A Simple High Impedance Fault Detection Method based on Phase Displacement and Zero Sequence Current for Grounded Distribution Systems

A new simple algorithm to detect high impedance high impedance fault (HIF) in grounded distribution networks with the combination of a wavelet transform and phasor measurement unit (PMU) techniques is presented in this paper. The protection algorithm observes the changing conditions of phase displacement between phase voltage and current signals and high frequency component present in the detail coefficient of zero sequence current of the specified measured terminal. The proposed method consists in three simple steps. The first step is checking whether the system is normal or abnormal by using the total sum of mean absolute values of phase displacements between phase voltages and currents. Then, the second step is whether system unbalance is fault or other load switching will be checked by using the sum of mean values of phase displacement between voltage and current. Finally, the algorithm will observe the present of high frequency transient components in the residual current signal to ensure that the system is under fault condition. The proposed PMU and wavelet-based fault detector has been tested with MATLAB Simulink-generated signals, more simple than conventional algorithms and methods. The scheme proved to be robust against transients generated during normal events such as feeder energizing and de-energizing as well as capacitor bank switching.