The Indian Electricity Grid Code (IEGC) 2006 is a regulation made by the Central Electricity Regulatory Commission (CERC) in exercise of powers conferred under The Electricity Act 2003. IEGC lays down the rules, guidelines and standards to be followed by the persons and participants in the system engaged in planning, developing and operating the Power system.
Further regulations were made by the CERC, called Central Electricity Regulatory Commission (IEGC) Regulations 2010, have superseded the IEGC and have come into force from May 2010.
Some of the definitions as mentioned in these regulations are:
1. Ancillary services: Ancillary services are those services necessary to support the power system operation in maintaining power quality, reliability and security of the system or the grid. Examples are active power support for real time load following, reactive power support, black start etc.
2. Black Start: Black Start means the starting of a power plant or system after a partial or total blackout in the region.
3. Available Transfer Capability (ATC): Available Transfer Capability is the Total Transfer Capability (TTC) minus Transmission Reliability Margin (TRM). ATC is the transfer capability of the transmission system, of the inter-control area, available for commercial transactions. These transactions may be through long term access, medium term open access, and short term open access in a specific direction considering the security aspects of the network.
4. Total Transfer Capability (TTC): Total Transfer Capability is the quantity of electric power that can be transmitted reliably over the transmission system of the inter-control area under a given set of operating conditions considering the occurrence of the worst credible contingency.
5. Transmission Reliability Margin (TRM): Transmission Reliability Margin is the margin in terms of MW kept in the Total Transfer Capability (TTC) required to ensure the security of the interconnected transmission system under a reasonable range of uncertainties.
6. Bilateral Transactions: Bilateral Transaction means a transaction for exchange of electrical energy in MWh between a given buyer and a seller from a given point of injection to a mentioned point of drawal for a fixed or changing quantity of power (MW) for any time period during a month. This transaction of electrical energy may be a direct transaction or through a trading licensee or power exchange.
7. Unscheduled Interchange: For a generating station or a seller, Unscheduled Interchange means the total actual generation minus its total scheduled generation in a given time block, whereas for a buyer or a beneficiary, it is total actual drawal minus its total scheduled drawal in the given time block.
8. Long Term Access: Long Term Access means the authority to use the Inter State Transmission System (ISTS) for a period more than 12 years, but not exceeding 25 years.
9. Medium Term Open Access: Medium Term Open Access means the authority to use the Inter State Transmission System (ISTS) for a period more than 3 months, but not exceeding 3 years.
10. Short Term Open Access: Short Term Open Access means the authority to use the Inter State Transmission System (ISTS) for a period upto 1 month at one time.
11. Inter State Transmission System (ISTS): Inter State Transmission System means any transmission system for the conveyance of electricity from one state to another, across the territory of an intervening state as well as within the state, built, owned, operated and controlled by Central Transmission Utility (CTU), i.e. Power Grid Corporation of India.
12. Control Area: Control area is an electrical system bounded by interconnecting Tie lines, metering and telemetry system which controls its generation and or load to maintain its scheduled interchange with other area and helps to regulate the frequency of a synchronously operating power system.
13. Congestion: Congestion is a case where the demand for transmission capacity exceeds the Available Transfer Capability.
14. Demand: Demand means the demand for active power in MW and reactive power in MVAr.
15. Load: Load is the MW/MWh/MVA/MVAh consumed by a utility or installation.
16. Ex-power plant: Ex-power plant means the net active power output in MW and energy output in MWh of a generating station after deducting the auxiliary consumption of the power plant and the transformation losses.
17. Despatch Schedule: Despatch Schedule is the net MW and MWh output of a generating station or power plant (ex-power plant) scheduled to be injected to the grid from time to time.
18. Spinning Reserve: Spinning Reserve means partly loaded generating capacity with some reserve margin that is synchronized to the rest of the system and is ready to provide increased generation at short notice pursuant to despatch instructions by the system operator or instantly in case of frequency collapse.
19. Independent Power Producer (IPP): Independent Power Producer is a generating company not owned or controlled by the Government (Central or State Government).
20. Forced Outage: Forced Outage means an outage of a generating unit or a transmission facility due to a fault or any other reasons apart from planned shutdown.
21. Connection Point: Connection Point is a point where a plant and or electrical apparatus connect to a transmission or distribution system.