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To mitigate climate change and meet increasing electricity demand, the global installed capacity of renewable energy sources like wind power is rapidly increasing. Further, external threats against the power system are expected to increase. The threats can arise from extreme weather events driven by climate change, or from antagonistic attacks like sabotage or military conflicts. The power grid is extensive and difficult to oversee due to its complexity and size and is therefore sensitive to such threats. Transmission lines are particularly vulnerable due to their exposure to harsh weather and the difficulty in monitoring them, making them susceptible to sabotage. With more wind power and external threats, it is crucial to study how wind farm integration affects power system resilience to severe line outages. In the present study, this scenario is investigated by simulating 29 different grid topologies 1 000 times each though Monte Carlo simulations. Each topology represents a case where conventional generators are replaced by wind farms. Severe line outages are triggered, and the effect is quantified in terms of disconnected load. The results show that replacing conventional generation by wind power can enhance the power system resilience. The outcome is determined by underlaying factors such as the installed wind power capacity, the electrical distance between wind farms, and the electrical distance between wind farms and loads. The finding that deliberate integration of wind power can enhance the resilience of a power system to severe line outages is important knowledge for transmission system operators and policymakers.

With the digitalization of mobile work machines, camera-based monitoring of machine conditions is becoming increasingly important. In the present application of an agricultural cultivator, the wear condition of its tines is monitored using a camera system and intelligent image evaluation. Extensive test drives are needed to develop such systems. This work proposes a methodology to reproduce real image data in high-resolution virtual environments to enable realistic virtual testing processes. The methodology consists of subprocesses for parameter identification and image reconstruction. In the context of parameter identification, accurate camera modelling is essential, requiring parameterization based on real camera calibration data, including image distortion. The subsequent image reconstruction process covers the fine-tuning of the virtual environment and its camera model, as well as the recording of the virtually generated images. After describing the methodology, the processes are evaluated using the example of the tool monitoring system for the above-mentioned cultivator. A comparison of the virtually generated images with the images from the real camera shows a good match of the images. Visible deviations are due to usage-related deformations of the real system. However, the deviations are small and the image quality high enough that the image recognition of the monitoring system can identify the cultivator tines and their elements. The evaluation shows that the potential for improving the methodology lies mainly in the automation of its process steps. It also highlights the importance of the robustness of tool monitoring systems with regard to geometric changes to the overall system.

Large-volume and heavy-duty transports are essential for the successful and timely execution of large-scale industrial, socio-political and climate-related projects. As these transports grow in size and complexity, the planning process becomes increasingly challenging for all stakeholders involved. To overcome these challenges, detailed planning processes are required, especially for the trafficability of narrow passages along the transportation route.

This paper introduces an advanced methodology for an enhanced 3D trafficability analysis with collision detection of large-volume and heavy-duty transports. By employing high-resolution, dense, colored 3D point clouds alongside detailed transport models, this approach offers a more accurate and comprehensive assessment of the feasibility of the transport.

The methodology is further generalized to accommodate a wide variety of transport configurations and maneuvers, allowing for automated analysis across different scenarios.

The primary contribution of this research lies in its ability to significantly improve collision detection accuracy and provide detailed visualizations, thereby optimizing the digital planning process of large-volume and heavy-duty transports. The findings demonstrate a distinct advantage of the 3D trafficability analysis over traditional 2D methods, especially in complex environments, leading to cost-effective and reliable transportation planning.

Geothermal energy, one of the most abundant yet underutilized renewable resource globally, offers significant potential for power generation, scalable heating and cooling, and increased energy security. Despite its advantages and demonstrated capacity, its integration into national energy strategies remains limited. The European Geothermal Action Plan, expected in 2026, is likely to become a key driver in advancing geothermal energy acrosss Europe. In Sweden, geothermal systems based on ground source heat pumps are well established; however, comprehensive assessments of deeper geothermal resources are still lacking. Existing data gaps and inconsistent reporting obscure the true potential of geothermal energy, hindering its inclusion in national energy strategies. The funding landscape for renewable energy research and innovation does not align with the national supply of energy. This study identifies opportunities for stakeholders and highlights the need to develop strategies for integrating geothermal heat, cooling, and power production into the national renewable and fossil free energy mix. Collaborative efforts, targeted funding, and strategic policy development will be essential to realizing the full potential of geothermal energy for energy transition in Sweden. 

