Unseasonal weather leaves Vietnam’s grid with power surplus, cuts across hydropower, wind, coal

The National Load Dispatch Center (NSMO) said operations in October and November had been challenging, as storms and heavy rain disrupted hydropower management at major dams while electricity demand stayed below expectations.

Although consumption remained low, evening demand spikes between 5:45 pm and 6:00 pm created sharp fluctuations in the grid, with northern loads swinging by as much as 10,000 to 11,500 megawatts between night lows and evening peaks, the NSMO said.

Normally, October and November mark the start of the water-storage season for hydropower reservoirs ahead of the dry months.

This year, repeated typhoons forced many northern dams — including Son La, Hoa Binh, and Lai Chau — to discharge water instead, reducing available generation capacity.

Wind generation also fluctuated sharply, with output briefly surging to 3,400–4,000 megawatts during storm conditions, three to four times higher than usual, according to the NSMO.

To meet evening peaks, the operator said it had to continue dispatching coal-fired plants, including about 4,000 megawatts from build-operate-transfer (BOT) projects under guaranteed offtake contracts.

Nearly 3,000 megawatts of coal capacity in the north remained on standby, while several gas turbines and LNG units were cycled to balance output.

Despite those measures, the system continued to experience excess power during off-peak hours at night and midday.

The NSMO said it had no choice but to scale back production evenly across hydropower, wind, and other renewable sources to maintain grid safety.

The operator described the curtailments as a technical requirement to ensure stable frequency and voltage, saying cuts were made based on transparent, non-discriminatory criteria.