| Popis: |
Medium voltage direct current (MVDC) distribution grids, that is proposed to improve power quality, enable high penetration of renewable sources, decrease operating losses, has drawn more and more attraction. However, dc faults ride-through remains to be a technical bottleneck constraining the extensive industry application of MVDC distribution grids, and the method based on DC circuit breaker (DCCB) is one of the most promising solution to deal with this problem. With features of no operating losses, low cost and free maintenance, the hybrid DCCB with current commutation drive circuit (CCDC) could be widely used in MVDC distribution system to interrupt DC fault current. During the current interruption process of DCCB with CCDC, circuit switching occurs twice, so the transient voltages are inevitable. In this paper, a simulation model of DCCB with CCDC is established by PSCAD, and the transient voltages are calculated. According to the simulation results, the transient voltages should be suppressed. Then, based on the mechanisms of the transient voltages, mitigation ways are proposed. In the end, the simulation results show that the transient voltages have been effectively suppressed and the reliability of DCCB with CCDC has been improved. |
