When large scales DG are connected to the distribution system of unidirectional power currents, bi-directional power currents are formed, making it impossible to use conventional overcurrent protection methods alone to detect and isolate fault sections for ground and short-circuit faults. To solve these problems, this study proposed the method of protection against single-line-ground fault of common neutral line multi-contact local power distribution system using distance relay and directional relay. The proposed protection method was applied to the common neutral multi-ground distribution system to validate the protection against single-line-ground fault through the PSCAD/EMTDC software package and effectively detect and isolate only the zone of single-line-ground fault without malfunctions.

中文翻译：

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用距离继电器和方向继电器保护含DG配电系统单线接地故障的方法

大型分布式电源接入单向电源电流分配系统时，会形成双向电源电流，因此无法单独使用传统的过流保护方法来检测和隔离接地故障和短路故障的故障段。针对这些问题，本研究提出了采用距离继电器和方向继电器的共中性线多触点就地配电系统单线接地故障保护方法。将所提出的保护方法应用于公共中性点多地配电系统，通过PSCAD/EMTDC软件包验证单线接地故障保护，并有效地仅检测和隔离单线接地故障区域而不会出现故障.