Earth fault location based on transient phase current in non-solidly earthed network

On the basis of analyzing the transient characteristics of three phase current in single-phase earth fault, a new method for fault location based on transient phase current is proposed. Before the fault point, the transient fault phase current is three times of the zero module current, and it flows from fault point to the bus. While the transient sound phase current is approximately equal to the transient zero module current after the fault point and it flows from the bus to the load. After the fault point, the fault and sound phase current are all approximately equal to the transient zero module current, and the direction is from the fault point to the load. According to the above characteristics, direction parameters can be defined to locate the fault section with the difference before and after the fault point. This method only uses three phase current. The voltage signals and the accurate time synchronization of different detection point are not necessary.