulated apparatus.

      Principal results
   In the selection of an alternative gas, high-pressure natural gases, such as air, nitrogen (N2), and
carbon dioxide (CO2) are promising environmentally friendly candidates. However, some strategies
for enhancing insulation performance are necessary for their practical applications to apparatus
because the dielectric strengths of these gases are about 1/3 that of SF6.
   In this study, we investigated the possibility of gas-insulated apparatus using a hybrid gas
insulation system. By applying the hybrid gas insulation system, a conventional SF6-gas-insulated
apparatus may be replaced with a natural-gas-insulated one without a considerable increase in
cross-sectional size.

  Future Developments
    We are carrying on research on practical insulation performance of basic models for conductor
joint to develop an environmentally-compatible gas-insulated apparatus using the hybrid gas-
insulation system, and we aim at the proposition of the basic specification.
             Conventional GIB                                            Hybrid gas-insulation system
                                                  Single-core type                                              Triple-core type




   Basic structure of hybrid gas-insulation system (schematic illustration): The hybrid gas-insulation system has a
   structure which the high-electric-field part is insulated using a solid insulator. The triple-core type conductor structure is
   also supposed for the viewpoint of such as flexibility of the subconductors.


                    Basic research equipment (photo)                                      High voltage
     Model electrodes for conductor joint, etc. are installed in the basic
   research equipment. We are carrying out high voltage insulation tests
   for obtaining data for insulation design of hybrid gas-insulation system.

                                                                     # Model electrode is installed.
                                                                     # Compressed N2 or CO2 is enclosed.
  SF6 is a colorless, odorless, and non-toxic gas. It has been applied to
  gas-insulated power apparatus owing to its excellent insulation and
  interruption performance. Moreover, it has been used by the magnesium
  industry, etc. other than electric power equipment. However, it has been
  identified as a greenhouse gas with a long atmospheric lifetime. Therefore,
  the amount of SF6 released into the atmosphere has been reduced by
  each industry.
                                                                             2.5                                                                                                               Search of SF66 substitute
                                                                                                                                                                                               Search of SF substitute
                                                                                                                                               CCl4 (toxicity)
                                                                                           : SF6gas
                                                                                           : Natural gas
                                                                                                                                                                                 Figure 1 shows dielectric strengths in different gases
                                                                                                                                                                                  Figure 1 shows dielectric strengths in different gases
                                                                                                                                          C2F5CN (toxicity)
                                                                             2.0
                                                                                           : PFC (Greenhouse gas)                                                            normalized by that in SF6 as functions of boiling temperature.
                                                                                                                                                                              normalized by that in SF6 as functions of boiling temperature.
                                 Dielectric strength (normalized by SF6)

                                                                                           : HFC (Greenhouse gas)
                                                                                           : Ozone-depleting gas                                     CCl3F                   In the selection of an alternative gas, it should be noted that
                                                                                                                                                                              In the selection of an alternative gas, it should be noted that
                                                                                           : Cyanic gas (toxic gas)
                                                                                                                                                                             an artificial gas in which a high dielectric strength is achieved
                                                                                                                                                                              an artificial gas in which a high dielectric strength is achieved
                                                                             1.5                                            CF3CN (toxicity)                                 often has some environmental restriction. Therefore, it is
                                                                                                                                                                              often has some environmental restriction. Therefore, it is
                                                                                                                                               c-C4F8
                                                                                                                                                                             thought that high-pressure natural gases, such as air,
                                                                                                                                                                              thought that high-pressure natural gases, such as air,
                                                                                              Candidate of
                                                                                                                              SF6     CCl2F2                                 nitrogen (N2), and carbon dioxide (CO2), are promising
                                                                                                                                                                              nitrogen (N2), and carbon dioxide (CO2), are promising
                                                                             1.0
                                                                                             "SF6 substitute"
                                                                                                                                      C3F8
                                                                                                                                             CF3I
                                                                                                                                                                             environmentally friendly candidates.
                                                                                                                                                                              environmentally friendly candidates.
                                                                                                                                 C2F6                                            In this study, we assume the complete substitution of SF6
                                                                                                                                                                                  In this study, we assume the complete substitution of SF6
                                                                                                                  C2F3H3
                                                                             0.5
                                                                                                   N2
                                                                                                                                                                             by a pure environmentally friendly gas (natural gas), although
                                                                                                                                                                              by a pure environmentally friendly gas (natural gas), although
                                                                                                          Air                             C2F4H2
                                                                                        H2                            CF4         CO2                                        we also assume the use of a gas mixture as the target gas
                                                                                                                                                                              we also assume the use of a gas mixture as the target gas
                                                                                                                                             or gas mixture                  from the viewpoint of the reduction in the amount of SF6
                                                                                                                                                                              from the viewpoint of the reduction in the amount of SF6
                                                                             0.0                                                             containing SF6
                                                                                      He      Ne        Ar                                                                   used.
                                                                                                                                                                              used.
                                                                               -300                -200                 -100                   0                 100
 Figure 1                                                                                                 Boiling temperature [deg]



                                                                                                                                                                              Insulation performance of compressed natural gases
                                                                                                                                                                               Insulation performance of compressed natural gases
                                                                                                                                                                                          (N22 & CO22) compared with SF66
                                                                                                                                                                                           (N & CO ) compared with SF
                                50                                           Negative
                                                                                                                            CO2                                                  Figure 2 shows breakdown strengths of N , CO and SF
                                                                                                                                                                                 Figure 2 shows breakdown strengths of N22, CO22 and SF66
 Breakdown strength [kV/mm]




