Optimization of DC Resistance Divider Up to 1200 kV Using Thermal and Electric Field Analysis

Self-heating and electric field distribution are the primary factors affecting the accuracy of the Ultra High Voltage Direct Current (UHVDC) resistive divider. Reducing the internal temperature rise of the voltage divider caused by self-heating, reducing the maximum electric field strength of the voltage divider, and uniform electric field distribution can effectively improve the UHVDC resistive divider’s accuracy. In this paper, thermal analysis and electric field distribution optimization design of 1200 kV UHVDC resistive divider are carried out: (1) Using the proposed iterative algorithm, the heat dissipation and temperature distribution of the high voltage DC resistive divider are studied, and the influence of the ambient temperature and the power of the divider on the temperature of the insulating medium of the divider is analyzed; (2) Established the finite element models of 1200 kV and 2 × 600 kV DC resistive dividers, analyzed the influence of the size of the grading ring and the installation position on the maximum electric field strength of the voltage divider, and calculated the impact of the shielding resistor layer on the vicinity of the measuring resistor layer. The research indicates that: (1) The temperature of the insulating medium is linearly related to the horsepower of the voltage divider and the ambient temperature; (2) After the optimized design of the electric field, the maximum electric field strength of the 1200 kV DC resistive divider is reduced to 1471 V/mm, which is about 24% lower than that of the unoptimized design; (3) Installing the shielding resistor layer can significantly improve the electric field near the measuring resistor layer. This paper has an important reference function for improving the accuracy of the UHVDC resistive divider.