THE NATIONAL Grid Corp. of the Philippines (NGCP) placed the Luzon grid on yellow alert Tuesday, citing the unavailability of over 1,500 megawatts (MW) due to four unplanned outages and reduced output at three plants.

When reserves fall below minimum levels, the system operator issues a yellow alert. The grid was under this status between 10 a.m. and 11 a.m., and 12 p.m. and 1:10 p.m.

In a Viber message to reporters early Tuesday, the NGCP said four-fired coal plants with a total capacity of 1,458 MW went on forced outage. These include the 460-MW plant run by Quezon Power Philippines Ltd.; Unit 1 of a plant operated by GNPower Mariveles Energy Center Ltd. Co. which took 316 MW off the grid; Unit 2 of the Sem-Calaca Power Corp. plant which removed 300 MW; and a unit of a coal-fired plant in Pagbilao, Quezon which took out 383 MW.

Meanwhile, it added that three plants were operating on de-rated or reduced capacity during this period, removing 64 MW from the Luzon grid. TeaM Energy Corp.’s Sual Unit 2 accounted for 57 MW, while units 1 and 3 of Southwest Luzon Power Generation Corp. plant were de-rated by 7 MW.

Early in the afternoon, NGCP lifted the grid’s yellow alert status due to “low actual system demand.”

When the grid’s reserves dipped below ideal levels Tuesday, distribution utility Manila Electric Co. (Meralco) said participants in the interruptible load program (ILP) expressed their willingness to voluntarily de-load from the grid.

“As of 1:00 p.m., 83 establishments or 52% from the total participants, with a load of 165.94 MW had committed to participate, if needed,” Meralco Vice-President and Head of Utility Economics Lawrence S. Fernandez told BusinessWorld.

The ILP was not activated, however, he said. “No participant was asked to de-load since the grid was not placed on red alert,” Mr. Fernandez added.

The ILP allows large power users with their own generating facilities to voluntarily not draw power from the grid when supply is tight. The Department of Energy works with distribution utilities and electric cooperatives to implement the program.

Asked to comment whether the yellow alert status could lead to higher power rates next month, Mr. Fernandez said it is still “too early to say.”

“This is the first yellow alert for the July supply month. In comparison, the preceding supply month was affected by three days of red alerts and one day of yellow alert,” he said.

Between May 31 and June 2, the Luzon grid was placed under a series of yellow and red alerts due to forced plant outages, thinning reserves and high temperatures.

Yellow alerts become red alerts if the supply-demand balance worsens, triggering rotating outages or brownouts. — Angelica Y. Yang