As a new transmission technology, low frequency transmission has good application prospects in several scenarios such as offshore wind power transmission and new energy field station transmission. However, with asymmetric faults, the power asymmetry on the fault side will affect the capacitor voltage balance of the M3C and affect the stable operation of the low frequency transmission system. Therefore, an M3C capacitor voltage balance control strategy that can realize asymmetric fault ride-through in low frequency transmission systems is proposed. First, the system structure and dual αβ0 mathematical model of an M3C are introduced, and the causes of capacitor voltage imbalance under asymmetric faults are analyzed. Second, based on the dual 0 mathematical model for the transmission line asymmetric fault case, the expression for the bridge arm power imbalance component is calculated. Then the M3C power balance relationship introduces the current compensation to eliminate the power imbalance. It also obtains the circulating currents control objective applicable to asymmetric faults. Then through the loop current control it achieves the M3C capacitor voltage balance under faults. Finally, a simulation model of the M3C-based low frequency transmission system is built to verify the feasibility and effectiveness of the proposed control scheme.