Equivalent temperature rise test and life evaluation of converter valve damping capacitor

The damping capacitor is core component of converter valve. Effectively evaluating life of damping capacitor is of great significance for the evaluation of the converter valve state and the stady of the localization of the damping capacitor. First of all,combined with the application principle of the damping capacitor of the converter valve,a multi-frequency point equivalent temperature rise test method is proposed. By equivalently calculating the loss of damping capacitor during actual operation and flexibly selecting the frequency and current for the test,the internal temperature and thermal resistance of damping capacitor during actual operation can be accurately evaluated. Then,considering the actual operating environment and working temperature of the damping capacitor of the converter valve,the life-influencing factors are analyzed.A life prediction method combining aging test and curve fitting is proposed based on the classical life prediction model. The proposed method can shorten time and cost of the test. Finally,the internal temperature rise and thermal resistance of the capacitor during operation are analyzed in combination with the actual engineering parameters,and the expected life of the damping capacitor sample is further evaluated by the life prediction test. The obtained results meet the requirements of ultra high voltage direct current projects.