A non-solid-earthed distribution fault location method based on unbalanced capacitance injection

In order to solve the problem of single-phase-to-earth fault location in non-solid-earthed distribution, the abnormal characteristics of bus voltage under non-solid-earthed distribution fault are analyzed. A method of single-phase-to-earth fault identification is proposed, and concrete steps and formulas are given. The power flow trend of the distribution network under unbalanced capacitance injection is analyzed in the case of non-solid-earthed fault. When the unbalanced capacitance is injected, the steady-state current change upstream of the fault point in the fault phase is different from the steady-state current change downstream of the fault point, and the steady-state current change with the non-fault phase is also different. Based on the above analysis, the non-solid-earthed fault location problem is transformed into the steady-state current comparison problem. The equivalent circuit diagram of unbalanced capacitance current and the detailed calculation formula are given, and the approximate calculation formula and phasor diagram of the fault phase current are given. Based on the mutual cooperation of DMS (Distribution Management System) and unbalanced capacitance, the method of non-solid-earthed distribution fault location based on unbalanced capacitance injection is proposed, and detailed steps and specific rules are given. The simulation results show that the proposed method has good judgment adaptability for permanent non-solid-earthed fault and intermittent non-solid-earthed fault with longer duration.