The Research On Neutral Grounding Mode For 10kV Distribution Network In Changsha

Under overall investigation on 10kV distribution network in Changsha district we notice that current neutral grounding mode via arc suppressing coil would not meet the demand sufficiently in three aspects: some of the arc suppressing coil failed to reach the capacity for practical application; supporting selected line equipment with small current ran under low accuracy; insufficient arc controller disturbed the full function of automatic tuning compensation arc suppression coil. Among practical accidents related to the incapacity of the grounding mode the biggest problem is that when one-phase-to-ground faults are detected arc extinction is difficult to complete and interface short circuit even poly-phase short circuit occurs instead. Therefore we try to introduce a novel neutral grounding mode via small resistance in distributing system which applies relay protection to cut off single-phase line faults for minimal electrical hazards.This paper describes the design and implementation of neutral grounding equipment and relay protection schemes. Lituo and Guangdian power stations are employed to illustrate the proposed ideasOverhead line trends to produce instantaneous ground faults caused by contact of branches and other aerial objects. Once such faults happen the reliability of distribution network would be damaged heavily because cut-off conductors in supporting neutral grounding system would react consequently under both permanent and impermanent fault conditions. Therefore we conclude from comprehensive investigation on suburban distribution network which be covered up mainly by 10kV overhead line that neutral grounding via small resistance fail to provide substantial ground-fault protection and insulation and continue to discuss the alternative approach for overhead line grounding protection in the paper based on the conclusion.On the whole, we try to propose innovative grounding solution for urban and suburban distribution network in this paper. Grounding mode via arc suppressing coil in heavy-load 10kV urban distribution network would be recommended to be replaced by neutral grounding mode via small resistance. On the other hand suburban overhead line network adopt KD-XH intelligent fast arc suppressing coil for grounding solution. We hold rational reasons to believe that the combination of grounding modes suitable for different distribution network would improve the power utilization in Changsha district largely.