基于电流差动的直流配电网保护方案

针对直流配电网在发生短路故障时,短路电流上升迅速,直流断路器无法快速动作从而切除故障的问题,首先基于三相两电平电压源换流器构建直流配网的电源模块。分析了单端电源向无源网络供电时发生极间短路故障和单极接地短路故障的故障特征,提出了一种低电压保护和电流差动保护联合的保护方案,并且通过投切后备电源提高了供电的可靠性。最后在PSCAD/EMTDC平台中进行了仿真验证,结果表明在直流配网发生短路故障时,该保护能够快速可靠动作,并具有良好的选择性和灵敏性。

Protection scheme of DC distribution network based on differential current

Aiming at the problem that the short circuit current rises rapidly and the DC breaker cannot move quickly and cut off the fault in the DC distribution network when the short circuit fault occurs.In this paper,a power source model is built based on DC distribution network by a three-phase two-level voltage source converter (VSC) and supply power.The fault characteristics of the short circuit fault and mono-polar grounding fault to passive network were analyzed,a united protection scheme of the under voltage protection and current differential protection was proved and improved power supply reliability by switching back power supply.Finally,the simulation verification is carried out on the PSCAD/EMTDC platform.The results show that the protection scheme can act quickly and reliably when short circuit fault occurs in DC distribution network,and has good selectivity and sensitivity.