Analysis of Overvoltage and Insulation Coordination on 500kV AC Cable Transmission Line

Based on the research of overvoltage on 500 kV typical AC cable transmission line, frequency transient temporary and slow-front switching overvoltage of cable under typical metal sheath wiring mode and high voltage reactor configuration schemes are simulated and calculated by ATP- EMTP program. The insulation coordination of 500 kV cable line is carried out. The research shows that the highest frequency transient overvoltage value of cable line is 1.39p.u..The rated voltage of lightning arrester on line both ends is recommended to be 420kV.The highest phase-to-ground switching overvoltage along the cable line closing operation is 1.92 p.u., the highest phase-to-ground switching overvoltage along the cable line switching-off overvoltage is 2.05 p.u. when SF6 circuit breaker is re-ignition and the highest switching overvoltage along the line fault unlocking is 1.75 p.u..It is suggested that the line breaker closing resistors on both ends of 500 kV cable line are unnecessary. The rated cable line switching impulse withstanding voltage is selected as 1175 kV. The study conclusions can be used for reference in engineering design for cable project.