Minimal disruption seen in shutdown of Biñan-Dasmariñas transmission line

The National Transmission Corp.(TransCo), Manila Electric Co. (Meralco) and National Power Corp. (Napocor) firmed up yesterday measures to cushion the impact of the four-month scheduled shutdown of the crucial 230 kilovolt (kv) Biñan-Dasmariñas transmission line in the Southern portion of Metro Manila.

Transco president Alan T. Ortiz said the agreement will ensure minimal disruption of the system when the high voltage line shuts down from July 15 to Nov. 15 for its programmed uprating.

"These discussions have brought about specific measures that will be to the best interest of all parties without sacrificing the interest of power users in Luzon," Ortiz said.

Ortiz said the completion of the Biñan-Dasmariñas line upgrading will minimize the use of expensive diesel plants like Malaya. "Ultimately, unclogging this bottleneck will optimize the use of Malampaya gas by allowing the gas-fired plants of Sta. Rita, San Lorenzo and Ilijan to be dispatched at their minimum energy quantities (MEQ)," he added.

He said the foremost concern is how to meet Luzon’s projected peak demand, or the highest electricity demand at any given time, during the months that the 14.5-kilometer transmission line is being upgraded.

Based on the agreement, there will be a transfer of loads within the Meralco system, the shutdown of some of Transco’s transformers in case of overloading and the implementation of the special protection system (SPS) scheme, which will entail the automatic isolation at one end of the Meralco line to prevent the occurrence of brownouts.

Transco and Meralco will carry out the temporary shift of load of a Rockwell transformer from the south sector – which serves the areas of Urdaneta, Sucat, Sta. Rosa and Sta. Rita – to the north sector, which covers Sta. Mesa, Araneta and Balintawak. The automatic tripping of the Zapote-BF-Parañaque 115-kv line will also be implemented to relieve overloading.

As a contingency, Transco is also prepared to automatically shut down a transformer at the Dasmariñas substation should overloading occurs at the Zapote line.

"These measures will be undertaken to ensure that the 6,500 megawatt (MW) system peak demand for the Luzon region will be met without dropping of loads as a result of the implementation of the project. The special protection system will also effect optimum utilization of power generated from the Malampaya natural gas plant," Ortiz said.

The Biñan-Dasmariñas uprating complements the Batangas transmission reinforcement project, the government’s solution to decongest the clogged transmission highway in the South Luzon sub-grid.

The southern part of Luzon hosts the country’s biggest power plants, from the baseload coal plant in Calaca and the Mak-Ban geothermal plant, to the facilities running on natural gas harnessed from Palawan.

The concentration of big capacity plants in the area has put considerable strain in the capacity of the transmission network to transport this generation capacity to the major load centers in the region.

The double circuit, single conductor Biñan-Dasmariñas line currently carries a load of 300 MW. Once upgraded, its transport capacity will be boosted four-fold per circuit, enough to carry the power generated by recently-built power plants in the area.