A Virtual-Capacitor-Based Inertia Enhancement Method for Switching Converters in DC Microgrids

The virtual inertia can effectively enhance the voltage stability of dc microgrids (dc MG) against disturbances. However, the existing approaches are generally criticized for delayed inertia provision and insufficient use of load-side inertia potential, without making maximal use of inertial resources. In this letter, a new perspective on enhancing dc inertia through virtual capacitor emulation is proposed. Based on this perspective, the load-converter virtual input capacitor (LVIC) and source-converter virtual output capacitor (SVOC) methods for PWM switching converters are introduced. It is the first time to achieve instantaneous virtual inertia support from both source and load sides of dc systems, leading to identical system dynamics as compared with the installation of real capacitors in dc MGs. Experiments on a 60 V, 850 W dc MG are performed to demonstrate the dynamic and stability performance of the proposed methods.