Low Voltage Arc Mechanism And Signal Characteristics Analysis

Low voltage electrical appliances and their lines prone to insulation aging,damage and other phenomenon due to long-term overload,this may lead to the occurrence of arc fault and electrical fire.When the fault arc occurs,in addition to the normal frequency current and voltage waveform and its harmonics will have a significant change in characteristics,but also produce a lot of high frequency current,which can make up for traditional methods in the DC system and early warning deficiencies.Based on this,low voltage arc mechanism and signal characteristics are studied by the combination of theory,simulation and experiment,and a fault arc detection scheme using high frequency current is proposed.In this article,the discharge mechanism of low voltage arc is studied from microcosmic angle,and the discharge process is simulated based on PIC-MCC method.The pulse current waveform of gas discharge is obtained.Then,the current waveforms of the fault arc are simulated by electromagnetic transient simulation software.Combined with empirical mode decomposition and Wigner-Ville distribution,the time-frequency analysis is carried out to verify the existence of high-frequency current in fault arc and provide a guide to choose the appropriate measurement band.Then a high-frequency current sensor is used to measure the fault arc generated by the standard arc generator.After using the improved wavelet threshold de-noising method,the time-frequency analysis and correlation analysis of signal is studied.Finally,the quantitative relationship between the attenuation of high frequency current and distance or frequency is deduced theoretically and empirically.Based on this,the multi-node arc fault localization scheme based on generalized correlation delay method and the single end arc fault localization scheme based on wavelet decomposition is proposed.