The Energy Regulatory Commission issued show-cause orders to two power companies and the transmission operator as part of the investigation on the unplanned outages of power plants with a combined capacity of 3,401 megawatts on Sept. 12.
It issued the show cause orders to Team Sual Corp., Masinloc Power Partners Co. Ltd. and the National Grid Corp. of the Philippines.
ERC commissioner Floresinda Digal said five other power plants that went offline in the period gave sufficient explanation, “per initial evaluation of the submission.”
The ERC said its task force determined that on Sept. 11 at 7:52 p.m., the Bolo-Nagsaag 500-kilovolt transmission line tripped, caused by the breach of line clearance between Towers 138 and 139.
It said the task force found that a bamboo shoot helped cause the tripping of the power transformers in the Bolo substation and the Bolo-Nagsaag 400-kV Transmission Line 2.
The tripping then resulted in the overloading of the Bolo-Balingue 230-kV line, which triggered the implementation of the Northwestern II System Integrity Protection Scheme to prevent the grid from further degradation.
The ERC said TSC unit 2 tripped because of the actuation of the Northwestern II SIPS, where the unit was part of the designed action to mitigate system imbalance. However, TSC unit 1 also tripped during the grid incident.
“As directed, we will reply to the ERC order to explain our side on this matter,” TeaM Energy said.
Meanwhile, the ERC said MPPCL’s generating units are connected to NGCP’s 230 kV Bolo substation. The regulator said MPPCL’s unit 2 recorded a system voltage of up to 250 kV, which was within the allowable voltage variation and should have remained online.
The ERC said the PGC prohibits gencos from disconnecting from the grid during disturbances unless certain circumstances exist.
Meanwhile, the ERC said the bamboo shoot issue should have been prevented if NGCP had complied with the Anti-Obstruction of Power Lines Act.
The ERC ordered the two gencos to submit their response within 15 days and NGCP within 30 days why no administrative sanction should be imposed on them for possible violation of the Philippine Grid Code.