Reclosing Current Limiting for DC Line Faults in VSC-HVDC Systems

The problem of reclosing current limiting in voltage source converter based high-voltage direct current(VSCHVDC) systems is becoming more and more serious. A soft reclosing scheme for DC permanent faults is presented in this paper. Because the converter voltages of stations at both terminals of the disconnected faulty line may be different, the choice of which terminal to reclose first will affect the reclosing overcurrent. A method for selecting the terminal to reclose first is investigated to achieve a minimum peak overcurrent during the reclosing process. In order to ensure that the hybrid DC circuit breaker(HDCCB) adapts to the needs of the reclosing process better, the traditional HDCCB is improved by adding a soft reclosing module(SRM). The energy dissipated in the arresters is significantly reduced when using the improved HDCCB. The improved HDCCB will be able to reclose multiple times safely and thus increase the possibility of successful reclosing. Moreover, the recovery time after the HDCCB is successfully reclosed is very short with the improved HDCCB and its control principles. Simulation results show that this proposed scheme is capable of limiting the reclosing overcurrent when the fault still exists.