Foundations and Challenges of Low-Inertia Systems (Invited Paper)

Milano, Federico; Dörfler, Florian; Hug, Gabriela; Hill, David J.; Verbič, Gregor

doi:10.23919/pscc.2018.8450880

Cited by 613 publications

(515 citation statements)

References 194 publications

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“…The model can further be used to assess the frequency stability of future power-grid structures, including in particular microgrids [8] or low-inertia grids [12]. Traditional dynamical stability analyses focus on local and global stability of fixed points and the impact of large isolated disturbances such as the sudden shutdown of power plant.…”

Section: Discussionmentioning

confidence: 99%

Stochastic properties of the frequency dynamics in real and synthetic power grids

Anvari

Gorjão

Timme

et al. 2020

Phys. Rev. Research

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The frequency constitutes a key state variable of electrical power grids. However, as the frequency is subject to several sources of fluctuations, ranging from renewable volatility to demand fluctuations and dispatch, it is strongly dynamic. Yet, the statistical and stochastic properties of the frequency fluctuation dynamics are far from fully understood. Here, we analyse properties of power grid frequency trajectories recorded from different synchronous regions. We highlight the non-Gaussian and still approximately Markovian nature of the frequency statistics. Further, we find that the frequency displays significant fluctuations exactly at the time intervals of regulation and trading, confirming the need of having a regulatory and market design that respects the technical and dynamical constraints in future highly renewable power grids. Finally, employing a recently proposed synthetic model for the frequency dynamics, we combine our statistical and stochastic analysis and analyse in how far dynamically modelled frequency properties match the ones of real trajectories.

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Section: Discussionmentioning

confidence: 99%

Stochastic properties of the frequency dynamics in real and synthetic power grids

Anvari

Gorjão

Timme

et al. 2020

Phys. Rev. Research

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“…At the heart of the energy transition is the change in generation technology; from fossil fuel based generation to converter interfaced renewable generation [1]. One of the major consequences of this transition towards a nearly 100% renewable system is the gradual loss of synchronous machines (SMs), their inertia, and control mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Frequency Stability of Synchronous Machines and Grid-Forming Power Converters

Tayyebi

Grob

Anta

et al. 2020

IEEE J. Emerg. Sel. Topics Power Electron.

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226

163

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An inevitable consequence of the global power system transition towards nearly 100% renewable-based generation is the loss of conventional bulk generation by synchronous machines, their inertia, and accompanying frequency and voltage control mechanisms. This gradual transformation of the power system to a low-inertia system leads to critical challenges in maintaining system stability. Novel control techniques for converters, so-called grid-forming strategies, are expected to address these challenges and replicate functionalities that so far have been provided by synchronous machines. This article presents a low-inertia case study that includes synchronous machines and converters controlled under various grid-forming techniques. In this work 1) the positive impact of the grid-forming converters on the frequency stability of synchronous machines is highlighted, 2) a qualitative analysis which provides insights into the frequency stability of the system is presented, 3) we explore the behavior of the grid-forming controls when imposing the converter dc and ac current limitations, 4) the importance of the dc dynamics in grid-forming control design as well as the critical need for an effective ac current limitation scheme are reported, and lastly 5) we analyze how and when the interaction between the fast gridforming converter and the slow synchronous machine dynamics can contribute to the system instability.

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“…The penetration rate of power-electronic converters in the modern power system is ever-increasing mainly because of the rapid development of renewables, energy storage systems and high-voltage dc transmission (HVDC) systems. The high controllability of power converters is making the power system more flexible, which allows auxiliary services such as frequency support, voltage support and oscillation damping to be provided for the power grid [1], [2].…”

Section: Introductionmentioning

confidence: 99%

H _∞-Control of Grid-Connected Converters: Design, Objectives and Decentralized Stability Certificates

Huang

Xin

Dörfler

2020

IEEE Trans. Smart Grid

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The modern power system features the high penetration of power converters due to the development of renewables, HVDC, etc. Currently, the controller design and parameter tuning of power converters heavily rely on rich engineering experience and extrapolation from a single converter system, which may lead to inferior performance or even instabilities under variable grid conditions. In this paper, we propose an H∞-control design framework to provide a systematic way for the robust and optimal control design of power converters. We discuss how to choose weighting functions to achieve anticipated and robust performance with regards to multiple control objectives. Further, we show that the operating mode of the converter (grid-forming or grid-following) can be conveniently specified by proper choice of weighting functions. Furthermore, based on the small gain theorem, we propose a decentralized stability criterion which enables to guarantee the small-signal stability of multi-converter systems through local H∞-control design of the converters. We provide high-fidelity nonlinear simulations to illustrate the effectiveness of our method.

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Foundations and Challenges of Low-Inertia Systems (Invited Paper)

Cited by 613 publications

References 194 publications

Stochastic properties of the frequency dynamics in real and synthetic power grids

Stochastic properties of the frequency dynamics in real and synthetic power grids

Frequency Stability of Synchronous Machines and Grid-Forming Power Converters

H _∞-Control of Grid-Connected Converters: Design, Objectives and Decentralized Stability Certificates

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Foundations and Challenges of Low-Inertia Systems (Invited Paper)

Cited by 613 publications

References 194 publications

Stochastic properties of the frequency dynamics in real and synthetic power grids

Stochastic properties of the frequency dynamics in real and synthetic power grids

Frequency Stability of Synchronous Machines and Grid-Forming Power Converters

H ∞-Control of Grid-Connected Converters: Design, Objectives and Decentralized Stability Certificates

Contact Info

Product

Resources

About

H _∞-Control of Grid-Connected Converters: Design, Objectives and Decentralized Stability Certificates