Application Of Neutral Point Smart Switch Earthing Way In Jiashan 20kV Distribution Network

Compared with lOkV in the voltage sequence,20 kV has technical advantages, economic advantages and significant social benefits. The first 20 kV system in Dingzha substation of Jiashan power grid proceeded smoothly in October 2010. Dingzha substation 20 kV system neutral point adopts small-resistance grounding mode, which has repeatedly leading to line tripping for transient line single-phase grounding fault during operation,resulting in certain loss of power, causing economic losses to the customer especially to users that have continuous power supply requirements. What’s more,power enterprises should also bear certain legal risks.This paper studies neutral grounding mode intelligent switching of 20kV distribution network, which combines the advantage of petersen-coil grounding mode and low-resistance grounding mode. A new neutral point intelligent switching grounding mode of distribution network is proposed. The control method can effectively avoid the disadvantages of the single grounding mode in the current distribution network, and improve the reliability of the distribution network power supply.Firstly, by comparing the advantages and disadvantages of petersen-coil grounding mode and low-resistance grounding mode,the framework of neutral point smart-switch earthing way in 20kV distribution network is puts forward. Furthermore,the switching action principle is preliminary designed Secondly, the optimization and selection of the core components of grounding system intelligent switching device (small resistance, high voltage contactor, arc suppression coil and intelligent controller,etcl) are carried out; Thirdly, based on the analysis of the functional requirements of the whole set of intelligent grounding control system, the principle and process of the complete set of program processing is designed, and the detailed control strategy is established; Fourthly, through neutral point intelligent switching parameter configuration and logic design, the corresponding solution for transient and permanent single-phase pick fault or intelligent switching loss of the failure are presented; Lastly, the comparison of the trip data before and after the implementation of intelligent switching grounding mode in Dingzha station, the neutral point intelligent switching grounding mode is significant to improve the reliability of power supply.This paper proposes a new neutral grounding mode intelligent switching of 20kV distribution network, which combines the advantage of petersen-coil grounding mode and low-resistance grounding mode. Applying intelligent control logic to realize automatic switching, can effectively solve the problem of low reliability of power supply in Jiashan 20kV distribution network neutral point through small-resistance grounding method, which also has a wide range of promotional value and good social benefits.