Spain’s energy regulator CNMC has launched a short public hearing on an urgent proposal to temporarily adjust four grid operating procedures aimed at stabilising voltage fluctuations in the peninsular power system, the regulator said on Wednesday.
The move follows a request from the system operator on October 7, citing rapid voltage swings observed over the prior two weeks. While these fluctuations remained within operational limits, they posed a risk of triggering demand or generation disconnections, potentially threatening security of supply.
CNMC opened a five-day consultation to consider measures including flexible timing for the publication of the provisional viable day-ahead schedule and provisions allowing upward reserve management within day-ahead technical constraints.
An investigation by ENTSO-E’s expert panel linked overvoltage conditions to the April blackout of the Spanish grid. The event was triggered by sharp voltage rises in southern Spain, which spread to Portugal, causing a cascade of generator trips and a rapid frequency drop.
The regulator attributed the current voltage volatility to factors such as rapid programme changes, increased penetration of power-electronics-based generation concentrated in certain grid areas, limited continuous voltage regulation from some technologies, slow response times from units with continuous control, and rising self-consumption during high solar periods, which reduces observed transmission demand and increases voltage sensitivity.
CNMC described the proposed package as “exceptional and temporary,” noting that deeper analysis is ongoing alongside the rollout of a new dynamic voltage-control service under operating procedure PO7.4.
The regulator said the temporary changes aim to manage potential impacts on balancing, grid constraints, and market competitiveness while ensuring system stability.
