Design and Stability of Load-Side Primary Frequency Control in Power Systems

TL;DR

This paper introduces a systematic design for load-side primary frequency control in power systems, ensuring stability and optimality through a distributed primal-dual algorithm that improves transient response after disturbances.

Contribution

It develops a novel distributed control method based on primal-dual algorithms, proving stability and optimality for load-side frequency regulation in power networks.

Findings

The control scheme guarantees global asymptotic stability.

Loads can make optimal decisions based on local frequency deviations.

Simulations show improved transient performance after disturbances.

Abstract

We present a systematic method to design ubiquitous continuous fast-acting distributed load control for primary frequency regulation in power networks, by formulating an optimal load control (OLC) problem where the objective is to minimize the aggregate cost of tracking an operating point subject to power balance over the network. We prove that the swing dynamics and the branch power flows, coupled with frequency-based load control, serve as a distributed primal-dual algorithm to solve OLC. We establish the global asymptotic stability of a multimachine network under such type of load-side primary frequency control. These results imply that the local frequency deviations at each bus convey exactly the right information about the global power imbalance for the loads to make individual decisions that turn out to be globally optimal. Simulations confirm that the proposed algorithm can rebalance power and resynchronize bus frequencies after a disturbance with significantly improved transient performance.