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  • 1.
    Möllerström, Erik
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik. Division for Electricity, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
    Bolin, Karl
    Marcus Wallenberg Laboratory, Department of Aeronautical and Vehicle Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Ottermo, Fredric
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Bååth, L.B.
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK).
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Noise directivity from a vertical axis wind turbine2015In: Proceedings of the 6th International Conference on Wind Turbine Noise 2015, New Brighton: INCE/Europe , 2015Conference paper (Other academic)
    Abstract [en]

    The directivity of wind turbine noise is of widespread interest and has received attention over an extended period. The reason for this is partly that noise optimization procedures can be implemented in order to increase the efficiency of the power output. Although directivity of horizontal axis wind turbines (HAWTs) are well understood, the directivity pattern around vertical axis wind turbines (VAWTs) are less well investigated.This paper presents measurements of directivity on a 200 kW VAWT, a so called H-rotor, with variable speed and a tower height of 40 m. The turbine, which is situated in a flat agricultural landscape close to Falkenberg at the Swedish west coast, is one of the world’s largest today operational VAWTs. Experimental results as well as a theoretical model based on the turbulent-boundary-layer trailing-edge (TBL-TE) noise suggest higher noise levels upwind of the rotor and the lowest noise levels in the perpendicular directions. Moreover, modulation analysis of the measurements indicates the presence of modulations but the results are inconclusive.

  • 2.
    Möllerström, Erik
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik. Uppsala University, Uppsala, Sweden.
    Eriksson, Sandra
    Uppsala University, Uppsala, Sweden.
    Goude, Anders
    Uppsala University, Uppsala, Sweden.
    Ottermo, Fredric
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Turbulence influence on optimum tip speed ratio for a 200 kW vertical axis wind turbine2016In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 753, article id 032048Article in journal (Refereed)
    Abstract [en]

    The influence of turbulence intensity (TI) on the tip speed ratio for maximum power coefficient, here called λCp-max, is studied for a 200 kW VAWT H-rotor using logged data from a 14 month period with the H-rotor operating in wind speeds up to 9 m/s. The TI - λCp-max relation is examined by dividing 10 min mean values in different turbulence intensity ranges and producing multiple CP(λ) curves. A clear positive relation between TI and λCp-max is shown and is further strengthened as possible secondary effects are examined and deemed non-essential. The established relation makes it possible to tune the control strategy to enhance the total efficiency of the turbine.

  • 3.
    Möllerström, Erik
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik. Uppsala University, Uppsala, Sweden.
    Larsson, Sebastian
    Halmstad University, School of Business and Engineering (SET).
    Ottermo, Fredric
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Bååth, Lars
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK).
    Noise Propagation from a Vertical Axis Wind Turbine2014In: Proceedings of 43rd International Congress on Noise Control Engineering: Internoise 2014 / [ed] John Davy, Charles Don, Terry McMinn, Liz Dowsett, Norm Broner & Marion Burgess, Brisbane, QLD: Australian Acoustical Society , 2014Conference paper (Refereed)
    Abstract [en]

    Initial noise measurements were performed on a 200kW vertical axis wind turbine (VAWT) and results were compared to that of a Vestas V27, a similar size horizontal axis wind turbine (HAWT). Multiple recording units were placed in line downwind of the turbine to investigate noise propagation. The frequency distribution of the noise were analyzed indicating that the VAWT has lower relative levels for frequencies under 3000 Hz, especially within 600-1200 Hz. Furthermore, VAWT noise seems to occur more around the same frequencies as the natural background noise, increasing masking probability. Results from propagation measurements seemed to indicate that noise declines more rapidly with distance for the VAWT then for the reference HAWT, possibly explained by the lower levels at low frequencies. Further investigation is needed to establish these differences and the 200 kW VAWT creates an opportunity doing so utilizing arguably the largest operational VAWT existing today.

  • 4.
    Möllerström, Erik
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik. Uppsala University, Uppsala, Sweden.
    Ottermo, Fredric
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Goude, Anders
    Uppsala University, Uppsala, Sweden.
    Eriksson, Sandra
    Uppsala University, Uppsala, Sweden.
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Bernhoff, Hans
    Uppsala University, Uppsala, Sweden.
    Turbulence influence on wind energy extraction for a medium size vertical axis wind turbine2016In: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824, Vol. 19, no 11, p. 1963-1973Article in journal (Refereed)
    Abstract [en]

