A Scalable Nyquist Stability Criterion with Application to Power System Small-Signal Stability

TL;DR

This paper introduces a decentralized, scalable Nyquist stability criterion for power systems that guarantees stability with only local information, accommodating heterogeneous subsystems including renewable energy sources.

Contribution

It develops a generalized Nyquist-based stability criterion applicable to diverse agents, enabling stability analysis of large, complex power networks with minimal information.

Findings

Validates the method on a nonlinear power system model

Ensures stability guarantees for systems with renewable energy integration

Applicable to systems with delays, unstable dynamics, and nonminimum phase actuators

Abstract

A decentralized stability criterion is derived for a power system with heterogeneous subsystems. A condition for frequency stability and stability of interarea modes is derived using the generalized Nyquist criterion. The resulting scalable Nyquist stability criterion requires only locally available information and gives a priori stability guarantees for connecting new subsystems to an arbitrarily large network. The method can be applied to a general set of agents. For instance, agents with time-delays, nonminimum phase actuators or even unstable dynamics. The scalable Nyquist criterion makes no distinction between nodes with or without synchronous inertia, making it easy to include converter-interfaced renewable energy in the analysis. The method is validated on a detailed nonlinear power system model with frequency droop provided by hydro governors assisted by wind power.