Admittance-type RC-mode droop control to introduce virtual inertia in DC microgrids

One of the major feature of DC microgrids is its high penetration of power electronic converters, as a result, the system inertia becomes a problem. In this paper, an admittance-type droop control with additional capability of introducing virtual inertia to the system. With the proposed method, each energy source will also contribute virtual inertia to the system, thus improving transient response and stability of the entire DC microgrid. The inertia issue of droop control is firstly analyzed. A comparative study is carried out between conventional method (i.e. impedance-type droop control method) and the new proposal in terms of their different control principles, characteristics of equivalent output admittance/impedance, and effectiveness in achieving desired virtual inertia introduction. Ultimately, simulations and experiments are carried out to verify proposed control methods. The results show improved system inertia and enhanced performance.