According to the National Power Transmission Corporation (EVNNPT), during periods of peak load in the North, the volume of power transmitted via the four North-South 500kV transmission lines accounted for nearly 20% of the region's total electricity demand. This serves as a vital supplementary source, helping to ensure a balance between power supply and demand while meeting the needs of residents and businesses for daily life and production activities.

Maximize one's potential

Currently, the North-South interconnection system comprises four 500kV transmission circuits; the first two were commissioned in 1994 and 2005, followed by the completion and energization in 2024 of the Quang Trach – Pho Noi 500kV line, Circuit 3, (a double-circuit line), creating the country's largest extra-high-voltage power transmission system.

Given that the Northern region frequently faces the risk of localized power shortages during the hot season, the four lines serve as the "backbone" of the national power system, enabling the efficient transfer of power from regions with surplus capacity to support the North.

North-South 500kV transmission lines (Circuits 1 and 2) effectively ensuring power supply for the North. Photo: Le Linh

In particular, the 500kV Circuit 3 transmission line (Quang Trach – Pho Noi) has significantly boosted transmission capacity along the North-South corridor. This project not only alleviates the load on existing transmission lines but also enhances the operational reliability of the national power system and increases the capacity to transmit power from the Central and Southern regions to the North during periods of peak demand.

The commissioning of the 500kV Circuit 3 transmission line has created significant additional headroom for more flexible power system dispatch, contributing to national energy security and the optimization of the power system amidst continued strong growth in electricity demand.

Proactively prepare well in advance.

To ensure the safe operation of the North-South 500kV transmission lines, EVNNPT implemented a comprehensive set of solutions at a very early stage.

From the beginning of 2026, EVNNPT directed its power transmission units to push up inspections and reviews of equipment conditions across all 500kV transmission lines and substations, and to thoroughly address any issues or defects that could compromise operations. Equipment maintenance and repair activities were carried out with a focus on optimizing power outage durations and minimizing impacts on transmission capacity.

Units are also stepping up the application of science and technology in operational management, such as using unmanned aerial vehicles (UAVs), thermal cameras, and online monitoring systems, to detect anomalies in power lines and substation equipment at an early stage.

Operator at Thanh Hoa 500kV substation on June 24, 2026. Photo: Le Linh.

Thanks to thorough and proactive preparation, the national power transmission system, particularly the North-South 500kV transmission lines, has consistently operated safely and stably during periods of peak load, thereby helping to ensure a reliable power supply for socio-economic development and the daily lives of the people.

During periods of peak heat, when electricity demand surges and the power transmission system operates under heavy loads, EVNNPT’s staff, engineers, and workers maintain round-the-clock duty at substations and along key transmission lines. Power transmission units step up field patrols and inspections, closely monitor equipment loading, and promptly detect and address potential risks to system operations.

Serving as the nation's "power superhighway," the North-South 500kV transmission system continues to demonstrate its strategic importance in ensuring national energy security. Notably, the Quang Trach – Pho Noi 500kV Circuit 3 line is delivering clear results, acting as a key factor in enhancing inter-regional power transmission capacity and helping to ensure a safe, reliable power supply for the North during peak heatwaves.

Translator: Nguyễn Thị Lan Anh