A Broadband Wide Area Network as an Enabler of by xvi11400



       A Broadband Wide Area Network as an Enabler
          of Improved Power System Maintenance
                          L. Nordström, Student Member, IEEE, and G. N. Ericsson, Member, IEEE1

    Abstract– Wide Area Networks are being deployed worldwide              tions with a broadband utility WAN as an enabler for im-
at power utilities. By replacing vintage narrowband solutions,             proved maintenance.
broadband communications can now be used for an entire utility                The paper starts in Section II with a classification of data
enterprise. One new possibility that has opened up is to improve
                                                                           communication, based on [2]. In Section III, a brief introduc-
power system maintenance. During the last ten years, the benefits
of adequate asset management have become increasingly clear in             tion to some key maintenance concepts is given. In
the power industry, due to the economic pressures and the aging            Section IV, the paper continues with an analysis of the areas
infrastructure.                                                            of improvement, in which IT-systems used in conjunction
    An apparent tool to improve the asset management strategies            with efficient broadband communication could improve power
is the implementation of IT-systems that support the operational           system maintenance. The paper ends with concluding remarks
processes. The impact of these systems can be further enhanced             and suggested further research works in Section V.
by efficient communications allowing the proliferation of func-
tionality and data access.                                                 B. Survey on IT-support for Power System Maintenance
    This paper describes the initial stages in analyzing the com-             The input to the research regarding IT-systems for Power
bined effects of enhanced communication and maintenance re-
quirements. It provides a useful maintenance categorization,
                                                                           system Maintenance stems from a survey that was conducted
based on empirical data. Also, areas of improvement for power              during the fall of 2003 in Sweden. The layout of the survey as
system maintenance are elucidated together with the benefit of             well as its results has been reported on in [9]. The survey in-
enhanced communications.                                                   cluded nine power distribution utilities, one hydropower com-
                                                                           pany, and two pulp and paper mills. The basic idea behind the
   Index Terms—Asset management, Broadband communica-                      survey was to get an indication if there are differences in use
tion, Communication, Power System Control, Power System                    of IT-support for asset management within different
Maintenance, SCADA system, Wide Area Network.                              industries. Such differences could include the level of IT use,
                                                                           integration of IT systems and overlap of functions. Secondly
                         I. INTRODUCTION                                   the purpose of the study was to investigate where the utilities
                                                                           were focusing their efforts to implement IT support for asset
T   HIS paper studies the interdependencies in development
    of two critical areas within Power Systems Engineering,
namely that of Power System Communication, see [1] and [2],

and Power System Maintenance, see [3], [4], and [5]. The                          II. CLASSIFICATION OF DATA COMMUNICATIONS
paper is based on two parallel efforts in these areas. Within                  Communication is and will increasingly be a necessary tool
Power system communications, the emergence of Broadband                    for the operation and maintenance of the power network, as
Wide Area (WAN) communication is enabling new operation                    well as for administrative purposes. Technically speaking,
and control as well as maintenance processes; see [2] and [6].             from being a limiting factor, the increasing communication
Power System Maintenance is at the same time undergoing                    capacity now provides possibilities for operating and main-
development as the industry is striving for improved cost-per-             taining the power network and related businesses in different
formance under re-regulation as well as optimization of life-              and more efficient ways. At the introduction of fiber optic so-
time of installed equipment; see [7] or [8].                               lutions, the narrow-band solutions (range of 100 bit/s) are be-
A. Purpose, Outline of the paper                                           ing replaced by broadband communication highways (range of
                                                                           100 Mbit/s). Hence, a factor of 106 in difference. Such high-
   The purpose of this paper is to present new opportunities
                                                                           ways make it possible to build a Wide Area Network (WAN),
that appear when developments in the areas of power system
                                                                           providing high capacity facilities to/from office sites and sub-
communications and power system maintenance are studied in
conjunction. The main focus here is to elucidate the implica-
                                                                               But the new possibilities must be utilized in a structured
                                                                           and effective way. Focus should to a greater extent be on ana-
      L. Nordström is with Industrial Information and Control Systems,
Department of Electrical Engineering, KTH – Royal Inst of Technology,      lyzing communication needs and requirements, providing a
10044 Stockholm, SWEDEN (e-mail: lars.nordstrom@ics.kth.se).               basis for a technical design. Such analyses have been
   G. N. Ericsson is with Svenska Kraftnät (Swedish National Grid),        deployed at the Swedish National Grid. The different needs
P.O. Box 526, 16215 Vällingby, Sweden (e-mail: goran.n.ericsson@svk.se).
                                                                           and requirements have been classified into three different

