Network Topology Invariant Stability Certificates for DC Microgrids with Arbitrary Load Dynamics

TL;DR

This paper introduces a decentralized stability certificate for DC microgrids that guarantees small-signal stability despite arbitrary load dynamics, facilitating plug-and-play operation.

Contribution

It presents a novel homotopy-based stability certificate applicable to various grid components, ensuring eigenmodes remain stable across controller gain variations.

Findings

The standards successfully certify stability in multiple test cases.

Numerical validation confirms effectiveness with buck and boost converters.

The approach enhances microgrid reliability and operability.

Abstract

DC microgrids are prone to small-signal instabilities due to the presence of tightly regulated loads. This paper develops a decentralized stability certificate which is capable of certifying the small-signal stability of an islanded DC network containing such loads. Utilizing a novel homotopy approach, the proposed standards ensure that no system eigenmodes are able to cross into the unstable right half plane for a continuous range of controller gain levels. The resulting "standards" can be applied to variety of grid components which meet the specified, but non-unique, criteria. These standards thus take a step towards offering plug-and-play operability of DC microgrids. The proposed theorems are explicitly illustrated and numerically validated on multiple DC microgrid test-cases containing both buck and boost converter dynamics.