Power output efficiency in large wind farms with different hub heights and configurations

Wu, Yu Ting; Liao, Teh‐Lu; Chen, Chang Kuo; Lin, Chuan-Yao; Chen, Po Wei

doi:10.1016/j.renene.2018.08.051

Cited by 47 publications

(30 citation statements)

References 15 publications

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“…In the studies associated with the wind farm layout under the same turbine siting density condition, both the AL and staggered layouts are classical turbine arrangement cases, and the latter can be divided into the lateral and vertical offset arrangements. The entire power generation in the wind farms with the staggered arrangement is found to be much better than that in the AL wind farm 27,29,30 because the staggered layout preserves a much longer turbine spacing along the wakewise direction for wake recovery. Besides, Wu et al 29 used the LES technique to model the power outputs in the large wind farms, which have an installation of 120 wind turbines arranged in AL, laterally staggered (LS), and vertically staggered (VS) layouts and with 30 turbine rows along the wakewise direction.…”

Section: Introductionmentioning

confidence: 94%

“…The AL conditions are known to cause severe power losses on the downstream turbines with full‐wake effects, whereas the unaligned conditions can bring about an increment in the total frontal area of the downstream turbines with no/partial wake effects to increase power generation. Previous studies have focused on the above‐mentioned turbine wake effects on the entire wind farm power generation performance in terms of the change of wind direction, 24,27 the change of wind farm layout, 29,30 and the change of incoming wind turbulence 31 . In the studies associated with the wind farm layout under the same turbine siting density condition, both the AL and staggered layouts are classical turbine arrangement cases, and the latter can be divided into the lateral and vertical offset arrangements.…”

Section: Introductionmentioning

confidence: 99%

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Effects of inflow turbulence intensity and turbine arrangements on the power generation efficiency of large wind farms

Lin

Chang

2020

Wind Energy

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In this study, we conduct a series of large-eddy simulations (LESs) to study the impact of different incoming turbulent boundary layer flows over large wind farms, with a particular focus on the overall efficiency of electricity production and the evolution of the turbine wake structure. Five representative turbine placements in the large wind farm are considered, including an aligned layout and four staggered layouts with lateral or vertical offset arrangements. Four incoming flow conditions are used and arranged from the LESs of the ABL flow over homogeneous flat surfaces with four different aerodynamic roughness lengths (i.e., z0 = 0.5, 0.1, 0.01, and 0.0001 m), where the hub-height turbulence intensity levels are about 11.1%, 8.9%, 6.8%, and 4.9%, respectively. The simulation results indicate that an enhancement in the inflow turbulence level can effectively increase the power generation efficiency in the large wind farms, with about 23.3% increment on the overall farm power production and up to about 32.0% increment on the downstream turbine power production. Under the same inflow condition, the change of the turbine-array layouts can increase power outputs within the first 10 turbine rows, which has a maximum increment of about 26.5% under the inflow condition with low turbulence. By comparison, the increase of the inflow turbulence intensity facilitates faster wake recovery that raises the power generation efficiency of large wind farms than the adjustment of the turbine placing layouts. K E Y W O R D Slarge eddy simulation, power output, surface roughness, turbulence intensity, wind farm layout

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Effects of inflow turbulence intensity and turbine arrangements on the power generation efficiency of large wind farms

Lin

Chang

2020

Wind Energy

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“…This implies that many large wind farms might never reach fullydeveloped conditions (e.g., Crespo et al 1999a Wind-farm layout has attracted a great deal of attention due to its strong impact on the flow development inside wind farms and, therefore, on their efficiency. Several recent wind-tunnel and LES studies have focused on the differences between two basic wind-farm layout configurations: (i) aligned, and (ii) staggered (e.g., Markfort et al 2012;Wu and Porté-Agel 2013;Archer et al 2013;Hamilton et al 2015;Stevens et al 2016a;Wu et al 2019). Overall, it is found that inside staggered wind farms, wind turbines are subject to relatively smaller wake effects (power losses and fatigue loads).…”

Section: Finite-size Wind-farm Flowsmentioning

confidence: 99%

Wind-Turbine and Wind-Farm Flows: A Review

Porté‐Agel

Bastankhah

Shamsoddin

2019

Boundary-Layer Meteorol

695

414

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Wind energy, together with other renewable energy sources, are expected to grow substantially in the coming decades and play a key role in mitigating climate change and achieving energy sustainability. One of the main challenges in optimizing the design, operation, control, and grid integration of wind farms is the prediction of their performance, owing to the complex multiscale two-way interactions between wind farms and the turbulent atmospheric boundary layer (ABL). From a fluid mechanical perspective, these interactions are complicated by the high Reynolds number of the ABL flow, its inherent unsteadiness due to the diurnal cycle and synoptic-forcing variability, the ubiquitous nature of thermal effects, and the heterogeneity of the terrain. Particularly important is the effect of ABL turbulence on wind-turbine wake flows and their superposition, as they are responsible for considerable turbine power losses and fatigue loads in wind farms. These flow interactions affect, in turn, the structure of the ABL and the turbulent fluxes of momentum and scalars. This review summarizes recent experimental, computational, and theoretical research efforts that have contributed to improving our understanding and ability to predict the interactions of ABL flow with wind turbines and wind farms.

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“…This result comparison between C3 and C5 demonstrates that a turbine operating at a faster blade rotating speed can generate a larger power output and extract less momentum from the inflow to produce a slightly weaker wake. This kind of control strategy can be applied to raise the power generation of the downstream turbines as well as the overall power productivity in large wind farms with different inflow conditions and placement configurations [26,27]. Acknowledgments: Computing resources were provided by the Taiwan National Center for High-performance Computing (NCHC).…”

Section: Discussionmentioning

confidence: 99%

An Experimental Investigation of Wake Characteristics and Power Generation Efficiency of a Small Wind Turbine under Different Tip Speed Ratios

Lin

Hsu

2020

Energies

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We carried out a wind tunnel experiment to examine the power generation efficiency of a stand-alone miniature wind turbine and its wake characteristics at different tip speed ratios (TSRs) under the same mean inflow velocity. Resistors in the electrical circuit were adjusted to control the TSRs to 0.9, 1.5, 3.0, 4.1, 5.2, and 5.9. The currents were measured to estimate the turbine power outputs versus the TSRs and then establish the actual power generation coefficient Cp distribution. To calculate the mechanical power coefficient, a new estimation method of the mechanical torque constant is proposed. A reverse calibration on the blade rotation speed was performed with given electrical voltages and currents that are used to estimate the mechanical power coefficient Cp, mech. In the experiment, the maximum Cp,mech was approximately 0.358 (corresponding to the maximum Cp of 0.212) at the TSR of 4.1. Significant findings indicate that the turbine at the TSR of 5.2 produces a smaller torque but a larger power output compared with that at the TSR of 3.0. This comparison further displays that the turbine at the TSR of 5.2, even with larger power output, still produces a turbine wake that has smaller velocity deficits and smaller turbulence intensity than that at the TSR of 3.0. This behavior demonstrates the significance of the blade-rotation control (i.e., pitch regulation) system to the turbine operation in a large wind farm for raising the overall farm power productivity.

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Power output efficiency in large wind farms with different hub heights and configurations

Cited by 47 publications

References 15 publications

Effects of inflow turbulence intensity and turbine arrangements on the power generation efficiency of large wind farms

Effects of inflow turbulence intensity and turbine arrangements on the power generation efficiency of large wind farms

Wind-Turbine and Wind-Farm Flows: A Review

An Experimental Investigation of Wake Characteristics and Power Generation Efficiency of a Small Wind Turbine under Different Tip Speed Ratios

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