Method for Short Circuit and Overcurrent Turn-Off Test of MMC Valves Based on Equivalent Current Source

To ensure the operational reliability of MMC valve, it is necessary to conduct short circuit and overcurrent turn-off tests before leaving the factory to investigate its ability to withstand critical stresses under actual working conditions and the correctness of its design. However, the existing test methods have a large volume of test devices, complex processes, and need for separate tests to verify the reliability of the devices. Therefore, with the goal of reducing device volume, cost, and completing multiple tests with a single device, a synthetic method based on an equivalent current source is proposed. Firstly, the DC bipolar short circuit current stress model is analyzed, and based on this, the device topology and its principle are proposed. Then, based on the experimental topology, a simulation model is built and a composite test of 8GW MMC valve short circuit and overcurrent turn-off is conducted. The result indicates the feasibility of the proposed experimental method.