After Iberian Blackout, India Stresses Timely Transmission Rollout for RE Evacuation

Spain and Portugal’s April 2025 blackout, which cut 12,800 MW of power and left the Iberian grid disconnected from continental Europe, has prompted Powergrid to draw lessons for India’s rapidly expanding  renewable-heavy system. With India already facing 68 renewable generation loss events in three years, officials warn that insufficient reactive power, inverter failures, and poor voltage control could trigger similar large-scale disturbances unless preventive measures are enforced.

On April 28, 2025, the Spanish and Portuguese electricity grids collapsed, causing a total voltage outage and disconnecting the region from the continental European grid. These lessons are particularly relevant for India, which is undergoing a transition toward higher shares of variable renewable energy (VRE). Due to this, Spain and Portugal faced public outrage, as the country reeled from low tolerance toward grid frequency disturbances.

The Incident

At the time, Spain and Portugal were experiencing low demand alongside very high renewable penetration—82% in Spain and 91% in Portugal. Voltage fluctuations, high voltages, and low-frequency oscillations led to a sudden voltage spike. This triggered large-scale generation disconnections, which in turn worsened the overvoltage situation and caused a blackout within 20 seconds.

The outage also forced many conventional power plants offline due to both planned and unplanned shutdowns. According to Powergrid’s report, around 7,400 MW of gas and 3,000 MW of nuclear capacity went offline, taking the total outage to 12,800 MW.

Factors Behind Grid Instability

Minutes of a meeting chaired by the Secretary (Power) on August 27, 2025, revealed that insufficient reactive power and voltage control, poor damping of oscillations, and cascade tripping due to overvoltage were the root causes of the blackout. Restoration was initiated through black starts at hydro and gas stations, supported by neighboring countries. Full restoration took around 19 hours.

Sometime ago, India faced a similar situation. Grid-India noted that the Indian system has faced around 68 instances of renewable generation loss over the past three years. Several of these involved more than 1,000 MW losses in large renewable complexes, mainly due to inadequate reactive support and fault ride-through failures. Low-frequency oscillations triggered by controller interactions were also observed during high renewable generation periods. Reactive power support refers to the management and provision of reactive power to ensure the grid operates reliably and efficiently. This is typically achieved using devices like:

• Capacitor banks – to supply reactive power

• Synchronous condensers – to generate or absorb reactive power

• Static VAR compensators (SVCs) – for dynamic voltage control

Grid-India noted that compliance efforts have already improved stability, reducing the frequency and magnitude of renewable tripping events. Highlighting some past experience, the report noted, "Between January 2022 and June 2025, 68 major generation loss events were recorded. Of these, 41 occurred between January 2022 and December 2023, with the largest loss at 7,100 MW. Another 27 events occurred between January 2024 and June 2025, with the maximum loss at 4,930 MW," the report added. 

Case Study: Bhadla, Rajasthan

The study noted one such major incident in Bhadla, Rajasthan, that caused widespread grid disturbance. Following an R-B phase fault on the 220 kV Bhadla–Clean Solar Power line, about 6,157 MW of generation was lost—5,807 MW from solar and 350 MW from wind.

The fault caused a voltage dip at the 400 kV Bhadla substation, and most inverters failed to recover within one second. The subsequent reduction in generation offloaded the EHV network, leading to sustained overvoltage, further losses under high-voltage ride-through (HVRT) conditions, and tripping of multiple transmission lines. The frequency dropped by 0.7 Hz, triggering under-frequency load shedding of roughly 750 MW.

Preventive Measures for India

To prevent similar conditions, a recent Ministry of Power (MoP) meeting concluded several key recommendations:

• Stricter enforcement of VRE compliance verification at both ISTS and InSTS levels.

• Periodic testing and tuning of controllers for all grid elements.

• Timely commissioning of transmission systems for renewable evacuation.

• Augmentation of intra-state transmission capacity.

• Ensuring flexibility and adequacy of generation through the timely deployment of energy storage systems.

The report added that India is working to address challenges associated with the large-scale integration of inverter-based resources such as renewables, battery storage, electrolyzers, and data centers.