Plans were activated, but did not stop the blackout
Independent experts investigating the causes of the blackout that affected Portugal and Spain on April 28 indicate that plans to defend the electrical systems of both countries were activated, but “were unable to prevent the collapse of the system” in the Iberian Peninsula.
The reason why these systems failed is one of the two questions that the investigation will seek to answer. The first, however, is to know why the generation plants in Spain disconnected from the system, causing a cascade of automatic trips that knocked out the electricity supply for many hours.
These two issues are included in an update made this Friday by the network of European system operators, ENTSO-E. The entity responsible for the independent investigation praised the actions of the Spanish network operators — REE — and the Portuguese — REN — for the rapid restoration of supply, “demonstrating the preparedness and efficiency” of the companies that had the support of the French and Moroccan networks.
ENTSO-E has launched a page on its website dedicated solely to this investigation, which it promises will become an information portal for all stakeholders in the energy sector. The first report of the independent investigation, which includes Portuguese expert Albino Marques, may take up to six months to be released, but the European electricity systems network promises to publish working documents on the page for general information.
This initiative comes in a context in which the Spanish authorities are being accused (above all by the electricity companies) of a lack of transparency about what happened, invoking judicial secrecy to justify not sharing more information.
However, the president of the Spanish Electricity Network, Beatriz Corredor, has already stated that the company complied with all legal rules and procedures and that it does not anticipate the need to set aside provisions in its accounts to pay any compensation for service interruptions.
According to the preliminary survey already released by the European network, the blackout was precipitated by generation losses in Spain that represented a capacity of 2,200 megawatts (MW), generating an overvoltage and a fluctuation in the frequency of the network that spread within a few seconds to Portugal and France, countries that were importing energy from Spain. France managed to limit the contagion by automatically shutting down the interconnection. Portugal, which has a much greater interconnection capacity, was dragged along.
To date, all that is known is that the loss of generation occurred in power plants in Granada, Seville and Badajoz — it is not known which ones. And there are records of episodes of instability in the voltage of the Spanish electricity grid hours and even days before the blackout, but no causal relationship has been established between these phenomena and the massive drop in generation in southern Spain. It is speculated that the reason may be poor or insufficient management of the injection of solar power — this technology supplied more than half of the consumption at the time of the blackout — without ensuring the level of inertia essential for the stability of the system. Inertia is ensured by the rotating turbines used in conventional, thermal and hydroelectric power plants, but it can also be achieved with batteries and other devices.
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