Model Predictive Control Based Dynamic Power Loss Prediction for Hybrid Energy Storage System in DC Microgrids

In islanding microgrids, supercapacitors (SCs) are used to compensate the transient power fluctuation caused by sudden variations of load demand and generation power to keep the output voltage stable and reduce the stress in batteries. However, SC current in dynamic response leads to transient power loss on power electronic converters, and it would cause an additional voltage ripple. To smoothen the voltage fluctuation, a dual-layer model predictive control (MPC) method is proposed in this article to control the charging/discharging behaviors efficiently. The dynamic power loss can be predicted by the predicted current and duty ratio in the primary layer MPC. The predicted dynamic power loss is one of the state variables in the secondary layer MPC to generate the more optimal power reference for the primary layer MPC, which can compensate the voltage ripple caused by the dynamic power loss and reduce the dynamic error and settling time. The proposed method is validated by simulation and hardware experimental results, demonstrating significant improvements than other methods.