Modeling of horizontal axis wind turbine wakes in Horns Rev offshore wind farm using an improved actuator disc model coupled with computational fluid dynamic

This study evaluated, by time-domain simulations, the fatigue lives of several jacket support structures for 4 MW wind turbines distributed throughout an offshore wind farm off Taiwan’s west coast. An in-house RANS-based wind farm analysis tool, WiFa3D, has been developed to determine the effects of the wind turbine wake behaviour on the flow fields through wind farm clusters. To reduce computational cost, WiFa3D employs actuator disk models to simulate the body forces imposed on the flow field by the target wind turbines, where the actuator disk is defined by the swept region of the rotor in space, and a body force distribution representing the aerodynamic characteristics of the rotor is assigned within this virtual disk. Simulations were performed for a range of environmental conditions, which were then combined with preliminary site survey metocean data to produce a long-term statistical environment. The short-term environmental loads on the wind turbine rotors were calculated by an unsteady blade element momentum (BEM) model of the target 4 MW wind turbines. The fatigue assessment of the jacket support structure was then conducted by applying the Rainflow Counting scheme on the hot spot stresses variations, as read-out from Finite Element results, and by employing appropriate SN curves. The fatigue lives of several wind turbine support structures taken at various locations in the wind farm showed significant variations with the preliminary design condition that assumed a single wind turbine without wake disturbance from other units.

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Correlations of power output fluctuations in an offshore wind farm using high-resolution SCADA data

Wind Energy Science ◽

10.5194/wes-6-997-2021 ◽

2021 ◽

Vol 6 (4) ◽

pp. 997-1014

Author(s):

Janna Kristina Seifert ◽

Martin Kraft ◽

Martin Kühn ◽

Laura J. Lukassen

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Power Output ◽

Wind Farm ◽

Offshore Wind ◽

Offshore Wind Farm ◽

Flow Conditions ◽

Output Fluctuations ◽

Power Difference ◽

Time Correlations

Abstract. Space–time correlations of power output fluctuations of wind turbine pairs provide information on the flow conditions within a wind farm and the interactions of wind turbines. Such information can play an essential role in controlling wind turbines and short-term load or power forecasting. However, the challenges of analysing correlations of power output fluctuations in a wind farm are the highly varying flow conditions. Here, we present an approach to investigate space–time correlations of power output fluctuations of streamwise-aligned wind turbine pairs based on high-resolution supervisory control and data acquisition (SCADA) data. The proposed approach overcomes the challenge of spatially variable and temporally variable flow conditions within the wind farm. We analyse the influences of the different statistics of the power output of wind turbines on the correlations of power output fluctuations based on 8 months of measurements from an offshore wind farm with 80 wind turbines. First, we assess the effect of the wind direction on the correlations of power output fluctuations of wind turbine pairs. We show that the correlations are highest for the streamwise-aligned wind turbine pairs and decrease when the mean wind direction changes its angle to be more perpendicular to the pair. Further, we show that the correlations for streamwise-aligned wind turbine pairs depend on the location of the wind turbines within the wind farm and on their inflow conditions (free stream or wake). Our primary result is that the standard deviations of the power output fluctuations and the normalised power difference of the wind turbines in a pair can characterise the correlations of power output fluctuations of streamwise-aligned wind turbine pairs. Further, we show that clustering can be used to identify different correlation curves. For this, we employ the data-driven k-means clustering algorithm to cluster the standard deviations of the power output fluctuations of the wind turbines and the normalised power difference of the wind turbines in a pair. Thereby, wind turbine pairs with similar power output fluctuation correlations are clustered independently from their location. With this, we account for the highly variable flow conditions inside a wind farm, which unpredictably influence the correlations.

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Real-Time Load Assessment of Wind Turbine Support Structures in an Offshore Wind Farm

10.1115/1.0001261v ◽

2021 ◽

Author(s):

Bryan Nelson ◽

Tsung-Yueh Lin

Keyword(s):

Wind Turbine ◽

Real Time ◽

Wind Farm ◽

Offshore Wind ◽

Support Structures ◽

Offshore Wind Farm

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Sequential Simulation Used in the Computer Aided Design of Airfoils for Horizontal Axis Wind Turbine Rotors

Volume 2: Fora ◽

10.1115/fedsm2005-77363 ◽

2005 ◽

Author(s):

Sarim N. Al-Zubaidy ◽

Alwyn Johnson ◽

Jacqueline Bridge

Keyword(s):

Growth Rate ◽

Wind Turbine ◽

Computer Aided Design ◽

Fluid Dynamic ◽

Numerical Procedure ◽

Design Procedure ◽

Horizontal Axis ◽

Horizontal Axis Wind Turbine ◽

Analysis And Design ◽

Turbine Rotors

In the past twenty years wind energy remerged on the world scene with a very healthy growth rate, it has outstripped photovoltaics as the world’s fastest growing energy source, with a growth rate in excess of 30 percent per annum. The proposed paper presents a numerical procedure for the analysis and design of Horizontal Axis Wind Turbine rotors for fabrication in countries with limited manufacturing base and limited design expertise. To ascertain the accuracy and to determine where further improvements could be initiated; numerical findings were then compared with published experimental test data, the compression showed an average deviation of less than 3%. Once the approach was validated and standardized an airfoil design was produced. A computational fluid dynamic code coupled with a simple numerical algorithm aided the inverse design procedure. The final design is well proportioned and theoretically able to meet the stated objective and satisfied the constraints. The generated geometrical data is in a form suitable for manufacture using local manufacturing capabilities, the primary objective of this work.

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Wind Farm Power Production Assessment: Introduction of a New Actuator Disc Method and Comparison with Existing Models in the Context of a Case Study

Applied Sciences ◽

10.3390/app9030431 ◽

2019 ◽

Vol 9 (3) ◽

pp. 431 ◽

Cited By ~ 2

Author(s):

Nikolaos Simisiroglou ◽

Heracles Polatidis ◽

Stefan Ivanell

Keyword(s):

Wind Farm ◽

Power Production ◽

Offshore Wind ◽

Offshore Wind Farm ◽

Actuator Disc ◽

Power Deficit ◽

The Given ◽

Method Show ◽

Do So

The aim of the present study is to perform a comparative analysis of two actuator disc methods (ACD) and two analytical wake models for wind farm power production assessment. To do so, wind turbine power production data from the Lillgrund offshore wind farm in Sweden is used. The measured power production for individual wind turbines is compared with results from simulations, done in the WindSim software, using two ACD methods (ACD (2008) and ACD (2016)) and two analytical wake models widely used within the wind industry (Jensen and Larsen wake models). It was found that the ACD (2016) method and the Larsen model outperform the other method and model in most cases. Furthermore, results from the ACD (2016) method show a clear improvement in the estimated power production in comparison to the ACD (2008) method. The Jensen method seems to overestimate the power deficit for all cases. The ACD (2016) method, despite its simplicity, can capture the power production within the given error margin although it tends to underestimate the power deficit.

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