By Joseph B.A. Marzan
Two coal-fired power plants supplying electric power to Iloilo province claimed to have lost more than P1 million during the three-day blackouts that hit the Western Visayas region.
System disturbances which started in the afternoon of April 27 indicated an increase in power demand, and such demand caused the plants to disengage from the grid.
This was the common statement given by representatives of the Panay Energy Development Corporation (PEDC) and the Palm Concepcion Power Corporation (PEDC) to Daily Guardian when asked about the blackouts.
Both companies provide power to the Iloilo Electric Cooperatives (ILECOs) in the province. PEDC is based in La Paz, Iloilo City while PCPC is in Concepcion town in northern Iloilo.
PEDC Assistant Vice President and Plant Manager Erick Sarino narrated that they had been operating normally from morning of April 27, when at around 1:51 p.m., the system fluctuated due to a tripping in the grid.
Sarino explained that their disengagement from the grid was to protect them from an overload in the demand and allow them to return to the system once cleared.
“All [power] plants, in their design, have protection in each their equipment, that in case of overload, for example, similar to a fuse in a home system, protect them from breaking down in a surge. The same thing in plants, it protects them from overloading as well, to allow them to come back [to the system],” said Sarino in a phone interview.
“What had happened then was, when the grid was at low voltage, since it was connected to the plant, the plant also went on low voltage. The plant had to disengage to protect itself from damage,” he explained further.
PCPC Vice President for Operations Albino Kintanar’s also had a similar explanation and likened their protection mechanism to a speed limiter which protects vehicles from overspeeding.
“Our plant has what we call ‘protective relaying’, so during April 27, power voltage in the grid went down, so our system frequency went up. When the system frequency goes up to a certain degree, our generator has the tendency to trip and disengage from the grid, so that’s what happened,” Kintanar said.
“Like in a diesel engine, it has a certain speed at which it can go. When it goes too fast, that’s already overspeeding, and it’s dangerous to the machine. That’s the same with our plant, at 63 hertz, that would be dangerous to our turbine, and to protect our turbine, we had to disengage,” he added.
Both plants had no choice but to observe and monitor developments as they happened round-the-clock while awaiting a go-signal from the grid operator, the National Grid Corporation of the Philippines.
They lost their full capacity to operate during the three days of fluctuating power, with Sarino estimating that around 130 megawatts (MW) were lost from PEDC’s Units 1 and 3 plants, while Kintanar said they lost all 135 MW of generation capacity.
Their estimated losses of more than P1 million, they said, were based on the prices set by the Wholesale Electricity Spot Market (WESM).
It took the PEDC from around 4 am to 6 am to get back online and re-synchronize with the grid, while the PCPC was able to get back to the grid at around 11:49 a.m. on Sunday, April 30.
Since the fault was attributed to NGCP, both officials said they would keep their existing protection systems, and that they could not do much on their end but coordinate.
“We consider this as a disturbance from the outside. Those that are internal, like [issues] within the power plant, we can definitely address them, but outside disturbance like that, we cannot do much about that. System voltage went down a number of times, so we couldn’t do much but disengage and restart the power plant. But we are definitely looking at how we can adapt to that,” Kintanar said.
Sarino said that they would have a further assessment with stakeholders and look at their equipment before making any pronouncements on further actions.
