What are rotational brownouts?
Parts of Luzon and the Visayas experienced rotating brownouts this week following issues in the power infrastructure.
The Department of Energy reported service failures in the Ilijan-Dasmariñas and Ilijan-Tayabas transmission lines, which carry 12% of Luzon's power.
"Kapag naputol ang mahahalagang transmission lines, naaapektuhan ang daloy ng kuryente sa grid, na maaaring magdulot ng overload sa ibang linya at pagbaba ng reserve power o ekstrang suplay ng kuryente," DOE said.
These failures interrupted the supply from two major natural gas-fired power plants: Excellent Energy Resources, Inc. (1,262.1 MW) and South Premiere Power Corporation (1,200 MW). Consequently, the National Grid Corporation of the Philippines placed the Luzon and Visayas grids under Red Alert status.
Officials cited "major grid disruptions" and the maintenance shutdown of several major power plants as the primary causes. The disruptions are scheduled to spread to the central islands, leading to seven-hour power cuts, NGCP said.
Aside from preparing for possible brownouts and blackouts and keeping track of local updates, it’s also useful to familiarize yourself with the electrical terms commonly used by power regulators.
Yellow alert
As per NGCP, a yellow alert is issued when the operating margin is insufficient to meet the transmission grid’s contingency requirement. This may not cause outages as the electric power supply still meets demand, although the grid's spare supply—maintained in case of a power plant break down—is falling below safe levels.
Red alert
Meanwhile, a red alert status is more concerning. NGCP says it is the highest alert level and is issued when power supply is insufficient to meet consumer demand and the transmission grid’s regulating requirement.
When this happens, everyone is advised to check for possible power outages in their area and get their essentials ready.
Manual load dropping
Manual Load Dropping is a scheduled power interruption implemented by utility providers, such as Meralco, through a rotating schedule across different areas. Its purpose is to reduce strain on the grid when electricity demand exceeds supply to prevent the entire grid from failing and avoid a widespread blackout.
Rotational brownout
A rotational brownout is the temporary and alternating loss of electricity in certain areas while manual load dropping is being implemented. These outages can last from a few minutes to several hours.
Peak demand
NGCP defined peak demand as the highest level of electricity consumption recorded during the day, typically during 1 a.m., 2 p.m., and 7 p.m. when households and businesses run appliances all at the same time.
Call for decentralized power system
In light of the latest power outages in the country, the Institute for Climate and Sustainable Cities—a Philippine-based non-governmental organization that advances climate, energy, and low-carbon solutions—is calling on the government to pursue "decentralized, diversified, and flexible power system."
“Reserves today are sized based on the largest power plant connected to the grid. But if a single shared facility, such as an LNG terminal or critical transmission corridor, can affect multiple plants at once, then that shared infrastructure should arguably become the benchmark for reserve requirements,” said ICSC Chief Data Scientist Engr. Jephraim Manansala.
In this proposed setup, ICSP said an outage on a single facility will not put the entire power grid at risk. The NGO suggests expansion to geothermal, hydropower, solar, and wind, backed by energy storage systems to diversify the country’s power sources.
They also said the government should invest in technology that can flexibly respond to power fluctuations through battery storage systems, pumped-hydro storage facilities, and other fast-ramping generation capacity.
