Spain's watchdog reviews grid voltage control rules

MADRID (Reuters) -Spanish competition and energy watchdog said on Thursday it has updated the rules establishing power grid voltage control obligations for power plants to expand the role played by renewables plants.

The review has long been in the making and its approval is one of the measures the Spanish government recommended in its report on the causes of the massive blackout across Spain and Portugal on April 28.

The government probe said that a surge in voltage was the immediate cause of the outage.

The updated rules, most of which are 25 years old, introduce new requirements for renewable plants like solar and wind when it comes to voltage control mechanisms. That means that these plants will be able to offer voltage control services that until now only conventional power plants - thermal power plants using coal, gas and nuclear - and hydraulic generation could offer.

Until now, when grid operator REE calculated the power mix for the following day, it could only call on conventional power plants to offer the bulk of voltage control capabilities.

The new framework gives "homogeneous treatment to the service provided by both renewable energy facilities and the rest of the generation facilities," the authority said in a statement.

The review was approved last week, it said, and comes as the blame game over the blackout has intensified after discrepancies in probes carried out by the Spanish government and the country's grid operator.

While the former point to both the grid operator - for miscalculating the correct mix of energy that day - and power generators - for some conventional power plants failing to help maintain an appropriate voltage level in the power system, the latter put the fault squarely on power plants.

The update was developed following a proposal by the grid operator in 2021.

(Reporting by Pietro Lombardi, Editing by Louise Heavens)