KORONADAL CITY (MindaNews/31 October)— The recent series of “red alerts” in the Mindanao grid is due to a generation deficiency caused by the scheduled maintenance of some power plants, and the unexpected shutdown or reduced capability of others, Cynthia Perez-Alabanza, National Grid Corp of the Philippines (NGCP) spokesperson explained in a statement late last week.
“Red alert” refers to the system condition when the contingency reserve is zero or a generation deficiency exists, while a “Yellow alert” is a system condition where 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.
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,” Alabanza said.
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.
“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,” she noted.
NGCP maintained the situation was isolated, and it is expected that the supply situation will normalize once the plants on scheduled or emergency shutdowns are back and synchronized to the grid.
Based on NGCP’s power outlook as of 6 a.m. today (Monday), the system capacity of the Mindanao grid stood at 1,276 megawatts (MW), with a system peak load of 1,067 MW, or a reserve of 209 MW.
Meanwhile, the five-hour power outage in nearby General Santos City and Sarangani province until Sunday evening was reportedly caused by a coconut tree that fell between two towers, another NGCP official said.
Milfrance Capulong, NGCP Mindanao regional corporate communications officer, said the power blackout started at 3 p.m with the tripping of the Matanao-GenSan 138 kilovolt (kV) line.
“A coconut tree fell in between tower numbers 38-39…clearing works were completed and power restored at 8:20 [p.m.],” she said in a text message.
The affected line is located in Barangay San Pedro, Kiblawan town in Davao del Sur.
Capulong did not say why the coconut tree fell on the transmission line. (Bong Sarmiento/MindaNews)