                                                                                                                                                                             as functions of gas pressure. In general, the breakdown
                                                                                                                                                                              as functions of gas pressure. In general, the breakdown
                                40
                                                                                   SF6              N2                                                                       strength of gases increase with the gas pressure. The
                                                                                                                                                                              strength of gases increase with the gas pressure. The
                                                                                                                                                    Sphere-to-plane          breakdown strength in CO22 of approximately 1.5MPa or in N22
                                                                                                                                                                              breakdown strength in CO of approximately 1.5MPa or in N
                                30
                                                                                                                                                                             of approximately 2.0MPa is nearly equal to that in SF66 of
                                                                                                                                                                              of approximately 2.0MPa is nearly equal to that in SF of
                                                                                                                                                                             0.5MPa (practical use). However, gas insulated equipment at
                                                                                                                                                                              0.5MPa (practical use). However, gas insulated equipment at
                                20
                                                                                                                                                                             a gas pressure of 3 or 4 times higher than conventional one
                                                                                                                                                                              a gas pressure of 3 or 4 times higher than conventional one
                                                                                                                  N2 (coaxial cylinder; Reference data)                      is not practical.
                                                                                                                                                                              is not practical.
                                10
                                                                                                                                                                                 Therefore, some strategies for enhancing insulation
                                                                                                                                                                                 Therefore, some strategies for enhancing insulation
                                           0
                                                                                                                                                                             performance are necessary for the practical applications of
                                                                                                                                                                              performance are necessary for the practical applications of
                                           0.0                                          0.5                     1.0                 1.5               2.0              2.5   these gases. By applying the hybrid gas insulation system, a
                                                                                                                                                                              these gases. By applying the hybrid gas insulation system, a
                                                                                                        Gas pressure [MPa(abs)]                                              conventional SF66-gas-insulated apparatus may be replaced
                                                                                                                                                                              conventional SF -gas-insulated apparatus may be replaced
 Figure 2                                                                                                                                                                    with a natural-gas-insulated one without a considerable
                                                                                                                                                                              with a natural-gas-insulated one without a considerable
                                                                                                                                                                             increase in cross-sectional size. In the case of applying
                                                                                                                                                                              increase in cross-sectional size. In the case of applying
                                                                                                                                                                             gases such as N22 and CO22, the use of the hybrid gas
                                                                                                                                                                              gases such as N and CO , the use of the hybrid gas
                                                                                                                                                                             insulation system may be effective as a method of achieving
                                                                                                                                                                              insulation system may be effective as a method of achieving
                                                                                                                                                                             a higher insulation performance.
                                                                                                                                                                              a higher insulation performance.

                                                                                                                                               Feature of hybrid gas-insulation system
                                                                                                                                               Feature of hybrid gas-insulation system
              Hybrid gas-insulation system has many advantages for electrical insulation such as electric field distribution, insulation
              Hybrid gas-insulation system has many advantages for electrical insulation such as electric field distribution, insulation
           performance with presence of metallic particles.
           performance with presence of metallic particles.

                                                                                                                                               Single-core type                                               Triple-core type
                                                                                                             ○Reduction of maximum electric field strength in gas                       ●Maximum electric field is higher than that of single-core.
      Electric field distribution
                                                                                                             ○Uniformity of electric field distribution                                 ○Reduction of highly stressed part (area) of conductor
                                                                                                             ○Improvement of breakdown strength under clean condition (increase of allowable electric field)
                                                                           Insulation
                                                                                                             ○Little influence of degradation of solid insulator by electric field stress
                              characteristics under
                                                                                                             ○Improvement of insulation reliability by avoiding the attachment of metallic particle on conductor
                    clean condition & with
                                                                                                             ○The harmful effect of a conducting particle may be reduced because discharge in the gas does not cause sudden breakdown
                     metallic foreign object
                                                                                                             (short-circuit or earth fault).
                                                                                                             ● It is necessary to consider triple junction like the                     ○The support points do not constitute weak points in the
                                                                            Spacer
                                                                                                             conventional apparatus                                                     insulation.
                                Conductor joint                                                              ●It is necessary to consider insulation performance for the interface of solid insulator.
      Construction                                                                                                                                                                      ○Flexibility of subconductor
(○: advantage,●: Problem)


                                                                                                                                    Future development of hybrid gas-insulation system
                                                                                                                                    Future development of hybrid gas-insulation system
                                  By applying the hybrid gas insulation system, a conventional SF -gas-insulated apparatus may be replaced with a natural-
                                 By applying the hybrid gas insulation system, a conventional SF66-gas-insulated apparatus may be replaced with a natural-
                              gas-insulated one without a considerable increase in cross-sectional size. To develop an environmentally-compatible gas-
                               gas-insulated one without a considerable increase in cross-sectional size. To develop an environmentally-compatible gas-
                              insulated apparatus using the hybrid gas-insulation system, we are carrying on research on the following problems, and we
                               insulated apparatus using the hybrid gas-insulation system, we are carrying on research on the following problems, and we
                              aim at the proposition of the basic specification.
                               aim at the proposition of the basic specification.
                              (1) Insulation design
                               (1) Insulation design
                              (2) Thermal design
                               (2) Thermal design
                              (3) Technology of conductor joint and conductor support
                               (3) Technology of conductor joint and conductor support
                              (4) Estimation of basic specification
                               (4) Estimation of basic specification
                              (5) Estimation of life cycle cost and life cycle assessment
                               (5) Estimation of life cycle cost and life cycle assessment
    Element Technologies
    for All-solid Insulated Substation
       Background
  Electric power equipment which has been introduced in large quantities during period high
economic growth must be replaced in the near future, due to exceeding their designed lifetime,
30 years generally. For the power equipment introduced in the future, more exquisite
consideration of the environmental aspect than that for the conventional equipment is required.
Insulating oils and SF6 gas are used as an effective insulation medium broadly, but rigorous
management is necessary from the aspect of the fire disaster prevention and global warming. In
contrast, for a solid insulation medium, there is no environmental load by leakage and no fear of
fire accident.
  We aim at the development of the next-generation substation which makes the best use of
solid insulation medium. We mainly investigate the element technologies in order to realize its
maintenance-freeness, intelligence, unitization as well as improvement of environmental
influence..

    Principal results
(1) Proposal of an all-solid insulated transformer
     We have proposed the following items for realization prospect of an all-solid insulated
   transformer with large capacity.
  (a) Improvement of heat dispersion radiation characteristics by adoption of the vertical
      windings.
  (b) Adoption of an electrical insulating materials with fillers with high thermal conductivity.
(2) Proposal of a compact all-solid insulated connection system
     A flexible connection system is required to connect each power equipment in order to make
   high flexibility in a layout of power equipment and minimize total setting space. We have
   proposed a all-solid insulated connection system which has compact connection system,
   "Hyper Connector" and a cable section with high flexibility.




