Microscopic Fluctuations in Power-Grid Frequency Recordings at the
					Subsecond Scale

Schäfer, Benjamin; Gorjão, Leonardo Rydin; Yalçın, G. Çiğdem; Förstner, Ellen; Jumar, Richard; Maaß, H.; Kühnapfel, Uwe; Hagenmeyer, Veit

doi:10.1155/2023/2657039

Cited by 3 publications

(1 citation statement)

References 42 publications

(75 reference statements)

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“…Just like one observes in utility grid recordings of utility power-grid frequency recordings, the data is noisy [6], [8], [22], [23]. The frequency trajectories are not as smooth as one expected for dynamical systems (not in chaotic states).…”

Section: ) Correlated Stochastic Noisementioning

confidence: 88%

Data-Driven Modeling of Frequency Dynamics Observed in Operating Microgrids: A South African University Campus Case Study

Maritz,

Gorjão,

Bester

et al. 2024

IEEE Access

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South Africa has been experiencing an energy crisis since 2007. Utility loadshedding became the main control for under-frequency events due to a mismatch in generation and consumption. Rolling blackouts are further supported by failing electrical infrastructure and illegal (non-metered) connections to the distribution network. A common remedy to mandatory South African loadshedding, from the perspective of university campuses, is to deploy hybrid photovoltaic-diesel (PV-diesel) microgrids that allow for an uninterrupted power supply for a few hours. Campus microgrids are typically smaller compared to national utilities (less inertia) and require sensitive control schemes to remain stable. In this paper, frequency recordings associated with the operating microgrid of the University of the Free State QwaQwa campus are analysed. A simplistic stochastic mathematical model is presented as a model describing the observed frequency dynamics, describing the transition between the utility grid and the microgrid state, the microgrid frequency controller response, and the influence of the PV generators. Moreover, inter-campus synchronous frequency measurements are showcased and the future implications thereof are discussed. The main contributions of this paper focus on the recording and modelling of the frequency dynamics of fully functioning campus microgrids, and the showcasing of continuous synchronous measurements of frequency at two different campuses.

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Section: ) Correlated Stochastic Noisementioning

confidence: 88%

Data-Driven Modeling of Frequency Dynamics Observed in Operating Microgrids: A South African University Campus Case Study

Maritz,

Gorjão,

Bester

et al. 2024

IEEE Access

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Quantifying fluctuations for dynamical power systems with stochastic excitations: A power spectral density-based method

Qing

Zhou

et al. 2023

Chaos: An Interdisciplinary Journal of Nonlinear Science

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Fluctuations of state variables play a pivotal role in analyzing small signal stability of the power system due to the integration of renewable energy sources. This paper develops a theoretical analysis methodology by using the power spectral density (PSD) for capturing the frequency and amplitude of state variable fluctuations in heterogeneous power systems with stochastic excitations. The fluctuations in generation and consumption occurring simultaneously are modeled by stochastic Ornstein–Uhlenbeck processes. The PSDs of the state variable fluctuations can be analytically calculated. PSD-based quantities have been proposed to evaluate angle and frequency deviations. Moreover, a global performance metric has been presented to measure the synchronization stability and calculated using the PSDs of frequency deviations. The underlying mathematical relationship between the metric and the primary control effort mimicking the H2-norm performance is explained in detail. Finally, the proposed analysis methodology is numerically illustrated on the IEEE RTS-96 test case. We investigate the impact of auto-correlations of stochastic processes on stability. Our results show the metric can be an alternative quantitative index of stability. We further find that the inertia allocation does not provide significant grid stability gain under small stochastic power fluctuations.

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Synchronization dynamics of phase oscillators on power grid models

Potratzki,

Bröhl,

Rings

et al. 2024

Chaos: An Interdisciplinary Journal of Nonlinear Science

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We investigate topological and spectral properties of models of European and US-American power grids and of paradigmatic network models as well as their implications for the synchronization dynamics of phase oscillators with heterogeneous natural frequencies. We employ the complex-valued order parameter—a widely used indicator for phase ordering—to assess the synchronization dynamics and observe the order parameter to exhibit either constant or periodic or non-periodic, possibly chaotic temporal evolutions for a given coupling strength but depending on initial conditions and the systems’ disorder. Interestingly, both topological and spectral characteristics of the power grids point to a diminished capability of these networks to support a temporarily stable synchronization dynamics. We find non-trivial commonalities between the synchronization dynamics of oscillators on seemingly opposing topologies.

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Microscopic Fluctuations in Power-Grid Frequency Recordings at the Subsecond Scale

Cited by 3 publications

References 42 publications

Data-Driven Modeling of Frequency Dynamics Observed in Operating Microgrids: A South African University Campus Case Study

Data-Driven Modeling of Frequency Dynamics Observed in Operating Microgrids: A South African University Campus Case Study

Quantifying fluctuations for dynamical power systems with stochastic excitations: A power spectral density-based method

Synchronization dynamics of phase oscillators on power grid models

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