Hybrid Impedance-Based Controller Design of Grid-Connected Converter for Whole-System Stabilization of Grid-Connected DC Microgrids

The grid-connected converter (GCC) in a grid-connected DC microgrid performs an important role in stabilising the interaction of the AC and DC sections. With the development of DC microgrids, the DC section will gradually integrate more distributed energy resources and be compatible with various system operations, so it will be increasingly challenging to design the controller of GCCs to ensure the whole-system stability. To address this problem, this paper proposes a hybrid impedance-based controller design from the whole-system stabilisation perspective. Based on the concept of hybrid impedance, a stability criterion considering theAC andDCcoupling dynamics is proposed as a benchmark for the controller design of GCCs. In addition, with the help of linear matrix inequalities, a step-by-step algorithm is developed to automatically and efficiently tune the control parameter to achieve the desired design criterion. The effectiveness of the proposed method is verified through case studies including simulation and hardware-in-loop experiment. The further comparison study also shows that the proposed method has a stronger whole-system stabilisation ability compared to some reviewed methods. In some specific tests, the proposed method can limit the current THD to about 2% compared to other methods that cause the THD to exceed 20%.