Study On Neutral Grounding Mode For 10kV Power Distribution Network

It is an important technical problem to neutral grounding mode of the electric power system which associates with voltage level, network structure, insulation level, reliability of power supply, protective relaying, electromagnetic interference, and personal safety.In China, the neutral grounding mode of the 10kV network used of none grounding, grounding by arc suppressing coils in the past. With the development of urban power network, especially the widespread use of cables, low resistance grounding mode was used to restrain the over voltage in Guangzhou, Shanghai, Beijing, and Zhuhai etc. It was reported that the over voltage level of low resistance grounding mode is lower than that of arc suppressing coil mode, but the operation carried out the other problems, including reliability of power supply rapidly dropping, and person safety being threatened. So interiorly the grounding mode selection of the 10kV network was disputed, which mainly focused on the fault form of 10kV network grounding, the apply area of arc suppressing coil grounding mode and low resistance grounding mode, reliability of power supply, person safety, communication interference and the work load of maintenance.This paper studied on how to select the neutral grounding mode of 10kV network. Firstly it analyzed the characteristic of grounding modes about 10kV network. Then with the demonstration of Maoping substation in Hubei province, this paper built a numerical value equivalent model. Taking account of the transformation of the capacitive current or the variety of the grounding point resistance, it simulated the over voltage level and the grounding point short current value of the network with arc suppressing coil grounding mode or low resistance grounding mode, in addition, this paper discussed the problem of restrained arc over voltage.In this paper , the technical parameters for the arc suppressing coil and associated equipment were calculated , and reasonable selection has been made to finally realize automatic tracing compensation for arc suppressing coil grounding mode.