main categories, reflecting the degree of importance of various       The communication is characterized by that interaction
communication needs [2]:                                           does not need to take place in real time. The time requirements
• Real-Time Operational communication requirements                 are moderate.
• Administrative Operational communication requirements               In addition to maintenance related communication, this
• Administrative communication requirements                        class contains, the following types of communication:
                                                                   • Maintenance Data
A. Real-Time Operational communication requirements
                                                                   • Fault localization
   Real-time operational communication encompasses com-            • Metering and transfer of settlement information
munication in real time that is required to maintain operation     • Security system
of the power system. The class is in turn divided into real-time   • Substation camera supervision
operational data communication and real-time operational
speech communication.                                              C. Administrative communication requirements
                                                                      Administrative communication includes voice communica-
   Real-time operational data communication encompasses:
                                                                   tion and facsimile within the company (also between the of-
• Teleprotection                                                   fices that are at different geographical locations) as well as
• Power System Control                                             to/from the company, where the communication has an ad-
   The communication is characterized by the fact that inter-
                                                                   ministrative purpose.
action must take place in real time, with hard time require-
ments. The communication requirements define the design of
                                                                                       III. POWER SYSTEM MAINTENANCE
the technical solutions.
   For teleprotection purposes, messages should be                 A. General Background
transmitted within a very short time frame. Maximum allowed           The task of maintaining a complex industrial system, such
time is in the range of 12-20 ms, depending on the type of         as a power grid, requires some form of systematic approach.
protection scheme. The requirement has its origin in the fact      In real life, as well as in theory, a number of such approaches
that fault current disconnection shall function within             are apparent. For example, the European Standard EN
approximately 100 ms.                                              13306:2001 [10] describes maintenance as illustrated in
   Power System Control mainly includes supervisory control        Figure 1.
of the power process on secondary or higher levels. These
systems are of the kind SCADA/EMS (Supervisory Control                                              Maintenance
And Data Acquisition/Energy Management System).
Measured values must not be older than 15 seconds, when
arriving at the control center. Breaker information shall arrive
                                                                                Preventive                            Corrective
no later than 2 seconds after the event has occurred.                           Maintenance                          Maintenance
   Real-time operational voice communication encompasses
traditional telephony; where voice communication has an op-
erational purpose, e.g., trouble shooting in a disturbed power       Condition Based     Predetermined        Deferred        Immediate
                                                                      Maintenance         Maintenance        Maintenance      Maintenance
operational case, power system island operations. The actual
possibility of having voice communication is, by the control
center staff, considered as one of the most important tools,       Figure 1. Breakdown of Maintenance into different types, dependent on when
both in normal and abnormal operation cases. Real-time op-         and why the activity is performed.

erational voice communication also includes facsimile for
switching sequence orders.                                            The main divider between the different types of Mainte-
   Also, the means of using electronic mail (e-mail) for trans-    nance is related to whether the maintenance activity is per-
fer of switching sequence orders is considered.                    formed before – in Preventive Maintenance (PM)– or after –
                                                                   Corrective Maintenance (CM) – a fault occurs. These two
B. Administrative Operational communication requirements           main types are then further divided into sub categories. De-
   In addition to real-time operational communication, infor-      pending on the terminology used, and the industry in which
mation is needed that, in more detail and afterwards, support      the terms are applied, this division of maintenance can be
description of what has happened in minor and major power          further elaborated on.
system disturbances. This class is referred to as administrative      The simplistic view on the maintenance approaches is to
operational communication. This is the class of communica-         prefer PM to CM, by this minimizing the number of faults.
tion that is of interest in this study. Maintenance data,          However, preventive maintenance solely is not only utopian,
although critical to reliable operation of the power network is    in that all faults cannot be prevented; it is also not desirable
not time critical. Examples of communication needs in this         due to the high costs involved. The real case is more
class are interactions with local event recorders, disturbance     complicated. For example, corrective maintenance may be
recorders, and power swing recorders, all usable as input to       more cost effective when the severity of the consequences of a
e.g. maintenance planning.                                         fault is low. The choice of maintenance approach is