    The relation between power performance and turbulence intensity for a VAWT H-rotor is studied using logged data from a 14 month (discontinuous) period with the H-rotor operating in wind speeds up to 9 m/s. The turbine, designed originally for a nominal power of 200 kW, operated during this period mostly in a restricted mode due to mechanical concerns, reaching power levels up to about 80 kW. Two different approaches are used for presenting results, one that can be compared to power curves consistent with the International Electrotechnical Commission (IEC) standard and one that allows isolating the effect of turbulence from the cubic variation of power with wind speed. Accounting for this effect, the turbine still shows slightly higher efficiency at higher turbulence, proposing that the H-rotor is well suited for wind sites with turbulent winds. The operational data are also used to create a Cp(λ) curve, showing slightly lower Cp compared with a curve simulated by a double multiple streamtube model. Copyright © 2016 John Wiley & Sons, Ltd.

  • 5.
    Möllerström, Erik
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik. Division for Electricity, Department of Engineering Sciences, Uppsala University, PO Box 534, SE - 751 21 Uppsala, SwedenDivision for Electricity, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
    Ottermo, Fredric
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Bernhoff, Hans
    Division for Electricity, Department of Engineering Sciences, Uppsala University, PO Box 534, SE - 751 21 Uppsala, SwedenDivision for Electricity, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
    Avoidance of resonances in a semi-guy-wired vertical axis wind turbine2014Conference paper (Refereed)
    Abstract [en]

    Resonance analysis for a vertical axis wind turbine is performed. The turbine may be described as semi-guy wired, being bolted stiffly to the ground as well as supported by guy wires. The influence of the first mode eigen frequency of the guy wires and how it is affected by wind load is examined. Using beam theory, an analytical model for calculating the first mode eigen frequency of the guy wire for different wind loads is derived. The analytical model is verified with FEM-simulations and then used to assemble a diagram showing how to combine the wire size, inclination angle and pre-tension for an eigen frequency range over the 3P load for nominal rotational speed and for a certain effective spring force acting on the tower. This diagram, here called an EA-T diagram, may be used as a quick tool for comparing wire setups and a similar diagram can be used for other guy wired structures.

  • 6.
    Möllerström, Erik
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Ottermo, Fredric
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Bernhoff, Hans
    Uppsala Universitet.
    Eigen Frequencies of A Vertical Axis Wind Turbine Tower Made of Laminated Wood and the Effect Upon Attaching Guy Wires2014In: Wind Engineering: The International Journal of Wind Power, ISSN 0309-524X, E-ISSN 2048-402X, Vol. 38, no 3, p. 277-290Article in journal (Refereed)
    Abstract [en]

    Eigen frequencies of a vertical axis wind turbine tower made out of laminated wood which are both bolted to the ground and supported by guy wires are studied and compared. Using beam theory, an analytical model taking the guy wires into account for calculating the first mode eigen frequency of the tower has been derived. The analytical model is then evaluated by comparing with FEM-simulations and measurements performed on the actual tower. The model is found to be reasonably accurate keeping in mind that the estimated masses and second moments of area are somewhat rough. Furthermore the model can be used to give an indication of the magnitude of change in eigen frequency when modifying a tower or guy wire property.

  • 7.
    Möllerström, Erik
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik. Uppsala University, Uppsala, Sweden.
    Ottermo, Fredric
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energiteknik.
    Bernhoff, Hans
    Uppsala University, Uppsala, Sweden.
    Noise Emission of a 200 kW Vertical Axis Wind Turbine2016In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 9, no 1, article id 19Article in journal (Refereed)
    Abstract [en]

    The noise emission from a vertical axis wind turbine (VAWT) has been investigated. A noisemeasurement campaign on a 200 kW straight-bladed VAWT has been conducted, and the result hasbeen compared to a semi-empirical model for turbulent-boundary-layer trailing edge (TBL-TE) noise.The noise emission from the wind turbine was measured, at wind speed 8 m/s, 10 m above ground, to96.2 dBA. At this wind speed, the turbine was stalling as it was run at a tip speed lower than optimaldue to constructional constraints. The noise emission at a wind speed of 6 m/s, 10 m above groundwas measured while operating at optimum tip speed and was found to be 94.1 dBA. A comparisonwith similar size horizontal axis wind turbines (HAWTs) indicates a noise emission at the absolutebottom of the range. Furthermore, it is clear from the analysis that the turbulent-boundary-layertrailing-edge noise, as modeled here, is much lower than the measured levels, which suggests thatother mechanisms are likely to be important, such as inflow turbulence.

