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Best Practices in Distribution Systems Operation and Maintenance (O&M )
Distribution Reform, Upgrades and Management (DRUM ) Training Program
DISTRIBUTION AUTOMATION
M. V. S. Birinchi, CORE International, Inc.
Power distribution systems have grown in size and complexity in the last decade. For
example, the consumer base in Andhra Pradesh has reached 13.6 million, which is
twice the figure in 1990s. With increase in volume of workload, the technologies also
should change. Continuance with conventional manual systems is going to prove a
luxury in terms of cost apart from resulting in consumer dissatisfaction at the quality of
service rendered.
The Athens Utility Board in North Carolina, U.S.A, which is perhaps the first utility in the
world to achieve 100% distribution automation by 1990, has observed in its report “It is
amazing how well this country has proposed on rule of thumb, flip a coin and gut feeling
decision making during 20th century. We will not be allowed this luxury in the 21 st
century”.
The utility has installed SMART meters at consumer‟s premises with miniature circuit
breakers that can be addressed and controlled from the utility. For example, when the
system is in distress, it can disable certain appliances like air conditioners, washing
machines, mixies, geysers, etc. from being used and enable lighting and fan loads.
Reading of meters, change over of feeds (reconfiguration), adjustment of transformer
taps for better voltages, switch-on capacitors, controlling distribution transformers and
online energy audit, etc are all achieved remotely.
This is apt time to start „Distribution Automation” starting with Metros and rolling it out
gradually to towns and villages. A clear road map towards achieving Distribution
Automation is to be laid down with no further delay and start implementation forthwith.
The automation system can be designed using available technology in computer
systems, control systems and metering systems and dovetailing the same into the
existing power systems. All the tools required such as Computers, Remote Terminal
Units (RTUs), breakers, Switched Capacitor Banks, OLTC Transformers, Auto
Reclosures, Sectionlisers, AMR Systems and Communication Systems are available.
An integrated Distribution Automation system enables utilities to have real time control
over the costly energy sold. Improved efficiency results in lower costs, better reliability in
power supply, planned control actions, optimum power factor, reduction in losses. It
enables online energy audit (AMR Systems), which is now receiving the focused
attention of all utilities.
An integrated distribution control system mainly comprises of systems necessary f or
Data Acquisition, Voltage & reactive power controls, System reconfiguration & Load
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Best Practices in Distribution Systems Operation and Maintenance (O&M )
Distribution Reform, Upgrades and Management (DRUM ) Training Program
Control. The components used for these are primarily Distribution remote terminal units,
Pole top units and Distribution control receivers.
APTRANSCO Experimental Projects
In 1992, a completely indigenous microprocessor based substation supervisory system
called INSYST 33 was commissioned at Indira Park, Greenlands and Kalyannagar
Substations and the RTUs were erected. The interfacing work with CTs, PTs and
auxiliary switches of circuit breakers, etc was done by Master Plan Circle. The RTU is
rigged up by a team of Engineers of BHEL (R&D) and Master Plan Circle, who worked
hand in hand to put the precept into practice. Remote acquisition of data and remote
control of the substations from Vidyut Soudha were achieved. It was then decided to
draw up a scheme for comprehensive Supervisory control and Data Acquisition
(SCADA) covering 120nos substations in and around Hyderabad and to control all of
them from a Host Station. The scheme is implemented and is in operation since one
year.
This scheme provides for real time monitoring of operating parameters of Amps, MW,
MVAR, PF, Frequency, Voltages, etc at all points of the substation, status of circuit
breakers, remote operation of circuit breakers and archiving of historical data, audio
alarm and annunciation for limit violations and breaker tripping, recording of sequence
of events, recording f maxima and minima of operating parameters with time of
occurrence, cumulative energy fed, etc. This is now integrated with Computerised
Trouble Call System, which receives all fuse off calls in twin cities.
This Distribution Automation System aims at achieving
- Control of DTRs, HT services and individual loads apart from 11KV feeders.
- Operation of lines sectionalisers, motorized isolators, auto Reclosures
- Data acquisition from load end CTs and PTs
- Operation of CBs for switched capacitors banks
- Use of customized EMS software packages with real time data collected through
RTUs
- Issue, control and receiving back of line clears, introduce interlock and safety
algorithm, password protected operating environment.
