To cater to the evolving needs of the power system on account of increasing renewable energy penetration, and ensure grid security and adequate resource availability, one of the key regulations for the power sector, the Indian Electricity Grid Code (IEGC) is being overhauled. Recently, the Central Electricity Regulatory Commission notified the draft IEGC Regulations, 2022. Among other things, the grid code contains provisions for roles, functions and responsibilities of the concerned statutory bodies, generating companies, licensees and any other person connected with the operation of the power systems.
Long-term integrated resource planning is one of the key aspects in the draft IEGC regulations to ensure resource adequacy. In the energy transition, the revamped grid code is expected to play a key role as it has provisions related to trial run and declaration of commercial operation for wind/solar/hybrid generators, energy storage systems (ESS) and pumped storage generating systems. Further, tests related to minimum turn down level as per Central Electricity Authority standards, reactive power capability and demonstration of primary response have been proposed. The new draft IEGC has also introduced a few new codes; protection code; commissioning and commercial operation code; cybersecurity, monitoring and compliance code. Further, it proposes a national reference frequency at 50.000 Hz, while the frequency band has been proposed to be tightened to 49.95 Hz to 50.05 Hz. More importantly, the scheduling code has been revamped in line with the general network access (GNA) regulations.
Key details of the draft IEGC regulations
For stable, reliable and secure grid operation and to achieve maximum economy and efficiency of the power system, the grid code, apart from the provisions relating to the role of various statutory bodies and organisations and their linkages, contains extensive provisions pertaining to reliability and adequacy of resources; technical and design criteria for connectivity to the grid; and protection setting and performance monitoring of protection systems, including protection audit. Further, it contains provisions for operational requirements and technical capabilities for secure and reliable grid operation including load generation balance, outage planning and system operation; unit commitment, scheduling and despatch criteria for physical delivery of electricity; integration of renewables; ancillary services and reserves; and cybersecurity.
The various codes covered in the draft IEGC Regulations, 2022 are:
Resource planning code: The draft provides for integrated resource planning. For this, a bottom-up planning approach has been proposed wherein demand forecasting will be done using state-of-the-art techniques, ensuring generation resource adequacy and reserve margins as well as adequate transmission resources. Each distribution licensee within a state will estimate the demand in its control area for the next five years starting from April 1 of next year and submit the same to the state transmission utility (STU) by July 31 every year. Based on the data, STU will estimate the demand for the entire state by August 30 every year, duly considering the diversity for the next five years, starting from April 1 of next year. Further, each distribution licensee will assess existing generation resources and identify the additional generation resource requirement to meet the estimated demand in different time horizons and prepare a generation resource procurement plan. For transmission resource adequacy, the central transmission utility (CTU) will undertake assessment and planning of the inter- and intra-state transmission system.
Connection code: This provides the technical and design criteria for connectivity, procedure and requirements for physical connection and integration of grid elements. According to this code, the connectivity to the interstate transmission system (ISTS) will be granted by CTU in accordance with GNA regulations. Transmission licensees will have to comply with technical requirements specified under this code prior to being allowed by the national, state or regional load despatch centre to energise a new or modified power system element. Further, after the grant of connectivity and prior to the trial run for declaration of commercial operation, tests as specified under this code need to be performed. Moreover, reliable speech and data communication systems should be provided to facilitate necessary communication, data exchange, supervision and control of the grid.
Protection code: This is a new code focusing on protection protocol, protection settings and protection audit plan of electrical systems. According to this code, there will be a uniform protection protocol for grid users for proper coordination of the protection system in order to isolate faulty equipment and avoid unintended operation of the protection system; have a repository of the protection system, settings and events at the regional level; specify timelines for data submission; ensure recording equipment health, including time synchronisation; and provide for a periodic audit of the protection system.
Commissioning and commercial operation code: This code covers aspects related to drawal of start-up power from and injection of infirm power into the grid; trial run operation; documents and tests required to be furnished before declaration of date of commercial operation (COD); and requirements for COD declaration. The COD in case of a unit of a thermal or hydro (including pumped storage) generation station or units of a renewable (including wind, solar, hybrid, ESS) generating station aggregating to 50 MW and above will be the date declared by the generating company/ station after undergoing a successful trial run. Meanwhile, the COD of an ISTS or an element thereof will be the date declared by the transmission licensee on which the transmission system or an element thereof is in regular service at 00:00 hours after successful trial operation for transmitting electricity and communication signal from the sending end to the receiving end.
Operating code: All entities such as national, state or regional load despatch centres, CTU, STUs, regional power committees, power exchanges, qualifying coordinating agencies, settlement nodal agencies, licensees, generating stations and other grid connected entities have to, at all times, function in coordination, to ensure stability and resilience of the grid and achieve maximum economy and efficiency in the operation of power systems. A national reference frequency has been proposed at 50.000 Hz and the frequency band has been proposed to be tightened to 49.95 Hz-50.05 Hz. A holistic framework for operation of reserves, including primary, secondary and tertiary reserves, voltage control reserves and black start reserves has been proposed as part of the operating code. Operational planning will be carried out in advance by national, state or regional load despatch centres within their respective control areas. The power system will be categorised under normal, alert, emergency, extreme emergency and restoration states, depending on the type of contingencies and value of operational parameters of the system.
Scheduling and despatch code: It deals with the procedure for scheduling injection and drawal of power by regional entities and modalities for exchange of information including scheduling for intra-state and cross-border entities transacting power through ISTS. Further, it covers provisions with respect to control area jurisdiction. A mechanism for security constrained unit commitment (SCUC) has also been proposed. The objective of SCUC is to commit a generating station or unit thereof, for maximisation of reserves in the interest of grid security, without altering the entitlements and schedule of buyers of the said generating station in the day-ahead time horizon.
Besides these, a cybersecurity code and monitoring and compliance codes have been proposed focusing on cybersecurity aspects and monitoring the compliance of regulations, respectively. In order to ensure monitoring of compliance, two methodologies based on self-audit and compliance audit have been proposed.
Conclusion
The process of comprehensively overhauling the IEGC is based on past experience, recent developments in the Indian power system, changes in the market structure, harmonious assimilation of higher shares of renewable penetration in the grid and introduction of new products in the market. Going ahead, the new grid code is expected to improve grid security, stability and flexibility in the operation of generating resources.
