Transient equivalent circuit and transient analysis of single-phase earth fault in arc suppression coil grounded system

Abstract

For traditional transient equivalent circuit of single-phase earth fault, the effect of aerial model networks is neglected, accompanying with the lack of parameters calculation method and inaccurate position of arc suppression coil. So that it cannot be used for quantitative analysis and calculation. Firstly, a distributed parameters model including informations of both sides of fault point was established. And then, it was simplied into a lumped-Γ circuit composed by equivalent resistance, inductance including aerial and zero modes components, distributed capacitance of feeders to ground and inductance of arc suppression coil by model simplification principle. In order to meet the demonds of engineering application, a simple parameters calculation method was proposed. Contrast with traditional transisent equivalent circuit, the circuits established in this paper contain information of aerial and zero modes components, where equivalent inductance is approximately equal to the sum of zero modes and 2 times aerial modes inductance of feeder form bus to fault point. Moreover, the arc suppression coil was connected to bus, which was more reasonable. Finally, expressions of transient current were presented with different fault resistance. According to the above, the change rule of main resonance frequency, amplitude, attenuation factors were analyzed, which was benefit for the analysis of transient characteristics. Simulations and field data verify the accuracy of transient analysis. The transient equivalent circuits established in this paper have higher calculation precision.