A Synthesized Control Scheme for Large Signal Stabilization of DC Microgrids

DC microgrids (MGs) have obtained extensive attentions due to their high flexibilities and efficiencies. In DC systems, power electronic loads and motor drives are normally modeled as constant loads (CPLs) which present negative incremental impedances and may cause stability problem. To mitigate the potential instability of CPLs, a novel synthesized control scheme is proposed in this paper. The scheme consists of a generalized proportional-integral observer (GPIO) and a backstepping controller (BC). The GPIO enables to exactly and rapidly estimate the output power of the source converters, and the estimated quantity will be decoupled by the BC in a feedforward way. By using the proposed synthesized method, large signal stabilization of the DC MG can be effectively realized. Destabilizing effects of CPLs could hence be fully compensated, thus safeguarding the stable MG operations. Simulations and experiments consolidate the effectiveness and feasibility of the proposed scheme.