POWER supply in the Mindanao grid is back in a precarious state after the National Grid Corp. of the Philippines (NGCP) imposed power cuts due to supply shortage.
NGCP initially issued a yellow alert notice for the Mindanao grid due to the failure of a 105-megawatts (MW) unit of the 210-MW STEAG coal-fired power plant. A yellow alert is issued when the contingency reserve is less than the capacity of the largest Synchronized Generating Unit.
But on Wednesday morning, NGCP raised the alert level to red from yellow due to another failure of one of its ancillary service providers, the second unit of Therma Marine Inc.’s Power Barges. A red alert notice is issued by NGCP when the grid contingency reserve is zero; there is generation deficiency; and, there is critical loading or imminent overloading of transmission line or equipment.
As of Saturday morning, NGCP’s web site indicated that the Mindanao grid continues to have a power-supply shortage of 31 MW as peak demand is expected to reach 1,178 MW, while generation capacity only stands at 1,147 MW.
As declared by NGCP, the failure of one unit of STEAG’s Power Plant and second unit of Therma’s Power Barges reduced the contingency reserve for the Mindanao grid to zero, which prompted NGCP to declare it on red alert status.
Based on existing protocol, a yellow or red alert declaration requires distribution utilities to limit their power importation to a certain level called “load to maintain.” Exceeding such limit will mean automatic disconnection from the grid. Therefore, distribution utilities with “load to maintain” that is less than their actual load will resort to power curtailment or blackouts in their respective franchise areas, or otherwise face a possible disconnection from the grid.
In the case of Cagayan Power and Light Co. (Cepalco), customers within its franchise area will not experience rotating blackouts despite the red alert condition of the Mindanao Grid as its other power suppliers or independent power producers (IPPs) that were embedded in its distribution system help in bridging the power-supply gap. Among these IPPs, is the 18.9-MW diesel-fired power plant of the Mindanao Energy System Inc.
Cepalco said the recent declarations of yellow or red alerts by NGCP confirm that the Mindanao Grid has shortage of capacity necessary to provide the required ancillary services.
For those distribution utilities or electric cooperatives experiencing rotating blackouts due to red or yellow alert situations, every kilowatt-hour (kWh) not served is equivalent to about P140/kWh.
The assumption, according to Cepalco, is based on the ratio of gross national product over the number of kWhs consumed nationwide in 2010. Hence, the figures for this year could be higher.
“The number of yellow and red alerts is expected to rise as grid consumption rises, even during these times of more than enough water in the Agus basin. And if nothing is done to add to the level of reserves, next summer can be as devastating to consumers as last year’s summer if it turns out to be as dry,” Cepalco warned.
