Study On Single-phase Grounding Fault Location In Distribution Network

The middle-low voltage distribution networks in China widely use non-effective grounding system(including neutral non-grounding and neutral grounding via arc suppression coil). When single-phase grounding fault happens, the problem of the single-phase grounding fault line selection and fault locating haven’t get very good solution, because of the weak fault current, unstable arc and other factors. The paper studied interval location and accurate location of single-phase grounding fault in distribution networks.It firstly analyzes the distribution of capacitance current in the branch line when single-phase grounding fault happens in the distribution network, then analyzes the fault mechanism of neutral non-grounding systems and neutral grounding via arc suppression coil system. It also makes modeling and simulation of the distribution network with PSCAD, and then analyzes the deficiency in interval positioning and location algorithm according to the simulation results.In order to make full use of the fault information, this article first analyzes the advantages and disadvantages of the method using the traditional zero sequence current amplitude, and then put forward the criterion for interval positioning with unit zero sequence differential current. A lot of analysis shows that unit zero sequence differential current of the non-fault line is approximately equal, unit zero sequence differential current of the fault line and the non-fault line is obviously different, sometimes the difference is above several times, positioning is very precision.