Statistical analysis of overvoltages due to the energisation of a 132 kV underground cable

Analysis by means of simulation studies is essential for providing useful information to distribution engineers and researchers regarding high frequency switching transients in cable systems. The behaviour of transients due to switching is strongly dependent on the pole closing span of the circuit breaker and also the closing angle of the power frequency voltage. This behaviour requires the study of overvoltage magnitude distributions to be carried out using a statistical approach. This paper presents an analysis of overvoltage sensitivity due to circuit breaker operations when energising an unloaded 132 kV underground cable system. Based on two approaches, the overvoltage values at the sending and receiving end tends to vary between approximately 1.8 p.u. to up to 2.1 p.u. respectively. Other related information is presented especially the useful data for consideration of protective schemes as well as the coordination of insulation systems.