Customers of Manila Electric Co. suffered a 15-minute rotating blackout Monday, after 2,196 megawatts of power capacity in the Luzon grid went offline at 3:14 p.m. amid soaring temperature.
Power supply in the affected areas of the Meralco franchise was restored at 3:29 p.m.
“At around 3:14 pm [Monday], an automatic load dropping occurred when Sual unit 2 [647 MW] tripped out due to still undermined cause,” Meralco spokesman Joe Zaldarriaga said.
Unit 2 of the Sual coal plant allegedly tripped due to “boiler feed pump” and was expected to be back online Monday midnight.
Therma Mobile Inc.’s unit 3 with a 67-MW capacity also tripped.
“Yellow alert is still in effect,” Zaldarriaga said as of 4:30 p.m. Monday.
A yellow alert means the grid has a limited or thin reserve power, according to Energy Secretary Zenaida Monsada.
Affected areas included parts of Quezon City, Muntinlupa, Las Pinas, Manila, Malabon, Caloocan, Valenzuela, Navotas, Pasay City, Parañaque and Manila.
Monsada told reporters more than 861 MW of capacity were on scheduled planned outage while the other plants went on unplanned shutdown Monday, including Sual (647 MW), Therma Mobile (67 MW) and Calaca (300 MW).
Monsada said Luzon had a forecasted demand of 9,179 megawatts amid high temperature, although the actual demand reached only 8,808 MW, while available capacity stood at 9,885 MW.
She said the regulating reserves, which were critical to grid stability, already included the projected capacity, but the contingency reserve of about 647 MW was not met.
“Our team is currently assessing the power supply situation by closely coordinating with the National Grid and the power plant owners/operators in Luzon, Visayas and Mindanao to make sure that the generating facilities which are currently on maintenance shutdown will be back online ahead of the election period,” Monsada said.
Monsada said the plants on maintenance shutdown were expected to return online by end of April.
The energy chief said some power plants went on planned outages to ensure they would be reliable and running during the election period.
She said the department had alerted the Power Sector Assets and Liabilities Management Corp., the operator of the 600-MW Malaya diesel power plant to run the generating facility if needed, in an effort to augment the power supply.
The Malaya plant, however, was forced to run after the Sual plant went offline and participants of the interruptible road program were not tapped because demand went down Monday afternoon.
“I hope there is no need to run Malaya because diesel is expensive,” Monsada said.
Participants of Meralco’s Interruptible Load Program, which have a combined capacity 826 MW, can be tapped to deload from the grid during supply shortages.
Monsada said she expected the 300-MW Calaca unit 2 which suffered from turbine problem and Therma Mobile’s units 5 and 6 totaling 119 MWwould be back online Monday night .
The Sual plant is not expected to come online anytime soon.
Other plants under scheduled maintenance are the 382-MW Pagbilao unit 1, 190-MW Magat hydropower plant and 145-MW San Roque unit 3.
Some geothermal power plants operated by Energy Development Corp. are also undergoing maintenance since January.
