Modulation and circulating current control of parallel connected back-to-back converters for WECS

This paper presents a modulation and control strategy for parallel connected back-to-back converters. The proposed modulation strategy has the following features: (i) to minimize the harmonic content of grid currents; (ii) to eliminate the circulating currents among the modules; (iii) to minimize the common mode voltage at the generator terminals. Furthermore, in the proposed strategy each power module has its own modulator and controller which make the overall system expandable to any number of modules in parallel. Finally, simulation results are presented to demonstrate the good performance of the proposed modulation and control strategies.