A decoupling design method for DC virtual inertia and voltage loop stability margin

The implementation of large virtual inertia with high stability margin is a significant challenge for DC microgrid system. In this paper, the filter time constant, a new degree of freedom, is utilized to enhance voltage loop stability and its relationship with virtual inertia and stability margin is further explored. Then, the virtual resistance concept is introduced as an intuitive design parameter to decouple stability margin from virtual inertia. In this way, large virtual inertia can be realized in a simple and practical way, making it easy to be emulated quantitatively and applied in engineering practice. Moreover, the performance analysis of virtual resistance is conducted, which suggests that virtual resistance with proper value brings little effect on its dynamic response while greatly enhances stability margin. Finally, the proposed decoupling method is validated in both simulation and experiment.