Abstract：Modular multi-level matrix converter（M3C）is a kind of new topology which can convert one

specified electric frequency to another directly，it is applicable to high voltage and large capacity scene. In the

fractional transmission system，the complete flow was introduced to achieve power frequency grid fault ridethrough.The arm power state equation of M3C in double α-β frame was introduced when power frequency voltage and fractional frequency voltage is unsymmetrical. The control strategy of switching on braking resistor in the fractional frequency side based on the average voltage of all sub-module capacitor was introduced，in order to

consume redundant power in the fractional frequency side. Positive and negative sequence reactive current based on

the power frequency positive voltage dips and negative voltage component were output. In addition，when power

frequency positive sequence voltage is too low，diagonal balancing control was converted to the fractional

frequency side from the power frequency side，which can realize the balance of all arm sub-module capacitor

voltage in the process of power frequency grid fault ride-though. At last，a 3.3 kV/3.3 kV/3 MV·A M3C model was

built in Matlab/Simulink，the effectiveness of power frequency grid fault ride-through strategy was validated.

      Key words：modular multi-level matrix converter（M3C）；power frequency grid fault ride-through；braking

resistor；balancing control