Power supply still unstable in Visayas
Power supply in the Visayas remains unstable, as damage to power generation and transmission facilities caused by the July 6 earthquake in Leyte mounts.
Geothermal plants in Leyte, which supply the Visayas power grid, tripped after a magnitude 6.5 earthquake struck near Jaro, Leyte, at 4:03 p.m. of July 6.
As of Tuesday, July 11, the National Grid Corporation of the Philippines (NGCP) in the Visayas said only parts of Leyte, Samar, Bohol and Biliran islands were getting power supply from Cebu through the Tabango-Ormoc bypass line.
“The estimate for full normalization can’t be established yet. But we are rushing everything. Simultaneous repairs and tests are ongoing,” Ma. Rosette Martinez, information officer of NGCP-Visayas, said in a text message.
She said the Visayas power grid was on “yellow alert,” a condition where reserve power is less than the capacity of the largest generating unit online.
As of 6 a.m. Tuesday, the Visayas had reserves of only 43 megawatts (MW). The largest plant in the Visayas is a 150-MW coal plant in Panay.
In its 2 p.m. July 11 advisory, NGCP said testing in its Ormoc Substation showed that all six transformers were damaged by the earthquake.
The company said it was planning to transport transformers from Cebu to Ormoc substation in order to replace the damaged transformers to be able to accommodate excess power supply from Cebu, if any, and distribute to the affected islands of Leyte, Samar, Bohol, and Biliran.
NGCP also said it was preparing, in coordination with Energy Development Corporation (EDC), for the energization of EDC’s marshalling substation.
The marshalling substation is where the power from the Malitbog, Upper Mahiao and Mahanagdong power plants is “pooled together” prior to transmitting the same from a “single point” to the islands of Leyte, Bohol, Cebu and Luzon as needed.
EDC reported to the stock exchange Monday that the marshalling station sustained visible damage, particularly to “a number of circuit breakers, current transformers and other ancillary switchyard equipment.”
In its 4 p.m. July 11 advisory, NGCP said it was prepared to provide feedback power to EDC’s geothermal plants “so that they can begin powering up.”
“Once EDC completes testing and receives feedback power, the Upper Mahiao and Malitbog geothermal plants, with a combined capacity of 129.5 MW, will be energized and ready to supply power after 16-18 hours of preparation, to be counted from the time feed- back power is received,” the advisory added.
EDC, for its part, said that as of Sunday, July 9, one unit each of both the 112.5-MW Tongonan and 232.5-MW Malitbog power plants will need to be on extended outage for repair works on damages to the structures of their respective cooling tower units.
NGCP said that once the transformers at the Ormoc Substation have been repaired and energized, together with the power coming from EDC’s in-island power plants and the supply from Tongonan power plant, 70 MW would be made available to the grid. Actual allocation will be subject to agreements made by the different distribution utilities in Samar, Leyte, Bohol, and Biliran.