Maintenance personnel from the State Grid Anhui Electric Power company conduct an overhaul and maintenance of equipment at the Guquan Converter Station, on Oct 29, 2024. [Photo provided to chinadaily.com.cn]
On Oct 28, at the ±1100 kV Guquan converter station located in Xuancheng city, Anhui province, two cranes and a lifting platform truck were utilized to replace wall bushings within the 30-meter-high valve hall. The 2024 annual maintenance of the Guquan converter station is currently in full swing.
The "Changji-Guquan" UHVDC transmission project currently holds the world record for the highest voltage level, largest transmission capacity, longest transmission distance and most advanced technology. Since its commissioning on Sept 26, 2019, the Guquan converter station, the landing point of the project, has delivered a cumulative total of over 280 billion kilowatt-hours of electricity. This summer, it has repeatedly set world records for power transmission projects, such as delivering over 250 million kilowatt-hours of electricity per day and operating at a high load of 10.8 million kilowatts for over 13.5 hours.
The primary maintenance period spans from Oct 26 to Nov 1 due to the substantial workload, limited time and multiple maintenance tasks to be carried out. Forty-one participating units and over 840 power maintenance personnel are scheduled to perform 6,537 routine maintenance tasks, 32 special maintenance tasks, 77 defect elimination tasks, 18 hidden danger mitigation tasks and 14 software modifications, among others.
Maintenance personnel from the State Grid Anhui Electric Power company conduct an overhaul and maintenance of equipment at the Guquan Converter Station, on Oct 29, 2024. [Photo provided to chinadaily.com.cn]
The overhaul, which is divided into 37 work areas, includes the replacement of the wall bushing in the extreme II high-end valve hall. The bushing is approximately 27 meters long, weighs 18.7 metric tons and is installed at a height of about 17.5 meters. During the installation process, strict stability requirements are imposed, making the operation challenging and a high safety risk. Guquan Converter Station, in collaboration with inspection units, has conducted multiple preliminary surveys and formulated a detailed lifting plan. By closely coordinating various operational steps and mobilizing multiple specialized vehicles for collaborative work, they successfully completed the disassembly and assembly of the wall bushing.
To ensure the safe and efficient conduct of the annual inspection, the company scientifically formulated a maintenance strategy and an on-site safety control plan. It comprehensively strengthened overall work coordination, scientifically divided work areas, refined operational procedures, strictly monitored key links and ensured a smooth, safe and efficient annual inspection process. In combination with the key tasks of the annual inspection and the management of equipment hazards, Guquan Converter Station also organized 30 Guquan Annual Inspection Seminars. In addition, it also checked and verified the arrival status of over 820 annual inspection materials and organized the preparation and review of 33 work permits and 184 operation permits.
Unlike previous years, in order to optimize the start-up process, Guquan Converter Station communicated and reported to the superior dispatcher in advance this year. By utilizing a partitioned operation and permit system for both DC and AC equipment, the start-up time of the DC system was advanced from 8:00 pm in previous years to 8:00 am, saving 12 hours. This provides a model experience for the annual lean maintenance of other converter stations.
This annual inspection serves as a comprehensive "physical examination" for the equipment at Guquan Converter Station, aiming to further enhance the operational health of the equipment and provide a robust guarantee for the stable power supply of the grid during the winter season and next spring.
