Study on the failure mechanism of TSC high voltage thyristor valve over-current

For studying the reliability, testing methods and the mechanism of thyristor switched capacitor (TSC), the over-current failure of high voltage thyristor valve, which is the core component of TSC, is analyzed. Firstly, the configuration of the TSC and its thyristor valve is described; the over-current fault is examined; the waveform and its analysis representation are given. Then, based on the different development stages of TSC over-current fault, the voltage, current and thermal stresses on valve is expounded, the expression of each stress is inferred; the inner physical processes of the TSC valve under variable stresses are expounded. Finally, the failure modes and failure indexes of TSC valve on different over-current stages are obtained, thus the failure mechanism of TSC high voltage thyristor valve over-current is revealed.