Transmission operator National Grid Corp. of the Philippines (NGCP) said Thursday it will implement manual load dropping (MLD), which will result in rotating brownouts once another large power plant trips in the Panay sub-grid.
The NGCP said that in order to preserve the integrity of the transmission system, NGCP implemented MLD and power in affected electric cooperatives/distribution utilities has already been restored as of 7:07PM.
The NGCP said there was an unscheduled power interruption in the Negros and Panay sub-grid at 6:48 PM Wednesday due to the unplanned outage of Panay Energy Development Corp. Unit 3 (121.11 megawatts) at 6:44 PM.
It said the unresolved internal issues of the remaining major power plants (PEDC Units 1 and 2, and Palm Concepcion Power Corp.) that precipitated the Jan. 2 power outages, qualify as a significant threat to system security following a credible N-1 event, and justifies manual intervention by the System Operator NGCP under Philippine Grid Code Section 6.2.3.4.
The NGCP earlier said it followed protocols set by the ERC in responding to the multiple plant shutdowns in Panay that led to the Panay sub-grid blackout last Jan. 2 to 5.
Based on the NGCP’s system records, the Jan. 2 incident was due to the unplanned outages of multiple power generators in Panay Island, triggered by the unexpected shutdown of PCPC, a large plant with a capacity of 135MW, and eventually cascaded to other plants in the island. Macon Ramos-Araneta
The NGCP said that while the company was ready to transmit power as early as Jan. 2, it took PCPC 59 hours to synchronize back to the grid at 1:33AM of Jan. 5.
The NGCP said section 6.2.3.4 of the Philippine Grid Code (PGC) states that in instances where there is an unplanned outage of a plant but the system remains stable, manual corrective intervention should not be imposed to anticipate the occurrence of a second event.
The company said this means that disengaging loads manually, or disconnecting thousands of households from their supply of power, as recommended by the DOE and the Independent Electricity Market Operator of the Philippines, in anticipation of a subsequent grid event, is prohibited under the rules.
Sen. Grace Poe meanwhile said the rotational blackout in parts of Western Visayas must be addressed before darkness engulfs the region anew.
The NGCP earlier warned of another blackout in Panay Island due to unresolved issues in some major power plants.
Poe, chairperson of the Senate Committee on Public Services, stressed that it is imperative for the NGCP, private firms and other concerned agencies to work double time to stem the problem, whether on the supply, generation, or transmission side.
She also cited the need to avert a repeat of the recent power outage. The rolling blackouts, Poe noted, must not be the way of life for the people. With Macon Ramos-Araneta
