Luzon grid on yellow alert as power plants forced to shut down

MANILA, Philippines — The National Grid Corp. of the Philippines (NGCP) said the Luzon power grid will be on yellow alert on Tuesday afternoon after several coal-fired power plants on the island went offline.

A yellow alert is placed over the grid when reserves fall below ideal levels. When the supply-demand balance worsens, a red alert, which points to a severe power deficiency that may lead to rotating power interruptions, is declared.

In a statement on Tuesday, NGCP reported that a total of 1,592 megawatts (MW) have been shaved off from the grid due to the forced shutdowns of coal plants. These are:

• The 460-MW Quezon Power Phils. Ltd. plant;
   
• The Southwest Luzon Power Generation Corp.'s units 1, 3 and 4 (200 MW total);
   
• The GNPower Mariveles Energy Center Ltd. Co. (GMEC) units 1 and 2 (632 MW), and;
   
• The 300-MW SEM Calaca Power Corp. (Calaca) unit 2

NGCP reported that the net operating margin of the Luzon power grid is 412 megawatts (MW). 

The grid operator did not disclose a reason for the forced shutdowns, but said that the Department of Energy (DOE) will be able to explain the cause of the outages. Hours later, NGCP said the yellow alert has been lifted since 4:00 p.m "due to receding system demand."

Department of Energy has yet to provide a statement on the matter. The story will be updated with their comments. 

Several alerts

Starting June 18, Saturday, the Luzon power grid has been placed on red alert once and on yellow alert three times. 

NGCP earlier noted a "grid disturbance" that led to the tripping of two lines which were part of the Hermosa-BCCPP 230 kiloVolt line. 

On Monday, the grid operator found that the so-called grid disturbance was caused by distribution lines of Peninsula Electric Cooperative, Inc. (Penelco) which were built underneath NGCP's transmission lines, within the operator's right-of-way.

The affected lines of the Hermosa-Bataan Combined Cycle Power Plant (BCCPP) transmission line were restored Saturday afternoon. The tripping of the lines caused rotating power interruptions in several areas in Luzon, including those under the franchise area of Manila Electric Co. (Meralco). 

In a statement, Meralco said that it had to perform an automatic load dropping, a procedure which cuts off power in certain areas when supply is low, on Saturday afternoon "due to the decrease of an approximate 1200 MW in Meralco's load."

It reported that around 1.6 million customers in parts of Metro Manila, Bulacan, Rizal, Laguna, Batangas and Cavite were affected.