Zhejiang completes major 500 kV shutdown

On Nov 7, four transmission lines at the 500-kilovolt Shunjiang Substation were simultaneously taken out of service for coordinated construction and maintenance work, in what was reportedly Zhejiang's largest and most complex operation of its kind this year.

The work included the installation of key equipment for the Ganjiang Ultra-High Voltage (UHV) transmission project and completion of comprehensive maintenance and secondary technical renovation, supporting reliable winter supply and Gansu wind and photovoltaic clean energy integration into Zhejiang.

Shunjiang supplies eastern Shaoxing, serves as a key hub in northern Zhejiang, and is an important landing point for Gansu green power. From Oct 21, the 500 kV Zhushun, Zhujiang, Shaojun, and Junming lines were shut down together.

State Grid Shaoxing Power Supply Company advanced UHV interval modification, maintenance and technical renovation in parallel. It completed the construction and relocation of 500 kV line intervals, maintained 94 devices across 20 intervals, and renovated 12 measurement and control devices. During the busiest period, 15 work sites ran in parallel, with an average of 117 workers on duty daily.

The shutdown window was rare but weakened grid operating modes and concentrated risks. The company used intelligent inspection systems and drones for 45 special inspections and protections of key channels and substations, keeping work safe and organized.

Since autumn inspections began on Sept 15, the Shaoxing grid has completed 15 comprehensive maintenance projects, including at the 220 kV Honglian and Pukou substations and 110 kV Xiguo Substation, plus 12 substation technical renovations. It eliminated 257 defects, improving equipment reliability for winter.