Converter transformer is the key equipment of HVDC transmission. During its long-term operation process

the valve side bushing of converter transformer will cause temperature rise of the bushing under the influence of eddy current loss

and the heating is an important reason for the deterioration of performance of bushing. The valve side bushing of converter transformer has inevitably such defects as metal particles in the process of production

installation and operation

which will cause cracks under the action of thermal stress. Studying the change in the temperature field inside the bushing under defect the conditions is of great significance for improving the design process of valve side bushing of converter transformer and enhancing its operation reliability. Based on the actual structure of bushing of converter transformer

in this paper the simulation calculation model of temperature field distribution of the bushing is constructed

the temperature rise of the bushing under different harmonic contents and hrmonic frequencies is simulated and studied

and the change of temperature field under metal particle defects and crack defects is analyzed by constructing a defect model of the bushing. The simulation results show that

in case of normal operation

the temperature of the epoxy resin capacitor core of the valve side bushing of the converter transformer decreases gradually along the radial direction. The higher the RMS value of harmonic current

the higher the harmonic current frequency

and the greater the maximum temperature inside the bushing. In case of increase of proportion of harmonic current

its influence on temperature rise increases. In case of metal particles in the bushing

the temperature gradient at the defect increases；and in case of cracks in the bushing

the temperature gradient at the defect decreases.