Spain says ‘overvoltage’ caused huge April blackout

MADRID: A major power outage that paralysed the Iberian Peninsula in April was caused by “overvoltage” on the grid that triggered “a chain reaction”, according to a government report released on Tuesday.

The April 28 blackout had “multiple” causes, Ecological Transition Minister Sara Aagesen told reporters, adding that the system “lacked sufficient voltage control capacity” that day. Overvoltage is when there is too much electrical voltage in a network, overloading equipment. Potential causes include surges in networks due to oversupply or lightning strikes, or when protective equipment is insufficient or fails.

When faced with overvoltage, protective systems shut down parts of the grid, potentially leading to widespread power outages. Aagesen singled out the role of Spanish grid operator REE and certain energy companies she did not name that disconnected their plants “inappropriately... to protect their installations”.

She also pointed to “insufficient voltage control capacity” on the system that day, due in part to a programming flaw, insisting that Spain´s grid was theoretically robust enough to handle such situations. Due to these misjudgements “we reached a point of no return with an uncontrollable chain reaction” that could only have been managed if steps had been taken beforehand to absorb the overvoltage problems, she added.

Asked if the head of the grid operator should resign, Aagesen said the report was “not any kind of trial. It set out to determine the causes and to make recommendations”. Authorities had scrambled to find answers after the outage cut internet and telephone connections, halted trains, shut businesses and plunged cities into darkness across Spain and Portugal as well as briefly affecting southwestern France.

Prime Minister Pedro Sanchez announced the formation of an inquiry commission led by the ecological transition ministry shortly after the blackout, urging residents not to speculate until detailed results were available.

He had warned that the probe´s conclusions could take several months given the complexity of the incident. The government, which has been mired in a corruption scandal involving a close aide of Sanchez, sped up the timeline in recent days.