Stress Analysis and Reliability Calculation of Saturable Reactor of HVDC Converter Valve in HEMP Environment

The threat of HEMP (high-altitude nuclear electromagnetic pulse) in power system deserves in-depth study. Saturable reactor acts as a protection device for the thyristor, and its normal operation determines the normal operation of the whole thyristor converter valve. The failure rate of saturable reactor is a key parameter for the overall reliability evaluation, whose value varies according to the electrical stress and thermal stress conditions. In this paper, a precision wideband model considering the different capacitive parasitic parameters of a saturable reactor is proposed. Then, the electrical stress, heat loss and instantaneous temperature rise of the saturable reactor in a single valve are accurately calculated. Finally, the failure mechanism of saturable reactor in HEMP environment is analyzed, which could be used in the further research on the reliability of thyristor converter valve in HEMP environment.