Study on characteristics and application of bypass-protected thyristor in VSC valve

Abstract

In order to improve the reliability of the system after the failure of the power module based on the modular multilevel converter valve, and to ensure that the system will not trip after the failure of a single module, this paper proposes a highly reliable bypass method for the power module based on the bypass-protected thyristor technology, which will be used as the last resort of bypass-protected measure for the power module. It also studies the effect of bypass-protected thyristor leakage current on the static voltage equalization characteristics of the converter valve. The results showed that the thyristor leakage current reduces the static voltage equalization dispersion of power modules and can improve the safety margin of the power module voltage. At last, this paper describes the bypass-protected thyristor over-voltage short circuit breakdown characteristic test, and the test results showed that the through current may be stabilized in a long run after thyristor over-voltage short circuit breakdown, and the faulty power module can be in the short-circuit state for a long time, which guarantees the safe and reliable operation of the VSC valve.