Shortfalls in power supply, mainly triggered by problems on power transmission lines, extended until yesterday, resulting in rotational brownouts in the Luzon and Visayas grids.

Electricity backbone concessionaire National Grid Corporation of the Philippines (NGCP) implemented manual load dropping (MLD) or energy rationing in parts of Luzon for one hour yesterday.

It also extended the red and yellow alert status in the Visayas including Metro Cebu due to insufficient power supply as there is high electricity demand.

NGCP’s grid data yesterday showed available capacity stood at 2,568 megawatts (MW), while peak demand reached 2,413 MW, having only a thin operating margin.

The problem stemmed from NGCP’s “transmission constraints” as having affected the dispatch of large power plants, according to Energy Secretary Sharon S. Garin.

On 13 May, the 500 kilovolts (kV) Tayabas-Ilijan and Dasmariñas-Ilijan Transmission Lines tripped, causing the disconnection to the grid of the Ilijan 1 and 2 (1,200 MW) and EERI Units 1,2, and 3 (1,262.1 MW). At 0634H, Masinloc Unit 3 (325 MW) also went on forced outage. 

Garin required NGCP to provide details of the incidents, particularly the transmission outages. At the same time, it ordered San Miguel Power Group Corp. to immediately restore the tripping of its Masinloc Unit 3 turbine.

In separate statements on Thursday, the Department of Energy (DoE) and the Energy Regulatory Commission (ERC) said the directive aims to address the incidents that have disrupted electricity supply and affected millions of consumers.

“The DoE is focused on ensuring a stable power supply, protecting consumers, and enforcing accountability across the power sector,” Energy Secretary Sharon Garin said.

“The public deserves a full and transparent accounting of the incidents that led to these grid alerts, and we are requiring NGCP to comply fully with all reportorial and regulatory obligations.”

The DoE said its technical teams are independently verifying the status of affected generating units and transmission facilities to determine whether NGCP and concerned generation companies complied with dispatch instructions and restoration timelines during the alert period.

“The DoE will continue to closely monitor grid conditions in both Luzon and Visayas, assess residual supply risks, and coordinate with NGCP, the ERC, the Independent Electricity Market Operator of the Philippines, distribution utilities, and all concerned generation companies to ensure the full restoration of supply adequacy,” the agency said.

ERC Chairperson and chief executive officer Francis Saturnino Juan personally visited the System Operations Command Center to verify the condition of the country’s transmission grid.

Juan said consumers deserve “a clear and comprehensive account” of the incidents behind the alert declarations.

“Visiting the System Operations Command Center enabled us to closely observe the situation and ensure that the commission bases its actions on verified information rather than assumptions,” he said.