Capacitor Current Control Based Virtual Inertia Control of Autonomous DC Microgrid

Virtual inertia (VI) control of dc microgrids (dc MG) is a potential solution to the voltage stability issue caused by the intermittency of loads and renewable sources. Existing VI strategies for dc MG rely on a first-order differential equation relating voltage (speed) with current (torque) to control the grid-forming converters that are crucial in an autonomous dc MG. However, the output impedance of these converters can distort the inertial response. Existing research works overcome this by using a feed-forward controller (FFC) necessitating an accurate system model for proper compensation. Hence, in this article, a novel VI scheme based on capacitor current control, which does not rely on any differential equation, is proposed. The proposed VI scheme employs a static gain to restrict the capacitor current for inertia emulation without any additional FFC. Furthermore, the proposed VI scheme is extended to parallel-connected converters to study their steady-state and transient coordination. Finally, the proposed strategy is validated in simulation using MATLAB/Simulink and is also experimentally verified in a laboratory prototype using the TMS320F280049C controller.