What is known about the role of renewable energies in the blackout on the Iberian Peninsula

The causes are still unknown and seem to be multifactorial. What role did renewables play in this blackout?

“Everything points to a combination of factors that led to the major blackout. I would like to emphasize that, personally, I do not believe that renewables were the cause of the problem. The only thing is that, due to their operation and connection requirements, they were quickly disconnected for safety reasons, which caused the energy imbalance and the outage to become even worse. It has been identified that some photovoltaic plants could have potentially disconnected 3 and 1.5 seconds before the blackout. It has also been seen that several minutes before, there was a low-frequency oscillation in the power grid, which, depending on its magnitude, could have led to the activation of grid protections. However, we still do not know for certain what caused them to disconnect. In addition, as is well known, renewable energies currently operate as grid following, which means that in order to function, they need to synchronize (rise) to the frequency of the grid, and when this is not available, they cannot enter or operate correctly.

How could something like this be prevented from happening again?

“First, in order to prevent something, we need to identify exactly what happened. But we must bear in mind that, given the high level of renewables we have, we will have to ask them to be responsible for helping the system with additional controls to support the grid, including inertia, among others; and that the option of switching from grid following to grid forming should be considered in order to help restore the grid. In addition, we would need to increase energy storage systems in the grid to ensure its continuous balance. Another important point is to reduce the energy island effect of the peninsular grid by connecting more with France or Morocco, as this greater interconnection can provide assistance in the event of problems. It should be remembered that we currently have around 5% of connections outside the peninsula, and it is usually recommended to have at least 10%.”

It can be said that the ultimate responsibility for the blackout has not been caused by renewables. We have had days during Easter week where there was more contribution of renewables in the mix and nothing happened. The fact that 15 GW of photovoltaic generation was disconnected in less than five seconds is a proven fact and probably the only 100% reliable information for now. But the reasons for the disconnection need to be checked. It seems that there have been two previous incidents, which are not yet well known, that have caused the disconnection. These incidents undoubtedly created an unfavourable situation in the grid, overvoltage, voltage dip or change in frequency, which is what caused the disconnection. Therefore, to find the origin, it is necessary to know the complete information that has undoubtedly been recorded in Red Eléctrica's substations.

The conclusion that can be drawn from all this, for the moment, is that our grid is not yet ready to support so much renewable generation and that it is still necessary to rely on so-called ‘firm’ generation that provides inertia and stability to the system, such as hydroelectric, gas and even nuclear. It is clear that the future lies in renewable generation but the problem is that before we run we should know how to walk and the deployment of new renewable plants is outpacing new grid management policies. It should be better coordinated.

To avoid such problems in the future, several things are needed. Firstly, it is essential to improve the transmission grid, as there are many nodes in the grid that are saturated and any small disturbance can be a problem. Secondly, the system must be provided with adequate flexibility mechanisms that allow efficient management of possible contingencies by creating incentive mechanisms for generators that provide flexibility services. Thirdly, it is necessary to improve storage by means of pumping and batteries, given that this is a minority in our country, as well as interconnections with our neighbours. And fourth, grid codes need to be updated to allow renewable plants to participate in the system's flexibility mechanisms.