针对串联直流电弧的电容电流时频检测方法

High frequency components accompany when series DC arc happens. A series DC arc fault detection method according to parallel capacitive current with time-frequency characteristics is proposed. A DC arc test platform is constructed to measure the current flowing through the internal filter capacitor of the DC source to detect the high frequency current generated by the arc fault. A simulation model is established with PSCAD/EMTDC, and the DC arc can be equivalent to a nonlinear resistance by the Nottingham formula. On the simulation platform, the time-frequency characteristics of the parallel capacitive current during the series arc generation are analyzed. The results show that when the series arc is generated, the parallel capacitive current changes suddenly, and the integral value in the 5-50 kHz band of the capacitive current spectrum increases. The simulation results are verified in the experiment. The parallel capacitance currents for different loop currents and electrode materials are tested. The rate of change of the capacitive current is proportional to the magnitude of the loop current, and it is inversely proportional to the boiling point of the electrode material. The current spectral integration difference is proportional to the loop current and the boiling point of the electrode material.