A "test" amidst heatwave’s peak

In late May 2026, northern Vietnam experienced a widespread heatwave, with temperatures exceeding 40 degrees Celsius in many areas. This extreme weather led to a sharp increase in electricity demand.

According to the National Power System and Electricity Market Operation Company (NSMO), from May 23rd to 28th, electricity demand nationwide and in the Northern region continuously set record levels in terms of power and consumption, with the Northern region recording an increase of over 25% compared to that of the same period in 2015, indicating a significant increase in power supply pressure during this year's heatwave.

PTC1 staff enhancing inspections and monitoring of equipment and transmission line corridors to ensure safe operation of 500kV power lines during peak hot weather. Photo: Ng. Tuan

Specifically, on May 25th, the national power system's peak capacity reached 57,120MW (at 1:40 PM). On May 26th, this figure increased to 58,103MW, and by May 27th, it reached 58,039MW. Similarly, total nationwide electricity consumption on May 25, 26, and 27 reached 1.171 billion kWh, 1.212 billion kWh, and 1.217 billion kWh, respectively. The figure recorded on May 27 marked the highest level of electricity consumption ever recorded in Vietnam's history.

In the North, the region directly affected by the heatwave, the peak power demand on May 27th reached nearly 30,000MW (an increase of over 6% compared to the peak in the same period of 2025), while power consumption reached approximately 631 million kWh (an increase of over 9% compared to the record in 2025).

When the load surges, the challenge lies not only in having sufficient power, but also in delivering power to areas in most need n. According to NSMO, despite the significant load increase during the recent heatwave, the national power system has remained safe, stable, and continuous; the voltage at system nodes and the load levels of equipment are all within permissible operating limits.

Expanding the transmission capacity between North and South Vietnam.

The recent heatwave is also an opportunity to test the effectiveness of the Quang Trach – Pho Noi 500kV circuit 3 transmission line after nearly two years of operation.

The transmission line is over 500 km long, passing through 9 provinces and cities (before the administrative unit merger). This is not only a large-scale power transmission project, but also a strategically important project for national energy security in the current period. Energized in September 2024, the project has contributed to increasing the transmission capacity on the  North-South 500kV power "highway" to nearly 5,000MW, almost double the previous capacity.

Technical solutions such as thermal imaging and equipment monitoring using enhanced technology being implemented to detect potential incidents on power transmission grid early. Photo: Ng. Tuan

For many years, the North has consistently had one of the highest load growth rates in the country. Meanwhile, many large-scale power sources, especially renewable energy sources and some gas-fired power plants, are more concentrated in the Central and Southern regions. Therefore, putting the  Quang Trach – Pho Noi 500kV circuit 3 transmission line into operation has created more operating space for the system, enhancing inter-regional power transmission capacity and increasing flexibility in dispatching. As a result, the system has more opportunities to effectively mobilize power from the Central and Southern regions to support the North.

Despite electricity demand continuously reaching record highs during heatwave at end of May 2026, national power system maintained safe and stable operation. Photo: Ng. Tuan

Also, according to data from Power Transmission Company No. 1, at the time of maximum transmission on the  Central-North 500kV corridor, circuit 3 alone at one time accounted for about 56% of the total transmission capacity on the route, showing the project's increasingly clear role in the national power system's operating structure.

From May 23rd to 27th, the transmission capacity on the Quang Trach-Pho Noi 500kV circuit 3 line consistently reached approximately 2,500MW, with an average daily electricity transmission volume of about 520 million kWh/day from Central Vietnam to Northern Vietnam.

At 1:20 PM on May 27th, when the peak power demand in the North reached 29,966MW – the highest level ever – the Northern power system was operating under extreme strain. With available power sources in the North being maximized and electricity imports increased, the amount of power transmitted from the Central region to the North via the 500kV corridor, especially circuit 3, continued to play a crucial role in maintaining power reserve for the system.

500kV substations play crucial role in receiving and transmitting electricity from central and southern regions to support northern region during peak load periods. Photo: Ng. Tuan

The operation of the power system during the recent period of extreme heat has clearly highlighted the important role of the Quang Trach–Pho Noi 500kV Circuit 3 Transmission Line in strengthening the national transmission network. The project has significantly improved power transfer capacity, helping ensure a stable power supply for Northern Vietnam during periods when electricity demand reached unprecedented peak levels.

Translator: Nguyễn Thị Lan Anh