Passivity-based Method Based on PCHD Model of Modular Multilevel Converter Circulating Current Suppressing

Modular multilevel converter (MMC) is widely applied to high power renewable energy generation, due to the randomness of the renewable energy fluctuation, the system parameter perturbation and the nonlinear characteristic of MMC. The traditional vector control method can suppress the MMC circulating current, but it is hard to make sure the system strongly global stability and robust performance. To solve this problem, a novel passivity-based circulating current suppressing method based on port-controlled Hamiltonian with dissipation (PCHD) model is proposed. Based on the MMC global energy function of the PCHD model, the passivity-based controller is designed to modify the energy of closed-loop system by shaping storage function, so that the system energy could obtain the minimum value at the desired equilibrium point. The global asymptotic stability of the system is realized. The simulation results of MATLAB/Simulink shows that the proposed passivity-based circulating current suppressing method of MMC has the advantages of simplicity and good transient performance, and the system is globally stable and strongly robust.