A METHOD FOR DETECTING EARTH FAULTS

摘要

The invention concerns a method for reliable detecting and monitoring of a multitude of different earth faults in three-phase electric power distribution networks. A method is presented which combines a transient estimation method with a modified phasor based wattmetric method. The transient method estimates the capacitance and conductance of each feeder and also for the neutral point device, and uses this to find the faulted feeder. The modification of the wattmetric method is to use the negative derivative of the neutral point voltage phasor magnitude to identify when the fault is not connected and then disable (block) the active power criterion.