基于控制与保护协同的直流配电系统单极接地故障保护策略

随着电力电子技术的发展,柔性直流配电系统逐渐成为研究热点。单极接地故障是直流配电系统中最为常见的故障类型,当交流侧通过高阻接地时,直流侧发生单极接地故障后,故障电流变化不明显,难以准确定位。文中提出了基于控制与保护协同的双端直流配电系统单极接地故障保护策略,通过就地检测交流接地支路电流微分判断故障发生,进而快速投切交流接地支路上并联的小电阻。相比于传统的差动保护方法,所提方法省去了通信时间,有效提高了保护的快速性。同时,根据保护可靠性的要求,优选了并联小电阻的阻值。最后,在PSCAD/EMTDC平台中进行了仿真分析,验证了所提保护策略的可靠性和快速性。

Protection Strategy of Single-pole Grounding Fault in DC Distribution System Based on Coordination of Control and Protection

With the development of power electronic technology, flexible DC distribution system has gradually become a research hotspot. Single-pole grounding fault is the most common fault type in the DC distribution system. When the AC side is grounded through high resistance, the change of fault current is not obvious after the single-pole grounding fault occurs on DC side, so it is difficult to accurately locate the fault. Based on the coordination of control and protection, a single-pole grounding fault protection strategy is proposed for double-terminal DC distribution system. By detecting the current differential of the AC grounding branch on the spot to judge the occurrence of the fault, the small resistor in parallel on the AC grounding branch can be switched on quickly. Compared with traditional differential protection methods, the proposed method saves the communication time and effectively improves the rapidity of the protection. At the same time, according to the requirements of protection reliability, the resistance value of the parallel small resistor is optimized. Finally, the simulation analysis is carried out in PSCAD/EMTDC platform to verify the reliability and rapidity of the proposed protection strategy.