Parking Strategies for Vertical Axis Wind Turbines

Ottermo, Fredric; Eriksson, Sandra; Bernhoff, Hans

doi:10.5402/2012/904269

Cited by 7 publications

(9 citation statements)

References 7 publications

(12 reference statements)

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“…As previously mentioned, using an electrically-braked turbine can reduce torsional vibrations in the shaft, as the generator can dampen these oscillations [7]. Hence, one should look at the entire system before deciding which parking strategy to use.…”

Section: Discussionmentioning

confidence: 99%

“…The torque from the generator is however low at low rotational speeds, and hence, the turbine can rotate slowly with the electric brake engaged. It was suggested by Ottermo et al to use electrical braking since it can dampen oscillations in the drive-train during parking [7]. Here, it is studied if this electric brake is suitable for parking the turbine in terms of aerodynamic loads or if an additional mechanic brake is required to lock the turbine to a fixed position.…”

Section: Introductionmentioning

confidence: 99%

“…Ottermo et al used simplified analytical expressions to estimate the extreme loads [7]. Paulsen et al have done computational fluid dynamics (CFD) studies covering both operational states and parked situations for the DeepWind concept [8].…”

Section: Introductionmentioning

confidence: 99%

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Force Measurements on a VAWT Blade in Parked Conditions

Goude

Rossander

2017

Energies

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Abstract:The forces on a turbine at extreme wind conditions when the turbine is parked is one of the most important design cases for the survivability of a turbine. In this work, the forces on a blade and its support arms have been measured on a 12 kW straight-bladed vertical axis wind turbine at an open site. Two cases are tested: one during electrical braking of the turbine, which allows it to rotate slowly, and one with the turbine mechanically fixed with the leading edge of the blade facing the main wind direction. The force variations with respect to wind direction are investigated, and it is seen that significant variations in forces depend on the wind direction. The measurements show that for the fixed case, when subjected to the same wind speed, the forces are lower when the blade faces the wind direction. The results also show that due to the lower forces at this particular wind direction, the average forces for the fixed blade are notably lower. Hence, it is possible to reduce the forces on a turbine blade, simply by taking the dominating wind direction into account when the turbine is parked. The measurements also show that a positive torque is generated from the blade for most wind directions, which causes the turbine to rotate in the electrically-braked case. These rotations will cause increased fatigue loads on the turbine blade.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Force Measurements on a VAWT Blade in Parked Conditions

Goude

Rossander

2017

Energies

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“…The 200 kW VAWT prototype with three straight blades was installed in early 2010 in Falkenberg, Sweden. This rotor, having NACA 0018 airfoils, provided 22.5 MWh of energy to the power grid during the tests within 1000 hours of operation (Apelfröjd at al., 2016;Ottermo et al, 2012). In the case of Φ-type rotors, in most commercial cases symmetrical airfoils of the 4-digit NACA series were used (Templin, 1979, Paraschivoiu, 2002Tjiu et al, 2015;Möllerström et al, 2019).…”

Section: Vawt Employing Naca Four-digit Airfoilmentioning

confidence: 99%

Performance analysis of a Darrieus-type wind turbine for a series of 4-digit NACA airfoils

Rogowski

Hansen

Bangga

2019

Preprint

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Abstract. The purpose of this paper is to estimate the H-Darrieus wind turbine aerodynamic performance, aerodynamic blade loads and velocity profiles downstream behind the rotor. The wind turbine model is based on the rotor designed by McDonnell Aircraft Company. The model proposed here consists of three fixed straight blades; in the future this model is planned to be develop with controlled blades. The study was conducted using the unsteady Reynolds averaged Navier-Stokes (URANS) approach with the k-ω shear stress transport (SST) turbulence model. The numerical two-dimensional model was verified using two other independent aerodynamic approaches: the vortex model developed in Technical University of Denmark (DTU) and the extended version of the CFD code FLOWer at the University of Stuttgart (USTUTT). All utilized numerical codes gave similar result of the instantaneous aerodynamic blade loads. In addition, steady-state calculations for the applied airfoils were also made using the same numerical model as for the vertical axis wind turbine (VAWT) to obtain lift and drag coefficients. The obtained values of lift and drag force coefficients, for a Reynolds number of 2.9 million, agree with the predictions of the experiment and XFoil over a wide range of angle of attack. The maximum rotor power coefficients are obtained at 0.5, which makes this impeller attractive from the point of view of further research. This work also addresses the issue of determining the aerodynamic performance of the rotor with various 4-digit NACA airfoils. The effect of two airfoil parameters, maximum airfoil thickness and maximum camber, on aerodynamic rotor performance is investigated. Research has shown that if this rotor were to work with fixed blades it is recommended to use the NACA 1418 airfoil instead of the original NACA 0018.

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“…The 200 kW system has been designed for modest wind conditions with an average wind of 6.5 m/s at hub height but rated as an IEC class II turbine, surviving extreme wind gusts of 60 m/s. Parking strategies for an H-rotor in a more general aspect are the focus of the work presented in [18]. The work considers a straight-bladed VAWT with a direct driven permanent magnet synchronous generator.…”

Section: Turbinementioning

confidence: 99%

A Review of Research on Large Scale Modern Vertical Axis Wind Turbines at Uppsala University

2016

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This paper presents a review of over a decade of research on Vertical Axis Wind Turbines (VAWTs) conducted at Uppsala University. The paper presents, among others, an overview of the 200 kW VAWT located in Falkenberg, Sweden, as well as a description of the work done on the 12 kW prototype VAWT in Marsta, Sweden. Several key aspects have been tested and successfully demonstrated at our two experimental research sites. The effort of the VAWT research has been aimed at developing a robust large scale VAWT technology based on an electrical control system with a direct driven energy converter. This approach allows for a simplification where most or all of the control of the turbines can be managed by the electrical converter system, reducing investment cost and need for maintenance. The concept features an H-rotor that is omnidirectional in regards to wind direction, meaning that it can extract energy from all wind directions without the need for a yaw system. The turbine is connected to a direct driven permanent magnet synchronous generator (PMSG), located at ground level, that is specifically developed to control and extract power from the turbine. The research is ongoing and aims for a multi-megawatt VAWT in the near future.

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Parking Strategies for Vertical Axis Wind Turbines

Cited by 7 publications

References 7 publications

Force Measurements on a VAWT Blade in Parked Conditions

Force Measurements on a VAWT Blade in Parked Conditions

Performance analysis of a Darrieus-type wind turbine for a series of 4-digit NACA airfoils

A Review of Research on Large Scale Modern Vertical Axis Wind Turbines at Uppsala University

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