determined by the continuous process of Maintenance                  graphic Information System (GIS). Documentation in a GIS
Management at the utility.                                           based platform has the obvious advantage of providing ease of
                                                                     access to the location of equipment, cables and overhead lines
              IV. IT SUPPORT FOR MAINTENANCE                         when access to the equipment is needed. It is also a matter of
    Clearly, the maintenance process can benefit from support        personal safety that high-voltage underground cables can be
from information systems. Computerized Maintenance Man-              pinpointed with high accuracy. However generally speaking,
agement Systems (CMMS) have a long tradition in many in-             there is room for improvement for Asset Documentation in
dustries. For example, such CMMS contain functionality for           two areas: data quality and data depth.
inventory and resource management, plant documentation and                  a) Data Quality
fault statistics; see [11] for an overview of functionality. Obvi-       The data quality issue is the historical concern of whether
ously these Information Systems are dependent on communi-            the data in the systems really represents a true image of the
cations networks to interact with the systems controlling the        grid. For the low-voltage section of a power grid, there is sel-
power grid and also to some extent the grid itself in terms of       dom any remote control, and thereby no automatic detection
the protection equipment.                                            of equipment status. Surprisingly often is the low-voltage
    The tradition of IT support for Maintenance is not as estab-     section of a utility documented by means of pen, paper, and
lished within the power industry as in other industries, e.g.,       needles on a map, with obvious consequences for data quality.
manufacturing or process industry. The survey [9] showed             The data quality issue is further complicated by the low IT
that, in the pulp & paper mills had achieved a much tighter          usage in the field by maintenance and repair crews.
integration of their Asset Management IT systems, one had                   b) Data depth
implemented a comprehensive CMMS and the other was in                    By data depth we mean the level of information of the asset
the process of implementing it. On the other hand none of the        in the database beyond merely its location. The historical use
surveyed utilities utilized a comprehensive CMMS in support          of GIS systems for asset documentation have led to a situation
of maintenance operation and planning. Instead, at the utilities     where documentation is lacking in detail with regards to both
a large collection of systems was used, ranging from office          static data such as manufacturer, age, and product specifica-
packages, e.g., Microsoft Excel and Access, to components            tions, as well as to dynamic data, such as latest overhaul,
from large scale business platforms, such as SAP R/3.                common faults, and connected customers.
    Common for all utilities was that at the center of the Asset        2) Implications of a Broadband WAN
Management tools was a Geographic Information System                     For Asset Documentation both challenges of data depth
(GIS) to which components have been added as new needs               and quality can be addressed with improved communications.
have arisen. The integration between the GIS system and the          A broadband WAN extended to equipment in the field adds
other components range from e-mail and “cut & paste,” as             the possibility of automatically uploading configuration data
indicated above, to moderate levels of integration, such as          (of course dependent on capabilities of the local control
sharing databases.                                                   systems) thereby mitigating the data quality issue.
                                                                     Additionally, ample communications at substations enable
A. Areas of Improvement                                              field personnel to communicate with central systems more
   The survey indicated a relatively diverse focus when it           effectively, thereby enabling the update of asset information
comes to the utilities’ plans for improvement of the IT              when actually on site, instead of having to do so once back at
support. However, the efforts can be categorized in the              the office.
following areas of opportunity:                                      C. Resource Management
        • Asset Documentation
                                                                         The concept of Resource Management refers to the IT sup-
        • Resource Management
                                                                     port for budgeting and follow-up of use of resources, in terms
        • Production Management
                                                                     of expenditure and internal resources, such as vehicles, tools,
        • Workflow Management                                        spare parts, and personnel. This is of course a corporate wide
        • Maintenance Planning                                       task, but it is here focused only on the aspect of Asset Man-
   In the following sections the potential for improvement of        agement.
maintenance IT support is discussed with a focus on the impli-           A general concern regarding Resource Management at the
cations and possibilities created by a Broadband WAN.                utilities is the differentiation between daily operation and pro-
B. Asset Documentation                                               jects initiated by an investment in, for example, network ex-
   The concept of Asset Documentation refers to understand           pansion or major overhaul of a substation. A common ap-
IT support for documenting all aspects of the grid, plant, or        proach among the utilities is to assign standing project codes
facility being managed. This includes documentation of the           for daily activities such as inspections or minor repairs, and
geographic location of the equipment, its age, type, status,         log all costs to these codes. More ambitious methods involve
latest events, etc.                                                  work-orders with cost center codes even for minor repairs. For
   At the utilities, Asset Documentation is very much centered       the surveyed utilities, no method was found to be in majority.
on documentation of the electric power network in a Geo-             Consistently smaller utilities used less ambitious methods.
                                                                         A trend among the larger of the surveyed utilities was to