  • 8.
    Ottermo, Fredric
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Möllerström, Erik
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Uppsala University, Uppsala, Sweden.
    Nordborg, Anders
    Sound View Instruments, Borrby, Sweden.
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bernhoff, Hans
    Uppsala University, Uppsala, Sweden.
    Location of aerodynamic noise sources from a 200 kW vertical-axis wind turbine2017In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 400, p. 154-166Article in journal (Refereed)
    Abstract [en]

    Noise levels emitted from a 200 kW H-rotor vertical-axis wind turbine have been measured using a microphone array at four different positions, each at a hub-height distance from the tower. The microphone array, comprising 48 microphones in a spiral pattern, allows for directional mapping of the noise sources in the range of 500 Hz to 4 kHz. The produced images indicate that most of the noise is generated in a narrow azimuth-angle range, compatible with the location where increased turbulence is known to be present in the flow, as a result of the previous passage of a blade and its support arms. It is also shown that a semi-empirical model for inflow-turbulence noise seems to produce noise levels of the correct order of magnitude, based on the amount of turbulence that could be expected from power extraction considerations.

  • 9.
    Rögnvaldsson, Thorsteinn
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Brink, Joachim
    Halmstad University.
    Florén, Henrik
    Halmstad University, School of Business, Engineering and Science, Centre for Innovation, Entrepreneurship and Learning Research (CIEL).
    Gaspes, Veronica
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Holmgren, Noél
    University of Skövde, Skövde, Sweden.
    Lutz, Mareike
    Halmstad University.
    Nilsson, Pernilla
    Halmstad University, School of Education, Humanities and Social Science, Research on Education and Learning within the Department of Teacher Education (FULL).
    Olsfelt, Jonas
    Halmstad University.
    Svensson, Bertil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Ericsson, Claes
    Halmstad University, School of Education, Humanities and Social Science, Research on Education and Learning within the Department of Teacher Education (FULL).
    Gustafsson, Linnea
    Halmstad University, School of Education, Humanities and Social Science, Contexts and Cultural Boundaries (KK).
    Hoveskog, Maya
    Halmstad University, School of Business, Engineering and Science, Centre for Innovation, Entrepreneurship and Learning Research (CIEL).
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Nygren, Jens
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Rosén, Bengt-Göran
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK).
    Sandberg, Mikael
    Halmstad University, School of Education, Humanities and Social Science, Center for Social Analysis (CESAM).
    Benner, Mats
    Lund University, Lund, Sweden.
    Berg, Martin
    Halmstad University, School of Education, Humanities and Social Science, Center for Social Analysis (CESAM).
    Bergvall, Patrik
    Halmstad University.
    Carlborg, Anna
    Halmstad University.
    Fleischer, Siegfried
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Hållander, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Mattsson, Marie
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Olsson, Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Pettersson, Håkan
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Rundquist, Jonas
    Halmstad University, School of Business, Engineering and Science, Centre for Innovation, Entrepreneurship and Learning Research (CIEL).
    Sahlén, Göran
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Waara, Sylvia
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Weisner, Stefan
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Werner, Sven
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    ARC13 – Assessment of Research and Coproduction: Reports from the assessment of all research at Halmstad University 20132014Report (Other (popular science, discussion, etc.))
    Abstract [en]

    During 2013, an evaluation of all the research conducted at Halmstad University was carried out. The purpose was to assess the quality of the research, coproduction, and collaboration in research, as well as the impact of the research. The evaluation was dubbed the Assessment of Research and Coproduction 2013, or ARC13. (Extract from Executive Summary)

  • 10.
    Sidén, Göran
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energy Science.
    Hylander, Jonny
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Energy Science.
    Winkler, Charlotta
    Danmarks Tekniska Universitet, Lyngby, Danmark.
    Stenqvist, Christian
    Lunds tekniska högskola, Lund, Sverige.
    100 procent förnybar elenergi år 2020 – 2025 – 2030?2016Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    Rapporten beskriver möjligheterna  att ställa om Sveriges elförsörjning till 100 procent förnybart i tre olika tidsperspektiv, fem, tio eller femton år.

    Scenarierna är genomförbara. Kostnaden för elproduktion från nya anläggningar för sol- och vindkraft är redan idag eller kommer snart att vara lägre än kostnader för energi från nya anläggningar för den fossilkraft eller kärnkraft som ska ersättas. Detta gäller i synnerhet om man tar hänsyn till de så kallade externa kostnaderna. Externa kostnader är kostnader för klimatpåverkan, kemiska och radioaktiva rutinutsläpp och stora olyckor som belastar samhället, men som inte betalas direkt av elproducenterna. Framtidens el från förnybar energi kan framställas till lägre kostnad än den vi har för dagens energiförsörjning.

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