Experimental Study On Typical Characteristics Of Series Fault Arc Under Complex Circuit Condition

In the low-voltage power system,multi-load parallel operation constitutes a more complicated multi-loop power supply line.Due to the variety of load types,the fault characteristics of each branch when fault arc occurs have certain concealment in the trunk road,fault arc It is difficult for the circuit breaker to detect the series fault arc of each branch.In order to solve the problem that the series fault arc is difficult to diagnose under complex circuit conditions,the fractal and energy characteristics of series fault arcs generated by different lines are studied,which is of great significance to improve the reliability and safety of low voltage power.Firstly,a series fault arc experiment platform was built,and single-circuit,double-loop and three-loop series fault arc experiments were carried out respectively.The current and arc voltage data of the main road and each branch under normal working and fault arc conditions were collected.The peak-to-peak value,variance,zero-crossing point,margin factor and THDi of the obtained trunk current waveform were analyzed in the time domain and the frequency domain respectively.Then the integrated empirical mode decomposition(EEMD)method is used to decompose the main circuit of the main circuit,and the effective IMF component is selected according to the fault information and reconstructed.The effective current signal including the fault arc characteristic is obtained.The reconstructed signal is reconstructed.The fractal feature analysis is carried out to calculate the correlation dimension of the effective current signal under the two working states of the trunk road and each branch.Finally,the wavelet packet is decomposed and demodulated by wavelet,and the AR(auto regressive,AR)spectrum analysis is performed on the reconstructed signals.The characteristic frequency bands are extracted and the wavelets of different frequency bands are analyzed.The variation of the band-AR spectral band energy in the event of a fault arc on different lines.The results show that the correlation dimension and wavelet packet-AR spectral band energy can effectively describe the characteristics of the series-type fault arc of multi-loop circuits,and provide an important theoretical basis for discriminating different fault arc branches from the trunk road under complex circuit conditions.