This paper proposes a multilevel series compensator(MSC) to deal with: i) voltage sags/swells, ii) harmonic compensation or iii) reactive power compensation. Such a device can be considered as a dynamic voltage restorer (DVR) or a  series active power filter (Series -APF). The MSC can improve the power quality of loads located in stiff systems. The configuration is based on three-phase bridge (TPB) converters connected by means of cascaded single-phase transformers. This arrangement permit s to use a single dc-link. A generalization for K-stages, in which K-transformers are coupled with K-TPB converters, is presented. The topology permits to generate high number of levels  in the voltage waveforms with a low number of power switches in comparison with a classic topology. The multilevel waveforms are generated by the converters through a suitable PWM strategy that takes into considerat ion the transformer turns ratios. Modularity and simple maintenance make the proposed MSC an attractive solution compared to some conventional configurations. Model, PWM strategy and overall control are discussed in this paper. Simulation and experimental  results are presented as well.