outsource functions such as inventory and field repairs to con-     quences of outages.
tractors. A rationale stated by all utilities that had outsourced      Documenting interruptions from a technical perspective has
all or parts of these functions, was to achieve better control of   a long tradition. However, the survey shows that technical or
resource usage and control of expenditures. Although, none          operational experiences are very seldom fed-back into the or-
could show any clear evidence of having achieved reductions,        ganization in a structured manner. Of course, individuals draw
since the concept was still new, most of the utilities reported a   their own conclusion and learn from mistakes in the past.
better visibility of costs. Outsourcing of inventory and field      However, on an organizational level, none of the utilities had
crews opens up the question of IT-support and ownership of          implemented IT support for collecting experiences from fail-
data and IT-systems for these functions. Regarding Inventory        ures. Such support can most easily be implemented by proper
management, the three utilities that had outsourced their in-       asset documentation and workflow support thereby enabling
ventory were also relying on the contractors’ IT support for        storage of data about events and actions taken and relating
managing the inventory and purchasing functions. For out-           them to objects in the network.
sourcing of field crews, the opposite solution had been                1) Implications of a Broadband WAN
chosen, where the one utility, which had completely                    Documentation of the operational experience of interrup-
outsourced their field repairs, managed the IT support itself       tions is clearly supported by improved WAN communication.
and let the contractor’s personnel report and work in that          Although, perhaps not used as part of resolving a fault, data
system.                                                             stored in local control systems at the substation level can be
   1) Implications of a Broadband WAN                               uploaded to provide after action analysis of faults. These,
    Efficient resource management is dependent on detailed in-      often large amounts of data are available only if the
formation on the utilization of resources, including staff,         communications network has the necessary capacity. By
equipment, and materials. Via a broadband, WAN resources            means of a broadband WAN, an analysis is enabled of large
in the field can communicate with a central system more             amounts of data from several distributed sources Also, the
effectively reporting status, and current activities, thereby       operational experiences can be much better documented.
providing the necessary detail for managing the resources
                                                                    E. Workflow management
efficiently. Additionally, third parties, such as maintenance
contractors, can be given access to local control systems via           The concept of Workflow Management refers to the IT
the WAN, thus enabling them to interact directly with local         support for managing the propagation of work tasks through
control systems.                                                    the organization. Typical examples are the chain of events that
                                                                    need to happen after a fault has been detected during an in-
D. Production Management                                            spection and some kind of repair needs to be done.
   The concept of Production Management refers to the IT                The survey showed that workflows within the maintenance
support used for tracking the quality of the delivered power,       and operations teams are very often managed manually, with
such as event reporting and outage management. This ties in         little or no IT tools used to guide the operation. This is true
closely with the role of SCADA systems used in operation of         both for planned activities as well as for event-based activities
the power network.                                                  such as responding to a reported power outage or other cus-
   Whereas SCADA systems are used to detect errors in the           tomer-experienced problem. Although all utilities had imple-
network and perform re-configurations to restore a failing grid     mented a project-planning tool, none used any workflow-sup-
to a stable state, IT systems for Production Management are         porting tool. Many respondents voiced the sentiment that too
used to record data about the incidents and provide support for     much support for the workflow would hamper the creative
actions to take to rectify the problem. A further function is the   nature of the individuals in the field.
generation of statistical data for quality analysis and network         1) Implications of a Broadband WAN
optimization. Production interrupting events can be evaluated       The area of Workflow Management is perhaps that which re-
from several perspectives. Two obvious perspectives are eco-        ceives the least direct support from a broadband WAN solu-
nomic consequences in terms of lost revenues and operational        tion. Clearly, improved remote communications enables use of
experiences to be drawn from the incident.                          more sophisticated IT support in the field. For workflow man-
   The economic consequences of an interruption are not only        agement, this indirectly means that field crews can communi-
internal to the utility, in terms of lost revenue for power not     cate more effectively with a centralized Workflow system,
delivered and direct costs to restore the failing equipment, but    both to receive new work tasks, and report the progress of as-
also costs incurred by customers for lost production due to the     signed tasks.
power outage. Despite these potentially large costs, the eco-       F. Maintenance planning tools
nomic consequences of an interruption have largely been ne-            The strategic planning process at the utilities regarding As-
glected. Instead, the focus is to resolve the problem and return    set Management is very long-term, due to the nature of the
to normal operation as smoothly as possible. All utilities in       power grid equipment. Typically, the equipment has a depre-
Sweden are now under mandate to report all planned and un-          ciation period of 40 years or more. As a result, the utilities
planned outages to the authorities. Furthermore, a new regu-        have had an opportunity to develop elaborate guidelines for
latory reform is currently being implemented that may change        maintenance and engineering of electric networks. However,
the previous lack of concern regarding the economic conse-