 Future Developments
 We will improve the design and evaluation methods of the all-solid insulated substation, and
promote the investigations in extending the developed designing techniques to the ultra-high-
voltage class substation as well as the distribution substation.
                            Transformer
                            Transformer
            Winding insulation Windings
                  巻線絶縁 巻線
                                         ・・・                                                                                                  Shape effect of coil windings (conventional and proposing
                                                                                                                                               Shape effect of coil windings (conventional and proposing
                                                                                                                                                                     vertical type)
                                                                                                                                                                     vertical type)
                                         ・・・
                                                                                                                                                Compared to the conventional windings (left side), the




                                                                                                        ・・・
                                                                                                                                                 Compared to the conventional windings (left side), the
                                                                                                                                              vertical windings (right side), which we have been
                                                                                                                                               vertical windings (right side), which we have been
                                                                                                                                              proposing, have a flat inner thermal gradient due to
                                         ・・・




                                                                                     巻線 巻線絶縁
                                                                                   Windings Winding insulation                                 proposing, have a flat inner thermal gradient due to
            Main主絶縁 層間絶縁
                insulation Layer insulation                                主絶縁                                                                elimination of the electrical insulation layer between
                                                                     Main insulation
                                                                                                                                               elimination of the electrical insulation layer between
                                         ・・・
                                                                                      Temperature difference
                                                                                      温度差                                                     windings that would be a large heat resistance. This
                                                                                                                                               windings that would be a large heat resistance. This
                                                                    Temperature
  Temperature




                                                                                                                                              lowers the maximum inner temperature.
                                                                                                                                               lowers the maximum inner temperature.
     温度




                                                                       温度




                                         位置
                                        Position                                                    位置
                                                                                                   Position
                                    (a) 従来型コイル
                            (a) Conventional coil windings                                   (b)縦型コイル
                                                                                   (b) Vertical type coil windings
                                                                                  半径方向の大きな熱絶縁となる
                                                                                  Having no electrical insulation
                                                                                  巻線間の電気絶縁層が無い
                                                                                    layer between windings

                                   Design temperature : 135 °C at windings

                                               This area shows the possible
                                                condition to design the all-
                                                                                                        Filling material in a epoxy resin
                                                solid insulated transformer.
                                                                                                                               Filling rate                                               Effect of filler
                                                                                                                                                                                          Effect of filler
Heat conductivity [W/m/K]




                                                                                                               Kind
                                                                                                                                (vol. %)                               We confirmed that adequate filling materials with
                                                                                                                                                                        We confirmed that adequate filling materials with
                                                                                                              No filler
                                                                                               ×
                                                                                                        (Epoxy resin itself)
                                                                                                                                     0                               high thermal conductivity such as Aluminum Nitride
                                                                                                                                                                      high thermal conductivity such as Aluminum Nitride
                                                                                              ▲
                                                                                                         fructured particle
                                                                                                                                   42.5                              (AlN) improves the heat dispersion characteristics of
                                                                                                                                                                      (AlN) improves the heat dispersion characteristics of
                                                                                                        (Commercial base)
                                                                                                       Spheroidized particle
                                                                                                                                                                     an epoxy resin. We confirmed that obtained results
                                                                                                                                                                      an epoxy resin. We confirmed that obtained results
                                                                                              ■                                     35
                                                                                                        (Commercial base)                                            fulfill the required specification for the all-solid
                                                                                                                                                                      fulfill the required specification for the all-solid
                                                                                              ●         Composite particles        40                                insulated transformer.
                                                                                                                                                                      insulated transformer.
                                                                                            Note: Plots show each estimated values at 135 ℃.




                                        AC breakdown stress
                                    for 0.5mmt specimen [kV/mm]


                                                                                                                                                                             300
                            Connection system (Hyper Connector)
                                                                                                                                                                             250
                                                                                                                                                 Im . b k o n v lta e [k ]
                                                                                                                                                   p rea d w o g V




                                        45mm                                                                   45mm                                                          200


                                                                                                                                                                             150

                                                                                                                                                                                            Mountain shape
                                                                                                                                                                             100
                                                                                                                                                                                            Wavy shape
                                                                                                                                                                                       ※ Plots with allow show that the
                                                                                                                                                                             50
                                                                                                                                                                                       breakdown occur at the bulk part of

                                                                                                                                                                              0
                                   (a) Mountain shape                                            (b) Wavy shape                                                                    0    1      2      3    4    5            6   7
                                                                                                                                                                                                   Specimen number

                            Outer view of the Hyper Connector (prototype)
                            Outer view of the Hyper Connector (prototype)                                                                Impulse breakdown voltage of the prototype Hyper Connector

                                                         Connection interface shape of Hyper Connector
                                                          Connection interface shape of Hyper Connector
                             We made prototype Hyper Connectors having two interface shapes, (a) mountain shape and (b) wavy shape,
                              We made prototype Hyper Connectors having two interface shapes, (a) mountain shape and (b) wavy shape,
                            which were subjected to impulse breakdown test. As a result, mountain shape could withstand higher voltage
                            which were subjected to impulse breakdown test. As a result, mountain shape could withstand higher voltage
                            which was confirmed from the electric field calculation along the interface which showed that the maximum
                            which was confirmed from the electric field calculation along the interface which showed that the maximum
                            stress of the mountain shape was lower than that of the wavy shape.
                            stress of the mountain shape was lower than that of the wavy shape.


                                                            400                                                                                                        Trial design of the Hyper Connector
                                                                                                                                                                       Trial design of the Hyper Connector
                                                                                     φ350                                                 The Hyper Connector has following features;
                                                                                                                                           The Hyper Connector has following features;
                                                                                                                                        (a) Shrinkage of longitudinal length by bent interface.
                                                                                                                                         (a) Shrinkage of longitudinal length by bent interface.
                                                                                                                                        (b) Prevention of local stress enhancement by rounding
                                                                                                                                         (b) Prevention of local stress enhancement by rounding
                                                                                                                                        bent interface.
                                                                                                                                         bent interface.
                              Trial design of 275 kV class Hyper Connector                                                                We carried out the trial design of 275 kV class Hyper
                                                                                                                                           We carried out the trial design of 275 kV class Hyper
                                                                                                                                        Connector, and we confirmed that it could be realized
                                                                                                                                         Connector, and we confirmed that it could be realized
                                                                                                                                        with a size of 135 mm in electrical insulation thickness,
                                                                                                                                         with a size of 135 mm in electrical insulation thickness,
                                                                                                                                        400 mm in length, and 0.04m33 in volume.
                                                                                                                                         400 mm in length, and 0.04m in volume.
      Superconducting Power Apparatus

         Background
   Zero electrical resistance in superconducting wires appears under the critical temperature (Tc). When
 applied to electrical equipment, it is expected to realize higher efficiency, smaller size and weight.
 However, in the case of the use of superconducting wires in an AC system, AC losses of
 superconducting wires cause the decrease in efficiency of equipment and the increase of refrigerator
 power.
   The technologies such as the precise AC loss measurement, the reduction of AC losses, and the
 improvement of superconducting properties have been developed to use the superconducting wires in
 an AC system in CRIEPI so far.


