Analysis of Heat Characteristics of Power Electronic UHV AC Controllable Arrester

The fast conduction characteristics of thyristor devices are utilized to dynamically adjust the volt-ampere characteristics of a power electronic controllable arrester, which deeply suppresses the overvoltage of the ultra-high voltage (UHV) AC system, therefore it is one of the development directions of overvoltage suppression technology in the future. Operating temperature is the key factor that affects the operation reliability of thyristor devices. The device failure caused by temperature accounts for as high as 55%, and thus, it is necessary to analyze the heat characteristics of thyristor devices in controllable arresters. According to the practice engineering parameters, the overvoltage of the UHV AC system was simulated under various conditions in this work, and the current waveforms of thyristor devices under various overvoltage types were obtained. The heat dissipation model of thyristor devices was built based on the finite element algorithm, and the heat characteristics of thyristor devices during the conduction process were analyzed by using the conduction current as the heat source. The simulation results show that under the lightning overvoltage condition, the thyristor junction temperature rise is only 0.0857 K; under the operating overvoltage condition, the temperature rise of the thyristor junction is only 0.0936 K; under the long-duration impact condition, the temperature rise of the thyristor junction is only 3.396 K; under the large impact current condition, the temperature rise of the thyristor junction can reach 36.745 K, and the temperature of the thyristor copper tube base has no obvious change. Therefore, there was no need to conFigure the additional auxiliary cooling system. The research results provide a basis for the prototype development of a power electronic controllable arrester.