Vehicle electrification along with the integration of renewable energy has been recognized as part of the long-term strategy towards zero carbon emission. However, in many countries, the transition to fully renewable electricity generation will likely take decades, a period during which electric vehicles may still be powered by carbon-intensive electricity. In this talk, I will present results on the fundamental role of transmission networks in both enabling and limiting carbon reduction from vehicle electrification.

Cascade failures in power grids occur when the failure of one component or subsystem causes a chain reaction of failures in other components or subsystems, ultimately leading to a widespread blackout or outage. Controlling cascade failures on power grids is important for many reasons like economic impact, national security, public safety and even rippled effects like troubling transportation systems. Monitoring the networks on node level has been suggested by many, either controlling all nodes of a network or by subsets. We identify sensitive graph elements of the weighted European power-grids (from 2016, 2022) by two different methods. We determine bridges between communities and point out "weak" nodes by the lowest local synchronization of the swing equation. In the latter case we add bypasses of the same number as the bridges at weak nodes and we compare the synchronization, cascade failure behavior by the dynamical improvement with the purely topological changes. We also compare the results on bridge removed networks, similar to islanding, and with the addition of links at randomly selected places. The synchronization improves the best by the bypassing, while the average cascade sizes are the lowest with bridge additions. However, for very large or small global couplings these network changes do not help, they seem to be useful near the synchronization transition region, where self-organization drives the power-grid. Thus, we provide a demonstration for the Braess' Paradox on continental sized power grid simulations and uncover the limitations of this phenomenon. We also determine the cascade size distributions and justify the power-law tails near the transition point on these grids.

Phys. Rev. Res. 6 (2024), 013194

Driven by the complexities of managing power systems amidst an increasing renewable integration and load uncertainty, we investigate emergency scenarios requiring temporary transitions to costlier secondary fuels. Our goal is to develop decision-support tools for operators during critical periods. Framing this as an optimization problem within a Markov Decision Process (MDP), we consider uncertainties like potential generator failures, operator stress, limited primary fuel availability, power forecasts, and the financial implications of load shedding. Through simulations, we identify feasible policies, validating our approach using realistic models and outlining future refinements.

We discuss the frequency of blackout or desynchronization events in power grids for realistic data input, in particular with time correlations in the fluctuating power production. Our desynchronization events are caused by overloads. We propose and discuss different methods of dimensional reduction to considerably reduce the high-dimensional phase space. The first method splits the system into two areas, connected by heavily loaded lines, and treats each area as a single node. This corresponds to the so-called synchronized subgraph approximation, here applied to the swing equations. The second one considers a separation of the timescales of power fluctuations and phase angle dynamics and completely disregards the phase angle dynamics. Rare events are captured by the WKB-method for classical stochastic systems. The resulting average desynchronization times obtained for the different versions of the dimensionally reduced system are compared with those obtained for the full system, simulated via the swing equations. As it turns out, the number of desynchronization events does not automatically increase with non-Gaussian fluctuations in the power production as one might have expected. We point out under which conditions the number of desynchronization events decreases.

T. Ritmeester and H. Meyer-Ortmanns, Rare desynchronization events in power grids: On data implementation and dimensional reductions, J. Phys. Complex. 3, 045010~1-28 (2022).

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