Calculation Method of Equivalent Core Impedance and Admittance Parameters of Long Distance Power Cable

Accurate core equivalent impedance and cable insulation equivalent admittance parameters are required for on-line monitoring insulation condition of long distance power cable. The long distance power cable has the characteristics of the metal sheath cross-bonded and voltage drop and ground potential difference at both ends, which brings confusion to calculate electric parameters of long distance power cable. The traditional method is not accurate which takes the cable size into formula to calculate cable core equivalent impedance and insulation equivalent admittance, the results will impact on parameters selection. The two terminals voltage and current measurement is proposed in the paper. The principle of the method is analyzed, and the formula derivation and theoretical verification are given. The cable core equivalent impedance and cable insulation equivalent admittance parameters can be obtained by using the core current and voltage at both ends of cable. The parameters can be used to monitor the insulation condition of cable. The method was simulated by using Matlab software. The results show that the simulation results of cable core equivalent impedance and cable insulation equivalent admittance are consistent with the theoretical calculation. The method was proved to be validity and feasibility in the paper, which provides a theoretical basis to monitor the cable insulation condition.