| 1. |
- Parwal, Arvind, et al.
(författare)
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Grid impact and power quality assessment of wave energy parks: Different layouts and power penetrations using energy storage
- 2021
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Ingår i: JOURNAL OF ENGINEERING-JOE. - : Institution of Engineering and Technology (IET). - 2051-3305. ; 2021:8, s. 415-428
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Tidskriftsartikel (refereegranskat)abstract
- Power fluctuations induced by wave energy converters (WECs) may reflect negative impact on the power quality of the power grid. Assessing their impact is an important step to ensure the grid compliance level of the energy park. The IEC 61000-4-15 standard classifies the allowable disturbances in the grid. This study analysed and assessed the grid impact in terms of flicker, harmonic distortion and voltage variations. The assessments were performed without energy storage and compared when using the energy storage. A single WEC is emulated as an irregular power output of a real WEC using a combined model of power take-off in the Simulink model. Time series based on data obtained in earlier offshore experiments, conducted at the Lysekil research site in Sweden, is used to emulate a wave energy park (WEP) power in a land-based test rig in real-time power hardware-in-the-loop simulations. A total of three and ten WECs are emulated by introducing a time delay in the time series to investigate the grid impact in each layout. Flicker emissions, voltage variations, individual and total harmonics of the voltage at the connection point in each layout are studied and compared with the limits to be grid compliant for layouts of the WEP. In addition, voltage and current harmonics for the single WEC and individual harmonics in each phase of the voltage are measured and analysed to assess the compliance level of the WEP.
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| 2. |
- Degen, René, et al.
(författare)
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CityInMotion : A Virtual Urban Test Environment for Automated Mobility
- 2021
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Konferensbidrag (refereegranskat)abstract
- Efficient methodologies for the development and validation of highly-automated vehicle systems play an increasingly important role in urban mobility. In addition, the requirements for simulation and verification environments are highly increasing due to a wide range of automation functions to be integrated and validated in the near future.This paper presents a new approach for developing a virtual test environment for highly automated vehicles based ona high-end virtual reality (VR) engine. The basis is a realistic,geo-referenced city model, which is reactively connected in Co-Simulation to a highly detailed vehicle model or even a Vehicle-in-the-Loop test bed. Through specific sensor model systems like camera radar and lidar, the vehicle can interact with the environment and traffic participants like VRU(Vulnerable Road Users) in real-time. The behaviour of real VRUs in the virtual test field is based on high-end motion-capture technology, which enables the integration of highly realistic avatars in real time.A proof of concept is shown by application of the virtual urban test field for validating an unmanned battery-electric vehicle. Finally, an outlook for the potential use of advanced VR technologies for agile development processes is given.
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| 3. |
- Degen, René, et al.
(författare)
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Integration of Driving Physical Properties into the Development of a Virtual Test Field for Highly Automated Vehicle Systems
- 2021
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Konferensbidrag (refereegranskat)abstract
- For many years now, models for representing reality have played a decisiverole in the development of control systems. By appropriate abstraction theyhelp to design an efficient development process. Especially in the developmentof Advanced Driver Assistance Systems (ADAS) a valid virtual developmentenvironment is crucial for functionality and reliability.This study aims the representation of driving physics in a virtual testenvironment for the development of robust ADAS systems. The overall systemconsists of a georeferenced virtual traffic environment, a multibody vehiclemodel and a driver model. The virtual environment includes a detailed 3D model of an urban city in consideration of specific height coordinates of theenvironment. The vehicle model is implemented by a simplified two-lanemodel based on geometric steering correlations. Alternatively, the vehiclekinematics are considered by a five-body dynamic model. This model iscombined by a semi-empirical tyre model for realistic modelling of the contactforces and torques between the tyre patch and the road. Finally, sensor modelsfor radar, lidar and camera are added to the vehicle model.To investigate real urban traffic scenarios an advanced driver model isincluded, which uses a pure pursuit path tracking algorithm to follow a giventarget trajectory. To investigate real pedestrian interaction, a real personsbehavior is included by motion capturing technologies. Those heterogeneousenvironments are combined by Co-Simulation to get a real-time connection andfinally the entire testbed.By applying the Co-simulation environment to a typical inner city trafficscenario, the verification of the system functionality is done. The outcome is asafe and efficient virtual city environment, which enables interactioninvestigations between typical traffic participants and highly automatedvehicles. In summary, the paper shows the high potential of virtual Cosimulationenvironments for progressing automated vehicle functionalities.
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| 4. |
- Degen, René, et al.
(författare)
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Methodical Approach to the Development of a Radar Sensor Model for the Detection of Urban Traffic Participants Using a Virtual Reality Engine
- 2021
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Ingår i: Journal of Transportation Technologies. - : Scientific Research Publishing. - 2160-0473 .- 2160-0481. ; 11:2, s. 179-195
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Tidskriftsartikel (refereegranskat)abstract
- New approaches for testing of autonomous driving functions are using VirtualReality (VR) to analyze the behavior of automated vehicles in variousscenarios. The real time simulation of the environment sensors is still a challenge.In this paper, the conception, development and validation of an automotiveradar raw data sensor model is shown. For the implementation, theUnreal VR engine developed by Epic Games is used. The model consists of asending antenna, a propagation and a receiving antenna model. The microwavefield propagation is simulated by a raytracing approach. It uses the methodof shooting and bouncing rays to cover the field. A diffused scatteringmodel is implemented to simulate the influence of rough structures on thereflection of rays. To parameterize the model, simple reflectors are used. Thevalidation is done by a comparison of the measured radar patterns of pedestriansand cyclists with simulated values. The outcome is that the developedmodel shows valid results, even if it still has deficits in the context of performance.It shows that the bouncing of diffuse scattered field can only be doneonce. This produces inadequacies in some scenarios. In summary, the papershows a high potential for real time simulation of radar sensors by using raytracing in a virtual reality.
