Distributed Transient Safety Verification via Robust Control Invariant Sets: A Microgrid Application

TL;DR

This paper presents a distributed safety verification method for inverter-based microgrids using robust control invariant sets, ensuring transient safety through SOS programming and set invariance principles.

Contribution

It introduces a novel set invariance-based distributed safety verification algorithm for microgrid inverters, utilizing SOS programming for robust control set design.

Findings

Successful numerical simulations demonstrate the effectiveness of the safety verification algorithm.

The method ensures transient safety under disturbances with limited data exchange.

The approach provides a systematic way to synthesize safety constraints for microgrid modules.

Abstract

Modern safety-critical energy infrastructures are increasingly operated in a hierarchical and modular control framework which allows for limited data exchange between the modules. In this context, it is important for each module to synthesize and communicate constraints on the values of exchanged information in order to assure system-wide safety. To ensure transient safety in inverter-based microgrids, we develop a set invariance-based distributed safety verification algorithm for each inverter module. Applying Nagumo's invariance condition, we construct a robust polynomial optimization problem to jointly search for safety-admissible set of control set-points and design parameters, under allowable disturbances from neighbors. We use sum-of-squares (SOS) programming to solve the verification problem and we perform numerical simulations using grid-forming inverters to illustrate the algorithm.