CEA Advises 100 Percent Grid-Forming Inverters for All Upcoming BESS Projects
The Central Electricity Authority has advised 100 percent Grid-Forming Inverters in all upcoming BESS projects, citing concerns over grid strength, low SCR and power-system oscillations amid rising renewable energy and storage capacity.
August 17, 2026. By Mrinmoy Dey
The advisory has been issued to the Central Transmission Utility of India (CTUIL), GRID-INDIA, State and UT Energy Departments, and State Transmission Utilities.
The CEA noted that India's total installed generation capacity stood at 542 GW as of May 31, 2026, including 157 GW of solar and 57 GW of wind capacity. According to Resource Adequacy studies, India's installed generation capacity is projected to reach 1,121 GW by 2035-36, comprising 509 GW of solar and 155 GW of wind. Energy storage capacity is projected at 174 GW/888 GWh, including 80 GW/321 GWh of BESS and 94 GW/567 GWh of pumped storage projects.
CEA observed that Grid-Following (GFL) inverters are currently being deployed across solar and BESS capacity. While these inverters perform effectively in strong-grid conditions, the increasing penetration of inverter-based renewable energy sources has created challenges including low Short Circuit Ratio (SCR), power system oscillations and inadequate system strength. Further additions of inverter-based renewable generation and BESS without sufficient grid-support capabilities could further reduce SCR, aggravate oscillatory behaviour and weaken overall system strength.
The issues have been discussed with stakeholders at various national forums, including the National Committee on Transmission (NCT) and Regional Power Committees (RPCs). According to CEA, GFM technology can help address these challenges by enhancing system strength and improving grid stability. GFM inverters can also provide black-start support, as they operate as a voltage source. Based on these considerations, CEA has advised that all upcoming BESS projects implement 100 percent GFM inverters.
The technical requirements attached to the advisory specify that GFM BESS must be capable of stable operation across a wide range of system strengths, including weak-grid conditions corresponding to an SCR of 2.0 or lower at the point of interconnection.
The systems are required to provide autonomous and near-instantaneous frequency and voltage support. CEA also recommends a short-term current overload capability of at least 1.5 pu for a minimum of 200 milliseconds to effectively utilise GFM capabilities. The BESS must also be capable of damping power-system oscillations within the 0.1–20 Hz frequency range.
GFM controls must remain operational whenever the BESS is connected to the network and must not change operating mode during network disturbances. The controls must also coordinate with current limits and other plant-level controls to avoid adverse interactions and maintain stable operation.
The advisory places significant emphasis on fast grid-support capabilities. GFM BESS must provide active power support against rate-of-change-of-frequency (RoCoF) conditions, with the facility designed to maintain the required active-power response for at least five seconds. The maximum response time following the start of a RoCoF event is specified at 5 milliseconds.
For voltage disturbances, the BESS must respond to both balanced and unbalanced voltage events, including undervoltage and overvoltage conditions resulting from faults. It must remain connected within the applicable low-voltage ride-through and high-voltage ride-through requirements. Reactive-power reaction time is capped at 5 milliseconds, with a response time of not more than 30 milliseconds following a voltage change.
The GFM BESS must also withstand a momentary voltage phase-angle jump of up to ±60 degrees at the point of interconnection without disconnecting or interrupting operation. Active-power reaction time following such a phase jump must not exceed 5 milliseconds, with a response time of not more than 30 milliseconds.
CEA has specified that GFM BESS with an aggregate capacity of 50 MW and above must be capable of providing black-start support. The capability will be utilised by the appropriate Load Despatch Centre based on system requirements and must be demonstrated during commissioning and periodically verified through testing.
The advisory also requires BESS to be capable of participating continuously in Automatic Generation Control (AGC) on a 24x7 basis. Systems must support seamless bidirectional power operation and frequent charging and discharging reversals within their rated operating limits, with no cooling period required between charging and discharging operations or between cycles.
Under normal system conditions, BESS is expected to operate at approximately one to two equivalent full charge-discharge cycles per day, while retaining flexibility for additional cycles based on grid requirements, ancillary services, reliability support, congestion management or emergency conditions. Developers must ensure that battery cycle life, energy-throughput capability and performance warranties are adequate for the anticipated utilisation over the project's design life.
The advisory also requires continuous communication of key parameters, including State of Charge (SOC), cycle count and State of Health (SOH), to the Load Despatch Centre's AGC/SCADA system. GFM control systems, inverter parameters and damping functions must be designed and tuned for stable operation, with compliance demonstrated through appropriate RMS and EMT studies and closed-loop testing.
please contact: contact@energetica-india.net.
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