Luzon grid placed on yellow alert

MANILA, Philippines, July 12 ----- Momentary power interruptions affected around 500,000 customers of the Manila Electric Co. (Meralco) yesterday following the tripping of the San Lorenzo natural gas power plant, which resulted in the Luzon grid being placed under yellow alert.

The National Grid Corp. of the Philippines (NGCP) raised a yellow alert notice from 1 p.m. to 4 p.m. The NGCP said Luzon grid’s available capacity stood at 12,705 megawatts while peak demand was at 12,222 MW. “A yellow alert is issued when the operating margin is insufficient to meet the transmission grid’s regulating and contingency requirement,” the NGCP said.

The Department of Energy (DOE) said the San Lorenzo natural gas power plant modules 50 and 60, with 267 megawatts (MW) each, tripped at around 10:58 a.m. The agency said the tripping caused the decline in grid frequency to 58.915 hertz. “Similarly, the DOE noted that the scheduled contingency reserve is below the level of the highest unit online,” it said. Meralco said an automatic load dropping occurred due to a tripping that led to the decrease of 396 MW in its supply.

The service interruption affected customers in parts of Metro Manila, Bulacan, Cavite, Laguna, Rizal and Quezon. Meralco said power was fully restored at around 11:06 a.m. or after eight minutes. With the NGCP’s declaration of a yellow alert, Meralco activated the Interruptible Load Program (ILP) to secure de-loading commitments from its big-load customers. The ILP is an energy demand-side management program through which large-load customers are asked to use their generator sets or reduce their operations, instead of drawing power from the grid. The DOE said it was coordinating with San Lorenzo gas plant and other stakeholders on the cause of the tripping. Meanwhile, 1,897 MW were on forced outage yesterday while additional 787 MW were missing from generators with de-rated capacities.

The DOE said those on forced outage were the South Luzon Power Generation Corp. Unit 1 at 150 MW, Ilijan plant Block A at 600 MW, Ilijan Block B at 600 MW, San Lorenzo plant module 50 at 266 MW, San Lorenzo module 60 at 264 MW, Ipower 1 at 11 MW and the La Farge 2 plant at six MW.

Source: philstar.com