The performance of a dc microgrid may be degraded when the tightly controlled electronic loads are connected, behaving as the constant power loads (CPLs) with negative impedances. In order to eliminate the oscillation in the microgrid, this paper proposes a simple model predictive stabilization method. This method is based on model predictive control, introducing a stabilization term into the cost function. By evaluating separate cost functions for the control objectives of the dc side and ac side in a cascaded way, the weigh factors are eliminated, which avoids tedious parameter tuning efforts, simplifying the design process. Moreover, current sensors in both the dc side and ac side are omitted, which are replaced by a full-order observer, reducing the size, cost, and isolation requirement of the system. The proposed method can stabilize a dc microgrid effectively by simple and cost-effective implementation. Meanwhile, the dynamic performance, such as small overshoot, fast and smooth response, is achieved. The effectiveness of the proposed stabilization method is validated by simulation results.
Cao et al. (Tue,) studied this question.