Hierarchical Power Flow Control in Smart Grids: Enhancing Rotor Angle and Frequency Stability with Demand-Side Flexibility

TL;DR

This paper introduces a hierarchical control system that leverages demand-side flexibility across transmission, distribution, and buildings to improve rotor angle and frequency stability in power grids with high renewable integration.

Contribution

It presents a novel multi-level control architecture integrating transmission, distribution, and demand-side management for enhanced grid stability.

Findings

Improved rotor angle stability demonstrated in hardware-in-loop tests.

Enhanced frequency regulation achieved through demand-side flexibility.

Feasibility validated with real-world microgrid hardware-in-loop experiments.

Abstract

Large-scale integration of renewables in power systems gives rise to new challenges for keeping synchronization and frequency stability in volatile and uncertain power flow states. To ensure the safety of operation, the system must maintain adequate disturbance rejection capability at the time scales of both rotor angle and system frequency dynamics. This calls for flexibility to be exploited on both the generation and demand sides, compensating volatility and ensuring stability at the two separate time scales. This article proposes a hierarchical power flow control architecture that involves both transmission and distribution networks as well as individual buildings to enhance both small-signal rotor angle stability and frequency stability of the transmission network. The proposed architecture consists of a transmission-level optimizer enhancing system damping ratios, a distribution-level controller following transmission commands and providing frequency support, and a building-level scheduler accounting for quality of service and following the distribution-level targets. We validate the feasibility and performance of the whole control architecture through real-time hardware-in-loop tests involving real-world transmission and distribution network models along with real devices at the Stone Edge Farm Microgrid.