- Real time logging of data / archived records of hours of service.
- Equipment data base
- Integration with Automated Mapping (AM) and Geographical Information System
(GIS) Software packages
- Integration with Distribution system engineering software for network planning
The other functions achievable through Distribution Automation are:
Network
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Distribution Reform, Upgrades and Management (DRUM ) Training Program
- Distribution Transformer control
- Monitoring and Control of LV breakers
- Trouble call management
Consumer Interface
- Load monitoring and control
- Voltage monitoring
- Metering and Billing through AMR
- Immediate detection of attempts for meter tampering
- DSM objectives (Individual pump control or group of pumps or DTRs)
- Monitoring of captive generation when synchronized with system network
Miscellaneous functions
- Load forecasts and load surveys
- System statistics
- Optimal network planning
- Energy Audit
A Distribution Automation system basically comprises of a distribution control center
(DCC), devices to be monitored / controlled like Substations, Switching Capacitors
Banks, line equipment and a reliable communication system that forms the backbone
for successful operation.
Distribution Control Centre (DCC)
The Distribution Control Modem Modem
Centre (as shown on the
right) consists of
Computer system with Communication Interface
software for Data
Acquisition and
applications, storage Data Acquisition Tele Control System
media for storing the
Data, Visual Display Long Term
Data Storage Computer Hardware and Software
Units (VDUs) for
displaying the data to
the operators and to Disc Operation and Supervision
issue control commands Storage
and communication
interfaces. Mimic Alphanu System
Board meric Console
VDU
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Distribution Reform, Upgrades and Management (DRUM ) Training Program
Communication Options
The communication options for achieving Distribution Automation are:
- Radio (UHF)
- DLCC uses the power lines for transmission of data (where commercially
available)
- Optic Fibre (Costly)
- Public switched telephone network and paging services for auto dial-up schemes
(where wide coverage is available)
One-way VHF radio can be used for load control because low cost load control switches
are available for this technology. VHF radio switches can also be used for capacitor
control on the distribution network, in lieu of more expensive RTUs with remote MARS
radios, if monitoring is not essential at the capacitor banks.
Communication Selection for Hyderabad SCADA Project
The Radio Technology based communication system is chosen for Hyderabad SCADA
project. In this a TDM / TDMA System operating in 2 Ghz band is chosen as the primary
communication. The Central Station for this system is located at DCC, which has 60
trunks of 64 Kbps capacity to provide high quality Data and Voice Communication.
Connectivity from DCC is provided by this system up to EHV substations which are
nodal points of the Power System by installing TDMA outstations. Two TDMA
Repeaters are also provided to overcome line of sight problems and to ensure better
coverage. At the 33/11 KV substations MAR remotes are installed. These are
connected to EHV substation by co-locating MARs Master Stations at nodal points and
by connecting them back to back to TDMA outstations. MAR remotes at 33/11KV
substations or at any field locations will be polled by the MARs Master Station. Thus
data acquisition / sending control commands to the controlled equipment is ensured in
this project.
Sub-Station Telemetry Equipment
Remote Terminal Units (RTU) are to be provided in each of the Substations for
acquisition of substation data parameters, transmitting them to the control centre. The
RTU‟s will be rugged, intelligent and microprocessor based. All activities including I/O
data processing and communication will be done using microprocessors. A typical RTU
is a self-contained unit with CPU, RAM, EEPROM, RS 232 communication ports, power
supply, protective circuitry, analogue and digital I/O channels with signal conditioning.
The I/O modules will be selectable to achieve the quantity and mix of I/O needs for each
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Best Practices in Distribution Systems Operation and Maintenance (O&M )
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substation. The RTU gives priority to telecommands from the control centre over its data
acquisition tasks and at the same time ensures that the background scan of all the
events at the controlled substations are carried out and no event is lost. A typical
schematic RTU is given below.
