The second 500kV shunt reactor at the Son La 500kV Substation has been successfully energized.

This project is part of the 500kV Shunt Reactor Installation Project to optimize compensation capacity after the 500kV Circuit 3 transmission line comes into operation.

The project "Optimizing Capacitor and Reactor Capacitor Capacity Calculation on the 500kV Power System," implemented by EVNNPT, aims to address the problem of voltage stability in the context of the increasingly expanding 500kV transmission grid and the high transmission pressure along the North-Central-South axis. This is a special-grade, Group B energy project with EVNNPT as the investor and CPMB as the project manager.

The project will be implemented within the premises of 8 existing 500kV substations currently operating on the national power transmission grid, including: Son La 500kV Substation (Son La province); Ha Tinh 500kV Substation (Ha Tinh province); Da Nang 500kV Substation (Da Nang city); Thanh My 500kV Substation (Da Nang city); Doc Soi 500kV Substation (Quang Ngai province); Pleiku 500kV Substation (Gia Lai province); Pleiku 2 500kV Substation (Gia Lai province); and Di Linh 500kV Substation (Lam Dong province).

The 500kV shunt reactor installation project at the Son La 500kV Substation involves the installation of two 500kV - 90 MVAr reactors and accompanying primary and secondary equipment. One reactor was commissioned on December 31, 2025. The commissioning of the second shunt reactor is of significant importance to the Northwest region's power grid – an area with many large-scale hydropower sources and highly variable operating conditions depending on season and hydrological conditions. The project contributes to absorbing excess reactive power, stabilizing voltage on the 500kV grid, reducing the risk of overvoltage during off-peak hours, and improving the reliability of power supply to the national power system.

A representative from CPMB stated: The construction process for installing the 500kV shunt reactor at the Son La 500kV Substation encountered some difficulties due to cramped working conditions, the substation's equipment being energized, and the high capacity of hydropower plants in the area being mobilized to supply water for the 2025-2026 Winter-Spring crop, making it difficult to schedule power outages. However, with the support of the dispatching authorities, Power Transmission Company 1, and Northwest Power Transmission Company 2, the project was completed on schedule.

This is the result of the close cooperation and efforts between the investor, consulting units, contractors, and operation management during the project implementation. The project's completion on schedule not only signifies a significant achievement celebrating the Party and the Lunar New Year, but also further refines the reactive power compensation configuration on the 500kV grid, contributing to ensuring safe, flexible, and efficient operation of the power system in the new phase.

Completing the project on the very day of the founding of the Communist Party of Vietnam is a practical action by EVNNPT and CPMB to celebrate the 96th anniversary of the founding of the Communist Party of Vietnam (February 3, 1930 - February 3, 2026) and to celebrate the success of the 14th National Congress of the Party.

Le Linh