Optimal load-side control for frequency regulation in smart grids

TL;DR

This paper introduces a distributed load-side frequency control mechanism for smart grids that maintains stability, operational constraints, and optimal load rebalancing, especially useful with increasing renewable integration.

Contribution

It presents a novel, distributed load participation control method that ensures stability, optimality, and constraint satisfaction in frequency regulation.

Findings

Proves global asymptotic stability of the control system.

Demonstrates robustness to unknown load parameters.

Shows effectiveness through simulations.

Abstract

Frequency control rebalances supply and demand while maintaining the network state within operational margins. It is implemented using fast ramping reserves that are expensive and wasteful, and which are expected to grow with the increasing penetration of renewables. The most promising solution to this problem is the use of demand response, i.e. load participation in frequency control. Yet it is still unclear how to efficiently integrate load participation without introducing instabilities and violating operational constraints. In this paper we present a comprehensive load-side frequency control mechanism that can maintain the grid within operational constraints. In particular, our controllers can rebalance supply and demand after disturbances, restore the frequency to its nominal value and preserve inter-area power flows. Furthermore, our controllers are distributed (unlike the currently implemented frequency control), can allocate load updates optimally, and can maintain line flows within thermal limits. We prove that such a distributed load-side control is globally asymptotically stable and robust to unknown load parameters. We illustrate its effectiveness through simulations.