An Identification Method for Biological Electric Shock in Low-Voltage Distribution Networks

Due to the difficulty of recognizing residual currents from biological electric shock (BES) and resistive leakage, existing residual current devices are unable to accurately remove BES from low-voltage distribution networks and ensure supply reliability at the same time. Therefore, this paper proposes a novel approach for identifying BES by utilizing measured impedance and transient DC components of residual currents. Firstly, this paper analyses the leakage current and residual current of two types of faults, BES and resistive leakage, respectively. Then two identification methods are proposed based on the residual current: the first one is to calculate the measured impedance based on the faulty phase voltage and residual current after the faulty phase is selected, to judge whether BES takes place according to its imaginary part. The second one is to extract the transient DC fraction of the residual current by Prony algorithm and compare it with the dynamic fixed value to determine whether BES is occurring or not. The logical coordination between the two methods is performed. Finally, the correctness and speed of the proposed methods are validated through Matlab/Simulink simulations. This method enhances the accuracy of the BES identification and the performance of available residual current devices in low-voltage distribution networks.