      Principal results
   The highly precise AC loss measurement method of coils wound by metal superconducting wires has
 been established. Metal superconducting wire with lower AC loss than conventional copper wire has
 been developed. It was applied to a field winding of a superconducting generator, and verified to have
 no reduction of performance in practical conditions including the daily start and stop operation for 30
 years.
   In high-Tc superconductors, fundamental technologies for practical use have been established by a
 field test of a 500m long the high-Tc superconducting (HTS) cable. The R&D of a reactor type current
 limiter and a high-performance cylinder using a thick superconducting film have been carried out. A
 low-cost and high-speed fabrication technique of YBCO superconducting films has been developed. In
 the introduction of various superconducting equipment to the power system, the introduction effects
 such as the efficiency improvement and the transmission stability have been verified by analyses.
   CRIEPI participated in national projects such as the SMES project and the super-ACE project, and
 contributed to development promotion such as the SMES, the superconducting cable and the
 superconducting current limiter.


  Future Developments
   CRIEPI will promote the investigation of the introduction effects for superconducting current limiters,
 the investigation of the applicability of the YBCO film fabrication technique to manufacturing process,
 and R&D for realization of superconducting electrical equipment.
   In addition, CRIEPI will participate in national projects and cooperate in the development of various
 superconducting electrical equipment. CRIEPI will also investigate the possibility of industrial
 applications of superconductors and new technologies to resolve environment problems by the use of
 superconductors.
                                                                                2.5
               Evaluation of AC loss of HTS cable
  To realize superconducting power equipment, it is important                    2
to evaluate the AC loss of superconductor. So we have
                                                                AC Loss (W/m)




measured the AC loss of superconductor cable.                                   1.5
  HTS power cable will be used under variable conditions, for
example various temperatures and load current, so it was                         1
difficult to evaluate the AC loss of HTS cable exactly. We
have measured AC loss under various temperatures and                            0.5
current using a 3m long HTS cable, and assumed that AC
loss would be estimated from the temperature dependence of
                                                                                 0
the critical current.                                                                 0     0.2         0.4         0.6        0.8          1      1.2
                                                                                          Normalized Transport Current by Critical Current It/Ic

                                                                                            Red:70.7K,Green:73.2K,Blue:73.5K
                                                                                               (Temperature at upper side)
                                        Field test of 500m long HTS cable
    The world’s first 500m-long HTS cable (upper photo) is a race track shape, which includes a 10m high
  rising and falling section simulating a bridge section over a river and an offset section for absorbing the
  thermal contraction and expansion. The field test of this cable was carried out during approximately one
  year. Fundamental technologies for a practical use have been established by stationary running test, a
  load changing test, and a critical limiting test in a power failure or a refrigerator failure.


                                                           Development of reactor type fault current limiter
                                                       A magnetic shielding type superconducting fault current
                                                     limiter (SFCL) has a simple structure, which put a coil
                                                     outside a superconducting cylinder. A large-scale
                                                     superconducting cylinder made by a Bi-2223 thick film
                                                     with a diameter of 450mm has been developed to apply to
                                                     this type SFCL. The development of the 60kV-class SFCL
                                                     is carried out by using this superconducting cylinder.

                                                     Photo: The Bi-2223 thick film on MgO cylinder



          Fabrication technique of the YBCO films
  Deposition and crystallization for the YBCO film
fabrication are successfully separated into each ways by
the use of fluoride as a part of starting materials. The
deposition without crystallization can be high-speed. The
heat treatment in a low pressure can be more easily
reacted than the conventional heat treatment. As a result,
the fabrication speed will be faster than the target value
of 5m/hr as an industrial fabrication speed.

Photo: A high-speed and dry fabrication system of the Y-
based superconducting films




                                            Improvement of critical current densities of YBCO thin films
                                      The introduction of artificial pinning centers (APCs) into YBCO films to
                                    improve the critical current density under a magnetic field have been
                                    studied. The APCs have a function to fix fluxoide in a superconducting film.
                                    The optimum structure of APCs can be clarified by investigation of
                                    microstructures of superconducting films introduced APCs.

                                    Photo: A microstructure of the superconducting films introduced nanorods
                                    as APCs.
     Preventive Technology against Lightning Damage

        Background
   Lightning is a main cause of faults in electric power systems. Lightning is also a main cause
 of damage and malfunction in information and telecommunication systems and home
 electronics, as these sophisticated apparatus have become popular items in the advanced
 society under information and communication technologies.
   CRIEPI has carried out a wide range of studies such as observation of lightning phenomena,
 test of lightning surge, and analysis of lightning surge phenomena. CRIEPI has also studied the
 preventive measures against lightning damage.


     Principal results
   To have a detailed knowledge of the characteristics of lightning phenomena is essential to
 prevent lightning damage. CRIEPI has developed various automatic observation systems for
 lightning phenomena (Fig.1), and elucidated the lightning characteristics in many local areas of
 Japan with other institutions including the electric power utilities.
   Furthermore, for preventing lightning damage, CRIEPI has conducted both experimental and
 theoretical studies (Fig.2), and proposed preventive measures and verified them. The
 effectiveness of these preventive measures for the electric power systems is compiled in
 three guidebooks for lightning-proof design (Fig.3).


 Future Developments
   CRIEPI will engage in advanced studies for
 protecting the energy-generating facilities using
 natural resources such as wind, as well as
 computer       systems,       information    and
 communication systems and control systems,
 from lightning damages. Moreover, CRIEPI will
 propose the lightning-proof design of higher
 effectiveness at lower costs.
                                                         Fig. 1. An example of observed result of
                                                                   winter lightning stroke

                           6.6kV-Lines


       Power Lines




                        Telecommunication Lines




                                                         Fig. 3. Lightning protection design guides for
Fig. 2. Test facilities of low voltage control circuit
                                                                electric power systems
Our research activities of lightning preventive technologies

                                                      Frame photograph




                                a) Still photograph


                                b) Leader developing process




                                        Current


                ALPS and observed results of upward leader
(ALPS: Automatic Lightning-discharge Progressing-feature observation System)




               Summer                                                Winter

  Lightning density map obtained from lightning location system (Times/year)




   Program for estimation of Lightning outage rates on transmission lines
    Evaluation Method of Electromagnetic Environment

       Background
  Demands for stable and safe electricity are increasing due to the recent development of the
information society and diversification of electric power sources, such as dispersed power
systems. To meet such demands, evaluation methods of electromagnetic environments are
being developed. The research subjects include: radiated emission in the frequency region of
wireless LAN, instantaneous voltage drop, and biological effect of magnetic field, in addition to
established countermeasures for corona interference caused by ultra high voltage (UHV)
transmission lines.


    Principal results
(1) Reduction of corona interference of UHV transmission lines
    Optimal design reduced the necessary number of conductors of UHV conductor bundle by
  20% based on experiments using a corona cage at Shiobara Testing Yard and a UHV testing
  line at Akagi Research Center. Recently, a novel method to effectively reduce corona
  discharges by reforming surface of conductor by oxidized titanium is being studied.
(2) Establishment of evaluation method of radiated emissions
    An evaluation method of radiated emission by dispersed power systems was established
  through experiments using a facility for evaluation of radiated emission at Akagi research
  center. The results are referenced in the action of revision of the Radio Law by Ministry of
  Internal Affairs and Communications.
(3) Research on biological effects of power frequency magnetic fields
    Methods for measurements, calculation and mitigation of magnetic fields generated by power
  facilities have been developed. In addition, a simple evaluation method of induced currents
  caused by human exposure to magnetic field is being developed.




