Study On The Selection Of Distribution Network Form And Voltage Grade Configuration Of DC Distribution Network

With the rapid development of social economy,two obvious contradictions have appeared in our country.One is the use of fossil fuels with the improvement of people's requirements for a better living environment.The other one is the existing 10 k V AC distribution network in China has the contradiction of insufficient transmission capacity,poor power quality,with the increasingly large social load density and increasingly high power quality index.In order to solve the contradiction,efficient and clean clean energy began to develop rapidly,so clean energy access to the power grid has become a major research topic.And with the development of science and technology,the continuous maturity of power electronics technology,DC distribution network advantage gradually revealed.The DC distribution network has excellent power quality,large transmission capacity,good reliability,good electrical performance and economic performance,low power loss and relatively simple system structure compared with the AC system,and can be conveniently connected to the distributed power supply and DC load.Therefore,it is of great significance to study the DC distribution network.DC distribution network is a very rich subject,in this paper,the DC distribution network voltage level sequence configuration is studied.This paper refers to the existing AC-DC distribution network test project at home and abroad,studies the rules of its voltage level configuration,and combines the conditions of the voltage level,and obtains the method of voltage level configuration.The configuration of voltage grade needs to consider many factors,and it must follow the principles and constraints,according to the principles and constraints of voltage grade sequence configuration,this paper gives an appropriate voltage grade sequence.For the given voltage grade series.Build a mathematical model of its economic,reliability,adaptabilityand other aspects of performance,obtain specific voltage grade performance indicators,and carry out comparative research and analysis.The index weight method and fuzzy expert scoring method are used to evaluate the voltage grade sequence.This paper also established two appropriate examples to analyze the distribution network structure and distribution network voltage level,and concluded that the DC 20 k V medium voltage DC distribution network scheme has excellent performance in terms of economy,reliability and adaptability.Therefore,the DC 20 k V medium voltage DC distribution network can be used as a reference for the future construction of DC distribution network in China.