This paper presents a novel dedicated PWM technique for use with modular, multi-cellular converter for flexible power management of future electricity networks. The proposed converter is capable of connecting asynchronous grids together as well as incorporating renewable energy systems into the grid and improving power quality. The modulation is tested in this paper on a prototype rated at 300kVA. The proposed modulation strategy is described in detail along with the concept of the modular converter and an outline of its construction. Verification of the modulation effectiveness is provided by a comparison, performed by simulation, with other common modulation strategies. Finally, experimental results obtained from a prototype of a 3-cell cascaded converter, connected between two low voltage grid systems, have confirmed the validity of the proposed strategy.