Real-time distributed grounding fault monitoring and control system considering human safety

Electric shock accidents caused by single-phase fault in distribution often occur in China, as for it, a real-time distributed grounding fault monitoring and control system is put forward in this paper. First, after considering the probability of ventricular fibrillation when people exposed to an electrical shock, a human safety current is proposed. Then a variable frequency current signal is injected into the neutral in network, the system to ground parameters are calculated after finding the harmonic frequency, which are used to detect ground fault; when fault detected, the fault phase voltage is controlled by the preset injecting current calculated by parameters measured before, meanwhile the fault current is compensated as well (patent number 201710544976.9). Experiments show the high accuracy of real-time harmonic measurement, and simulation proves the system can suppress the fault current in the range of human safety current.