Power system neutral point grounding
Keywords:Neutral point grounding, compensation coil, shunt trip circuitbreaker, earth-fault protection, earth fault
The method used for neutral point grounding is very important for power network operation. There are many ways of grounding, which are used in practice, and the decision on the method of neutral grounding depends on the situation in the network connected to the substation. When deciding on the method of neutral grounding it is necessary to thoroughly consider all the advantages and disadvantages of individual modes of neutral grounding, and then choose the best technical and economical solution. This paper analyzes the ways of neutral point grounding in medium voltage networks used in the current practice in Croatia which are isolated neutral point, low resistance earthing, partial compensation and resonant earthing. The use of shunt circuit-breaker is also described. Additionally, a survey of the relays used for the neutral point grounding system inside the substations was conducted and a brief analysis of the results is presented in the paper.