NRPC Flags Grid Stability Risks After Multiple Renewable Generation Loss Events

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					</table>The Northern Regional Power Committee (<a href="https://nrpc.gov.in/" target="_blank" rel="noopener">NRPC</a>) has directed renewable energy developers, inverter original equipment manufacturers (OEMs), and power project controller (PPC) suppliers to implement technical and operational improvements after repeated generation loss events.
These events have exposed weaknesses in the performance of several large solar and hybrid projects during grid disturbances.
NRPC recently discussed the May 13 disturbance at the Khavda Renewable Energy Park in Gujarat, which resulted in the loss of about 8,963 MW of renewable generation.
During the event, all-India solar generation declined from 69,224 MW to 60,611 MW. Grid frequency fell from 49.953 Hz to 49.398 Hz in 19 seconds, crossing the first underfrequency relay threshold of 49.4 Hz.
Tehri Pumped Storage Project and battery energy storage systems (BESS) operating in charging mode did not disconnect automatically. BESS charging was stopped only after instructions from the Northern Regional Load Despatch Centre (NRLDC), reducing system demand by about 650 MW. Tehri also reduced its pumping load after NRLDC instructions before later switching to generation mode.
Following the event, NRPC decided that BESS charging should automatically disconnect at 49.6 Hz, with a 50-millisecond delay. Tehri and other pumped storage projects operating in pumping mode should disconnect at 49.5 Hz with the same delay.
Although the Khavda event occurred in the western region, NRPC said it reinforced concerns over renewable project performance and highlighted the need for stricter compliance across the northern region.
Other Renewable Generation Loss Events
The Renewable Energy Subcommittee reviewed two other renewable generation loss events in northern India following similar disturbances in February 2026.
On April 13, 2026, about 1,100 MW of renewable generation was lost after a sharp voltage dip even though no fault was observed. On May 12, 2026, a phase-to-phase fault on the 765 kV Sikar II to Aligarh Circuit 2 resulted in another 1,500 MW of renewable generation loss. The corresponding frequency reductions were 0.16 Hz and 0.18 Hz.
Based on supervisory control and data acquisition (SCADA) and phasor measurement unit (PMU) data, NRLDC concluded that several renewable projects failed to comply with Low Voltage Ride Through (LVRT) and High Voltage Ride Through (HVRT) requirements under the Central Electricity Authority&#8217;s technical standards.
The regulations require renewable energy projects to remain connected during specified voltage disturbances and restore at least 90% of pre-fault active power within one second after voltage recovery.
Projects Failed to Recover Required Generation
NRLDC presented project-wise analyses of both events.
During the April 13 event, Azure Power Thirty Four recovered 82% of its pre-event output immediately after the disturbance, ACME Chittorgarh recovered 77%, NTPC Kolayat 86%, Rising Sun Energy 61%, NTPC Nokh Solar 86%, SBSR Power Cleantech Eleven 82%, ReNew Solar Urja 89%, Adani Hybrid Energy Jaisalmer Two 82%, and AMP Energy Park 65%. Gorbea Solar tripped completely, with generation recovery falling to zero immediately after the disturbance.
The May 12 event affected a larger group of projects. Among the affected projects, Adani Solar Energy Jodhpur Two recovered 63.64%, Clean Solar Power (Bhadla) 63.64%, Azure Maple 83.5%, Azure Power Forty One 85.27%, ReNew Solar Power Bhadla 46.95%, and SB Energy Four 82.04%.
Azure Power Thirty Four&#8217;s output dropped to zero immediately after the event. NTPC Kolayat recovered 84.98%, Avaada Sunrays 6.13%, AMP Energy Green Six 30.21%, Adani Solar Energy Jaisalmer Two Private Limited Project Two 22.35%, Nedan Solar NTPC 69.91%, and Adani Solar Park 68.75%.
Adani Hybrid Energy Jaisalmer Three recovered 74.2%, Adani Hybrid Energy Jaisalmer One 78.88%, ReNew Solar Urja 47.04%, Adani Green Energy Twenty Four 50.87%, and Renew Surya Roshni 87.15%.
NRLDC attributed the generation losses primarily to LVRT non-compliance, failure to restore active power within the prescribed time, and undesirable inverter tripping.