many of these guidelines have been developed during the long       factor, not the available technique itself. Also, to investigate
period of monopoly, when customer tariffs where cost driven,       the maintenance requirements imposed on the needed commu-
and the expense of periodic maintenance could easily be for-       nication capacity is another important work to carry out.
warded to the customer. Another consequence of the longevity
of the network is that equipment, once top of the line, is aging                              VI. REFERENCES
and sometimes stands side by side with high tech equipment,        [1]  G. Ericsson: “On Communication in Power System Control,” Ph.D.
creating a very heterogeneous environment with very different           Dissertation, ISRN KTH/ICS/R--96/2—SE, Royal Institute of Technol-
                                                                        ogy, Stockholm, SWEDEN, 1996.
requirements on maintenance.                                       [2] G. Ericsson: “Classification of Power Systems Communications needs
    IT tools for planning of maintenance activities, and also           and requirements: Experiences from Case Studies at Swedish National
support for “replace versus repair” decisions are not in any            Grid,” IEEE Transactions on Power Delivery, vol. 17, no. 2, April 2002,
common use, and this is an apparent area for improvement.               pp. 345-347.
                                                                   [3] L. Pintleton, N. Du Preez, F. Van Puyvelde, " Information technology:
Today most planning activities are done using pen and paper             opportunities for maintenance management," Journal of Quality in
and sometimes documented in spreadsheets. For periodic                  Maintenance Engineering Vol 5, No. 1, pp 9-24, 1999.
maintenance this may be sufficient, but cleverer use of re-        [4] Bertling L., Eriksson, R., Allan R.N. ”Impact of maintenance on cost and
                                                                        reliability of distribution systems”, In Proc of 17th International
sources require a more elaborate way to plan maintenance ac-            Conference on Electricity Distribution Barcelona, 12-15 May 2003
tivities. Ideally, systems for maintenance planning would be       [5] P.Verho, K. Nousiainen, "Advanced use of information systems provides
integrated with resource and workflow management, as well               new possibilities for asset management of high voltage devices," In
                                                                        Proc. NORD-IS 03 Nordic Insulation Symposium, Tampere, Finland
as with asset documentation systems.                               [6] G. Ericsson: “Communications Requirements – Basis for Investment in a
   1) Implications of a Broadband WAN                                   Utility Wide-Area Network,” IEEE Transactions on Power Delivery,
    Maintenance planning is dependent on both operational as            vol. 19, no. 1, January 2004, pp. 92–95.
and historical data. Operational data is collected via two chan-   [7] J. Endrenyi et.al. "The present status of Maintenance Strategies and the
                                                                        impact of Maintenance on Reliability”," IEEE Trans. Power Systems,
nels: via routine inspections by field crews, and via event log-        vol. 16, No 4, pp. 638-646, Nov 2001.
ging by the operations staff. A broadband communication fa-        [8] M. Gammelgård and L. Nordström, "Effects of new regulatory frame-
cility will enable more data to be gathered from the power              works on utilities investment in Asset Management," in Proc. 2004 In-
                                                                        ternational Conference of Maintenance Societies.
system. Locally stored error logs at substations or generation     [9] N. Jonsson and L. Nordström “Strategies for implementing IT support
facilities can be uploaded to central planning systems provid-          for Asset Management” in Proc Powercon 2004, Singapore.
ing much more information than the limited data collected by       [10] European Standard EN 13306, Maintenance Terminology, European
                                                                        Committee for Standardisation, Ref No EN 13306:2001E
the SCADA system. With a more detailed view of the status          [11] C-G Lundqvist, J. Jacobsson, “Enhancing Customer Services by effi-
of equipment, the maintenance efforts can be more precisely             cient integration of modern IT-systems for Asset Management and Net-
planned and executed.                                                   work Operation, In Proc of PowerCon 2002, Kunming, China, October
                                                                        14-16, 2002.

