College of Electric Power Engineering, Shanghai University of Electric Power, Shanghai 200090, China

In order to realize voltage smoothing control of the DC microgrid with high proportion of renewable energy, this paper proposes a coordinated control method of multiple DC electric springs (DCESs) based on differential flatness theory. Considering the nonlinear characteristics and multiple working modes of multiple DCESs in the DC microgrid, the differential flatness control method is designed for the upper layer to directly compensate nonlinear components, which ensures stable DC bus voltage under the condition of renewable energy output fluctuation and system parameter perturbation. The stability and robustness of the system are improved, and the reference trajectories of inductor currents are provided for the lower layer. The model predictive control (MPC) method based on the working modes of DCESs is designed for the lower layer. By simplifying the optimization calculation, the rapid dynamic response of the system can be ensured, and the tracking of reference trajectory of inductor current and the voltage fluctuations of various DC bus segments can be achieved without communication. The simulation results based on MATLAB/Simulink and the experimental results based on dSPACE show the correctness and feasibility of the proposed method.