Research On Technology Of Neutral Grounding Method Transformation In Medium Voltage Distribution Network

The choice of neutral point grounding mode for medium voltage distribution network has always occupied an important position in the power system.It has also been a difficult point in the construction and operation of power grids in various regions of the country.It is necessary to consider not only the characteristics of the local area but also the regional load situation.Impact on grid operation mode,power supply reliability,equipment insulation level,relay protection configuration,and life safety.At present,there are two main methods of grounding and non-grounding in the power system,and the neutral grounding system can be divided into direct grounding,arcing coil grounding and small resistance grounding.This paper starts with the principle and theoretical calculation of different types of grounding methods for neutral point of medium voltage distribution network,analyzes its essence and characteristics in depth,compares the advantages and disadvantages of several grounding methods,and classifies and summarizes its applicable conditions and applicable scope.The characteristics of 10 kV power grid system in Shijiazhuang area,finally got the advantage of grounding through the arc suppression coil device,and designed a new dynamic compensation arc suppression coil,which can compensate the capacitor current in real time,which has very important practical significance.This paper first investigates the development status of neutral point grounding operation mode of medium voltage distribution network at home and abroad,and studies the problems it faces.Then the operation characteristics,advantages and disadvantages of the three grounding methods are studied in detail,which provides a theoretical basis for the research of the project.After that,various conventional capacitor current detection methods based on arc-suppression coil grounding were studied,and a new injection signal method was used to detect the capacitance current.At the same time,by studying the traditional hysteresis comparison method,a hysteresis loop with variable loop width was proposed.The method controls the arc suppression coil,and the mathematical model of the new dynamic compensation arc extinguishing device is established,and its working principle is expounded.Finally,the simulation analysis using Matlab/Simulink verifies the correctness of the scheme.