Research on Transient Voltage Characteristics of EHV Cable Considering Corrugated Sheath

Electromagnetic transient characteristics in EHV cable systems are essential for the calculation of overvoltage and the design of insulation co-ordination. In this paper, an improved transient model of EHV cable with a structure of corrugated sheath is proposed to calculate parameters of wave propagation. In this method, the corrugated sheath is equivalent with a smooth structure based on the geometric mean radius and length, to obtain the accurate impedance and admittance of complex cross-section cable. Then, a transient test on a 500 kV EHV cable circuit is carried out to verify the accuracy of the proposed model for the transient voltage. Compared with the frequency-dependent phase model in PSCAD, the calculation accuracy of the modified model is improved by more than 5% with a relative error of 4%. This increase in calculation accuracy is caused by the errors of corrugated sheath thickness and surface area in the PSCAD model. Therefore, it is necessary to consider the influence of the corrugated sheath when calculating the transient wave propagation and designing the protection strategies of the EHV cable.