Research on composite grounding method of neutral point in distribution network

With the rapid development of distribution network, the proportion of cable is gradually increasing, and the inherent fault location method is not applicable. The composite grounding mode, which is aimed at different fault types, chooses different working modes, and combines the advantages of various grounding modes. However, there are still some problems such as simple fault identification and imperfect control strategy. This paper studies the composite grounding mode, designs the hardware structure according to its functional requirements, and proposes an improved control strategy based on fault type identification: when the arc fault occurs, put in the arc suppression coil to extinguish the arc, if the arc extinguishment fails, put in the small resistance to cut off the fault line; when the permanent fault occurs, put in the small resistance to cut off the fault directly. The theoretical analysis of the proposed control strategy provides the basis for fault line selection. Finally, the theoretical analysis results are verified by simulation, which proves that the composite grounding method has certain advantages.