Saturday quake took out 1,647MW from power grid

LUZON lost a total of 1,647 megawatts (MW) when an intensity six earthquake hit on Saturday with Mabini, Batangas as epicenter, causing several power plants to trip simultaneously, the National Grid Corp. of the Philippines (NGCP) said on Monday.

“Before the earthquake occurred, the previous numbers did not show any problem,” Energy Undersecretary Felix William B. Fuentebella said on Monday in a news conference that was also attended by representatives of attached agencies and the country’s largest distribution utility Manila Electric Co. (Meralco).

The earthquake, which happened at 3:09 p.m. on Saturday, hit six power plants, causing system frequency to dip. It came at a time when other plants were also on maintenance shutdown, resulting in a total capacity loss of 2,584 MW.

First Gen Corp.’s Avion, San Gabriel and Sta. Rita plants, as well as plants operated by Sem Calaca Power Corp., and Southwest Luzon Power Generation Corp. and Bac-Man Geothermal, Inc. were the ones affected by the quake.

With the reduced power supply, electricity reserves in Luzon thinned and fell below what is required to maintain stable supply, prompting the grid operator to declare a “red alert” from 1:00 p.m. to 3:00 p.m. on Monday. The warning gave rise to the possibility of power interruptions.

As of 10: 00 a. m. on Monday, NGCP said the Luzon grid lost 2,905 MW of supply, of which 1,550 MW were due to the earthquake. It identified the affected plants as Avion’s unit two, San Lorenzo’s units one and two, as well as the Ilijan and San Gabriel plants.

NGCP lifted the red alert at 3:00 p. m. The available capacity at that time was at 9,772 MW as against peak demand of 9,351, or a buffer of 421 MW. It maintained a “yellow alert” until 4:00 p.m., citing insuff icient operator power.

The country’s power system has three layers of power reserves at any given time. Regulating reserves address the temporary variation in load and unintended fluctuation in generation. Contingency reserves are back-up generating units that can respond to changes in frequency caused by the loss of a large generating unit. Dispatchable reserves are support generating units to replenish the contingency reserve.

Ideally, supply should be 1,200 MW higher than demand after deducting regulating reserves and contingency reserves, each of which should be around 647 MW.

Meralco said automatic load dropping — the utility’s safety procedure to cut off power in certain areas when power supply is very low — was resorted to after the earthquake.

Mr. Fuentebella said consumers should still brace for supply risks but demand should ease starting Wednesday as holidays have a tendency to reduce electricity consumption, especially during Holy Week.

NGCP said its forecast peak demand remains at 9,870 MW, which it expects to happen in May. So far this year, the running peak demand was at 9,459 MW, which was recorded on March 24.

To augment power supply, the Department of Energy instructed the operation of government-owned Malaya units one and two, which has a combined dependable capacity of 450 MW.

As of 10:00 a.m. on Monday, 135 participants in the interruptible load program (ILP) have confirmed they are running their generator sets with a total capacity of 196 MW.

Under the ILP, big load customers of distribution utilities and electric cooperatives run their stand-by generation sets in times of energy supply deficiency to prevent power outages. —