Stability and optimality of distributed secondary frequency control schemes in power networks

TL;DR

This paper introduces a systematic approach for designing distributed secondary frequency control schemes in power networks that ensure stability and economic optimality, adaptable to various dynamics and verifiable via linear matrix inequalities.

Contribution

It provides a unified framework for stability and optimality in distributed frequency control, including higher order dynamics and demand measurement relaxation techniques.

Findings

Stability guaranteed through dissipativity conditions.

Economic optimality achieved with decentralized steady state conditions.

Validated with simulations on a 140-bus power system.

Abstract

We present a systematic method for designing distributed generation and demand control schemes for secondary frequency regulation in power networks such that stability and an economically optimal power allocation can be guaranteed. A dissipativity condition is imposed on net power supply variables to provide stability guarantees. Furthermore, economic optimality is achieved by explicit decentralized steady state conditions on the generation and controllable demand. We discuss how various classes of dynamics used in recent studies fit within our framework and give examples of higher order generation and controllable demand dynamics that can be included within our analysis. In case of linear dynamics, we discuss how the proposed dissipativity condition can be efficiently verified using an appropriate linear matrix inequality. Moreover, it is shown how the addition of a suitable observer layer can relax the requirement for demand measurements in the employed controller. The efficiency and practicality of the proposed results are demonstrated with a simulation on the Northeast Power Coordinating Council (NPCC) 140-bus system.