Small-Signal Stability Analysis of a DC Shipboard Microgrid With Droop-Controlled Batteries and Constant Power Resources

TL;DR

This paper analyzes the small-signal stability of a dc shipboard microgrid with droop-controlled batteries and constant power loads, considering converter duty cycle dynamics to derive stability conditions.

Contribution

It introduces a detailed mathematical model including converter duty cycle dynamics and identifies stability conditions specific to droop-controlled energy storage and fuel cells.

Findings

Derived stability conditions based on droop coefficient, capacitor, and inductances.

Enhanced understanding of stability margins in dc microgrids with CPLs and droop control.

Validated model parameters to match practical electrical behavior.

Abstract

The presence of constant power loads (CPLs) in dc shipboard microgrids may lead to unstable conditions. The present work investigates the stability properties of dc microgrids where CPLs are fed by fuel cells (FCs), and energy storage systems (ESSs) equipped with voltage droop control. With respect to the previous literature, the dynamics of the duty cycles of the dc-dc converters implementing the droop regulation are considered. A mathematical model has been derived, and tuned to best mimic the behavior of the electrical representation implemented in DIgSILENT. Then the model is used to find the sufficient conditions for stability with respect to the droop coefficient, the dc-bus capacitor, and the inductances of the dc-dc converters.