China's First Hybrid AC-DC Power Transmission Project Completes First Scheduled Maintenance

YANGZHOU, China, Sept. 24, 2025 /PRNewswire/ -- State Grid Zhenjiang Power Supply Company announced on September 23 the successful completion of the first annual maintenance for China's inaugural hybrid AC-DC power transmission project—the Yangzhou-Zhenjiang ±200 kV DC transmission system. The work is designed to enhance system reliability ahead of the high-demand winter season, supporting a stable electricity supply throughout the Yangtze River Delta region.

The initial phase of the Yangzhou-Zhenjiang DC project, which entered service in late April last year, spans approximately 110 kilometers from Gaoyou in Yangzhou to Zhenjiang Economic and Technological Development Zone. A crew of 48 technicians conducted thorough inspections of all 284 transmission towers along the route. Despite challenging conditions, including ongoing construction for subsequent project phases and coordination among multiple work teams, maintenance was carried out efficiently through detailed scheduling, ensuring all tasks were completed safely and without operational disruptions. 

The maintenance program also emphasized environmental stewardship, with crews installing protective measures such as insulated covers and artificial nests. These steps are crucial in the ecologically sensitive Yangtze River Delta, a major migratory bird flyway, as they prevent bird electrocution and protect the line's reliability from nesting activities.

The project is an important step in addressing renewable energy integration in Jiangsu Province. It transmits wind and solar generation from the north across the Yangtze River to help meet peak electricity demand in the south. Initiated in late 2022, the project repurposed an existing AC corridor into a dedicated DC transmission line, making it possible to reduce carbon dioxide emissions by an estimated 1.6 million tons annually.

SOURCE State Grid Zhenjiang Power Supply Company