The sudden forced outages at the units 1 and 2 generating units of the Kalayan hydropower plant in Laguna past 4:00pm on Tuesday served as the final trigger to the rotational brownouts that had been scheduled in some provinces in the Luzon grid.

By 4:15pm, system operator National Grid Corporation of the Philippines (NGCP) apprised the media that manual load dropping or rotational brownouts had already been implemented and had affected the consumers of Benguet Electric Cooperative in Baguio City and Benguet; then parts of the service areas of Ilocos Sur Electric Cooperative, Nueva Ecija Electric Cooperatives 1 and 2 as well as Aurora Electric Cooperative.

As of press time, there are no exact figures yet on the number of customers affected and on the scale of megawatts dropped on power supply to customers.

In the franchise area of Manila Electric Company (Meralco), no reports yet of rotational brownouts schedule as of 5:00pm; although red alert for Luzon grid has been extended until 11:00pm.

“Red alert status in Luzon has been extended due to the outage of 2 additional plants, Kalayaan 1 and 2 at 180MW each. Manual load dropping was first implemented at 4:15pm with rotational power interruptions affecting parts of northern Luzon,” the grid operator stated.

Earlier in the day, NGCP indicated that the brownout warnings at 2:00-3:00pm for Ilocos Norte Electric Cooperative, Isabela Electric Cooperative, Cagayan Electric Cooperative, Batangas I Electric Cooperative and Olongapo Electricity Distribution Company, did not materialize because supply held on during those peak demand timeframe.

And as earlier announced by NGCP, red alert hours on power supply will still be sustained at prime time hours of 6:00 to 9:00pm – and that had been precipitated by the forced outages of 21 electric generating units in the Luzon grid, including the latest sudden downtime of the Kalayaan plant’s two units.

A red alert, in particular, is declared by system operator NGCP when the reserves requirement in the system would fall below 4.0 percent vis-à-vis projected peak demand.

The power grid operator emphasized that “19 power plants are on forced outages; while three others are running on derated capacities, or a total of 2,117.3 megawatts unavailable to the grid.”

Apart from that, yellow alert or a state of power reserves insufficiency had also distressed Luzon grid from 1:00pm to 2:00pm; then will keep on at 4:00 to 6:00pm and 9:00 to 11:00pm; while the same yellow alert has also been raised for Visayas grid from 2:00 to 4:00pm and 6:00 to 7:00pm.

For Visayas, NGCP noted that “12 power plants are on forced outages; while five others are on derated capacities for a total of 676.5MW unavailable to the grid.”

Plant outages

Based on data from NGCP, the electric generating units suddenly taken out from the system in the Luzon grid due to forced outages have been those of Masinloc 1; Southwest Luzon Power Generation Corp 2; Santa Rita plant module 40; Binga 1, Binga 4, Ambuklao 1 and 2; Bakun 1 and 2 units; Maris 1 and 2 units; the generating unit of the National Irrigation Administration; Bineng plant; Irisan;  Pagbilao units 1 and 2; VS Gripal plant and BT 2020 generating units.

From the forced outages of the generating facilities, it was reported by the grid operator that there was a loss of aggregate 1,811.3 megawatts in the system.

On top of that, there are also three major plants with capacity de-rating (reduced power generation) of at least 306MW - including those of the South Luzon Thermal Energy Corporation units 1 and 2; as well as the Ilijan Block A generating unit.

For Tuesday (April 16), the estimated peak demand for Luzon grid was at 13,024 megawatts; while available capacity was extremely tight at 13,537MW.

In the Visayas grid, peak demand forecast was at 2,440MW; while available capacity had been pegged by the system operator at 2,742MW.

The plant outages in the Visayas grid have been: San Carlos biomass plant; HPC cogeneration plant; Victorias Milling Co. plant; Palm Concepcion Power; Power Barges 101 units 2 and 3;  South Negros BioPower Plant; Therma Visayas Inc. unit 2; First Farmers Holding Corp plant; and Panay diesel power plant unit 3-G; while those with de-rated capacities are the Leyte A geothermal plant; Palinpinon geothermal power plant; Cebu Energy Development Corp unit 3; Tongonan geothermal power plant and Panay diesel power plant unit 3-E facility.

As conveyed by the hydro plants, the unavailability of their capacities had been mainly due to extremely low water elevation – which is a cyclical phenomenon during summer months; and it was aggravated this time by the El Nino phenomenon.

For the Ambuklao plant in Northen Luzon, SN Aboitiz Power (SNAP) advised that the plant was already back on-line as of 3pm; while two units of the Binga hydro plant were “generating at minimum load while the other two are on shutdown.”

The company explained that “the units are on ‘outside management control’ shutdown due to fluctuating inflows,” hence the plant operator will “have to wait until the reservoirs have enough water to generate; and once it falls below the threshold, we need to stop and wait for the reservoirs to fill up.”