THE National Grid Corporation of the Philippines (NGCP) has lifted the red alert status over the Mindanao power grid after several hours of tight supply conditions on Monday, August 10, as available capacity recovered and eased pressure on the grid.
The Mindanao grid was placed under red alert twice during the afternoon and evening peak demand periods, from 3 to 4 p.m. and again from 5 to 8 p.m., before shifting to yellow alert from 4 to 5 p.m. and from 8 to 10 p.m.
By 9:20 p.m., NGCP said the yellow alert over Mindanao had also been lifted.
At that time, the grid had an available capacity of 2,728 megawatts (MW) against a peak demand of 2,426 MW, leaving a 302-MW margin.
“A red alert status is issued when power supply is insufficient to meet consumer demand and the transmission grid’s regulating requirement,” NGCP said.
The grid operator explained that a red alert indicates a more critical power supply condition because the available generation is not enough to cover the demand of consumers while also maintaining the required regulating reserve for the transmission system.
A yellow alert, meanwhile, is issued when the operating margin is insufficient to meet the transmission grid’s contingency requirement. Unlike a red alert, a yellow alert does not necessarily mean that supply is already insufficient to meet demand, but it signals that the grid has limited reserves to respond to a sudden loss of generation or other system disturbance. NGCP has previously described yellow alert conditions as occurring when the available contingency reserve falls below the required operating margin. For Mindanao, NGCP identified an increase in forecast system demand as the reason for the red and yellow alerts.
The red alert periods coincided with the hours when electricity consumption was expected to rise, putting additional pressure on the grid's available generating capacity.
The power situation in Mindanao also affected the interconnected Visayas grid, which experienced its own series of alerts on Monday.
NGCP placed the Visayas grid under a red alert from 3 p.m. to 9 p.m., followed by a yellow alert from 9 p.m. to 10 p.m. The grid operator cited limited power imports from Mindanao, amid high system demand, as one of the factors contributing to the alert declaration.
At 9 p.m., NGCP lifted the red alert over the Visayas grid, although the area remained under yellow alert until 10 p.m.
The Visayas grid had an available capacity of 2,389 MW against a peak demand of 2,292 MW when the red alert was lifted.
NGCP earlier said prolonged forced outages involving some of the Visayas' largest generating plants, coupled with limited power imports from Mindanao, had tightened the region's power supply.
Power grid alerts are issued by NGCP to signal the adequacy of available supply and reserve capacity. A red alert represents a more serious condition in which available power is insufficient to meet demand and the grid's required regulating requirement, while a yellow alert serves as an early warning that reserve capacity is becoming inadequate to withstand unexpected generation losses or other contingencies. DEF
