A New Model Predictive Current Control Strategy for Hybrid Energy Storage System Considering the SOC of the Supercapacitor

In this project, a new model predictive current control (new MPCC) strategy for HESS based on MPC and PI controllers. This method reduces current ripples, and meanwhile enhances system stability and rapidity. MPC is adopted as the outer loop, and calculates reference values for the inner PI current loop. Furthermore, the state of charge (SOC) of the supercapacitor (SC) is considered based on fuzzy control to optimize the reference power of SC inner controller. Firstly, the topology and mathematical model of HESS in DC microgrid are analyzed. Then based on PI control and MPC, the new MPCC is proposed, and compared with MPC and PI methods respectively. Finally, the fuzzy control method takes SOC of SC into account to optimize the SC reference current. Simulation and experimental results show that the proposed new control strategy could effectively decrease current ripples and dynamic processes, and entirely perform high energy density characteristic of batteries and high power density characteristic of SC. The simulation results can be evaluated by using Matlab/Simulink Software.

Keywords:  Fuzzy control, hybrid energy storage system (HESS), model predictive control (MPC), new model predictive current control (new MPCC), PI inner control loop, state of charge (SOC).