Study on the Influence of Different Soil Moisture on the Characteristic Impedance of the Detection Model of High-Voltage Cable Sheath

With the continuous development and modernization of power systems, the application of high-voltage cables in power transmission is becoming more and more extensive. The damage to the high-voltage cable sheath may lead to safety hazards in the power system, and the time-frequency domain reflectometry (TFDR) is a nondestructive testing technology that can detect defects in the high-voltage cable, and the construction and study of the detection model can provide an effective theoretical basis for detection. Therefore, this paper firstly establishes a TFDR-based detection model of high-voltage cable sheath and proposes the calculation model of shunt capacitance and shunt conductance. Then two identical high-voltage cables were selected to be placed in relative parallel, and the characteristic impedance of the calculated model was measured. The correctness of the model calculation method was verified by comparison through MATLAB simulation calculation. In addition, the characteristic impedance of the soil with different moisture was measured and calculated, and the results showed that the higher the soil moisture, the greater the capacitance and conductance in the model, and the smaller the characteristic impedance.