WHILE the Terra Solar Power Project would significantly increase the country’s renewable energy mix, the National Grid Corp. of the Philippines (NGCP) on Wednesday warned that heavy reliance on intermittent power sources such as solar energy could affect the power grid’s stability.
The project has a total capacity of 2,500 megawatts (MW), supported by a 1,125-MW battery energy storage system capable of sustaining output for about four hours.
In a statement, NGCP said the project may cause fluctuations in system frequency and voltage that if not properly managed, could lead to under-frequency load shedding or rotating power interruptions in some areas.
Just the same, the NGCP welcomed renewable energy initiatives such as the Terra Solar Power Project.
“Any new power source introduced into the system will help keep supply stable. However, not all renewable energy technologies are equal. Some technologies [such as wind or solar] are, by nature, variable or supply intermittently, and therefore need to be handled more carefully,” it cautioned.
The NGCP said operational considerations must be carefully managed on both the side of the transmission, “and more importantly, on the side of the generating plant.” “Doing so will help grid stability and mitigate any fluctuations inherent in variable renewable energy sources (VREs). In addition, all required facilities on the plant side, as determined in the system impact study, must be fully complied with,” it said.
It cited a recent voltage fluctuation incident in Northern Luzon, which happened due to the unstable output of renewable energy sources in the area.
The incident highlighted how sudden variability in renewable energy generation can affect voltage levels and system stability, said the NGCP which immediately took actions to prevent further disturbances.
It said that the operational experience at the San Marcelino Solar Farm in Zambales would indicate that short-term solar variability of up to 300 MW could occur due to brief cloud cover.
“While such variability can be effectively managed with fast-acting resources, conventional generation [such as coal power plants] has limited capability to respond quickly due to longer ramping times,” the NGCP said.
“Battery energy storage systems are among these fast-acting resources, and therefore play a critical role in providing rapid support to maintain frequency stability as solar penetration increases,” the company added.
Based on a power supply agreement, the solar power project would be supplying 850 MW to the Manila Electric Co. mainly during the daytime while the remaining 1,650 MW will be injected into the grid via the Wholesale Electricity Spot Market.
The Terra Solar Power Project operates on a must-dispatch basis under Republic Act 9513, which mandates that all variable renewable energy sources, including solar farms, must be given priority in scheduling plants for dispatch into the transmission grid.
Reiterating its call on the Department of Energy for more incisive and progressive policies on the entry of VREs, the NGCP said the entry of bulk VRE should be complemented by dependable baseload and fast-ramping energy resources to ensure a stable and reliable power supply for the country.
Source: Heavy reliance on solar power may hurt grid stability – NGCP
