ENERGY SUPPLY | Workers work on a transmission station of the National Grid Corp. of the Philippines in Navotas. (INQUIRER FILE PHOTO)
MANILA, Philippines — At least half a million power consumers in Metro Manila and its nearby regions of Central Luzon and Calabarzon (Cavite, Laguna, Batangas, Rizal, Quezon) experienced brief power interruptions on Tuesday afternoon after a transmission line tripped in a natural gas-fired plant in Batangas province.
This prompted the National Grid Corp. of the Philippines (NGCP) to issue a yellow alert status in Luzon from 1 p.m. to 4 p.m., as available capacity in the grid was at 12,705 megawatts (MW) while peak demand stood at 12,222 MW.
NGCP raises the yellow alert status when the operating margin is not enough to meet the transmission grid’s regulatory and contingency requirements.
This means there is a low electricity supply because the power grid’s power reserve is below the required level. Yellow alerts do not necessarily lead to power outages.
Meanwhile, a red alert is raised when the power supply is insufficient to meet consumer demand and the demand will most likely outstrip available generating capacity and cause power outages.
Low reserves
The Department of Energy (DOE) said the tripping, or power line failure, was reported in First Gen Corp.’s San Lorenzo natural gas plant modules 50 and 60, which have a combined capacity of 534 MW, in Batangas on Tuesday morning.
“Similarly, the DOE noted that the scheduled contingency reserve is already below the level of the highest unit online,” the agency said in a statement.
The line failure decreased the supply of power distributor Manila Electric Co. (Meralco) by 398 MW, resulting in an eight-minute automatic load dropping, or service interruptions due to abnormal grid conditions, in parts of Metro Manila and the provinces of Bulacan, Cavite, Laguna, Rizal, and Quezon.
The incident comes a day after Meralco assured its customers that it was not expecting any yellow alerts to be raised within this week even as the threat of the El Niño weather phenomenon loomed.
Redirection
To augment supply, the company said it activated its Interruptible Load Program (ILP) that would allow its big-load customers to temporarily disconnect from the national grid by using their own generators.
ILP, a voluntary demand-side program, is critical in times of red alerts, or when power reserves are at a low and cannot meet demand, it said.
Meralco’s ILP capacity is at 616 MW. This could be redirected to thousands of households to spare them from power interruptions.
The DOE power bureau said the yellow alert status was lifted as the San Lorenzo power plant returned to normal operations at 4 p.m. on Tuesday.
The plant is among the natural gas-fired facilities run by the Lopez family-led First Gen Corp. that rely on output from the depleting Malampaya gas field off Palawan province for supply.
These power plants — Santa Rita (1,000 MW), San Lorenzo (500 MW), San Gabriel (420 MW), and Avion (97 MW) — supply a fifth of the country’s power requirements.