Research Of Frequency-dependent Model And Location Principle Of DC Cable

Smart grid is the latest trend of power system development and changes,and DC system has its features of large capacity of power supply,economical and high power quality and so on.DC system has broad prospects for development.DC power distribution system carries different types of distributed power,and it also has its features of less energy conversion and higher energy utilization,which can promote the electric vehicles,DC home appliances and DC intelligent building development.Urban distribution power network uses a large number of cables,which mostly laid underground.After the cable line fails,if the fault location is not accurate,will waste a lot of manpower and resources and time.However,as one of the key technologies of the development of DC power distribution system,the fault location technology of DC line fault is lack of practical engineering application and widely adopted positioning scheme.Therefore,the effective positioning method of DC distribution system fault has important value and significance to the development of electric system.Firstly,focuing the work on the equivalent mathematical model of the frequencydependent model,and simulation research to the frequency-dependent model.On the modified frequency-dependent model,some problems in the application of the model to DC line are analyzed.And the parameter calculation method of the frequencydependent model using the modulus transformation in the DC circuit.The relationship between distribution parameters and frequency is obtained,which will lay the foundation for the establishment of DC line simulation model and the study of fault location theory.Secondly,on the basis of researching status methods of faulty location at home and abroad,giving the analyzed of each location method influences to the in frequencydependent model and DC link.The two-terminal location method is used to locate the line of DC frequency-dependent parameter model.The wavelet algorithm is combined with the calculation of the transient electrical quantities in the double-ended positioning.The idea that wavelet can only be used to extract traveling wave head in fault location is broken through.Accuracy is higher than the traditional positioning method using only the double-end power frequency electric quantity localization.