A Novel DC Arc Fault Detection Method Based on Electromagnetic Radiation Signal

Because of lack of current zero, dc arc is hard to be extinguished, which has become the main reason causing faults in dc system. To find an effective method to detect dc arc faults is of great significance. In this paper, a method for detecting dc arc fault based on electromagnetic radiation signal is presented. A dc arc generating device is designed to simulate dc arc faults caused by loose connection in dc systems. A fourth-order Hilbert curve fractal antenna is adopted to detect the electromagnetic radiation signals of dc arc. The amplitude and spectrums of electromagnetic radiation signals measured under different circuit currents are analyzed. A photovoltaic (PV) system is constructed and the dc arc generated in that system is measured. The test results show that, under the present experimental condition, the electromagnetic radiation pulses have an obvious characteristic frequency, which are in a range of 39-41 MHz. The characteristic frequency of electromagnetic radiation of dc arc generated in PV system is around 39 MHz. Moreover, the characteristic frequency of dc arc is compared with that of switch operation. The dc arc has higher characteristic frequency and longer interval of each electromagnetic radiation pulse than those of the switch operation. The results indicate that the characteristic frequency of electromagnetic radiation signals can be used as the detection parameter of dc arc.