Real
Analog
Interface Card
Time
I/O
(Rs.232)
A/D Clock
Progra Dat
Converte m a Communication
Mode equipment
r PROM R m
EEPRO
M &
Digital Memory M
Central Processor
Interface
Module
Circuit
Breaker
The functional capabilities of the DAS (Distribution Automation System) for distribution
operation are:
Supervisory Control and Data Acquisition (SCADA)
Historical Accounting and Reporting
Load Control of HT consumers
Automatic Meter Reading
Feeder SCADA including fault localization, restorations of supply and load
balancing
Integrated volt/VAR control
Automatic Mapping and Facilities Management
Trouble Call Management System
Pole – Top RTUs
Functions in the field are performed through Pole Top RTUs. They are similar in
functionality to the RTUs except that their I/O handling capacity is small. These are
installed on Distribution poles to control the equipment online, such as a line AB
switches, capacitor banks, voltage regulators, etc. To obtain information form pole-top
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Distribution Reform, Upgrades and Management (DRUM ) Training Program
RTUs when needed, operators shall be able to manually request the polling of any
specific pole top RTU. It would be possible to issue polling requests for an RTU by
selecting a cursor target from any display, tabular schematic, on which that RTU is
displayed. Manual polling requests shall be processed on a higher priority than any
periodic scan activities. Scanning of pole-top RTUs shall be distributed over time in
order to minimize the impact on the faster substation scan.
Distribution Automation – Operational Methodology
Voltage Control
A pole top RTU with a MARS remote is installed at each voltage regulator / capacitor
bank location and interfaced with it for getting input data of feeder voltage at the
monitored point, reactive loading, current tap position of voltage regulators, on/off status
of capacitor banks and to do switching operations of capacitors and voltage regulators.
The location and capacity of capacitors / voltage regulators shall be decided using an
optimal strategy. The switching schedule of capacitor banks is to be obtained for
minimal loss strategy while simultaneously satisfying the maximum /minimum voltage
constraints on the feeder. A similar method is required for determining the voltage
regulator taps also. Here, the regulator tap position is placed in maximum possible
position as long as the voltage at the maximum affected node does not exceed
maximum permissible voltage limit. The on / off switching commands for capacitor
banks and raise / lower commands for voltage regulators shall be issued to pole top
RTUs either through supervisory control automatically or through manual control by the
operator. A feedback of the change in status due to control commands have to be
obtained and the results have to be displayed with any alarm / even messages as
required.
Fault localization and Restoration
Whenever there is any fault on a feeder, the circuit breaker (CB) for that breaker trips.
Test charging is done by closing the CB for two to three times at an interval of a few
minutes, to ascertain whether the fault is a transient one. The last test charging is done
by opening the isolator and closing the breaker to ensure that the fault is not in the
breaker. If it is ascertained that the fault is permanent and is on the feeder, the circuit
Breaker is charged again and the switches are closed one after another starting from
the substation end. When the breaker is in closed position and if it trips before the first
switch Sectionlisers is closed, that fault is noted to be in between the substation and the
first switch (i.e. in the first section). Every sectionlisers closes after a definite time and
interval and the fault is noted to be in the section beyond the most recently closed
sectionlisers switch. The fault section is isolated by opening switches at both ends of
the section. Supply to the healthy between the substation and the faulty section is
resorted.
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Provision for sectionalisers to close can be by stand above automation by a software
program for operation of switches by the operator through SCADA.
Trouble Call Management System (TCMS)
The outage of supply is reported by the consumers to a centralized Fuse Off Call
Centre. TCMS helps to analyze the reasons for outage reported by the consumer /
consumers and take remedial action to restore supply speedily using this function. For
instance, when outage of supply is reported by a large number of consumers in one
area, it may be probable to trace the reason to blowing off of a sectional fuse of
distribution transformer. By maintaining database of consumers connected to each
transformer or feeder, such an analysis could be made easily. By providing SCADA
connectivity to fuse off call centres, the operator at DCC will be able to analyze the fault
and send rectification gangs for speedy restoration. This function helps to reduce losses
due to long interruptions and improve customer relations.
Conclusions
Implementation of Distribution Automation cannot be delayed anymore. Infact
delay in automation may prove to be a luxury.
Substation Automation, 11KV feeder controls, LV System controls, AMR, DSM,
Online Energy Audit can be achieved.
The cost towards Automation is generally recoverable in two to three years pay
back period.
