In the design of ultra-high voltage direct current voltage transformers

the temperature rise and distribution uniformity of internal measuring components may affect the measurement accuracy and the safe operation of the equipment. It is necessary to conduct detailed research on their thermal characteristics and variation laws. In this study

the computational fluid dynamics method is used to analyze the temperature distribution characteristics of an UHVDC transmission

and the accuracy of the grid model and the selection of the numerical model are investigated. Through analysis

it was found that the internal and external flow fields of the equipment are mainly dominated by natural convection

and under the combined effect of the temperature difference between the internal components and the inner wall of the cylinder

as well as the flanges

the internal flow field present with a locally small circulation. The temperature of the internal components of the equipment gradually decreases from the resistor to the capacitor and the flange. Under the natural convection in the vertical direction

the temperature shows a distribution of lower and higher. Under extreme conditions of an ambient temperature of 60 ℃

the maximum temperature of the resistor can reach 85.14 ℃

and the inter stage temperature difference can reach 13.24 ℃. Refer to the thermal characteristics of the equipment

it was found that increasing the gap between the flange and the cylinder wall can enhance the strength of natural convection inside the equipment and reduce the overall internal temperature. By installing heat sinks on both sides of the top head of the equipment

the heat dissipation capacity of the upper part of the equipment can be improved

and the temperature difference between the resistors can be reduced. Finally

the adjoint method was used to optimize different heat sink structural parameter schemes

and a comprehensive thermal characteristic optimization scheme was proposed to provide reference for engineering design.