First investigations into the root cause of the Iberia blackout on 28 April revealed that Spain’s high-voltage grid suffered more power generation disruptions than previously known, ahead of the country’s largest ever blackout. Environmental Transition minister Sara Aagesen said on 5 May “We are seeking to identify the plants where the generation collapsed and why this happened”.
A statement by Eurelectic, the association that represents the common interests of the EU’s electricity industry, said that there were reports of anomalous oscillations in the high voltage lines before the power shut down. These oscillations caused synchronisation failures between the electrical systems and eventually ended in disturbances across the interconnected European network. However the Spanish system operator was able to rule out cyber attack as the cause.
Some reports have suggested that the Spanish system was tied to too much renewable energy at the time of the failure. Virginia Tech professor and director of the Power and Energy Centre, Ali Mehrizi-Sani, whose team is carrying out research aimed at ensuring grids can endure higher amounts of renewables, commented that such reports still need to be fully investigated, but it could be a contributing factor. However, he said, “The main issue is not the generation source itself, but how that generation source is controlled. Renewables introduce a new paradigm in electric power generation – they generate power without needing large rotating masses. This means that with more renewables, the inertia of the power grid is reduced. Less inertia can make the grid more agile but also more fragile during sudden disturbances.” His team is using control modes referred to as grid-forming controls. These help renewables mimic the stabilising effect of traditional generators. An expert panel is being set up by ENTSOE-E to investigate the incident.