Distribution networks provide an interface between the consumers and the utility
and any amount of sophistication on the upstream side with a less efficient
distribution system cannot provide satisfaction to the consumers.
Intelligent Distribution Transformers
Distribution Transformers (more popularly referred to as DTRs) from the essential link
between a power utility and millions of its LT Consumers. Phenomenal technology
advancements have taken place in Generation and Transmission sectors but the same
in Distribution are not equally spectacular. The engineers in-charge of Distribution deal
with lesser quantum of power and energy but have to provide satisfactory power supply
to a very large number of consumers. The technological solutions for adoption in
Distribution Sector shall be a compromise between „technically desirable‟ and
„economically viable‟. The efficiency of monitoring the Distribution System essentially
lies in the effective performance monitoring of a DTR.
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DTRs are supposed to be least prone for failure as they are most rugged with all their
components tightly clamped and no rotating or moving parts inside. It is unfortunate that
in most of the Indian Power utilities, the rate of incidence of failure of DTRs is around 20
percent per year.
All the reasons for failure like loss of diversity, overloading, unbalance in loads, low oil
levels, loose spans, improper earthing, inadequate protection, etc., are being explained
away stating that they are unattended and unmanned. It is true that the DTRs are very
large in number and are scattered over large areas but technology can always find a
solution for overcoming the problem. When the volume increases, technology shall
change and adherence to old conventional manual systems can no longer be continued.
Attempts have been made on a pilot basis to implement Distribution Automation. The
first of one such attempts is Gachibowli Distribution Automation Project in Hyderabad,
Andhra Pradesh
Gachibowli Distribution Automation Project
In the year 1995, the Department of Electronics (Govt. of India) has awarded a Pilot
Distribution Automation Project called Gachibowli Distribution Automation Project to be
implemented jointly by erstwhile APSEB and CMC the project was implemented
covering one 33/11KV Substation, 20 nos., Distribution Transformers, 50 nos.
Agricultural pumpsets, two High Tension services, two numbers Capacitors banks and
10 nos., load break switches to be controlled from Gachibowli Substation. Pole top
RTUs with two way Multiple Address Radios (MARS) Communication was used to
control DTRs, H.T. services, capacitor Banks and load break switches, VHT one way
radios were used for the control of agricultural pumpsets (i.e.) to enable or disable a
consumer from running his pumpset.
Pole top RTU employed in Gachibowli DA Project
The pole top RTU (PRTU) developed in Gachibowli Project is similar in functionality to a
normal Remote Terminal Unit (RTU) but has less input / output handling capacity. The
I/O handling capacities provided are Digital Input module – 16 inputs, Digital Output
module – 16 inputs and Analog Input module – 16 inputs.
These PRTU is designed to be powered either by 110V or 230 V AC. The RTU has a
serial port to which a radio can be connected for data transmission to the control centre.
The PRTU is built to house a MARS radio in it through which it communicates to DCC at
selectable baud rates.
IIT Kanpur Experiment
Government of India (Ministry of Power) has identified IIT, Kanpur as lead agency for
developing technologies in the area of Distribution Automation and a workshop cum
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technology dedication event was held at Kanpur on 22 nd & 23rd February, 2003. A
practical demonstration of a pilot level project covering one 33KV SS with two power
transformers, two 33KV circuit breakers with their isolators, three DTRs with 11KV & LT
Load break switches (LBS) installed within IIT campus was made and the indigenous
technology developed is dedicated to the nation by Secretary, MOP of Government of
India.
Remotely operable LBS (Load Break Switches) for 11KV operation and MCCBs
(Moulded Case Circuit Breakers) for 415 volts have been developed and field-tested in
the Distribution network inside the IIT Campus. The 11KV three pole LBs for outdoor
operation are rated for 80 Amps., with an opening time of 100 milli seconds. They can
sustain a fault current of 16 KA for one second and have a breaking capacity of 1.5
MVA to 0.7 pf and with a dynamic peak withstand capacity of 40 KA.
The LT LBSs are designed for a rated current of 200 Amps., with rated short circuit
withstand strength of 35 KA between phases and 21 KA between each phase and
neutrals for one second. These are designed with „Solenoid Plunger‟ arrangement as
operating mechanism.
