The reason why electricity took more than 15 hours to restore 100% in Spain: the feared “Black Start”

The Iberian Peninsula went out at 12:33 of April 28. In just five seconds, two southwest disconnections of the peninsula They removed more than half of the instant demand from the network. The frequency collapsed and interconnection with France jumped by instability. Spain stayed at 0 MW and 0 Hz, never seen. Resting the service was the real challenge.

15 hours of surgical work. At 03:30 on Tuesday, Red Eléctrica, the Spanish electrical system operator, announced that 99.95% of the demand was covered again (100% was not reached until the afternoon in the afternoon).

Spain starred in greater practical exercise of replacement of a European network From the great continental blackout of 2006, The first on this scale from a country that obtains its energy mainly from renewable sources.

The dreaded Black Start. Turn on the light out of nowhere, start the zero power grid. With 50 million users, Spain has faced One of the most challenging cases of “Black Start” They are remembered.

He needed 15 hours because he had to go step by step, first starting the most flexible plants: hydroelectric plants, enabled for Black Start with diesel structure to feed pumps, valves and control systems).

Mainless Spain redeemed. With 10% of the Spanish mix and 25% of the Portuguese, the pumping hydraulics was the first ammunition: The hydroelectric plants of the Muela and Aldeadávila They synchronized in three minutes, moving from zero to 3 GW.

Each central created its 50 Hz “island” (the frequency at which the turbines have to turn) before introducing load. Red Electric was connecting the turbines one by one and introducing load in a dosing way so as not to stop them.

Gas for climbing. With the nuclear off (except for the imported of France, which provided 1.4 GW of power in the replacement), the gas plants became the backbone of the network before reincorporating renewables.

Monday’s wind was almost calm and the photovoltaic disappeared at nightfall, so the weight fell on water and gas. Morocco injected several hundred MW who were critical to start plants in Andalusia.

As for nuclear. The automatic cut of five of the seven reactors generated a radio traffic jam: the xenon-135 accumulated after a sudden stop absorbs neutrons and blocks the reaction for 24-48 h.

32 hours after the blackout, No nuclear had yet been synchronized. That 3-4 GW hole synchronous forced to squeeze hydraulics and gas and delayed total recovery.

The fuses jumped. When the blackout occurred, more than 70% of the generation was renewable (37% solar, 32% wind). 3.4 GW of nuclear energy, 1.6 GW of cycles and 1.4 GW of cogeneration provided the synchronous inertia of the network, but were not enough to compensate for the disconnection of two stations.

Neither The interconnected network was enough to sustain the frequency (only 3 GW with France and 700 MW with Morocco). The substations acted as giant fuses against imbalance and isolated the network to avoid catastrophic damage. That is why it is said that Spain and Portugal are energy islands, despite being in the same network as the rest of European countries.

Some lessons. With high renewable quotas, which They do not have the inertia of other energy sources To stabilize the network, it takes a greater resilience than the European electricity grid.

In other words, invest in investors at network level, batteries and renewable synchronous (biomass or more pumping hydraulics). As well as in better interconnections. All this is planned, but it was not on time to avoid the blackout and the Black Start.

Image | Electric Red

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