Improved Switching Ripple Suppression Strategy for Multi-Paralleled Grid-Connected Inverters System

The switching operations of inverters in the distributed system inevitably introduce high-frequency harmonics into grid, which may make influences on electrical devices. To address it, this paper proposes a ripple suppression strategy based on active cancellation combined with passive filtering. The active cancellation is realized by carrier-phase-shift (CPS) technique and the passive filtering is achieved by filters. Furthermore, two component-shared LCL-type filters improved by traditional LCL filters are studied from the points of resonance and accuracy of grid-injected current. To valid the effectiveness of the proposed strategy, simulations and experimental test are carried out. The results show that the proposed strategy can effectively suppress high-frequency harmonics and two component-shared LCL-type filters can become promising filters for the multi-paralleled grid-connected inverters.