EDC Malitbog plant plays key role in quick end to Visayas blackout

LEYTE - The Malitbog power plant of Energy Development Corporation (EDC) played a significant role in the speedy restoration of electricity in the Visayas after the area suffered a 10-hour blackout last week.

Malitbog is the biggest power facility in EDC’s Unified Leyte plants that also include the Upper Mahiao, Mahanagdong and Optimization plants. The Unified Leyte plants are responsible for maintaining a power supply performance that ensure very high availability and reliability factors, even exceeding the company’s targets of 95.62 percent on availability and 99.43 percent on reliability, according to EDC Deputy President Richard Tantoco.

The Malitbog facility is the only plant capable of blackstarting the grid from the Leyte side and it was through the Malitbog plant that power was restored in the Leyte-Samar-Bohol-Luzon and the Leyte-Cebu lines, Tantoco said.

Initial reports still being verified said the blackout happened after a bamboo fell on the power line resulting in a line-to-ground fault. This caused the Cebu-Leyte line to trip, cutting off power supply to Cebu, Bohol, Leyte, Samar, Negros, Panay, Biliran and Siquijor provinces.

The disturbance occurred in a portion of the transmission line in Tabango town, some 28 kilometers away from the EDC geothermal complex located in Kananga town, and is beyond EDC’s area of responsibility.

Tantoco said that in spite of this ground fault, the Malitbog plant sustained the hit and still provided power to the Leyte-Samar-Bohol-Luzon grid. EDC attempted to re-energize the grid but it turned out that the line-to-ground fault had not yet been remedied. This triggered the tripping of the Malitbog plant itself and caused the transmission line to trip again.

Tantoco clarified that although the company was doing meter calibration work at that time, this had nothing to do with the blackout. He explained that the power system consists of two parallel power lines. EDC’s maintenance work, he said, was being done on Line 1 while the tripping happened along the Leyte-to-Cebu Line 2. Had there been no disturbance along Line 2, the system could have sustained the power supply even if Line 1 had been shut down, Tantoco said.

“After EDC took over the Upper Mahiao, Mahanagdong, Malitbog and Optimization plants from CalEnergy and Ormat, it has been operating the Unified Leyte plants at full capacities. We even exceeded the 130-MW capacity of the Upper Mahiao power plant, generating peak loads of up to 136 MW for this facility, which is a unique and complex geothermal plant,” Tantoco added.

EDC’s Leyte Geothermal Production Field (LGPF) supply the steam used by the Unified Leyte plants and the 112.5-MW Napocor-owned Tongonan I geothermal plant for power generation. The LGPF is EDC’s biggest steam field, accounting for close to 60 percent of the company’s total installed capacity.