Hybrid passivity-based control for stability and robustness enhancement in DC microgrids with constant power loads

In a DC microgrid, the negative damping characteristics of a constant power load can deteriorate the stability of the whole system. To improve the robustness and stability of the DC microgrid, a hybrid passivity-based control of damping injection is presented in this paper. The stability of the closed-loop system is ensured by the energy dissipation property of the passivity-based control. A proportional-integral controller is integrated with the passivity-based controller to form a hybrid passivity-based control to improve control robustness. A small-signal model of a DC power system with constant power load is derived in detail, and the stability of the system is analyzed with the Lyapunov eigenvalue method. The proposed hybrid passivity-based control provides the system with a faster recovery and a larger power boundary when compared with the typical voltage-current dual-loop control. First, the proposed control is verified by simulation of the DC power system based on MATLAB/Simulink, and the feasibility and superiority of the proposed control are further verified by hardware-in-loop (HIL) experiments based on real-time laboratory (RT-Lab) and a TI DSP TMS320 F28335.