Mindanao grid still on yellow alert; 11-hour outage to hit South Cotabato Sunday

KORONADAL CITY (MindaNews/05 Nov)—The Mindanao grid remains on “yellow alert” as of Saturday as power supply reserve in the island dropped due to ongoing maintenance shutdown operations by the producers, a company official said.

Milfrance Q. Capulong, National Grid Corp. of the Philippines (NGCP) corporate communications officer for Mindanao, said they were not advised when the maintenance operations would end that would allow the return of sufficient reserve for the island.

“We’re still on “yellow alert” with the reserve power supply becoming thinner,” she said in a phone interview.

A yellow alert is a system condition where the total of all reserves is less than 13.2% of the required capacity. When system reserves are more than sufficient to meet the reserve requirements of the grid, the system is considered to be under normal condition. The system alert, and the corresponding power curtailment, if any, is lifted once demand recedes or once there is enough available capacity coming into the grid from the power plants.

Meanwhile, majority of South Cotabato and parts of Sultan Kudarat will experience an 11-hour power outage Sunday.

Santiago Tudio, South Cotabato Electric Cooperative (SOCOTECO) I manager, said the NGCP scheduled the power shutdown for the Tacurong-Koronadal-Surallah 69 kilovolt (kV) transmission line from 6 am to 5 pm.

The NGCP will install scaffoldings in preparation for the last stringing portion and dismantling of the existing 138 kV transmission line, Tudio said in a report from the regional office of the Philippine Information Agency.

The SOCOTECO I will also implement maintenance work while the NGCP personnel do their task, Tudio said.

SOCOTECO 1 covers this city and the municipalities of Banga, Norala, Surallah, Sto. Niño, Lake Sebu, T’boli, and Tantangan in South Cotabato and Lutayan in Sultan Kudarat province.

Amid the “yellow alert” system in the Mindanao grid, Capulong said tomorrow’s blackout in the coverage area of the SOCOTECO I is not an offshoot of a power curtailment but a pre-scheduled grid work by the NGCP.

As of the 6 a.m. Saturday, power situation outlook of the NGCP, Mindanao’s system capacity stood at 1,267 megawatts (MW) with a system peak load of 1,181 MW, or a reserve of only 86 MW.

In  last Monday’s NGCP power outlook, the system capacity of the Mindanao grid was at 1,276 MW, with a peak load of 1,067 MW, or a reserve of 209 MW.

NGCP is the private operator of the country’s transmission network.

During periods of generation deficiency, NGCP implements the Mindanao grid-wide power load curtailment to maintain the power grid’s security and reliability.

“It is NGCP’s obligation under the law and its franchise to ensure that the grid operates at an optimum level with due consideration for safety, security and reliability,” NGCP spokesperson Cynthia Perez-Alabanza said in an earlier statement.

The level of curtailment is based on the Mindanao generation deficiency matrix issued to the NGCP by the Power Sector Assets and Liabilities Management (PSALM) Corp and the National Power Corp (NPC), Alabanza said.

The NGCP does not, by itself, determine which franchise area or distribution utility gets what portion of the available supply, she said, adding they only follow the matrix supplied to them by PSALM/ NPC.

Beginning October 19, NGCP implemented load curtailment based on PSALM/ NPC’s matrix when available reserve energy levels dropped to negative 12MW, and persisted until October 24 when reserves were at negative 45MW, according to Alabanza.

Owing to the negative reserves attributed to the scheduled maintenance of some power plants, and the unexpected shutdown or reduced capability of others, the NGCP had declared a series of “red alerts” in the Mindanao grid.

“Red alert” refers to the system condition when the contingency reserve is zero or a generation deficiency exists

“Grid conditions improved to a yellow alert status on October 25, the day one of the plants on scheduled maintenance went back online. Still, the reduced capability of other plants led to a situation where the available reserves were insufficient to meet the grid’s required contingency,” Alabanza said. ( Bong Sarmiento/MindaNews)