Luzon power grid on yellow alert again

MANILA, Philippines – The National Grid Corporation of the Philippines (NGCP) on Thursday, September 28, placed the Luzon power grid under yellow alert again after some power plants went offline.

"Luzon grid is on yellow alert due to the unexpected shutdown of some power plants and high forecasted demand," the grid operator announced on Thursday.

Yellow alert is a situation when reserve power falls below the required level. Reserves are inadequate to cover the largest running generating unit at the time, but this does not necessarily lead to power outages. 

The NGCP said the yellow alert notice took effect on Thursday from 11 am to noon and 2 pm to 3 pm. (READ: Luzon on power 'yellow alert' after series of earthquakes)

Luzon's available capacity stood at 10,473 megawatts (MW) as against a peak demand of 9,676 MW.

The yellow alert was eventually lifted by the NGCP at 2:30 pm of Thursday due to sufficient operating reserves and low actual system demand.

Since August 30, there have been 4 instances of yellow alerts raised.

DOE: Not alarming

But for the Department of Energy (DOE), a yellow alert notice is "not alarming."

"That is one thing we want to clarify…A yellow alert is not a deficit in supply, it is only a signal that reserves are becoming smaller
. The deficit is only in the reserves, not in the supply," Energy Undersecretary Felix William Fuentebella said.

"The red alert is the one that should be alarming
," he added. 

Red alert is raised when power demand is seen to exceed supply.

The DOE reported that the following power plants that suddenly went offline were units of Ilijan B (600 MW), Limay 7 (60 MW), Makban 5 (55 MW), and Sual 2 (647 MW).

Fuentebella said the DOE would call the attention of these power plants. "We will also audit them again."

"Some plants' capacity are derated
, but it will only cover two hours in the morning and two hours in the afternoon. It's basically thinning of reserves by about 150 MW from expected 624 MW required
," he added.

Meanwhile, the Manila Electric Company (Meralco) said it has placed its interruptible load program (ILP) on standby.

"As part of our initiative to prepare in case this deteriorates further to a red alert status, we informed participants under the ILP to be ready. As of 10 am, there is a total of 126 accounts with a load of 189.22 MW that have committed to deload, if necessary," said Meralco spokesperson Joe Zaldarriaga.

Meralco senior vice president and head of utility economics Lawrence Fernandez has expressed concern over the frequent incidence of yellow alerts.

"We are concerned. Since August 30, there has been a once-a-week incidence of yellow alert. Our concern is that while it has not led to red alerts, automatic load dropping occurs when power plants trip. This means some of the customers lose electric service because of the tripping of some power plants," Fernandez said. – Rappler.com