A practical demonstration of remote monitoring and controlling of DTRs has been made
during the workshop-cum-technology dedication event in February 2003 at IIT Kanpur.
APCPDCL Experiment
Andhra Pradesh has a flair to embrace and adopt new technologies and try them out on
pilot basis in practical networks. The Central Power Distribution Company of AP has
adopted the technology and four distribution transformers located in different districts
are being monitored from centrally located DCC (Distribution Control Centre) at
Hyderabad using Cell Phone connectivity. This exercise is being done successfully from
January 2003 on the following DTRs.
District 33KV SS 11KV DTR location Monitoring
Feeders being done
Rangareddy Himayatsagar Azeeznagar Umpathy 3 Phase current
Gardens and voltages, pf
load survey with
last 35 days
data storage
Rangareddy Kesavaram Anantharam SSI - do -
Medak Narsapur Kagaz Jamathota Instant values of
Mazdoor 3 phase
currents,
voltages, p.f, etc
Nalgonda Bhongir Chandupatla SS – 17 - do -
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The successful experiment clearly demonstrates that a Distribution Engineer can
monitor on real time the operating parameters of every DTR and infact he can chit chat
with his DTR as frequently as is necessary.
Electronic meters (CT operated) with RS232 port are erected at the DTRs and have
facility of storing data for the last 35 days for conducting load survey. Cellular
connectivity using GSM Modem is employed for data transmission to DCC using
Wireless Access Protocols. Instantaneous readings of three phase currents, voltages,
phase angles, power factor, active power, status of CTs, etc., are obtained and printed
out at DCC for these DTRs. Also load survey with 24 hours data on any selected date
can be retrieved remotely from DCC.
The meter proper is capable of measuring electrical energy in all four quadrants, active
as well as reactive, max demand, etc., and has all facilities for TOD, tamper proof data,
self diagnostics, and an optical port for communicating with CMRI or to an external
device like RTU for SCADA application. These meters are now to be equipped with a
remotely operable relay, which in turn closes or opens LBs and also report back status
using potential free auxiliary contact.
Communication Options
Unlike traditional communication options, the approach is to have a core communication
controller at the Base Station, which can support diverse choices of communication
media (i.e.) Dial up, Ethernet, WLL (CDMA), GSM, etc, for cost effective
implementation. Out of the options of PSTN, PLCC, Radio, etc., the employment of
GSM modems is found to be best suitable in areas having cellular corridors.
Intelligent DTRs
It is desirable to have inbuilt intelligence into the DTR, considering the following aspects
i. Monitoring the various operating parameters of the DTR such as load,
temperature rise and oil levels which are helpful to detect the abnormalities and
provide opportunities to take corrective actions to avoid failures.
ii. Measurement of energy sent out to achieve effective energy audit.
iii. Housing the electronics and communication interfaces capable of withstanding
the heat and oily environment in a safe way within the DTR to avoid meddling by
consumers.
It will be advantageous if DTRs are manufactured with built in facilities of CT operated
electronic meter which can store data for the last 30/60 days, remote reading facility,
and a remotely operable relay to perform control operations. A float switch to monitor oil
level in the DTR can also be incorporated. A comprehensive unit, which can be called
“Intelligent DTR” can be manufactured with totally indigenous technology.
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Initial estimates indicate that the cost of an Intelligent DTR may be twice the cost of a
conventional DTR of equal rated capacity but substantial reduction can be achieved if
these are procured in very large quantities.
Power utilities are spending large amounts on repairs to DTRs and with the amount
spent on rectification of every three failed DTRs, a new DTR can be procured. To start
with repairs of failed DTRs which are 20 years old, those which have already failed
twice, and those requiring replacement of all three limbs can be dispensed with and new
DTRs can be procured with built in intelligence. This may incidentally from step no.1
towards Distribution Automation in Indian Power utilities.
International experience shows that, the automation projects have high benefit cost
ratios and less payback times. Now there is no option except to go in for Automation of
DTRs as they are large in number and are continuously increasing to improve quality of
service.
Several leading Indian Transformer manufactures of CSP and amorphous core
transformers in the country have come forward to manufacture “Intelligent DTRs” (i.e.)
DTRs with inbuilt facilities for remote monitoring and control adopting totally indigenous
technology. The R&D activity has already started and catching up momentum as they
have setup a short-term goal to achieve this.
