Simulation Analysis of Voltage Fluctuation at the Sending End of UHVDC System Caused by Commutation Failure

Commutation failure is an inherent defect of UHVDC. Starting from a commutation failure, this paper leads to the problem of voltage fluctuation at the sending end of power grid caused by commutation failure. Based on Lingzhou-Shaoxing UHVDC project, the model is built on PSCAD / EMTDC simulation platform. Based on the simulation results, the relationship between the change of electrical quantities and the change of converter bus voltage after commutation failure is described in three stages: converter bus voltage sag stage, converter bus voltage surge stage and converter bus voltage recovery stage, and the mechanism of voltage fluctuation caused by commutation failure is analyzed. The results show that during the commutation failure, the reactive power exchanged between the rectifier station and the grid at the sending end changes greatly, which leads to the fluctuation of the bus voltage at the sending end.