Research on detecting single-phase-to-ground faulted feeder in resonant grounded power distribution system

In the resonant grounded power distribution system, the magnitude and direction of zero sequence measuring current in the faulty line is different from the current in the ungrounded power system when a single phase earth fault happens because of the compensation effect of the inductive current in arc suppression coil on the capacity ground current. Because the magnitude of zero sequence measuring current is connected with the compensation degree of arc suppression coil, the condition in resonant grounded power distribution system is more complicated than in ungrounded power system. Therefore the fault detection in a resonant grounded power distribution system is a tickler in indirectly earthed power system and the most existing methods used in field have the question which cannot find the faulty line accurately. On the basis of detailed analysis of the zero sequence measurement current distribution in resonant grounded power distribution system, a new detecting one-phase-to-ground fault feeder calculation method is proposed in this paper, which adds the arc suppressing coil compensation current to the zero sequence current of every feeders, is armed at the resonant grounded power distribution system and is based on the stable state analysis. EMPT simulation and analysis show that this calculation method has effectively raised the protecting abundant degree. The operation results of the power system indicated that the device which is developed in the calculation method has a high accuracy in the detecting fault feeder in the indirectly earthed power system regardless of running state including under compensation state, full compensation state and over compensation state.