Enhancement in Robust Stability Delay Margins for an Interval Shipboard Microgrid With Virtual Inertia and Damping Control

ABSTRACT

The study describes the mathematical calculation of the robust stability delay margin (SDM) of an interval shipboard microgrid (SMG) equipped with a virtual inertia‐damping (VID) control loop. The utilization of communication networks to coordinate and manage distributed energy sources inevitably introduce time delays, and these delays can compromise the SMG's frequency stability. This problem is compounded by the limited rotational inertia and low damping associated with renewable energy sources (RESs) and uncertainties in system parameters. Consequently, understanding how communication delays influence system stability under parametric uncertainty is essential. To enhance the SMG's frequency response, the study first integrates a VID control loop into the system. It then introduces a novel approach for computing the robust SDMs of the resulting SMG‐VID system. The proposed method combines Kharitonov's Theorem and the Rekasius substitution with Resultant Theory. Using this framework, robust SDMs are calculated for different controller gains and varying levels of uncertainty in the system parameters. These calculations are used to assess how VID control and parametric uncertainty affect the delay tolerance of the system. The findings show that incorporating the VID control loop substantially expands the robust SDM, thereby improving the system's ability to tolerate communication delays. However, the robust SDM decreases as the level of parametric uncertainty rises. Lastly, time‐domain simulations are conducted to substantiate the theoretically calculated SDMs. The findings are further corroborated via a quasi‐polynomial mapping‐based root‐finding (QPmR) algorithm.