THE National Grid Corporation of the Philippines (NGCP) issued another yellow alert for the Mindanao power grid on September 12, as several generating plants remained unavailable and continued to limit the grid’s operating margin.
The yellow alert was scheduled from 5 p.m. to 7 p.m., according to NGCP’s 8 a.m. grid status update.
NGCP reported 2,623 megawatts (MW) of available capacity against a projected peak demand of 2,456 MW during the alert period.
The grid operator said 13 generating plants were on forced outage this September, while seven other plants were operating at derated capacities.
The outages included seven plants that had been unavailable since August, four since July, one since June, two since January, one since 2025 and another since 2024.
Together with the derated generating units, the unavailable capacity reached 740.7 MW.
NGCP identified the unavailability of Mindanao’s large coal-fired generating units GNPower Kauswagan (GNPK) Units 2 and 3 as a factor contributing to the yellow alert.
“A yellow alert is issued when the operating margin is insufficient to meet the transmission grid’s contingency requirement.”
The latest declaration followed a series of red and yellow alerts that have affected the Mindanao grid in recent weeks.
On September 11, NGCP placed the grid under red alert from 1 p.m. to 8 p.m., with yellow alert periods before and after the red-alert window. The declaration reflected tight supply conditions amid unavailable generating units and rising demand.
The repeated alerts have raised concerns over the reliability of Mindanao’s available generating capacity, particularly as several plants have remained on forced outage for extended periods.
A forced outage generally refers to an unplanned shutdown or unavailability of a generating unit, which removes part or all of its capacity from the grid. When several large units become unavailable simultaneously, the remaining plants have to cover a larger share of demand and the required operating reserves.
A yellow alert, however, does not automatically mean that consumers will experience power interruptions. It indicates that the operating margin has fallen below the level required to meet the grid’s contingency requirements.
The situation becomes more critical under a red alert, when available supply is insufficient to meet the forecast demand and the required reserve.
The continuing outages have also prompted questions about the measures being undertaken to restore unavailable generating units and strengthen Mindanao’s power supply.
As of press time, NGCP had not issued a public statement detailing what specific measures it planned to undertake for generating plants that have remained on forced outage for prolonged periods, or how the grid operator planned to address recurring supply constraints associated with unavailable generating capacity.
During a private discussion with this writer earlier this week, NGCP said it planned to hold a press conference to explain the Mindanao power situation and provide the public with more information on the recurring alerts.
NGCP also assured that consumers should not be overly concerned about the current situation.
Meanwhile, the latest alert underscores the importance of monitoring both electricity demand and the availability of generating units as Mindanao continues to operate with a significant portion of its potential capacity unavailable.
Consumers are likewise encouraged to conserve electricity, particularly during peak-demand periods, as lower consumption can help ease pressure on the grid while supply remains tight. DEF
