Analysis on the Influence of Stray Inductance on Overvoltage of Hybrid DC Circuit Breaker During Breaking Process

DC circuit breakers are the key equipment in maintaining safe and reliable operation of DC system. The presence of stray inductance in each branch of the hybrid DC circuit breaker generates overvoltage due to a high rate of current rise during breaking operation, which brings negative effects to the flexibility and reliability of DC system. The objective of this paper is to investigate the influence of internal stray inductance on overvoltage when the hybrid DC circuit breaker operated. The stray inductance components of main branch, transfer branch and energy consumption branch in hybrid DC breaker were analyzed and the integrated inductance of the three branches were obtained. Based on PSCAD/EMTDC, a 500kV hybrid DC circuit breaker model was established. By changing the size of stray inductance in each branch, the influence rules of stray inductance on overvoltage of circuit breaker during the breaking process were simulated and studied. The results indicate that the increased stray inductance of main branch has no obvious effect on overvoltage of hybrid DC circuit breaker during breaking process. Whereas, for transfer branch, the increased stray inductance results in a decline on overvoltage, which is unfavorable to the establishment of the breaking voltage. And the increased stray inductance of energy consumption branch extends the energy consumption time. This paper provides references for parameter design and insulation coordination of hybrid DC circuit breaker.