THE National Grid Corp. of the Philippines (NGCP) continues to implement the necessary actions prior to the actual repair of one of its 138-kilovolt (kV) high voltage submarine cable in Amlan, Negros Oriental, the transmission utility, in a statement, said.
The said cable was damaged last June 15 during the dredging and re-channeling activities undertaken by the Department of Public Works and Highways (DPWH) along the town's Bio-os River.
The two circuits of the 138kV submarine cable have a total capacity of 180 megawatts (MW).
The NGCP said with the loss of one circuit due to the damage caused by the incident, the transmission capacity of the submarine cable between Negros and Cebu has been halved to only 90 MW.
The incident caused congestion along the Negros-Cebu transmission corridor affecting the Negros and Panay sub-grids, it said.
The NGCP has coordinated with concerned local government units of Amlan, the Department of Environment and Natural Resources (DENR), and DPWH regarding the incident, as well as the Department of Energy (DOE) to request their support in relation to its repair.
The unique underwater nature of the facility necessitates a pre-inspection of the nature and extent of the damage prior to actual repair, the utility said, adding that the cable’s manufacturer and service provider is currently conducting a “cut and inspection” of the submarine cable to determine this.
The statement further stated that subject to the manufacturer’s findings, target completion of repairs is estimated in February 2022 if the water ingress does not exceed 400 meters, and only 500 meters of the cable using available spares need replacement.
“Should water penetration exceed 400 meters, there is a need to replace a longer length of the cable or manufacture a new set; further extending the timeline of repair. The penetration of the water to the submarine cable is the main factor considered in determining the best course of action,” it added.
The NGCP also noted that the incident caused a steep increase in electricity prices in the Negros and Panay islands, as reported by the Independent Electricity Market Operator of the Philippines (IEMOP).
However, the Energy Regulatory Commission (ERC), in its letter to the Philippine Electricity Spot Market Corporation (PEMC) dated September 20, 2021, has instructed the latter to halt the collection of congestion charges and other applicable fees, and refund those which were collected in previous billing months until the affected line is completely restored and back to normal operations.
“Fixing damaged submarine cables is a little more complex than restoring ordinary transmission lines. We need enough time to determine the exact extent of the damage before proceeding with the actual repair,” the firm said.
“This entails diving, crane lifting, and testing activities to be performed by experts with specialized equipment. We are well aware of the difficulties this incident has caused, and we are doing all we can to expedite the process,” it added.