Utility-scale Wind Turbines and Wind Farms
2: Turbulance and Energy Laboratory, University of Windsor, Windsor, ON, Canada
Wind power is a pillar of low emission energy systems. Designing more efficient wind turbines and farms, and increasing reliability and flexibility, is an area of intense research and development. In order to overcome the intermittent character of wind power, both the individual turbines and the wind farm as a whole must be considered. Many recent advances have been achieved in multiple aspects of utility-scale wind power. This structured research review conveys recent progress, with chapters written by an international team of experts. Organized into five parts, the book covers the aerodynamics of turbines and farms including layout; control techniques; environmental concerns including noise and bird and bat collisions; the intermittency issue including forecasting, storage and hybrid wind-PV plants; and offshore wind farms. From the general principles of aerodynamics to detailed and systematic coverage of the latest developments, Utility-scale Wind Turbines and Wind Farms provides a convenient and up-to-date source of information for academic researchers and R&D professionals working in this field.
Inspec keywords: power grids; wind power; wind turbines; rotors; wind power plants
Other keywords: wind turbines; renewable energy sources; wind power; power overhead lines; poles and towers; aerodynamics; rotors; load forecasting; power grids; wind power plants
Subjects: General topics in manufacturing and production engineering; Handbooks and dictionaries; Education and training; General and management topics; Monographs, and collections; Engineering mechanics; Winds and their effects in the lower atmosphere; General electrical engineering topics; Mechanical components; Wind power plants; Power and plant engineering (mechanical engineering); Textbooks; Control of electric power systems
- Book DOI: 10.1049/PBPO171E
- Chapter DOI: 10.1049/PBPO171E
- ISBN: 9781839530999
- e-ISBN: 9781839531002
- Page count: 381
- Format: PDF
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Front Matter
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1 The current status of wind power
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At the beginning of 2020, wind power capacity worldwide exceeded approximately 650 GW, covering less than 5% of the global electricity demand. This current global wind power capacity is enough to power more than 400 million average houses. The International Renewable Energy Agency projects that wind will generate approximately 35% of the total required electricity by 2050. Technological developments in towers, foundations, rotors, and drivetrains will enable this accelerated expansion of the wind industry. After presenting a brief on the current state of these significant wind energy technology pillars, the chapter lays out the various topics that the present book covers.
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Part I Aerodynamics
2 Advances in the aerodynamics of horizontal axis wind turbines
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Wind turbine technology enhancements have, in the last two to three decades, been through developmental progression. Several efforts tailored toward improvement in power generation at reduced cost have dominated global research activities. These activities include wind turbine design improvements, control efficiency enhancements, blade shape design and optimization, flow separation and control, system stability measure, and condition monitoring. Among all of these research efforts, the contributions of the aerodynamics of rotor blades vis-à-vis the complexities of the flow structure around the rotor-blade system have dominated recent research focus. The efforts aim to have an operable system that is more efficient and environmentally friendlier. Thus, this study focuses on the advances in the aerodynamics of horizontal axis wind turbines. The chapter reviews some of the research efforts that have been carried out on this topic and the developments that have emanated from such efforts. Considerations are given to blade geometry modifications for effective power production, flow regimes and control, application of wind-lenses, and flow stream modification through the implementation of various flaps, airfoil concavity, shrouds, and flanges. Some of the researchers' documented efforts to augment the power coefficients beyond Betz's limit are also surveyed and criticized.
3 Scaling utility-scale wind turbines
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This chapter provides guidelines for designing utility-scale wind turbines for wind tunnel testing. While one might think scaling down all dimensions of a utility-scale wind turbine with the same scale factor suffices, the aerodynamic results obtained for such a scale model significantly differ from those of the full-scale turbine. It is essential to scale a turbine so that its power coefficient and tip speed ratio remain unchanged.
4 Advances in aerodynamics of wind farms
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In the current chapter, we summarize the recent state-of-the-art advances in the aerodynamics of wind farms deployed in ABLs. This chapter particularly discusses the progress in high-fidelity numerical framework, in particular LESs and the wind turbine models for computing large wind farm layouts. We have reviewed the LES framework for asymptotically large wind farms, the analytical models relying on momentum/energy equilibrium framework to describe such infinite layout including Frandsen-Calaf theory and the two- scale momentum theory (Nishino model).