 Corona discharges on conductor surface                Corona cage at Shiobara Testing Yard
                                                          Z (cm)
   Facility for evaluation of radiated emission
      (Example of utilities interconnection)


            Radiated emission (red)
                                          AM radio




                                                                         X (cm)

                                                               Current distribution in Japanese
                                                               human     model     induced     by
                                                               exposure to magnetic field.
           background noise(blue)                               The model contains 8 million
                                                               voxels with 2 mm resolution, and
                                                               simulates 50 tissues.
                                                                The figure shows the case for
                                                               coronal exposure to uniform
                                                               magnetic field (0.1 mT, 50 Hz).
                     Frequency(MHz)

Radiated emission generated by inverter circuit




Future Developments
  Evaluation methods of electromagnetic environment are being developed for electric power
facilities to be acceptable in the civil society.

(1) Low-corona conductor will be developed by surface modification, and its applicability for
   practical use will be evaluated.
(2) Interference of the radiated emissions to electronic devices and telecommunication
   systems will be clarified by experiments, and the estimation method of the interference
   will be developed.
(3) Contribution to government Ministries and utilities will be made with obtained knowledge.
    Analytical Tools for Transient Phenomenon and
    Electromagnetic Field

      Background
  Lightning is one of the main causes behind accidents involving power equipment. Once
lightning strikes electric towers, power lines or buildings, the large current of the lightning
propagates along the equipment themselves, transmission lines, and sometimes even the
ground, and is finally discharged to the earth while generating a transient electromagnetic field.
In addition, as the information society develops, the number of incidents of damage to
surrounding electric machinery, such as computers, communication devices, and electric home
appliances, as a result of lighting surges, is increasing.
  To avoid lightning damage, it is important to simulate where the current from lightning that
strikes electric towers or buildings flows and where and what kind of electromagnetic field it
produces during the flow. However, it is impossible to accurately analyze the voltage caused
by the lightning current (lightning surge) by conventional analytical methods, which frequently
require the use of approximation. Therefore, numerical electromagnetic analysis methods to
accurately treat electromagnetic phenomena are required.
  Furthermore, power-electronics apparatus will be massively used for the efficient integration
of renewable-energy and energy-storage apparatus into power systems. Since next-
generation power-electronics apparatus will utilize very fast switching devices, conventional
simulation programs cannot give accurate results for simulations of such power circuits. Thus,
a new simulation method should be developed.




    Principal results
(1)Analytical program of electromagnetic field, VSTL
  We developed a program, Virtual Surge Test Lab (VSTL) based on finite difference time
domain method, which enables us to analyze the transient electromagnetic field that is
produced when lightning strikes transmission towers or buildings (Fig. 1).
(2) Analytical program of electromagnetic field, PFIT
  We developed a Parallel Finite Integral electromagnetic Transient program (PFIT) based on
finite integral method. By PFIT, it is possible to analyze the transient grounding resistance
of mesh electrodes, which are frequently used to be as grounding electrodes of electric
equipment and buildings (Fig. 2).
(3) Electromagnetic transient analysis program for power systems, XTAP
  We have developed a simulation program called XTAP (eXpandable Transient Analysis
Program) for electromagnetic transient analysis of power systems. The program can give
accurate simulation results for circuits including many switching devices (Fig. 3).




Future Developments
  We will elaborate each analytical metho andl improve the graphic user interface to increase
its user friendliness.
                                                                      Current injection wire
                                                                                                                           1
                         Upward current with polarity




                                                                                                  injection current [A]
                                                                                                                                              Simulation
                         inverse to that of injection current                                                                                 Measurement
                                                                                                                                                                                                      Measurement
                         (simulating return stroke current)                                                               0.5                                                                            result

                                      Pulse generator
                                                                                                                           0
                     Injection current (simulating                                                                          0                                10          20
                                                                                                                                                                   time [ns]
                                                                                                                                                                                        30

                     lightning current that flows
                                                                                                                                 Injection current waveform
                     into building)




                                                                                            2.1 m
                                                                                                                          Simulation of perfect-conductor
                         Simple model of building                                                                         ground surface                                                               Simulation
                             A simple model considering                                                                           A perfect-conductor ground                                             result
                                                               1.0 m
                             only columns and beams is 1.0 m                                                                      surface is assumed to
                             frequently used.           Copper plate                                                              simplify comparison
                                                                                                                                  between measurement and
                                                                                                                                  simulation.                                              Distribution of vertical
                                                                                                                                                                                          magnetic field inside model

                                                   Fig. 1 VSTL analysis of magnetic field in building

                                                                                                                           Mesh electrode composed of φ13 copper wires and buried at 0.5 m depth.                                  Impulse
      Mesh electrode buried                                                                                                current is injected at point A, where its potential and current are measured. The
           in ground                                                         Current
                                                                             auxiliary line                                value obtained by dividing the voltage by the current at each time point is defined as

                                                          Current injection point A                                        grounding resistance.                        There is general agreement in the current, voltage, and
                                                                                                                           grounding resistance between the experiment and analysis, excluding the initial
                                                                                                                           current during the rise time.

                   200                                                                                  10                                                   200                                                                   10
                                                                      Voltage [V]                                                                                                                           Voltage [V]
                   150                                                Resistance [ohm]                  7.5                                                  150                                                                   7.5
                                                                                                                                          Resistance [ohm]




                                                                                                                                                                                                            Resistance [ohm]
Resistance [ohm]




                                                                      Current [A]                                                                                                                           Current [A]
                                                                                                                                            Voltage [V]
  Voltage [V]




                                                                                                                            Current [A]




                                                                                                                                                                                                                                          Current [A]
                   100                                                                                  5                                                    100                                                                   5

                   50                                                                                   2.5                                                  50                                                                    2.5

                    0                                                                                   0                                                     0                                                                    0

                   -50                                                                                  -2.5                                                 -50                                                                   -2.5
                         0                0.5                 1           1.5                 2                                                                    0            0.5               1              1.5           2
                                                  Time [micro sec.]                                                                                                                     Time [micro sec.]

