Study on local fault diagnosis of cable based on input impedance spectrum and electromagnetic coupling field

New energy distributed power generation through the substation after boosting for power transmission, high-voltage power cable as a key carrier as the transmission link, different faults will have a great impact on the transmission steady state. The traditional fault diagnosis techniques - time domain reflection method and frequency domain reflection method are difficult to be applied to the increasingly complex transmission and distribution lines, both of which have the problems of limited types of diagnostic faults and lack of accuracy, so this paper proposes a cable fault diagnosis method based on the input impedance spectrum and electromagnetic coupling field joint diagnosis. Firstly, the defects of traditional fault diagnosis technology are analysed, and the basic principles of input impedance spectrum and electromagnetic coupling field and fault identification method are clarified on the basis of power cable distribution model. Then, the changes of input impedance spectrum and electromagnetic field under different circumstances are analysed and combined with time domain and frequency domain diagrams to make judgments. On this basis, the simulation models of input impedance spectrum and electromagnetic coupling field are established to analyse the changes under different faults (short circuit, open circuit, high resistance, etc.). Finally, the experimental scheme of the proposed method in this paper is designed. The final results show that the method used in this paper has good accuracy and better fault identification capability.