Spain’s energy regulator CNMC has opened a short public hearing on an urgent resolution to temporarily modify four grid operating procedures to stabilise voltage on the peninsular power system.
The move follows a 7 October request from the system operator, which reported rapid voltage swings over the previous two weeks that, while within limits, risk triggering demand or generation trips and jeopardising security of supply, prompting a cut to a five-day consultation.
And ENTSO-E expert panel investigation found overvoltage was an issue in the April blackout of the Spanish grid, which occurred when voltages in southern Spain rose sharply and spread into Portugal, triggering a cascade of generator trips and a rapid frequency decline.
The changes being proposed by CNMC including a flexible publication time for the provisional viable day-ahead schedule, allowing upward-reserve management within the day-ahead technical constraints process and others.
CNMC links the volatility to rapid programme changes, growth of power-electronics-based generation concentrated on parts of the grid, limited continuous voltage regulation by some technologies, slow responses from units with continuous control, and rising self-consumption that lowers observed transmission demand during high solar periods and heightens voltage sensitivity.
Given potential impacts on balancing, constraints and market competitiveness, the package is framed as exceptional and temporary while deeper analysis proceeds and the new dynamic voltage-control service under PO7.4 rolls out, it said.