Please explain SLDC and SCADA. What is the relevance of SCADA in modern power
Ans.: There are multiple agencies within a state
engaged in generation, transmission, and distribution of electricity. State
Load Dispatch Centre monitors these operations and keeps the account of
quantity of electricity transmitted through the state grid. SCADA is a part of
it. Supervisory Control And Data Acquisition System (SCADA) is a high tech
computer system with associated communication network that enables supervision
and control of power system network. Demand for power is increasing very fast
due to continual improvement in quality of urban life style as well as
expansion of industrial sector. The rapid increase in demand for power is
associated with growing level of power system network complexity in terms of
need for unified grid operation while maintaining the operational parameters.
Further increased openness in the power sector economy has put additional
pressure on the power companies to manage the power system resources in the
most optimum manner within regulatory constraints imposed by Regulator.
To meet the above challenges the need for a Real Time
SCADA system in any modern power system utility is indispensable.
The direct benefits of a modern SCADA system are:
• Constant access to Real Time picture of entire network showing power system
voltage, frequency, MW, MVAR, etc.
• Supervision, monitoring and control of power in Real Time.
• Optimal operation of power system, i.e. generation and associated resources.
• Minimum of outage and faster restoration of the system in the event of Grid
• Improvement in the quality of supply through better control of frequency,
voltage and other parameters.
• Less dependence on basic telephone system.
Q.2 : When did
this department come into existence?
Ans.: This was conceptualized in the early 90s during
the period of DESU when the need for acquisition of a modern real time SCADA
system to manage the real time load dispatch functions was felt. All the
focused efforts resulted in DTL joining the Unified Load Dispatch and
Communication Scheme of Power Grid along with other constituent states of
Northern Regional and Central Sector.
Accordingly the state of the art SCADA system was
establish in DTL at a total capital cost of Rs. 47.03 crores which became
operational on 01 .07.2002.
Q.3 : What is the scope of
Ans.: Initially the scope of Unified Scheme covered
all generating stations of Delhi, 2 numbers 400KV, 15 numbers 22OKV and 3
numbers 66KV RTU (Remote Terminal Utility) grid stations. Subsequently, three
number 66KV grid stations were dropped as they were placed under the
jurisdiction of distribution company M/s BSES and M/s NDPL after unbundling.
Under the scheme one SLDC at Minto Road and four Area Load Despatch Centre
(ALDCs) at Bamnauli, Bawana, Ghazipur and Gopalpur have been established and
are operational. All the generating stations of Delhi and grid stations have
been grouped in four distinct areas, each reporting to respective ALDC and in
turn ALDC sent their data to SLDC Minto Road.
Q.4 : What is its functional
Ans.: DTL has three level of control hierarchy where
at the bottom are the RTU (Remote Terminal Unit) at grid stations / generating
stations at the middle level are ALDCs and at the top level is SLDC. Real Time
Data flows from bottom to top. SLDC data in turn flows to NRLDC, Power Grid. As
per policy of Govt. of India it was envisaged that in future all regional Load
Dispatch Centers shall report to proposed National Grid for Unified Grid
Operation at National level.
Q. 5:How does it work?
Ans.: Sophisticated computers and communication
equipments are installed at SLDC and ALDCs, which have been interconnected
through associated communication network comprising of Fibre Optic
Communication Link, Microwave and PLCC links. The network also acts as a bridge
connecting NRLDC with rest of the Northern Region constituent States as their
data flows to NRLDC through DTL communication network.
The DTL network is a part of entire Northern Region,
which include constituent states, central sector, and Power Grid. This vast
communication network allows on-line availability of field data of entire
northern region at our SLDC Minto Road, which helps system engineers to know
the real time status of entire northern grid for taking prudent decisions in
the event of most complex power system scenario.
One Video Projection System (VPS) having 134" large screen, besides high speed
data servers, computer operator consoles, is installed at SLDC building at
Minto Road which depicts various network scenarios displayed in text as well as
graphic form which provide instant overview of the power system to the
operators for load dispatch.
The SCADA system is equipped with self-diagnostic
features along with facilities for recording of Sequence of Events (SOE) giving
the type, location and occurrence of specific events. This information is used
for post fault diagnosis/studies. Apart from above, the system is also equipped
with historical data recorder (HTR) which records power system dynamics even
under normal conditions which can be replayed at any point of time for
reference or analytic studies.
Q.6 : What is its role in
forecasting demand of power?
Ans.: The SCADA system also incorporates load
forecast feature that enable short-term load forecast based on similar weather
day conditions. The input to the load forecast system is from our weather
station installed at SLDC Minto Road as well as well as weather forecast data
from Indian Metrological Department and through Internet.
The above information enables DTL engineers in
preparing most realistic load schedules for better load management that results
in economic and effort based management with the available resources on real
As a step towards meeting the quality power supply
requirement of NCT of Delhi, DTL as a strategic planning, is consistently
striving for acquisition of most modern appropriate cost effective technologies
in the field of IT based tools related in the field of power engineering such
as real time SCADA system, etc. as well as nominating its engineers for various
training programs to keep abreast with latest happenings in the power sector.
The benefits of above technology transfer can be observed in terms of changed
orientation of DTL work force in the emerging competing work environment, which
is essentially required also.