State Load Despatch Center, Delhi                                                           An ISO 9001:2008 Organization
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Frequently Asked Question


Q1   Please explain SLDC and SCADA. What is the relevance of SCADA in modern power system?

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 disturbances.
• 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 the department?

Ans.:The scope of Unified Scheme covers all generating stations of Delhi, 4 nos. 400KV and 35 nos. 220KV grid stations. Under the scheme all the generating stations and grid S/Stations are equipped with RTUs/SAS and are directly reporting to SLDC at Minto Road via various communication links like optic fiber, Microwave.


Q.4 : What is its functional hierarchy?

Ans.: Presently two levels of control hierarchy is being followed in DTL,  where at the bottom are RTUs (Remote Terminal Units)/SAS at the grid S/stations/generating stations and top level is SLDC.  SLDC data in turn flows to NRLDC, POSOCO.  All the regional Load Dispatch Centers are reporting to NLDC (National Load Dispatch Centre), to have Uniform grid operation at national level.


Q. 5:How does it work?

Ans.: Sophisticated computers and communication equipments are installed at SLDC, which have been interconnected through associated communication network comprising of Fibre Optic Communication Link, Microwave. 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 cox power system scenario.
One Video Projection System (VPS) having 252" 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 time basis.

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.

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