Sixty-three districts in the country are chosen for APDRP (Accelerated Power
Development Reform Programme) and the District Head Quarters shall be the first to be
automated. The Distribution networks in these towns shall be upgraded to 100 percent
technical standards and made amenable for Automation. CSP transformers have
already got a breaker inside the transformer which open out for overloads or excessive
temperature and these can be attempted for conversion as Intelligent DTRs.
Fruits of Implementation
If the above Scheme is implemented, the following benefits can be achieved which will
be the beginning of a new era of efficient distribution systems in the country.
DTRs continue to be unattended but will be monitored remotely online.
Instantaneous voltages, currents, active power, reactive power, power factor
(perhaps temperature and oil level also) can be monitored remotely.
Unbalances in voltages and currents can be detected and corrective action can be
initiated
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Hours of power supply through each DTR can be monitored and data stored to
compute the reliability
Energy Audit will be possible at grass root level
Substantial reduction in failure rate of DTRs as impending failures can be
detected in advance
Quality of power supply will be of the highest order
Load survey makes Distribution Network planning and meaningful
Phenomenal reduction in losses can be achieved through reconfiguration
roistering, etc., which is possible to do remotely.
Total consumer satisfaction
Information Technology Initiatives in Electricity Distribution Systems
(Those implemented in AP are explained)
1. The IT initiatives in power distribution systems are aimed at
Improvement of efficiency by way of elimination of delays, duplication, drudgery
in paper work
Reduction in over all expenditure
Provides quick and efficient information systems like online Billing & Collections,
online report generation
Customer satisfaction
Very fast reconciliation between important activities of Metering, Billing &
Collections
Web based services for 24 hours X 365 days
To attain transparency and gain credibility
2. The initiatives are broadly classified as per activity in which the initiatives are taken
as follows:
(a) Power Supply (b) Metering, Billing & Collection
SCADA (Supervisory control & Common Billing System
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Data Acquisition
TCMS (Trouble Call Spot Billing through hand held
Management Systems computers with GSM
connectivity
Micro Controllers (Power Networking of Electricity
Supply & Control) Revenue Officer with e-Seva
collection Centres
Data loggers for feeders Remote metering with tamper
(monitoring of power supply & proof data for High value
energy) series
Intelligent DTRs (Remote AMR Systems for on line
monitoring & load survey on energy Audit
feeders)
Mobile Vans with GSM CAT software for analysis of
connectivity for very fast Risk
restoration of supply
GIS & GPS Profile Consumer
(c) Performance Management (d) Investments for System
Improvement
PMRS (Performance DISBUT (Software developed
Monitoring & Review System) In-House and other advanced
software tools
Uploading of PMRS data at Integrated optimum System
field level and transfer through planning for maximum LRVI
VSAT (Loss Reduction & Voltage
Improvement) with least cost
TIMS (Transfer Information Prioritisation of works based
Management) on High benefits cost ratio and
least pay back period.
MIMS (Meter – tracking)
FM
AM
HRD
BCM
Loss Study
Finance Management
Office Automation
The expected results are
- Loss Reduction
- Increase in specific revenue
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- Improvement in Collections
- Fast & Better Consumer Servicing
- Quick feedback
- Reduction in interruptions
- Above all Total Consumer Satisfaction
SCADA - (Supervisory Control and Data Acquisition)
SCADA involves net working of a group of substations (especially in Metros & large
towns) for data collection in respect of all equipment at a host station. The distribution
system can be monitored on real time and also controlled by issuing commands to
remote stations where RTUs (Remote terminal units) are located.
The aim of the system is effective load management of the distribution system to
improve reliability and efficiency of supply.
SCADA is more effective if integrated with load control, AMR, emergency load
shedding, integrated Var Control, fault location through sectionalisers, trouble call
management, and facilities management.
Apart from achieving efficient distribution management, accurate fault analysis and
prompt restoration of supply, it will be possible to identify malfunctioning of equipment in
advance for taking corrective action. Historical data for say two years can be sorted for
future analysis.
The system mains comprises of
– Control Centre equipment
– Application software
– Distribution Management Software
– Communication System
– RTUs for field data acquisition
– Ups, etc.
