Gansu EPRI Completes Converter Station Back-Energization Test with China's Largest High-to-Low Voltage Differential

Recently, the State Grid Gansu Electric Power Research Institute (Gansu EPRI) successfully completed commissioning tests to energize the 750 kV AC equipment at the Wuwei ±800 kV Converter Station through back-energization. As a key milestone for the Gansu-Zhejiang Power Transmission Project, this marked the first back-energization test of its kind in Northwest China and involved the largest voltage differential between the high- and low-voltage sides of any such converter station test in China.

Staff verify control cabinet operating parameters

Three months ahead of the test, Gansu EPRI mobilized a technical team to run system and equipment simulations. The team conducted granular simulation analyses across the entire back-energization test process, systematically identifying potential risks and tailoring prevention measures. In parallel, they finalized the commissioning, dispatch, and emergency response plans, calculated and issued test-specific relay protection settings, and embedded risk controls throughout the process, providing end-to-end technical support for a safe, orderly operation.

During the execution phase, Gansu EPRI directed operations with precision. All test objectives were successfully met over an 11-hour window, with field data matching the results of the earlier simulation analyses exactly. This outcome reflects the institute's technical expertise accumulated over many years, industry-leading grid simulation capabilities, and growing proficiency in managing new-type power systems. Throughout the operation, engineers conducted a range of diagnostic tests on energized equipment—including ultra-high-frequency (UHF) and ultrasonic partial discharge detection, infrared and ultraviolet inspections, and oil and gas testing—to perform a comprehensive assessment of equipment health.

This milestone establishes a solid technical foundation for the timely, high-quality commissioning of the Gansu-Zhejiang Project and the large-scale transmission of clean power from Gansu's desert, Gobi, and wasteland energy bases. It also provides valuable engineering experience for subsequent back-energization tests at similar ultra-high-voltage (UHV) converter stations nationwide. (Text and photo by Zhao Zhongxin)