By Myrna M. Velasco – December 5, 2016, 10:01 PM
from Manila Bulletin
As explosion at its substation was directly tagged as the cause of the November 15 rolling brownouts, system operator National Grid Corporation of the Philippines (NGCP) was directed to review and assess the operation and specifications of its protection systems so it will not trigger another round of pestering service interruptions in the future.
This has been contained in the memorandum submitted by the investigation body to Energy Secretary Alfonso G. Cusi, summing up the incident report relating to last month’s power outages.
In the report, it was specified that “the explosion of the San Jose substation capacitor bank 1 power circuit breaker (PCB) CB04 is deemed the root cause of the Luzon grid significant incident on November 15, 2016 which resulted in the severe voltage dip and frequency anomalies which caused the tripping of several power plants, and the actuation of ALD (automatic load dropping) and MLD (manual load dropping) to stabilize the system frequency.”
As an aftermath of that incident, it has been recommended that NGCP shall “review fault clearing time of protection settings and should be consistent with the fault clearing time allowed by the Philippine Grid Code.”
The grid operator was further asked “to conduct an assessment of the main protection of all capacitor banks.” It was noted that the failure of its redundancy protection system to isolate the November 15 incident had been due to ‘not apt specification’ of its equipment.
NGCP was similarly urged “to conduct an accounting and review of PCB’s specifications for capacitor banks in the Luzon, Visayas, and Mindanao grids to ensure that the PCBs currently installed are definite-purpose PCBs with pre-insertion resistors consistent with its network protection philosophy Section 10.0.”