Research On The Flexible Grounding Mode Of 20kV Distribution Network In SuQian Wu-Xing Substation

The choice of grounding mode of power distribution network is a traditional subject,which derives such problems as insulation protective configuration,overvoltage control and operation maintenance management.In recent years,with the continuous progress of science and technology,the theories and practice of power system have been developed and improved,many technical difficulties have been solved.Automatic tracking compensation technology,decentralized compensation and flexible grounding modes are new technologies and ideas developed in recent years.The choice of grounding mode for 20 kV voltage class is a technical topic which is firstly attempted to promote by Jiangsu Electric Power Company.However,due to the absence of a wide range of ready-made experience,new problems and contradictions have emerged in the course of actual construction and transformation.This paper systematically illustrates the key technology in the selection and transformation of 20 kV voltage-class grounding mode,summarizes and discusses difficulties involved above.Meanwhile,it also sets transformation project from 110 kV five-star variable to 20 k V as an example to design a feasible and flexible grounding transformation project.This thesis firstly reviews the technical standards,advantages and disadvantages as well as application scope of neutral point grounding mode of the 20 kV distribution network.It also introduces the arc suppression coil decentralized compensation technology,which has been applied.Emphasized on the choice of key technologies of 20 kV small resistance grounding mode and the choice of key equipment technical parameters,this paper analyses and compares the flexible grounding schemes.In particular,a detailed analysis is made on the constraints of schemes selection of 150 ampere standard of capacitive current,pointing out the theory limitations of capacitive current excessive capacity control schemes,which include decentralized compensation and automatic and flexible grounding cases.The specific content of transformation program of five-star variable grounding mode is then demonstrated in the paper,together with relevant selection standards of technical parameters and matters needing attention.The end of this thesis is the development prospect of distribution network grounding mode on the basis of the vigorous promotion of smart grid technology,the paper finally concludes that multiple grounding modes still coexist,solutions are found gradually and power supply is improved significantly.