การวิเคราะห์แรงดันเกินสวิตชิงและเทคนิคการป้องกันสำหรับ การจ่ายไฟฟ้าและการจ่ายไฟฟ้าซ้ำของระบบสายเคเบิลใต้ดิน ที่เชื่อมต่อกับสายเคเบิลใต้น้ำระดับแรงดัน 115 กิโลโวลต์

Abstract

In this thesis, switching overvoltages analysis based on the statistical study approach according to IEC 60071 Insulation Co-ordination are analyzed for the energization and re-energization of the connected 115 kV underground and submarine cables system from Khanom power plant to Samui Island substation to determine the maximum switching overvoltage and 2 % statistical switching overvoltage. The digital computer simulations are made using PSCAD/EMTDC software. Comparative analysis of protection schemes including controlled switching and metal oxide surge arresters are analyzed for controlling switching overvoltages. Test results show that the maximum switching overvoltage and 2 % statistical switching overvoltage from energization are 2.077 pu and 2.046 pu, respectively. Moreover, the overvoltage values from re-energization after single line to ground fault are more than those from energization which can reach up to 2.688 pu. In addition, controlled switching of circuit breaker operation for switching overvoltages protection is more effective than surge arrester. Using both protection techniques, switching overvoltage can be reduced to 1.131 pu.