                                 1) Experimental result at point A                                                                                                             2) Analytical result at point A

                              Fig. 2 PFIT analysis of transient grounding resistance of mesh electrode


                                                                                                                                                                                                                   u-v voltage


                                 s1                  s3                 s5

                                                                                                                   各 30 Ω
                                                                                                                   30Ω each
                                      u
                                                10 mH                                  iu
                         150 V
                                                          v
                                                                  10 mH                        iv
                                                                             w
                                                                                     10 mH                                 iw
                                                                                                                                                                                 iu          iv        iw
                               s2                    s4                 s6




                             (a) Circuit simulated                                                                                                                       (b) Simulation result by XTAP
                                  Fig. 3 Simulation result of a three-phase PWM inverter circuit by XTAP.
    Arc Plasma Waste Treatment Technology

        Background
   Construction of a resource-circulating society is desired. An arc plasma heating technology can
melt waste by its high temperature to achieve volume reduction and detoxifying. Therefore, it is
possible to make efficient use of final disposal sites. For example, many local government have
introduced plasma melting facilities for municipal waste incineration ash in recent years.
  On the other hand, the arc plasma ignited under low-pressure atmosphere can remove metal
oxide film on the metal substrate without heavily damaging metal. CRIEPI has been studying (i)
Evaluation of application of arc plasma technology to radioactive waste melting treatment, (ii)
Detoxifying and recycling of asbestos waste, (iii) Removing technology of radioactive metal oxide
film of radioactive waste (Decontamination technology).


     Principal results
 (1) Evaluation of application to the melting technology with high volume reduction for low-
     level radioactive waste
      We clarified that arc plasma melting technology is applicable to melting treatment for low-
    level miscellaneous radioactive waste based on experimental results of leaching rates of
    radioactive nuclides from solidified products, and migration behavior of radioactive nuclides
    in melting. A series of these results contributed to progress in practical use of plasma
    melting treatment for low-level miscellaneous radioactive waste.

 (2) Detoxifying and recycling technology of asbestos waste
     Melting asbestos waste promises to offer rocky or glassy safe slag. We clarified that
   plasma melting technology can be applied to detoxifying various asbestos waste. In addition,
   slag after melting asbestos waste can be recycled as roadbed materials and fine aggregates
   for concrete effective.
 (3) Radioactive cobalt decontamination performance
     Test pieces with corrosion products film were made under the conditions simulating
   primary-coolant system of atomic power plant. We clarified that more that 90% of cobalt in
   the test pieces can be removed.

  Future Developments
     Surface decontamination technology for radioactive waste by low-pressure arc will be
    enhanced.

                                    Low-pressure arc
                                                                                 アーク
                                                                                 プラズマ
                                               Photos of low-pressure arc ignited with
                                               metal oxide film on metal substrate.
                   Anode                       ‘Cathode spots’ formed inside the low-
                             Low-pressure      pressure arc can move by themselves with
                                 arc           searching metal oxide film, therefore these
                                               cathode spots can remove metal oxide film
                                               selectively and quickly.
      Cathode spots        Metal oxide film
                                                Arc plasma melting technology

                                           Arc plasma
                                                                       Aspects of melting fly ash by arc plasma.
                                                                       Center region colored white is arc plasma with
                                                                       the temperature of more than 10,000℃.
                                 melting                               Orange colored region is melting fly ash with
                                 fly ash                               the temperature of around 1,550℃.




                                                                   melting                            ( rocky slag )



                                                                                                      ( glassy slag )
                                       Asbestos fibers
                   (1) Harmful asbestos fiber disappeared and became rocky or glassy slag by plasma melting.
                   (2)The slag satisfied the standard for sub-base course material by mixing crushed stone
                     with particle size under 5mm. It can achieve the same mechanical strength as natural
                     sand when used as aggregate for mortar.




                                            Surface decontamination technology
                                                                         Photographs of test pieces before and after
                                   写真
                                   Photos               photos
                                                    SEM 写真
                                                                         low-pressure arc treatment. Metal oxide film
                   処理前
                   Before




                                                                         formed under the conditions simulating
                                                                         primary-coolant system of atomic power plant
                                                                         was removed by low-pressure arc. Metallic
                                                                         luster can be observed after removing of black
                       処理後
                        After




                                                                         metal oxide film in left-hand photo. Grain
                                                                         boundary of crystal of corrosion products film
                                                                         disappeared in right-hand SEM photo.


                   100                                                              φ39            Low-pressure      arc was
                                                                                                   applied to pipe shaped test
Co removal ratio (%)




                         80
                                                                                                   pieces     with    corrosion
                                                                                                   products     film   including
                                                                                             100




                         60
                                                                                                   cobalt-60 on its inner
                         40                                                                        surface. Repetition of low-
                                           gas:argon                                               pressure arc treatment can
                                           pressure:40Pa
                                             ガス:アルゴン
                                                                             Pipe with             improve     the    cobalt-60
                         20                  圧力:40Pa
                                           arc currents:60A                  corrosion product     removal ratio, and finally
                                             アーク電流:60A
60




                            0                                                film including        more than 90% of Co-60
                             0    2     4 6  8    10          12             cobalt-60
                                                                                                   removal ratio was achieved.
                                      クーロン量(×104 C)4
                                 Electric charges (×10 C)
         Synthesis of Aluminum Nitride Nano-particles
         by Arc Plasma

             Background
      CRIEPI is now investigating all-solid insulating substation which is beneficial from
    environmental and disasters-preventing viewpoints. In order to develop solid insulating materials,
    the addition of large quantities of aluminum nitride (AlN) particles with high thermal conductivity
    to organic insulating materials was considered. Mixing nano-particles with large particles (a few
    microns particles) is a good way to achieve high ceramic particle content. However, the low
    production capacity of nano-particles makes it extremely expensive. Methods that utilize arc
    plasma have potential to raise the production rate because they allow plasma power to be
    upgraded with ease.

         Principal results
      Purified AlN nano-particles of 30nm in diameter were synthesized by injecting Al particles
    (20μm) into an arc plasma (Photos 1-3). For the purpose of raising the synthesizing rate of
    AlN nano-particles, the proper conditions of injecting Al particles (position, angle, gas velocity)
    were clarified, in which the Al particles were wholly evaporated.

     Future Developments
     The mass production technology of AlN nano particles will be developed. Furthermore, high-
   dispersed AlN nano particles will be synthesized so that the nano particles don’t agglomerate in
   the organic insulating material.


                                                                             State during experiment
                                                                             (Photo 2)
                                                                Arc
                                                                plasma       Al particles are evaporated in
                                                                             the arc plasma, and the Al
                                                                             vapor reacts with and is
                                                                             quenched by ammonia (NH3)
                                                                             gas that is blown downstream
                                                                Al vapor     from the arc plasma. As a
                                                                             result, AlN nano particles are
                                                                             synthesized. The AlN content
                                                                             increases (>99%) by passing
                                                                             the synthesized nano-particles
                                                                             through ethanol.




