Official Cause Of Unprecedented Spain-Portugal Blackout Is Unveiled

MADRID, June 18 (Reuters) - Spanish grid operator Redeia disputed the findings of a government report that said failure by the operator to calculate the correct mix of energy was one of the factors that led to a massive blackout in Spain and Portugal on April 28.

Redeia operations chief Concha Sanchez also told a news briefing on Wednesday that its own investigation had discovered anomalies in the disconnection of power plants on April 28, even though voltage in the system was within legal limits, as well as an anomalous growth in demand from the transport network.

Then, in the first seconds of the blackout, a combined-cycle plant that was supposed to provide stability to the system disconnected when it should not have, she said.

“Based on our calculation, there was enough voltage control capabilities planned” by Redeia, she said. “Had conventional power plants done their job in controlling the voltage there would have been no blackout.”

The government’s report released on Tuesday said Redeia’s miscalculation was one of the factors hindering the grid’s ability to cope with a surge in voltage that led to the outage.

According to Redeia’s Sanchez, the system was in “absolutely normal conditions” at noon just before the blackout.

Redeia will release its own full report on the causes of the outage, its chair, Beatriz Corredor, told the same news briefing.

(Reporting by Pietro Lombardi, writing by Inti Landauro, editing by Andrei Khalip)