A DC-Equal-Area Based Virtual Inertia and Damping Evaluation Method for Ship VSM-Controlled Electric Propulsion

In electric propulsion systems, virtual synchronous motor (VSM) control plays a critical role in buffering large power surges. Its performance is contingent upon the tuning of parameters including virtual inertia and damping, which should be optimized according to the dynamics of the dc capacitor. Conventional tuning methods often neglect these dc capacitor dynamics, leading to either overutilization or underutilization of the capacitor’s buffering capabilities. The complex, high-order nonlinear equations involved make it challenging to analytically derive the relationship between the VSM parameters and dc capacitor dynamics. Inspired by the classical equal-area criterion of stability, this article proposes a dc-equal-area method to represent the capacitor dynamics as a whole and thus estimate the optimal parameters that maximize the inertial capacity of the dc capacitor. A small-signal model, encompassing both the typical fluctuation power and the controller dynamics, is developed. The proposed method achieves up to a 25% improvement in load fluctuation smoothing compared to existing approaches, as validated through hardware-in-the-loop (HIL) experiments conducted on the RT-LAB platform.