Multi-Functional Distributed Generation Unit for Power Quality Enhancement

A multi-functional distributed generation unit (MFDGU) and its control strategy are proposed in this paper for the purpose of enhancing power quality in low-voltage networks. By using the 3H-bridge converter structure, an MFDGU can be applied in 3-phase 4-wire low-voltage distribution networks to compensate harmonic, reactive, and unbalanced currents. A reduced-order model of the MFDGU is derived through a weighted-average-current-feedback (WACF) approach, showing the robustness and stability of the proposed approach. The Fryze-Buchholz-Dpenbrock (FBD) power theory is employed to generate the current reference of the MFDGU, which can be easily implemented in three-phase networks. A 15kVA prototype consisting of three full bridge converters has been built and tested. Experimental results show the feasibility of the proposed topology and control strategy.