Marine current power is attracting more attention as a renewable energy option. Similar to wind power, marine current power often requires a maximum power point tracking (MPPT) method to optimize power extraction from the free-flowing water. Research into MPPT methods for marine current power remains limited. Therefore, this paper presents a comprehensive investigation of MPPT methods for marine current power, building upon similar research in wind power. Three methods, namely the optimal tip speed ratio (OTSR), optimal torque (OT), and two variants of the perturb and observe (P&O) method, are explored. Using a simulation model developed for a specific marine current energy converter, where hydrodynamic calculations are coupled with electrical simulations, the study demonstrates that the OTSR method achieves MPPT with a comparably fast convergence time. After a change in water speed, the OTSR method achieves optimal operation within two turbine rotations. Additionally, the P&O methods are shown to achieve MPPT, albeit with a significantly longer convergence time. However, the P&O methods can be more convenient since no model of the system is required, and no water speed measurements are necessary. The proposed implementation of the OT method underperforms but positions the system close to the optimal operational point.

In agricultural technology, the importance of near-operational complete vehicle tests is constantly increasing due to the growing degree of automation. This is because the interaction of attachments, tractors and drivers, sometimes with several assistance and automation functions, requires significantly more test kilometers in the field. However, additional test kilometers mean additional time that needs to be invested. Testing in the agricultural field is more dependent on weather conditions and seasons than in other sectors. Also, defined scenarios with certain crops are only available temporarily depending on the harvest year. One solution are virtual test fields: A principle, which has already become firmly established in automotive development. They offer fully reproducible test scenarios, temporal independence and test parameters that can be varied at will, while being significantly more cost and time efficient. In this work, the needs of the industry and the state of the art of highly realistic virtual test fields for agricultural applications will be discussed. Based on this, a modular approach for implementation will be presented. Subsequently, individual modules and their interfaces will be introduced. Rounded off by the presentation of practical application examples from the field of environment detection, the article concludes with insights into future development perspectives and functional enhancements.

Marine current energy represents a globally abundant yet largely untapped renewable energy source, offering greater predictability than other sources such as wind. Consequently, it has the potential to play a vital role in the green transition. A critical consideration for harnessing marine current energy is the design of the electrical grid to accommodate multiple turbines. Therefore, this paper presents a study that explores three types of DC collection grids (series, parallel, and star) for a specific marine current energy converter. A simulation model developed for the marine current energy converter is introduced and utilized to assess these topologies for grids comprising ten identical turbines subjected to varying water speeds. The designed topologies are intended for low-voltage and nearshore applications. The simulation results demonstrate that the series collection grid requires a significantly higher DC grid voltage compared to the other topologies for the turbines to operate correctly. Additionally, the study reveals that all three grid topologies can effectively transmit power to the distribution grid with similar power losses.

With converters taking an increasing part in the grid, the impact of supraharmonic disturbances increases. The impact of these disturbances is, to a large extent, dependant on the grid impedance at the place and frequency of the disturbance. The grid impedance, in turn, is dependent on both the grid topology and the surrounding loads. This paper shows that the impedance of an aggregated distant load impacts the grid impedance in distinct ways for different frequencies. Additionally, the paper shows that the length of the cables closest to the measurement site have a larger impact on the maximum possible impedance than the cables closer to the variable load.

In the next decades, the dependencies on power production from renewable energy sources are expected to increase dramatically. A transition towards large-scale offshore wind farms together with an increased electrification of the industry and transportation sectors introduces new vulnerabilities to society. Further, extreme weather events are expected to increase in intensity and frequency, driven by climate change. However, there are significant knowledge gaps concerning the impacts of severe weather conditions on the resilience of power systems with large dependencies on offshore wind. In the present study, a comparison between two different power systems’ resilience to historical extreme storm conditions has been conducted. The power systems are the IEEE39-bus New England model and the Great Britain model. The results show significant differences between the two power systems, which underlying reasons are analysed and explained. With an offshore wind penetration level of 30 %, the New England model stays intact in terms of connected load. When increasing the penetration level to 40 %, about 10 % of the total connected load gets disconnected, whereas about 33 % of the load gets disconnected with a penetration level of 50 %. The Great Britain model stays intact in terms of connected load with a penetration level of at least 49 %.

Important questions to enable the use of marine current energy are how the electrical system is designed, how multiple energy converters are interconnected offshore and how the power is transmitted to the shore. The Division of Electricity at Uppsala University have constructed and deployed a marine current energy converter in the river Daläven in Söderfors, Sweden. In the study presented in this article, a model of a near-shore low-voltage AC collection grid and a near-shore low-voltage DC collection grid is presented for the technology at the Söderfors test site. The models are implemented in MATLAB/Simulink. For collection grids of five turbines, it is shown that the proposed control schemes are able to deliver power to the distribution grid. The controllers are able to achieve this even when one turbine is suddenly disconnected from the grid. Furthermore, it is shown that the conduction losses of the DC system are higher than the losses of the AC system for nominal and high water speeds. However, in a qualitative comparison between the systems it is concluded that despite the higher losses, the DC system can be an interesting option. This is because fewer components need to be placed in the turbine, which is beneficial in offshore systems where space is a limiting factor. Furthermore, a DC system can be less expensive since fewer cables are needed.