Owing to the extreme tightness of supply, power utility giant Manila Electric Company (Meralco) announced that it has implemented rotational blackouts of two-hour duration, initially affecting parts of Cavite and Laguna, as well as key cities in Metro Manila, including Marikina, Novaliches, Paranaque and Makati.

This developed as the National Grid Corporation of the Philippines (NGCP) said forced outages and de-rating of power plants that took out more than 1,350 megawatts of capacities in the system plunged Luzon grid into "red aler"’ on Monday, May 8.

NGCP raised ‘red alert’ status in the grid between 1:00-4:00pm; then from 6:00-8:00pm on Monday (May 8) – entailing extreme insufficiency of power reserves in the system, hence, it directed relevant distribution utilities (DUs) like Meralco to prepare for the activation of participants in the interruptible load program (ILP) in case strain on supply would worsen.

“Five power plants are on forced outage; while three others are running on derated capacities, for a total of 1,354MW unavailable to the grid,” the system operator stated, adding that “a red alert is issued when the operating margin is insufficient to meet the transmission grid’s regulating and contingency requirement.”

The power generating assets on unplanned shutdowns had been unit 1 Calaca coal-fired power plant; units 1 and 4 of the Binga hydropower facility; and units 1 and 2 of the Masinloc coal-fired power generating facilities – which shaved off at least 940MW of supply from the grid.

Additionally, it was reported that the generation capacity of Sual plant’s unit 1 had been extremely de-rated at 67MW; and Sual unit 2 at 227MW – from their original capacities of 647MW each.

The other generating facilities with de-rated or reduced scale of electricity production had been unit 2 of the Calaca plant at 120MW from 300MW capacity – bringing the total reduced capacity to 414MW.

Based on information gathered from the ground and as affirmed by the Electric Power Industry Management Bureau of the Department of Energy (DOE), the forced outage of the Masinloc plant had been due to ‘balancing problem’ in the system of NGCP which triggered the tripping of its Masinloc-Bolo line 2 transmission facility.

For the Calaca facility, it was conveyed by the plant operator that “unit 1 went on emergency outage last May 1 due to boiler tube leak; while unit 2 is running on de-rated capacity due to generator vibration.”

On the Binga hydropower facility, facility owner SN Aboitiz Power (SNAP) specified that the plant is “under outside management control (OMC) outage,” which entails that there is “hydrological constraint due to the low reservoir elevation.”

This ‘red alert’ status in Luzon deviates from earlier forecast of the energy department that supply in the main power grid will not be reaching such proportion, although it qualified that the differentiating factor will be the forced outages of power plants and other technical glitches in the system.