No Root Cause Reports
The committee noted that only Avaada and Juniper had submitted root cause analysis reports for earlier renewable generation loss events.
NRLDC also observed that developers at Khavda had submitted event data within the prescribed timelines, while compliance among developers in the northern region remained inadequate.
The committee said the non-submission of disturbance reports violates provisions of the Indian Electricity Grid Code and has delayed the identification of recurring technical issues.
It also found that project-level simulation models submitted during connectivity and first-time charging approvals frequently failed to reflect actual field behavior because they did not fully incorporate inverter protection settings and other field-implemented elements.
PMU Data Missing 
NRLDC identified widespread gaps in phasor measurement unit reporting during the disturbance events. The committee listed more than 35 renewable projects where PMU data was unavailable during one or both events. The affected projects included facilities operated by Azure Power, ACME, Adani, ReNew, NTPC, Juniper, Transition Energy, Serentica, TP Surya, and Khidrat Renewable Energy.
The absence of PMU data hampered disturbance reconstruction, delayed root cause identification, and weakened compliance assessment.
Recommendations
 The committee adopted recommendations prepared by a national panel constituted by the Central Electricity Authority to study renewable generation loss events.
Renewable energy developers were directed to improve project-wide protection coordination, validate field settings against approved studies, conduct playback studies using disturbance recorder data, maintain centralized protection databases, archive high-resolution disturbance records, and create dedicated teams for simulation studies and post-event analysis.
Inverter OEMs were asked to configure LVRT and HVRT logic in line with grid code requirements; provide at least 90% active power recovery within 1 second; prioritize reactive current support during faults; improve weak-grid performance; provide detailed electromagnetic transient models; and update firmware where required.
Power project controller suppliers were directed to improve coordination between project controllers and inverters, optimize voltage control algorithms, tune post-fault recovery, prevent controller interactions between feeders, and validate controller performance against measured field behavior.
The forum directed developers to ensure that inverter and PPC suppliers implement the recommended actions.
Transmission Constraints Continue
The committee also reviewed voltage oscillations and transmission constraints around Rajasthan&#8217;s renewable energy complexes.
Renewable energy developers have previously <a href="https://www.mercomindia.com/rajasthan-renewable-curtailment-continues-as-grid-constraints-limit-evacuation?" target="_blank" rel="noopener">raised</a> concerns about the curtailment of nearly 4 GW of solar and wind capacity due to evacuation constraints. Delays in associated transmission systems have also <a href="https://www.mercomindia.com/transmission-system-delay-stalls-evacuation-of-8-1-gw-renewables-in-rajasthan?" target="_blank" rel="noopener">affected</a> the evacuation of 8.1 GW of renewable capacity from the state.
Serentica Renewables reiterated its proposal for an interim transmission arrangement connecting the proposed Bikaner III to Neemrana II 765 kV corridor with the Sikar II to Narela 765 kV line to improve evacuation capacity from Bikaner.
The Central Transmission Utility informed the committee that it had completed the study and submitted an interim report to the Central Electricity Authority and GRID India for review. NRPC asked CTU to finalize the interim arrangement as early as possible to reduce renewable energy curtailment.
Power Outlook Raises Fresh Concerns
The Operation Coordination Committee projected a 2,756 million-unit energy shortfall for the northern region in July, equivalent to 5.1% of the region&#8217;s energy requirements.
Projected peak availability exceeded the region&#8217;s projected peak demand by about 14,700 MW. However, states were warned that energy shortages were likely during non-solar hours because of reduced hydro generation and tighter evening supply conditions. NRPC advised states to arrange power procurement in advance, as exchange availability during peak hours may be limited.
Haryana projected an energy deficit of 15.1% and a peak deficit of 15.4%, while Punjab projected an energy deficit of 14.6%.
The committee also approved a shutdown of NHPC&#8217;s Salal hydropower station from July 17 to July 26 for reservoir flushing and asked beneficiary states to arrange alternative power supplies during the outage.
Subscribe to Mercom&#8217;s real-time <a href="https://mercomindia.com/product/mercoms-renewable-energy-regulatory-updates/" target="_blank" rel="noopener">Regulatory Updates</a> to ensure you don&#8217;t miss any critical updates from the renewable industry.

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