Research on neutral point grounding mode and single-phase earth fault location of medium voltage island microgrid

Abstract

Abstract For medium voltage islanding microgrid, the voltage clamp of the main network neutral arc suppression coil or small resistance is lost. Multiple PTs parallel operation will occur because different entities of a microgrid independently measure the voltage. It is necessary to consider the influence of multi PTs ferroresonance on the neutral grounding mode of islanding microgrid. The neutral point ungrounded, neutral point grounded by arc suppression coil and neutral point grounded by small resistance are analyzed respectively, considering multi PTs ferroresonance and single-phase earth fault location, it is determined that the islanded microgrid adopts neutral point grounded by small resistance. On this basis, the zero sequence current distribution is used to locate the single-phase earth fault. Finally, a simulation example is built to verify the correctness of the proposed method.