Robustness Analysis of Classical High Voltage Joint Design Under High Voltage DC Stress

Abstract

The demand for extruded HVDC cable systems for higher voltages has been increasing in different fields. This demand comes from the need for higher transmission capacity in applications such as integration of wind power, power system interconnectors and connection of offshore oil and gas platforms to land. Prefabricated joints are used to connect the cable delivery lengths. If badly designed, the possibility of breakdown in the joints is higher than in other parts of the system because of the number of interfaces and triple points between different materials. Due to the huge potential costs and the down-time imposed to the system in case of a joint failure, the robustness of the joints is of great importance. Two main approaches in the design of prefabricated joints for extruded cables exist in which the more recent one takes advantage of the nonlinear properties of modern field grading materials. In this work, we have examined the design challenges with focus on robustness issues in a 150 kV classical joint design without field grading material. The results show that with this approach, there are serious robustness issues which are challenging to overcome without field grading material.