Space electromagnetic interference analysis of secondary equipment signal cable

In the field of high-voltage transmission and distribution, the secondary equipments are influenced by the electromagnetic coupling effect generated by the primary circuit, which causes strong interference to the signal cable. In this paper, an equivalent circuit model is established for the secondary cables in different forms, namely conventional cable, coaxial cable and twisted pair cable, based on transmission line theory. Based on the model, the responses of these three kinds of signal cables under the impact of spatial plane electromagnetic wave are analysed in frequency domain. Different impedance characteristics of the cables at the near-end and far-end, and different cable layouts, and different injection directions of the electromagnetic wave are considered in the analysis. The response characteristics of different kinds of signal cables subjected to electromagnetic wave are obtained in frequency domain. By comparing the response characteristics of different kinds of signal cables in different conditions, measures to supress the interference from the coupling of electromagnetic wave are obtained. It can be used to guide the selection and cabling of the signal cables for the secondary equipment in power system.