Study On Diversified Neutral Grounding Modes And Reliability For 10kV Power Distribution Network

The neutral point grounding mode seriously impacted on the performance and reliability of the power grid. Since more and more cables have been used, the past neutral grounding modes could not be suitable for the rapid development no longer.The neutral point grounding modes were closely related to operating condition when earth fault happed. In order to ensure the security and stability of power system, the appropriate neutral point should be choosed. It is necessary to study neutral grounding mode.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, especiallythe widespread use of cables, low resistance grounding mode was used to restrain the over voltage Combined with the actual data, the simulation modes of different neutral groundings in distribution network were established based on the PSCAD software. The results of simulation carried out the transient and steady state characteristics of the fault in different groundings to compare the advantages and disadvantages of every mode.According to the classical arc model theory, the modified arc simulation model was established. In an attempt to verify the accuracy of arc mode,we compared it with the experimental result. The arc ignition time was set at the peak of the fault voltage and the arc extinguishing was set at zero point of the current.The purpose of simulation was to analysis the practical effects of intermittent arc overvoltage in different neutral grounding modes.Besides,we put forward the method of selecting the best grounding resistance.The hybrid grounding has existed for a long time in the course of the power grid transformation.Combined with the actual conditions of contact, the hybrid grounding fault modes were set up to analysise characteristics in different operation modes and different fault locations. The paper put forward proposals and some improvements of protection scheme to run the hybrid grounding system.At last,the trip rate models were calculated by the method of FMEA. The influence of the neutral point grounding on the reliability of the distribution network were evaluated in details. According to the given example and reliability standard, we illustrated the results under different neutral point grounding modes. This calculated result were designed to give advices to neutral point grounding mode decision method which made the reliability and economic coordination...