Abstract
The drive towards renewable energy generation is causing fundamental changes in both the structure and dynamics of power grids. Their topology is becoming increasingly decentralized due to distributed, embedded generation, and the emergence of microgrids. Grid dynamics are being impacted by decreasing inertia, as conventional generators with massive spinning cores are replaced by dc renewable sources. This leads to a risk of destabilization and places an upper limit on the volume of renewable power sources that can be installed. A wide variety of different control schemes have been proposed to overcome this problem. Such schemes fall into two broad categories: so-called “grid-following” controllers that seek to match output ac power with grid frequency, and “grid-forming” systems that seek to boost grid stability. The latter frequently work by providing synthetic inertia, enabling dc renewable sources to emulate conventional generators. This paper uses the master stability function methodology to analyze the stability of synchrony in microgrids of arbitrary size and containing arbitrary control systems. This approach provides a powerful and computationally efficient framework in which to benchmark the impact of any number of renewable sources on grid stability and thereby to support microgrid design strategies. The method is demonstrated by computing stability bounds for two different grid-forming systems, providing bounds on the feasible number of generators that can be accommodated. In addition, we contrast our results with predictions from a simplistic but widely used phase-oscillator model, finding that such descriptions significantly over estimate the grid stability properties.
- Received 24 July 2023
- Revised 14 December 2023
- Accepted 2 February 2024
DOI:https://doi.org/10.1103/PRXEnergy.3.013011
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
The rapid expansion of renewable energy is revolutionizing power transmission networks through increased decentralization of power generation. This transformation presents a critical challenge: a substantial decrease in grid inertia, a vital component for ensuring safe and reliable power grid operation. This challenge threatens the widespread adoption of renewable energy generation and progress to a low-carbon power grid. To counter decreased inertia in renewable-energy-powered grids, complex control systems are used; however, existing methods to test these systems rely on time-consuming large-scale simulations. This study introduces a mathematical toolbox that provides stability bounds for any number of control systems on a network, independent of network size. It enables quick benchmarking without time-consuming simulations, facilitating rapid prototyping of new control systems. This advancement supports renewable generation uptake, bringing us closer to net-zero-emission power.
