Sumatra Blackout Serves as Wake-Up Call for Power Grid Resilience

The blackout affecting Sumatra’s power system serves as an important reminder that national transmission network resilience depends not only on generation capacity but also on the interconnection system’s ability to maintain stability during disruptions. Head of INDEF’s Centre for Food, Energy and Sustainable Development, Abra Talattov, said the recovery process for Sumatra’s power system following the interconnection disturbance follows a pattern similar to major global blackouts, prioritising system stability through gradual, cautious, and measured recovery stages. ‘In large interconnected systems, the most challenging part is often the recovery process. Operators must ensure frequency, voltage, and synchronisation between generators remain stable to prevent the system from collapsing again once it starts to recover,’ Abra stated on Tuesday, 26 May 2026. He noted similar patterns in major blackouts in the United States, India, Spain, the UK, and South Australia, all triggered by transmission issues or interconnection instability. Abra cited the 2003 North American blackout, which escalated into a systemic failure causing over 100 power plants to disconnect. In India in 2012, interconnection issues spread due to regional load imbalances. Similar scenarios occurred in Pakistan and Turkey, where system operators had to carefully synchronise generators to prevent further disruptions during power restoration. According to Abra, global experience shows the recovery phase is often the most critical, as synchronisation errors during restart can trigger follow-on outages or even a second blackout. ‘If synchronisation is done too quickly before the system stabilises, generators may trip again and cause further disruptions,’ he said. ‘Operators are therefore extremely cautious during the recovery process,’ Abra added. Abra noted that the phased recovery approach for Sumatra’s power system reflects the common approach used in handling interconnected system blackouts globally to maintain stability until full supply is restored. He explained that hydro and gas-powered plants can act as fast responders in the initial recovery phase due to their quicker return to the system. However, thermal plants such as PLTU require longer time; PLN stated the process can take 15 to 20 hours from startup, synchronisation, to full operation. ‘Therefore, the public needs to understand that blackouts in large interconnected systems differ from local power outages,’ he said. ‘When a large system experiences frequency disturbances, it cannot simply be switched back on like a light switch. There must be steps for synchronisation and stabilisation to prevent follow-on issues,’ Abra added.