柔性直流电网故障限流技术分析与探讨

Analysis and discussion of fault current limiting technology in flexible DC grid

故障限流技术是实现柔性直流电网保护和故障隔离的重要过渡手段。基于柔性直流电网的故障特征,结合国内外研究成果,从交流侧限流、换流器限流以及直流侧限流3个方面分析了柔性直流电网各类限流技术和方法的原理及性能,对相关限流技术和方法进行了仿真测试和比较。基于对比分析结果,提出了一种改进的电感型限流电路拓扑。所提出的限流电路能够有效抑制故障电流,在配合直流断路器开断故障的情况下,可加速故障电流衰减。最后探讨了未来直流电网故障限流技术可能的研究方向。

Fault current limiting technology is an important transition mean to realize the protection and fault isolation of flexible DC grid.Based on the fault characteristic of flexible DC grid and research re sults at home and abroad,the principle and performance of various current limiting techniques and methods are analyzed considering three aspects,including current limiting at AC side,current limiting by converter and current limiting at DC side.In addition,simulations are carried out to test and evaluate those current limiting techniques and methods.An improved hybrid current limiting circuit is proposed based on the comparative analysis results.The current limiting circuit is able to limit the fault current effectively and accelerate the fault current decay during fault interruption with a DC circuit breaker.Finally,possible re search directions for fault current limiting technology of flexible DC grid are also discussed.