The National Grid Corporation of the Philippines (NGCP) raised yellow alerts on Thursday over the Luzon and Visayas grids, citing critically thin operating reserves following widespread plant outages and reduced generation capacity.
A yellow alert indicates that available reserves are insufficient to fully meet contingency requirements. While it does not immediately result in rotating brownouts, it signals that the grid is operating with a very narrow supply buffer.
The Luzon grid was placed under alert from 4:00 p.m. to 10:00 p.m., with available capacity at 12,223 megawatts (MW) compared to a projected peak demand of 11,966 MW.
NGCP attributed the tight supply condition to multiple factors, including the forced shutdown of several generating units and reduced output from others. In total, more than 5,137 MW of capacity was unavailable.
Among the affected facilities were Units 1, 2, and 3 of Excellent Energy Resources Inc. plant, Blocks A and B of the Ilijan plant, and four units of the Magat Hydroelectric Power Plant.
In the Visayas, a yellow alert was also issued from 6:00 p.m. to 7:00 p.m., with available capacity at 2,597 MW against peak demand of 2,368 MW. The region experienced a loss of 679.2 MW due to 15 forced outages and 13 derated power plants.
The situation was further affected by the absence of imported power from Luzon through the high-voltage direct current (HVDC) interconnection link.
Despite tight conditions in the northern and central grids, the Mindanao grid remained on normal operating status, with no alerts issued as of Thursday evening.