采用阻容电流转移支路的直流电网故障清除及重合闸方案

DC Grid Fault Clearing and Reclosing Scheme With R-C Current Transfer Branch

为了解决直流电网故障清除及重合闸问题,提出了一种采用阻容电流转移支路的直流电网故障清除及重合闸方案。该方案新增的阻容电流转移支路可辅助切除故障线路,同时可起到支撑直流母线电压作用,防止非故障线路断路器因换流器直流母线电压过低而发生误动作。该方案通过分析故障类型判别支路电流,从而区分瞬时性故障与永久性故障,避免盲目重合闸于永久性故障对系统造成严重危害。最后,利用PSCAD/EMTDC仿真验证所提方案的准确性与适用性,并对比分析了文中方案与混合式直流断路器方案的器件用量,仿真结果证明换流器联结的直流线路越多,文中方案的经济性优势越显著。

In order to solve the problems of fault clearing and reclosing in the DC grid,a fault clearing and reclosing scheme with resistance-capacitance current transfer branch for DC Grid is proposed.The R-C current transfer branch of the scheme can assist the isolation of the fault line.What is more,it can support the DC bus voltage to prevent non-fault line breakers from a maloperation due to the low DC bus voltage.The scheme can distinguish between the temporary fault and the permanent fault by analyzing the current of the fault type judgment branch to avoid greater damage to the system.Finally,we build a simulation model in PSCAD/EMTDC to verify the accuracy and applicability of the proposed scheme.Besides,we compare the device usage of the proposed scheme with that of the hybrid DC circuit breaker scheme.The results show that the more the converter outgoing lines are,the more economical it is to use the proposed scheme.