Electric field calculation and optimization of the UHVDC converter valve shield case

The converter valve is one of the key equipments in the ultra-high voltage direct current (UHVDC) transmission systems. Shield case design is an important part in the process of converter valve design, appropriate shield case configuration can improve the electric field distribution of converter valve, extend the service life and enhance the long-term operation reliability of the UHVDC systems. In this paper, an electric field distribution equivalent calculation model of the double converter valve was discussed, and a 3-D transient calculation model of ±800 kV double converter valve was established by using a finite element method (FEM) analysis software ANSYS. The calculation results of potential and electric field distribution of the double converter valve were presented, the law of electric field distribution of the shield cases which run on different working conditions and locate in different positions of the double converter valve was revealed, the effect of electric field and potential distribution of different shield cases configuration schemes was discussed, and an optimal scheme was put forward. Verified by the computer simulation, the optimal scheme satisfied the external insulation and electromagnetic environment requirements of the double converter valve. The results provide an important basis on the design of the UHVDC double converter valve.