The Department of Energy (DOE) closely monitors the power situation in the country. Based on the latest report it received, the Yellow Alert Status in the Luzon grid was lifted by the National Grid Corporation of the Philippines (NGCP) due to sufficiency operating reserves at 5:25 p.m. (Friday).
Tripping of the Pagbilao-Tayabas Transmission Line 1
According to the consolidated reports submitted to the DOE, the issuance of red and yellow alert statuses by the NGCP in Luzon started with the tripping of 230 kilovolt Pagbilao-Tayabas Transmission Line 1 at 9:04 a.m. This caused the isolation of Pagbilao Coal-fired Power Plant Units 1 and 2 in Quezon.
Other plants on forced outage at that time are: Calaca Coal-fired Power Plant Unit 2 in Batangas; GNPower Coal-fired Power Plant Unit 2 in Bataan; Masinloc Coal-fired Power Plant Unit 1 in Zambales; and, Sual Coal-fired Power Plant Unit 2 in Pangasinan. These incidents resulted in a total power capacity loss of 2,342 megawatts (MW).
At 09:53 a.m., only Pagbilao Coal-fired Power Plant Unit 2 went on line upon the availability of Pagbilao-Tayabas Line 1.
QPPL Forced Outage
At 9:57 a.m., the 456 MW QPPL Co. Coal -fired Power Plant in Mauban, Quezon tripped due to the vibration of the boiler booster pump. This resulted in an accumulated reduction of 2,416 MW of power supply in the Luzon grid.
The tripping and outages caused the initial power interruption in Luzon at that time. The Manila Electric Company (MERALCO) reported, however, that it immediately restored power supply in its franchise area at 10:04 a.m.
NGCP Issuance of Red and Yellow Alert
Because of these incidents, the NGCP issued a red alert status from 11:00 a.m. to 12:00 nn and 2:00 p.m. to 4:00 p.m. The yellow alert status was also issued covering the period of 12:00 nn to 1:00 p.m., and 4:00 p.m. to 9:00 p.m.
The derating of San Gabriel Natural Gas Power Plant in Batangas and Pagbilao Coal-fired Power Plant Unit 2 contributed an additional reduction of 422 MW. This brought the total loss of 2,838 MW capacity in the Luzon Grid.
At 12:00 noon, Interruptible Load Program (ILP) participants in the MERALCO franchise area have been advised and 68 ILP participants committed to deload a total of 111 MW.
NGCP Adjusted Alert Statuses
By 12:30 p.m., the red alert notice was lifted by the NGCP after Pagbilao U2 and San Gabriel were delivering at full capacity. The NGCP issued the yellow alert status from 2:00 p.m. to 9:00 p.m.
At 2:53 p.m., QPPL Coal-fired Power Plant went online contributing more power supply to the grid. This eventually resulted in the lifting of the yellow alert status 5:25 p.m.
The DOE reminds the consumers that “yellow alert” means operating reserves have dropped below the required 647 megawatts (MW) contingency in Luzon, 100 MW in Visayas and 150 MW in Mindanao. “Red Alert”, on the other hand, means that the reserve left on the grid is regulating reserve or equivalent to 4% of the current demand and power interruption may occur.