MANILA, Philippines - The National Grid Corp. of the Philippines (NGCP) has completed the repair of two substations located in Metro Manila, the system operator and transmission service provider said.
The replacement of transformers in the Las Piñas and Quezon City substations will ensure the availability of power supply in Manila Electric Co. (Meralco) service areas.
“System reliability and operational confidence levels have significantly improved after the said replacement,” NGCP said.
Specifically, NGCP replaced a damaged transformer at its Las Piñas substation (formerly named Zapote) 10 days ahead of schedule.
“Full restoration was done in time for the 45th Annual Meeting of Asian Development Bank’s Board of Governors in Metro Manila on May 2 to 6,” NGCP said.
On March 20, a 300-megavolt ampere (MVA) transformer at the substation malfunctioned, resulting in the automatic tripping of its 230-kiloVolt (kV) and 115-kV breakers.
“Subsequent tests revealed that the incident was due to an internal fault, with a damage that required total replacement of the winding which would take several months,” NGCP said.
Through the N-1 contingency, the NGCP said it was able to isolate the damaged transformer from the rest of Meralco system and prevented widespread power interruptions in Metro Manila.
NGCP said it transferred one of its 300-MVA transformers from the nearby Dasmariñas substation in Cavite to Las Piñas substation last month.
A spare transformer supplied by Hyundai with the same capacity replaced the transferred transformer at the Dasmariñas Substation.
“NGCP’s Las Piñas and Sucat Substations are among the five critical substations that supply electricity to Meralco’s 115-kV sub-transmission grid, which distributes power to the whole Metro Manila,” the company said.
In the south sector of Metro Manila, Las Piñas substation is looped with Sucat and Dolores substations to redirect power flow in case of emergencies. The same goes for the north sector, which relies on the looped substations of Araneta, Balintawak, and Duhat substations.
Furthermore, the grid operator said it also repaired a substation in Quezon City ahead of schedule.
“The NGCP has restored normal power delivery services to Meralco from its Doña Imelda substation,” the transmission firm said.
For the substation, NGCP replaced a damaged 115-kV Bus A Voltage Transformer at the Doña Imelda (formerly named Araneta) 115-kV gas-insulated substation on April 8.
On Feb. 9, the substation’s 115-kV Bus A Voltage Transformer broke down, which resulted to the limited delivery of power supply to Meralco.
The said equipment, also known as an instrument transformer, is used mainly for monitoring and protecting the power system.
NGCP said its technical personnel conducted repair and maintenance throughout the Lenten Season on April 4 to 8 when the power demand was low.
“These activities usually require nine days to finish under normal circumstances,” NGCP said.
The repair work included the removal of Meralco loads, shutdown of the whole 115-kV gas-insulated substation, and removal and replacement of damaged disconnect switches.