基于模型识别和电流极性的混合式双极型直流输电线路纵向保护

针对混合式双极型直流输电系统,结合模型识别和电流极性保护原理,提出一种新的输电线路纵向保护原理。分析故障网络发现:当逆变侧前端故障时,故障模型等效为电容模型(C模型),当逆变侧背面故障时,故障模型等效为阻感模型(RL模型);当整流侧前端故障时,整流侧故障电流具有正极性,当整流侧背面故障时,整流侧故障电流具有负极性。区内故障时,即逆变侧和整流侧的前端同时故障时,故障模型匹配C模型,同时故障电流具有正极性;当故障发生在区外时,即逆变侧和整流侧的前端不是同时故障时,逆变器侧的故障模型不匹配C模型,或者整流侧故障电流具有负极性。由此区分直流线路外部和内部故障。仿真结果表明,该原理可以补偿主保护,作为备用保护的改进。

Longitudinal protection of hybrid bipolar DC transmission lines based on model identification and current polarity

Aiming at the hybrid bipolar DC transmission system, combined with the principle of model identification and current polarity protection, a new principle of longitudinal protection of transmission lines is proposed. This paper analyzes the fault network and finds :when the front end of the inverter side fails, the fault model is equivalent to the C model, and when the back side of the inverter side fails, the fault model is equivalent to the RL model; when the front end of the rectification side fails, the rectification side fault current has a positive polarity, and when the rectification side back side fails, the rectification side fault current has a negative polarity. In conclusion, a failure in the area, namely the inverter side front and rectifier side front fault at the same time, the fault model matching C model, there was a positive polarity fault current at the same time; Outside of a failure, namely the inverter side front and rectifier side front no fault at the same time, inverter side failure model does not match the C model, or rectifier side fault current with a negative polarity. This distinguishes between external and internal faults in the DC line. The simulation results show that the new principle can compensate for the main protection as an improvement of the backup protection.