Input-output analysis and decentralized optimal control of inter-area oscillations in power systems

TL;DR

This paper introduces non-modal analysis tools for better understanding and controlling inter-area oscillations in power systems, proposing sparse wide-area controllers that improve robustness and performance.

Contribution

It develops a non-modal input-output analysis framework and designs sparse decentralized controllers that enhance oscillation mitigation in power systems.

Findings

Non-modal analysis provides new insights beyond modal approaches.

Sparse controllers effectively mitigate oscillations.

Retuned decentralized control improves robustness.

Abstract

Local and inter-area oscillations in bulk power systems are typically identified using spatial profiles of poorly damped modes, and they are mitigated via carefully tuned decentralized controllers. In this paper, we employ non-modal tools to analyze and control inter-area oscillations. Our input-output analysis examines power spectral density and variance amplification of stochastically forced systems and offers new insights relative to modal approaches. To improve upon the limitations of conventional wide-area control strategies, we also study the problem of signal selection and optimal design of sparse and block-sparse wide-area controllers. In our design, we preserve rotational symmetry of the power system by allowing only relative angle measurements in the distributed controllers. For the IEEE 39 New England model, we examine performance tradeoffs and robustness of different control architectures and show that optimal retuning of fully-decentralized control strategies can effectively guard against local and inter-area oscillations.