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| 5. |
- Degen, René, 1994-
(författare)
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Urban Virtual Test Field for HighlyAutomated Vehicle Systems
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Autonomous driving is one of the key technologies for increasing road safetyand reducing traffic volumes. Therefore, science and industry are workingtogether on new innovative solutions in this field of technology. One importantcomponent in this context is the approval and testing of new solution concepts,with special focus on the ones for urban environments. Not only because ofthe high diversity of traffic situations, but also because of the close contactbetween vulnerable road users (VRU) and automated vehicles.In the course of this work, a novel approach for testing automated drivingfunctions and vehicle systems in urban environments is presented. The goal isto create a safe and valid environment in which the automated vehicle and theVRU can meet and interact. The basis is a highly realistic virtual model of acity center. The physical behavior of the vehicle and VRU is recorded usingmeasurement technology and transferred to the virtual city model.Based on representative urban traffic scenarios, the functionality of the urbantest field is investigated from various points of view. Thereby, the focus is onreal-time capability and the quality of interaction between the vehicle and theVRU.The investigations show that both the real-time capability and the interactionpossibilities could be demonstrated. Further, the developed methodologies aresuitable for real time applications.
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| 6. |
- Degen, René, et al.
(författare)
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Virtual Urban Traffic Infrastructure for Testing Highly Automated Mobility Systems
- 2021
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Konferensbidrag (refereegranskat)abstract
- Recently, virtual realities and simulations play important roles in the development of urban traffic infrastructure. By anappropriate abstraction, they help to design, investigate and communicate inner-city development processes. Especially,to investigate interactions between infrastructure and future mobility participants, a valid virtual model is essential forfunctionality and reliability.The aim of this study is the investigation of interactions between a virtual infrastructure model and virtual sensor modelsof highly automated mobility systems. The overall system consists of a georeferenced virtual city model and probabilisticsensor models, which are part of an automated vehicle model. The virtual environment comprises a comprehensive,virtual 3D model of a representative German inner-city scene, considering specific height coordinates. The probabilisticsensor models represent real radar and lidar sensors and comprehensively replicate their physical functionalityin a virtual environment. Considering different levels of detail, the realistic representation of physical effects of thevirtual city model on the virtual sensors is investigated. The investigated scenarios are derived from representativeurban traffic situations. The complexity as well as the level of information of the virtual city scenarios is iterativelyincreased. Subsequently, the effects on the model validity of the overall system is checked and analysed.The results show that the developed virtual environment performs well for different levels of detail of representativevirtual traffic scenes. In addition, the selected modelling depth is very suitable for the high-performance investigationof interaction between virtual urban environment and virtual autonomous vehicle.
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| 7. |
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| 8. |
- Ekergård, Boel, 1985-, et al.
(författare)
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Eddy Current Losses in Solid Pole Shoes in a Two-Pole Permanent Magnet Motor
- 2021
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Ingår i: Engineering. - : SCIRP. - 1947-3931 .- 1947-394X. ; 13:10, s. 536-543
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this paper is to present the eddy current losses in solid pole shoes in a permanent magnet two-pole electric motor. In the presented paper, the authors have chosen to work with three different analytical models, Carter’s theory, Gibb’s theory and Lawrenson’s theory, each with different degree of accuracy and simplifications. The results from the analytical models all present relatively low eddy current losses, giving the designer valuable arguments to utilize solid pole shoes, as a rotor with solid poles is from a construction point of view a more suitable choice, increasing the mechanical stability and reducing the production cost, compared to the laminated design.
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| 9. |
- Eklund, Petter, 1989-, et al.
(författare)
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Experimental Evaluation of a Rare Earth-Free Permanent Magnet Generator
- 2021
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Ingår i: IEEE Transactions on Energy Conversion. - Piscataway : Institute of Electrical and Electronics Engineers (IEEE). - 1558-0059 .- 0885-8969. ; 36:1, s. 3-10
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Tidskriftsartikel (refereegranskat)abstract
- Low speed, high torque machines are used in wind turbines where the turbine rotor is directly connected to the generator. A permanent magnet synchronous generator using high-energy rare-earth permanent magnets (PMs) is one common choice for this application, but rare-earth PMs have supply insecurities and cost risks. A rare-earth free 32-pole PM generator, using ferrite PMs in a spoke-type rotor, for use in a 12 kW experimental wind turbine is built and tested. Voltages and currents at load and no load are measured, as well as the magnetic field in the end regions of the machine. The generator can deliver the required power at nominal speed and has low harmonic content in the output. The electrical measurements are compared to two-dimensional finite element design calculations and the experimental results are lower than expected from simulations. The measured voltage is lower than expected, requiring a higher current than calculated for the rated power. Three-dimensional magnetic field simulations show that there are leakage flux paths in the end-regions that the two-dimensional design calculations overlook, explaining the discrepancy between simulations and measurements.
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| 10. |
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