Research on the Converter Valves Charging and Triggering Passive Inversion Test of Xiamen Flexible DC Transmission Project

In order to ensure the safety of Xiamen flexible DC project converter valves, it is necessary to confirm the correctness of the triggering phase sequence of converter valves before the first time deblock of converter valves with line breaker. According to the real bipolar connection mode of Xiamen flexible DC project, the test scheme of converter valves charging and triggering passive inversion is proposed. Firstly, the converter valves are charged without control and the voltage of unworking pole control system is used as the voltage of working pole control system for phase-locking and control. Then, the line breaker is disconnected, and in order to prevent excessive bypassing of valve submodules under low voltage, the pole control and protection system deblocks converter valves automatically for 200 ms to complete the passive inversion after the breaker returns to the node. The field test result verifies the feasibility and effectiveness of the scheme, and proves the correctness of the working among pole control and protection system, valve basic controller and converter valves, and the safety of converter valves is assured. According to the test results, the method for determining the time delay of the control system and the corresponding compensation method are put forward. The scheme can also provide a useful reference for other similar projects.