A single-phase low frequency AC(SLFAC)transmission method is proposed based on full-bridge modular multilevel converter(FMMC). A quasi-square voltage waveform is generated for low frequency side(LFS)

which can not only lift the restriction on the frequency of LFS and realize the power transmission with the frequency of 1 Hz or even lower

but also minimize power ripple on LFS and eliminate charging currents of transmission cables. Besides

it is proved that the transmission capacity of SLFAC can be increased close to that of HVDC. Comparisons have been done among LFAC and HVDC

SLFAC in aspects of technology and economy. A power balancing strategy is proposed to adapt to the FMMC-SLFAC system. Under the premise of ensuring the balance for system active power

power ripples of LFS are absorbed by capacitors of FMMC and do not inject into power frequency side. Furthermore

the voltage ripple of capacitors caused by the power ripple of LFS is derived in formula

and the period of switching sine wave is given in formula under the restriction of capacitor voltage ripple. Finally

a comprehensive control strategy is presented and the simulation results verify the feasibility and effectiveness of FMMC-SLFAC.