Unbalanced Currentanalysis of Capacitor of Converter Station ac Filter Based on PSCAD/EMTDC

The AC filter is an important part of the DC transmission system, whose operating conditions directly affect the power transmission of the DC transmission system. Combined with the actual operation experience of AC filter, this paper analyzes the abnormal unbalance of C1 capacitor of AC filter, and concludes the main unbalance faults, which maintain Internal component failure of single capacitor and Capacitor discharge failure. Besides, the article analyzes and verifies that the interlayer discharge fault has a worse impact on the operation of AC filter through PSCAD / EMTDC simulation. The improvement measures of strengthening site inspection, increasing bird driving measures and monitoring the change times of C1 unbalanced current are put forward, which have practical significance for the safe operation of AC filter in converter station.