Intermittency of Solar Power and Stability Challenges
On April 28, 2025, a massive power outage occurred in Spain and Portugal. The incident was triggered by a voltage surge in the early morning. Spain's power grid failed to absorb the surge effectively due to inadequate planning and response measures. Some power plants shut down prematurely, exacerbating the situation. Within seconds, the power supply dropped by about 60%, causing widespread disruption. The outage led to transportation paralysis and communication breakdowns.
Intermittency of Solar Power and Stability Challenges
Spain has a relatively high proportion of solar power generation in its energy mix. On the day of the blackout, the output of solar power plummeted dramatically within just a few minutes, from over 18 gigawatts to merely 8 gigawatts. The intermittent nature of this energy source led to significant fluctuations in power output, which in turn posed considerable challenges to grid frequency and voltage stability.
Moreover, less than 30% of Spain's new energy units meet the standards, and low-voltage ride-through functions are not widely installed in photovoltaic and wind power units. These units are highly sensitive to grid fluctuations, and even minor voltage oscillations can trigger protective shutdowns.
Insufficient Grid Infrastructure Exacerbates Stability Issues
Spain's grid infrastructure also played a role in the stability problem. The country has a limited energy storage capacity, with only 2.1 gigawatt-hours available, which is insufficient to buffer the impact of the volatile power generation from renewable sources.
Additionally, the grid is aging and lacks sufficient interconnections. About 40% of the transmission grid equipment has been in operation for over 30 years, and key nodes are prone to overloading and melting under extreme load conditions.
During the power outage, it was revealed that Spain's grid had inadequate voltage control capabilities. The planning and response measures were found to be insufficient, failing to absorb the voltage surge in time and leading to a series of uncontrollable chain reactions.
Lessons Learned and Measures to Be Taken
The power outage in Spain serves as a stark reminder of the impact of the increasing share of solar and other renewable energies on grid stability. Moving forward, it is crucial to accelerate the development and application of energy storage technologies to enhance the grid's ability to buffer the fluctuations in renewable power generation. Upgrading the grid infrastructure and improving its intelligence level are also essential to strengthen voltage control capabilities.
Furthermore, comprehensive power system planning and emergency response plans need to be established. Clear division of labor, enhanced coordination, and increased transparency are necessary to ensure effective responses to unexpected situations and maintain stable grid operations.