   By introducing a broadband utility wide area network, im-
provements will mainly be found in “class B,” i.e., in class of
communications for administrative operational purposes.
Here, the broadband possibilities will act as an enabler for
transmitting large bulks of data from end to end. It is also in
this class of communication that the bulk of maintenance data
belongs. Based on a survey of Maintenance IT system
improvements the paper highlights specific benefits of
improved communication, divided into:
        • Asset Documentation
        • Resource Management
        • Production Management
        • Workflow Management
        • Maintenance Planning
   For each of these areas, the implications of using a broad-
band WAN is elucidated. In general, the high-speed communi-
cations make it possible to transfer large amounts of data, pro-
viding the actual means of more structured handling of data
loads. For example, byte-size demanding maps, drawings,
manuals, etc., can now be transferred in digital form to/from
the central office and a substation.
   A suggestion for further work is to more deeply analyze
how to use the available bandwidth for a utility. Here, the
imagination of the human being is most likely the limiting

                     VII. BIOGRAPHIES
Lars Nordström (S’2004) graduated from the Royal Institute of
               Technology in Stockholm in 1998, and holds a M.Sc.
               EE and Licentiate of Technology in Industrial Control
               Systems. Currently Mr. Nordstrom is active in the
               EFFSYS research program working on use of
               Information      Technology       for   Maintenance
               Management in the Power and Pulp & Paper
               Industries. Mr Nordstrom is also Program Manager for
               the “IT in the Power System” research program at the
               Swedish center of Excellence in Power Engineering.

                       Göran N Ericsson (S’90 – M’96) was born in
                       Huddinge, Sweden, in 1963. He received the
                       Ph.D. degree from the Royal Institute of Tech-
                       nology (KTH), Stockholm, Sweden, in 1996. In
                       1997, he joined Svenska Kraftnät (Swedish
                       National Grid), Vällingby, Sweden, to work on
                       data- and telecommunication-strategic issues.
                       From 1998 to 2000, he was the Manager of the
                       Telecommunications Department. Since 2001,
                       he is a telecommunications planning and project

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