The Study on the Design of Grading Electrodes in Water‐Cooling System of <scp>HVDC</scp> to Eliminate Corrosion of Aluminum Heat Sinks

The corrosion of aluminum heat sinks by leakage currents in different branch pipes is identified as the primary cause of deposition on the surfaces of grading electrodes in the cooling water system in high voltage direct current converter valves. Up to now, the effect of the parameters of grading electrodes on corrosion is not completely understood and the corrosion suppression is limited. A three‐dimensional quasi‐static electric field finite element method model was built. The influence of grading electrode radii on leakage currents was analyzed. The optimal installation positions of the grading electrodes under different electrode radii were determined. Their relationships were fitted using polynomial functions. A novel and practical configuration for grading electrode arrangement was proposed. The suppression efficiency of the total leakage current is up to 99.69%. This proposed method can be utilized for the optimal design of grading electrodes in the cooling systems of high‐voltage direct current converter valves. The problems of corrosion and deposition in converter valves may be resolved in the future. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.