A study on the suitability of cable models to simulate switching transients in a 132 kV underground cable

Switching transients resulting from the energisation of high voltage cable systems may have a significant effect on both the cables being switched as well as the power system components in the vicinity. The impacts of these transients on such cables are measured based on the stress arising as a result of the voltage and current peaks and the frequency of oscillatory transients. These quantities are typically obtained from a simulation by using a suitable cable model, normally with the capability to predict the transient behaviour in the range up to several 10 kHz. To obtain a cable model that enables the accurate determination of the switching transient behaviour of a cable system in service, comparison of simulated data with actual measured data is a vital process before the cable model is selected and then used for further transient analysis. Statistical studies are then carried out to simulate the stress experienced by the underground cable under study. In this paper, the authors have carried out studies on the suitability of various cable models available in PSCAD/EMTDC investigate the ability of the two available Frequency-Dependent (FD) cable models in predicting the peak, frequency and oscillatory nature of current energisation transients resulting from the switching of an unloaded 132 kV underground cable. Using the most accurate cable model evaluated from the first stage of the study, a statistical analysis of over-voltage distribution to analyse the over-voltage stress at the sending and receiving ends of the cable is also presented. This study employed two different techniques based on probabilistic and deterministic approaches to measure the distribution of over-voltages at the sending and receiving ends of the cable.