                                                                               Synthesized nano
                                                                               particles (Photo 3)
                                                                              The AlN nano-particles of 20-
 Experimental setup (Photo 1)                                                 30nm     in   diameter    are
Long arc plasma (max. 300mm) can be                                           synthesized. The AlN content
generated, therefore the raw particles injected                               is more than 99%.
into the arc plasma can be wholly evaporated.
The kinds of reacting/quenching gas can be                          20nm
changed. Hence, nano-particles other than
AlN can be synthesized in principle.
        Thermal conductivity of insulating material
        Thermal conductivity of insulating material                                                                         Image of high particle content
                                                                                                                             Image of high particle content

                                Organic                         Inorganic                   A few microns particle                             Nano particle
 Material                           Epoxy         SiO2          Al2O3          AlN

 Thermal
conductivity                         0.2          1~5          5~10          100~200
  [W/m/K]

   At present, epoxy resin mixed with SiO22 (silica) or
    At present, epoxy resin mixed with SiO (silica) or
   Al22O33 (alumina) is usually used as solid insulating
    Al O (alumina) is usually used as solid insulating                                     In order to develop solid insulating material with
                                                                                            In order to develop solid insulating material with
   material for electrical equipment that requires high
    material for electrical equipment that requires high                                   high thermal conductivity, it is necessary to add
                                                                                            high thermal conductivity, it is necessary to add
   thermal conductivity. The power of electrical
    thermal conductivity. The power of electrical                                          large quantities of AlN particles to epoxy resin.
                                                                                            large quantities of AlN particles to epoxy resin.
   equipment for all-solid substation that CRIEPI
    equipment for all-solid substation that CRIEPI                                         Mixing a small-grained particle with a large-
                                                                                            Mixing a small-grained particle with a large-
   investigates is so high that the solid insulating
    investigates is so high that the solid insulating                                      grained particle is considered to be a good way of
                                                                                            grained particle is considered to be a good way of
   material requires higher thermal conductivity.
    material requires higher thermal conductivity.                                         achieving a high particle content. Commercially
                                                                                            achieving a high particle content. Commercially
   Therefore, CRIEPI investigates using AlN particles
    Therefore, CRIEPI investigates using AlN particles                                     available AlN particle has a size of a few microns,
                                                                                            available AlN particle has a size of a few microns,
   as fillers of epoxy resin.
    as fillers of epoxy resin.                                                             therefore AlN nano particle is required as a small-
                                                                                            therefore AlN nano particle is required as a small-
                                                                                           grained particle.
                                                                                            grained particle.



                 Conditions of synthesizing purified AlN
                 Conditions of synthesizing purified AlN                               Results of numerical analysis on evaporation
                                                                                       Results of numerical analysis on evaporation
                 nano particles
                 nano particles                                                        behavior of Al particle under chosen conditions
                                                                                       behavior of Al particle under chosen conditions

                     100
                                                                                                                     Distance from the torch axis
      AlN content [%wt.]




                           80   Torch gas                                                                                                Plasma
                                                                                                                                            torch
                                                                                              Distance from the torch tip




                           60
                                                                                                                                        Injection of
                                                                                                                                        Al particle
                           40
                                                                                                                                  Temperature [K]
                                     Reacting/quenching gas
                           20                                                                                                        3,000
                                      * Plotted point: average of 2-4 data
                                      * Error bar: max-min                                                                           7,000         is the region where
                           0                                                                                                                   temperature of Al particle
                                0     20 40 60 80 100                                                                                11,000    reaches its boiling point.
                                    NH3 content in gas [%vol.]
                                                   (mixed with N2 gas)

  Chemical equilibrium composition calculations and
   Chemical equilibrium composition calculations and                                     Numerical analysis clarified temperature and
                                                                                          Numerical analysis clarified temperature and
  experiments were carried out, in which the kinds of
   experiments were carried out, in which the kinds of                                   velocity in the arc plasma and evaporation
                                                                                          velocity in the arc plasma and evaporation
  gases of “Torch gas” (for generating arc plasma) and
   gases of “Torch gas” (for generating arc plasma) and                                  behavior of Al particle in the arc plasma. Proper
                                                                                          behavior of Al particle in the arc plasma. Proper
  “Reacting/quenching gas” (for blowing into Al vapor
   “Reacting/quenching gas” (for blowing into Al vapor                                   conditions of injecting Al particles (position, angle,
                                                                                          conditions of injecting Al particles (position, angle,
  downstream from the arc plasma) were changed. As a
   downstream from the arc plasma) were changed. As a                                    gas velocity) were chosen from the viewpoints of
                                                                                          gas velocity) were chosen from the viewpoints of
  result, when N22 was used as the “Torch gas” and NH33
   result, when N was used as the “Torch gas” and NH                                     evaporation behavior of Al particles and thermal
                                                                                          evaporation behavior of Al particles and thermal
  was used as the “Reacting/quenching gas”, nano
   was used as the “Reacting/quenching gas”, nano                                        damage of injection port due to high temperature of
                                                                                          damage of injection port due to high temperature of
  particles of 90% in AlN content was synthesized (non-
   particles of 90% in AlN content was synthesized (non-                                 the arc plasma. The numerical analysis was
                                                                                          the arc plasma. The numerical analysis was
  reacted Al content in the synthesized particles was
   reacted Al content in the synthesized particles was                                   considered appropriate because the evaporation
                                                                                          considered appropriate because the evaporation
  10%). The AlN content in the synthesized particles
   10%). The AlN content in the synthesized particles                                    region of Al particle in an experiment agreed with
                                                                                          region of Al particle in an experiment agreed with
  increased (>99%) when the synthesized particles
   increased (>99%) when the synthesized particles                                       the calculation results approximately.
                                                                                          the calculation results approximately.
  passed thorough ethanol because the Al nano
   passed thorough ethanol because the Al nano
  particles reacted with the ethanol and were trapped.
   particles reacted with the ethanol and were trapped.
    Applied laser/photon diagnostics

       Background
  Laser technology enables non-contact and remote information acquisition, and is one of the
key technologies in lifetime evaluation of electric power equipment and in environment
monitoring system. We carry on developments of new diagnostics technology based on x-ray
generation using a ultra-short pulse laser (T3 Laser: Table Top Terawatt Laser) and laser radar
systems for atmospheric observation.

    Principal results
  Laser technologies for x-ray transmission inspection and remote measurement of aerosol
constituents using a laser which concentrates energy in a short time (50 femtoseconds), gas
leakage detection, power plant flue gas measurement, non-contact temperature measurement of
high temperature metal parts, and flaw detection of metal parts have been developed. For
environmental monitoring, a laser radar which can measure atmospheric SO2, NO2, and O3 with
the world’s highest sensitivity has been developed.

