Electrical Power Grid in India
Indian electrical power grid network is one of the biggest networks in the world. India has concentrated generating stations away from load centers while the demand for electricity is everywhere. Most of the Thermal power plants are located in Jarkhand, Uttar pradesh and other states where plenty of coal reserves are available while most of the hydro power generation comes from North Eastern States. Demand for electricity is widely even in India. Therefore in order to facilitate power transmission to load centers from generating stations India requires long transmission networks to cater the demand. In India Power Grid Corporation is the only central transmission utility connecting generating stations and distribution centers
Five Regional Grids:
For transmission of power in India, Power Grid is categorized into 5 regional grids. Northern Grid (NR), Southern Grid (SR), Western Grid (WR), Eastern Region (ER) and North Eastern Regional Grids (NER). Out of the above classification made Northern, Western, Eastern and North Eastern Grids and interconnected with synchronous links (Power transfer between all these regional grids will be based on supply and demand) while only Southern Regional Grid is connected to other grids through asynchronous links (Power flow between Southern Grid and other grids will be manually operated). The reason why Southern Grid is segregated from the rest of the transmission system is that the frequency in which Southern Grid operating is slightly lesser than the remaining regional grids. Hence because of the frequency mismatch Southern Grid alone operates independently from the rest of the regional grids.
If all the grids are interconnected any variation in frequency in one region can cause cascade effect in the entire grid. This is the reason earlier five independent regional grids was made for effective operation. But in the recent years because of the enormous addition of installed capacities, reserve margins and strict grid code to be followed by utilities the frequency mismatch between the regions come down. Hence this is the reason why other than Southern Grid other regional grids are interconnected.
However it was proposed that by 2013-14 Southern Grid is also made to connect to other grids synchronously and will become one single national grid
The backbone transmission voltage in India is through 400kV transmission system running more than 1,00,000 kilometers distance. Highest AC voltage transmission in India is at 750kV level with more than 5000 kms and many long distance interconnection projects with 750kV transmission system is under commissioning. Along with this HVDC transmission system at +/- 500kV back-to-back links of length approximately more than 10,000 kms with power transfer capability of more than 30,000 MW between different regional grids was under operation
Objectives of Transmission System:
Some of the objectives of power grid is to:
- Strengthening the National Grid
- To transfer power at cheaper price (minimum cost for MW of power transferred) by high voltage transmission corridors
- To minimize the Right of way
- To reduce impact on environment
- To reduce the losses in the system
Load Dispatch Centers:
India has three tier load dispatch centers based on the hierarchy:
- National Load Dispatch Control Center
- Regional Load Dispatch Control Center
- State Load Dispatch Control Centers
National Load Dispatch Control Center:
The function of load dispatch control center includes optimum scheduling, dispatch of power across various regions and coordination the event of power exchange between different regions in real time. This control center is located in New Delhi
Regional Load Dispatch Control Center:
The function of RLDC is to operate in real time for grid control and dispatch of power within regional grid through secure and economic operation of regional grid as envisaged in grid standard and grid code. Regional Dispatch centers each in one region is located in New Delh, Kolkatta, Mumbai, Bengaluru and Shillong respectively
State Load Dispatch Control Centers:
The function of State Load Dispatch Center is similar to Regional Dispatch Center. However the ability to operate limits within the state. With in State Load Dispatch Center Area Load Dispatch Centers (ALDC) and Remote Terminal Units (RTUs) are located at various substations and generating stations.
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