Analysis of switching transient overvoltages and protection techniques for the energization of the connected 115 kv underground and submarine cables

In this paper, switching overvoltages analysis based on the statistical study approach according to IEC 6007 Insulation Co-ordination are analyzed for the energization of the connected 115 kV underground and submarine cables from Khanom power plant to Samui Island substation. Comparative analysis of protection schemes including metal oxide surge arresters and controlled switching are analyzed for controlling switching overvoltages during cable energization. The digital computer simulations are made using PSCAD/EMTDC software. Test results show that the overvoltage values at the sending and receiving ends from the cable energization without surge arresters and controlled switching of circuit breaker can reach up to 1.6-2.0 p.u. In addition, the switching overvoltages can be mitigated by the provision of surge arresters at the two line terminations. Additional limitation of these overvoltages, controlled switching involving individual closing of each phase in the circuit breaker at the optimal point-of-wave can be used.