Design of Prefabricated Joints for HVDC XLPE Power Cables
The similarity of constitutional equation in alternating current(AC) and direct current(DC) insulation suggests the similarity of structure and design principle for DC and AC cross linked polyethylene(XLPE) accessories.However,the characteristics of intrinsic parameter in the two kinds of electric field are different,which makes the design of DC XLPE accessories be different from AC XLPE accessories.Drawing lessons from AC XLPE accessories,we propose a detailed design method for the structure of DC XLPE accessories.In designing DC XLPE joints,the suppression of interfacial space charge is the most important,which depends on the reasonable permittivity and conductivity coordination of the two insulations.Finally,by taking the joint's design of 30 kV DC XLPE cable as an example,the conductivity ratio which meets the design requirements for optimization of stress cone is proposed from the result of simulation.