Research On DC Distribution Network Line Fault Characteristics Analysis And Location Method

In recent years,the continuous development of the economy has caused new demands on the quality of electricity and the power supply.The traditional AC distribution network can no longer meet its needs,and the concept of the DC distribution network provides a new development direction of the solution to the above problems.However,the current research on DC distribution network related technologies at home and abroad is still in infancy.In the meantime,there are still many technical bottlenecks.Protection technology is one of the key technologies to be solved urgently,among which fault characteristic analysis is an important theory for fault diagnosis and protection design basis.In view of this,this paper mainly focuses on fault diagnosis and protection technology of DC distribution network.Firstly,a comprehensive introduction to the related technologies of the DC power distribution network,including the advantages and disadvantages of its topology,DC system grounding methods,operating principles and control strategies of key components such as AC/DC converters,etc.Compared with DC power distribution network in many aspects,the advantages of DC power distribution method are explained.Then,In accordance with the fault occurrence area,the fault types of the DC distribution network are clarified,and typical faults such as asymmetrical faults on the AC side of the converter and pole-to-pole short-circuit faults on the DC side are analyzed theoretically.The particularity of DC distribution network fault and protection is discussed.Use Matlab/Simulink simulation platform to build a double-ended DC distribution network model to simulate fault conditions and verify the theoretical analysis process.At last,a fault location method based on the transient characteristics of the fault is proposed.A mathematical model of the short circuit fault on the DC side is established.The fault characteristic equation is solved with the voltage information of the current-limiting reactor collected by the protection measuring device,which can obtain the fault distance.The influence of the transition resistance is eliminated by using the double-ended electrical quantity,and the redundant data is processed by the principle of the least square method,thereby improving the positioning accuracy.A fast main protection scheme based on single-ended voltage is designed,which can realize fast fault identification for short-circuit faults in DC distribution network.