Statnett

The electric power system is essential for modern society, and a malfunction may immediately lead to severe financial damage and, in the worst case, personal injuries. For this reason, extensive measures are taken to ensure the highest possible level of system reliability. Global electricity consumption is expected to grow significantly by 2050 compared to today’s levels. Besides the amount of consumption, the load patterns will be more temperature sensitive and volatile. Furthermore, there is likely to be growth in domestic, selfsufficient, distributed, and clean electricity generation.

This paper investigates machine learning and feature selection methods to identify consumer groups of price elastic, flexible households. A dataset of $\mathbf{1, 1 3 6}$ Norwegian households collected between 2020 and 2022, covering the period of unusually high electricity prices forms the foundation of the analysis presented in this paper. Multiple machine learning models were assessed, with Support Vector Machines combined with Partial Least Squares (PLS) components achieving the highest accuracy of approximately $70 \%$. The study demonstrates that feature-engineering choices are equally, if not more, influential than model choice in such analysis, and provides a methodological foundation for identifying consumer groups relevant for targeted demand-side flexibility measures.

The concept of risk is used across disciplinary boundaries by researchers as well as practitioners. In this paper, we aim to explore the implications of such a use for the development of the theory and practice of risk analysis, understood broadly as covering risk assessment, risk perception, risk communication, risk management, and policy on risk. As an analytical frame, we consider risk as a "boundary object" around which different communities of practice organize their interconnections. One key implication for theory is that the way risk is conceptualized needs to balance being adaptable to disciplinary needs, yet retaining a common identity across disciplines, and we find that there are perspectives that, at least conceptually, accommodate risk functioning as a boundary object. Practitioners should expect to find that different communities of practice assign somewhat different meanings to the concept of "risk." Such inconsistencies should be taken as an opportunity to explore and learn rather than an occasion for policing and eradicating deviant discourses. Based on our findings, we outline a research agenda for advancing the understanding of risk as a boundary object, including empirical studies of whether this is actually taking place.

The Ongoing Green Transition is arguably the largest change in the European power system for several decades. Traditional dispatchable generation sources like coal and nuclear power plants are being replaced by massive amounts of wind and solar generation with less predictability and no inertia. These renewable sources give larger and faster changes in flow patterns and balancing, and the power system operation is moving from a “generation must follow load” to “load must follow generation” paradigm. In addition to this fundamental change in the physical properties of the power system, common European rules and regulations for markets and system operation are being implemented, including flow-based market clearing, 15-min time resolution in day-ahead and intraday markets, and increased cross-border trading of both energy and reserves.

Recent numerical simulations have shown that in future HVDC power transmission systems faults may lead to transient overvoltages of types not covered by present HVDC cable type tests. Among these are the so-called Temporary Overvoltages (TOVs), characterized by a very slow front and long tail transient superimposed on a dc voltage. To clarify to what extent HVDC cable grade mass-impregnated paper insulation withstands such TOVs, the maximum withstand fields of small-scale samples subjected to same polarity TOVs of different front and decay times are measured. The samples are made by stacking five layers of 90 μm thick paper with an air-filled slit in the third layer simulating a butt gap. As expected, the majority of the breakdowns go through this weak point. The maximum withstand levels are around 150 kV/mm, with a substantial statistical scatter. More importantly, Weibull analyses disclose only modest differences in dielectric strength between samples subjected to the different TOVs, even though the front time spans from 0.25 ms (as in a standard switching impulse) to 10 ms, and the decay times are up to several seconds. This suggests that extending the qualification and type tests to also include long TOVs may not be necessary.