Calculation of Sheath Overvoltage for 220 kV Long-segment Cable and Design of Sheath Voltage Limiter

The application of long-segment cables could reduce the number of intermediate joints, thus effectively suppressing the failure rate of the cable system. However, the increase in cable length makes the energy absorption capacity of traditional sheath voltage limiters (SVLs) far from meeting the requirements that they should be re-designed. In this paper, a model of a representative 220 kV cable system is presented. We delve into an analysis of the induced overvoltage properties pertaining to the cable sheath, as well as the energy absorption capacity characteristics of the SVL. These investigations are conducted under various conditions, encompassing short-circuit overvoltage, operational overvoltage, and lightning-induced overvoltage. Furthermore, the research addresses these scenarios in the context of multi-segment and dual-loop cables employing a single-ended grounding configuration. It was found that the substantial energy generated under during instances of short-circuit overvoltage, particularly after an increase in cable length, contributed to the explosion of the SVL. Finally, we design a new SVL based on the principles of insulation fit and energy absorption, which rated voltage is 7 kV, energy absorption capacity is 67 kJ. The new SVL can be used in cables up to 1100 m long in single-ended interconnection ground configurations. These findings are expected to provide theoretical guidance for the determination of the critical length of long-segment cable and the selection of the SVL.