Open circuit fault detection of Modular Multilevel Converter based on Grubbs

With the development of the medium and high voltage field, modular multilevel converters (MMC) have been applied in the Alternating Current(AC)/Direct Current(DC) conversion engineering of medium and high voltage. MMC contains multiple sub-modules, which simultaneously contain the same number of Insulated Gate Bipolar Transistor(IGBTs).High speed opening and closing of these IGBTs may result in switch failures and other issues. In order to solve the problem of faults, considering the ability of Grubbs algorithm to eliminate outliers, the calculation result of dividing the deviation by the standard deviation in the algorithm is taken as the eigenvalue, and the eigenvalue is compared with the Grubbs critical value to solve the problem of open-circuit fault.The simulation results show that in the case of an open-circuit fault, the characteristic quantities obtained from the calculated results are easy to distinguish after the fault occurs, and the algorithm can effectively locate the fault sub-module in about 4 ms.