TCMS
The objectives are development of consumers profile each DTR wise, recoding of
complaints, quick compliance, confirmation of compliance, dynamic display of control
system (as a map display) evaluation of working patterns and plan work allocation, and
online information flow to managers.
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The database required is pole wise consumer identify, Substation wise supply system
configuration, location of fuse of call offices with their jurisdiction.
The Telephone # (say 1912) is allotted as a toll free connection to cater to the needs of
consumers in a Metropolitan City or a large area with heavy load density (MW / Sq KM)
CSC (Customer Services Centres) are established as single point of contact for
redressal of all customer grievances including release of new service connections.
The complaints received and computerized to be attended as per Citizens charter.
Cases of supply failures are communicated to concerned fuse call office or mobile vans
for quick compliance. The communication system updates status of compliant and
provides information to administrators through Internet based GIS and also priorities the
works to be attended.
GIS mapping and geo referencing and integration with TCMS for development of DTR
based consumer data will greatly help Discoms.
MICRO CONTROLLERS
Micro controllers are provided at each of the 33 KV substations to achieve the following:
- Ensuring number of hours of power supply including implementation of
restrictions and control measures when in force
- Automatic tripping to supply if load exceeds a pre set value during specific hours
to avoid over loading of equipment.
- Monitoring of uniform distribution of load as per schedules
- Reading of all events and data of all parameters is provided generates reports
data of feeder wise hours of supply and also complete data required for
conducting load survey
This logged data can be periodically retrieved through an hand held terminal for post
processing and monitoring apart from report generation. The Micro Controllers work as
per microprocessor based control logic and derives inputs from CTs & PTs of each the
feeders picking up signals and converting them to digital from (A.D converters).
Depending on availability of incoming power supply to SS, and as per pre programmed
time settings, each of the feeder breakers will be enabled or disable for switching ON.
Also at pre-determined timings the circuit breakers will be switched off. Further during
such timings when lighting load is permitted and three phase power loads (such as
pumpsets or LT industry) are not allowed to run, the controller trips the feeder breaker if
the load exceeds a pre programmed value.
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The microprocessor based control logic has got current and voltage sensors
(CTs & PTs) for each feeder and samples the data on continuous basis,
conditions the signals and converts to digital form for processing, decision
making and logging purpose.
Based on incoming power availability and based on predefined time settings, the
individual feeders will be enabled for switching „on‟ and at the end of elapsed
time the same will be tripped „off‟. During the two-phase condition, if the power
drawl exceeds the rated load, the control mechanism will trip the feeder.
The processor logic also logs all the events and parameters on regular intervals.
The logged data can be periodically down loaded to a Hand Held Terminal for
post processing or for report generation.
MBC (Metering, Billing & Collections)
Common Billing System (CBS)
A common software for both HT & LT billing, revenue collection, New customer
accounting, change of ownership of service, dismantlement & termination of service etc
is developed so that the entire MBC function is a common platform.
Networking
All Electricity revenue offices and collection centres are networked. The Billing data is
updated on real time basis so as to enable consumers to pay their Bills at any of the
collection centres (e-Seva Centres) of the Distribution Company.
SBS
“Spot Billing is done through Hand Held Computers” which are fast, versatile, intelligent,
affordable, portable and user programmable.
Electronic Spot Billing has resulted in reduction of time of billing cycle, thus improving
cash flow. Bills are given on the sport and the due dates for payment are getting
scattered avoiding rush at cash counters. This also provides additional time to attend to
Meter exceptional such as non-performing & under performing meters.
Remote Metering
Almost all 11KV feeders especially those with predominantly agricultural loads, major
industrial load and selected High Value Consumers are equipped with data loggers
which store data of three phase currents, voltages active & reactive power, power factor
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etc for the last 30 days which can be retrieved locally through CMRI. They have
communication port RS 232 and are read remotely through dial up modems. This helps
in conducting load survey and initiate corrective action to avoid overloading of
conductors and also in reduction of losses.
Also the meters at selected High value services are read remotely and consumption
pattern is monitored. Meters tampered or not recording properly are instantly detected.
Cases of pilferage are also detected as meters have tamper proof data logged.
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