 Future Developments
  New measurement diagnostics technologies which will enable non-destructive, non-contact,
real time, remote measurement will be developed. These technologies are expected to
contribute to lifetime elongation and efficient operation of electrical power transmission and
distribution equipment, thermal power generation equipment, and nuclear power generation
equipment. These technologies will also be applied to environmental monitoring and contribute to
solution of environmental problems.
                                                                    T3 laser system
                                                      This system can emit ultra-high intensity laser
                                                     beam with only 1Joule energy because of the
                                                     ultra-short pulse duration (50fs) .


                                                           X-ray generation using T3 laser
                                                      Focus irradiation of ultra-high intensity laser on
                                                     a copper film generates high-temperature and
                                                     high-density plasma instantaneously. X-ray is
                                                     generated by electrons emitted from the plasma.
                                                     Since laser-plasma x-ray can be superior to an
                                                     x-ray tube or an isotope in small size, high
                                                     energy and high spatial-resolution, application to
                                                     precise radiographic testing in a narrow space is
                                                     expected.




Concept of x-ray generation using T3 laser             An example of x-ray imaging using the
                                                       laser-plasma x-ray (IC circuit)
                          Laser beam profile                                                Na fluorescence




                                                                   Intensity (Arb. Units)
                                    Filaments                                                                Saltwater
                                                                                                             aerosol




                                                                                                                Reference light
                                      Laser beam
                                                                                             580      590         600         610
                                                                                                     Wavelength (nm)

   Filament propagation and laser beam profile               Spectra of Na fluorescence from saltwater aerosols

   Remote measurement of constituents of microparticles in air by laser-induced breakdown spectroscopy
Propagation of an ultrashort high-intensity laser pulse in the atmosphere produces a bundle of filaments, which can
propagate with focused condition for a long distance. We demonstrated remote measurement of Na fluorescence from
artificial saltwater aerosols in air at a distance of 16 m by laser-induced breakdown spectroscopy (LIBS) using filaments.
This technology is useful for identification of the constituents of atmospheric aerosols and diagnostics of equipments.


                                                                                                       Remote leak gas detection
                                                                                                        using Raman scattering
                                                                                                     When laser light is irradiated on
                                                                                                     gas, Raman scattering light,
                                                                                                     whose wavelength depends on
                                                                                                     the type of gas, is generated. By
                                                                                                     spectral analysis of Raman
                                                                                                     scattering light, the gas can be
                                                                                                     identified. This technology is
                                                                                                     useful for remote detection of
                                                                                                     gas leaks in industrial plants.

                                                                                                            Flue gas measurement
                                                                                                     Measuring SO3 concentration in
                                                                                                     flue gas in thermal power plants is
                                                                                                     important for their efficient
                                                                                                     operation. A method for high
                                                                                                     resolution measurement of SO3
                                                                                                     concentration using conversion of
                                                                                                     SO3 to SO2 was developed.


                                                                                                        Non-contact temperature
                                                                                                          measurement of high
                                                                                                        temperature metal parts
                                                                                                     Internal temperature of metal parts
                                                                                                     can be measured by measurement
                                                                                                     of propagation speed of ultrasonic
                                                                                                     waves, which can be generated and
                                                                                                     detected using       lasers. This
                                                                                                     technology can be used for non-
                                                                                                     contact measurement of rotating
                                                                                                     parts under high temperature, and
                                                                                                     can also be applied to flaw
                                                                                                     detection.
   High Power Testing Laboratory


     Laboratory Accredited to ISO/IEC17025
 High Power Testing Laboratory (HPTL) of Electric Power Engineering Research Laboratory,
CRIEPI got the accredited High Power Testing Laboratory in Japan based on ISO/IEC guide25
on Dec., 2001, and ISO/IEC 17025 on Dec., 2002 by JAB (The Japan Accreditation Board for
Conformity Assessment).

  The high power test facilities were originally
installed in the High Voltage Power Laboratory
Foundation Inc., Yokosuka (at present Electric
Power Engineering Research Laboratory, CRIEPI) in
1963. In 1994, a short-circuit generator was
renewed and a DC short-circuit test facility and an
indoor test cell with a soundproofing were installed.


    Accreditation Tests
Making and breaking test of switchgear
・Short-circuit tests and out-of-phase making and breaking tests for circuit-breaker
(Test capacity: up to rated voltage of 36kV, up to rated short-circuit breaking current of
25kA)
Test excluding making and breaking tests for switchgear
・ Short-time withstand current and peak withstand current tests for circuit-breaker,
disconnector and earthing switch, load switch, switch-board, gas insulated switchgear,
Instrument transformer, common standard.
(Test capacity: Current up to 150kA, duration up to 1 sec./ Current up to 60kA, duration up
to 2 sec.)
・ Short-circuit tests for power transformer, surge arrester and current-limiting fuse
(Test capacity: depending on test item and object)



       General Tests
High power arc tests (AC/DC)                            Short-time current tests (AC/DC)
・Insulator                                              ・Insulator assembly
・Insulator assembly                                     ・Cable
・Switchgear                                             ・Cable assembly
・Cable                                                  ・Transformer
・Cable assembly                                         ・Other equipment
・Transformer

Synthetic test, etc.
・Synthetic test for circuit-breaker
・Duty test for surge arrester
    Shiobara Testing Yard

  Shiobara testing yard was established in 1961 to develop 500 kV class AC transmission lines.
Since then, intensive researches on corona effects and on electrostatic induction below the
line had been conducted by using the test line. Also 10 MV impulse generator, which was the
largest in the world, had been used for the research on the insulation design. The study for
protecting facilities against lightning strokes was continued.
  In 1970, the test line and the power source were modified for developing DC transmission
lines and the research on the corona effect of DC lines was started.
 In 1982, 12 MV impulse generator and UHV DC test line were installed fir developing AC and
DC UHV transmission lines. Results of the research have been reflected on the design of the
UHV transmission line.
  Now, studies are going on to prevent damage from lightning strokes for power transmission
line and distribution line and to improve electrical environment.




                                                                                   Experiment on lightning protection of
                                                                                   distribution lines


  12 MV impulse generator                 Experiment on artificial
                                          lightning using 12 MV-IG

                                                                     Width : 61m
                                                      Hight : 76m




          Distribution line
                                                                                                            246m
                                                                                         Test line


                                                                                          310m



                                                                     194m




                                                    10 MV impulse generator
      Corona cage             Measuring room
         URL:http://criepi.denken.or.jp/




Access