5 Wind farm layout optimization
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There are many factors affecting the performance of a wind farm, including site location and layout. Wind farm layout optimization has become one of the critical approaches to increase power output and reduce the total cost of a wind farm. Wind farm layout optimization focuses on optimizing the layout of a wind farm using different intelligent algorithms to maximize its power output or minimize its levelized cost of electricity generated. Some offshore wind turbines are reaching rotor diameters larger than 200 m. The separation between wind turbines in layouts has increased accordingly to minimize the impact of the wake effect. However, this has caused areas occupied by wind farms to grow exponentially. Since regions with optimal wind resources are limited, this poses a problem on the saturation of equipment and interference with other economic, transportation, and residential activities. Instead of continually increasing the number and the size of wind turbines in a given wind farm, new optimization methods are being developed to manage and control the operation of these enormous wind turbines in the wind farms under different wind conditions to reduce the wake effect and maximize their power output under any given wind farm layouts. For instance, a new method identified a selected number of wind turbines to be deactivated according to changing wind conditions, improving the wind farm total power output. The method identifies wind turbines that generate greater interference due to the wake effect than the power they can generate. Other equipment stops receiving negative interference by deactivating these turbines and generating additional power output.
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Part II Control
6 Analyzing data obtained via wind farm supervisory control and data acquisition
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In this chapter, we first discuss the application of SCADA data and CMS data in wind farm operation and maintenance (O&M) by reviewing the commonly used technologies and analytics. Next, the discussion is devoted to a unified framework for building a cyber- physical wind farm, and several case studies are provided to demonstrate the idea. Finally, we highlight the existing challenges and future works.
7 Innovative control strategies for wind turbines
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When operating below its rated wind speed, a variable- speed wind turbine (VSWT) often uses maximum power point tracking (MPPT) to maximize wind energy extraction. However, as wind resources in regions with high wind speeds have been widely exploited, energy extraction from VSWTs is increasingly challenged by unfavourable wind conditions, such as low wind speeds and strong turbulence. Meanwhile, the inertia of wind turbine rotors increases with the scale of wind power genera-tion systems. Consequently, the divergence between turbulent wind speeds, which hinder MPPT, and slow dynamics of the large-scale VSWT rotors becomes prominent, leading to substantial tracking loss and even tracking invalidity. The effects of turbulence on wind energy extraction are analysed in this chapter to address this divergence. Then, a tracking range reduction method is proposed to improve the wind energy extraction efficiency, considering the slow dynamics of wind turbine rotors. This method mainly modifies the reference input for MPPT control. In the wind turbine control and control theory in general, enhancing the control performance of a system depends on improved control strategies. Nevertheless, few studies have focused on modifying the reference for changing the MPPT target and improving the control performance. Based on the concept of tracking range reduction, the effective tracking range (ETR) can be determined and applied to the conventional optimal torque (OT) control for increasing wind energy extraction.
8 Recent advances in vibration control for wind turbines under multiple hazards
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The increasing demand for affordable, reliable, and clean energy drives the research for more advanced wind turbines. Wind farms are growing, with larger and taller wind turbines. However, wind turbines may be installed or planned to be installed under natural and mechanical multiple hazard dynamic loadings. Excessive vibrations, due to these loads, can have detrimental effects on energy production, structural lifecycle, and the initial cost of wind turbines. To alleviate these issues, we developed a novel control theory that enables semi-active controller tuning under the complex structural behaviour and inherent system nonlinearity. The theory applies to different types of structures. The proposed theory enables the evaluation of semi-active controllers' performance of multi-degrees-of-freedom systems, without the need for time-consuming simulations. With this analytical probabilistic control theory, a wide range of controllers can be tested in a fraction of a second, and their parameters can be tuned to achieve system-level performance for different optimization objectives. Vibration reduction can prevent malfunctioning of the mechanical acceleration-sensitive parts, with increased wind turbines' availability and reduced maintenance costs. This can also lead to reduced capital cost, and therefore less expensive and more competitive generated electricity.
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Part III Environmental concerns
9 Wind farm noise propagation and viable noise reduction strategies
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This chapter aims to present the key mechanisms of wind turbine noise generation, how people are affected by it, and how noise-related problems can be reduced. Initially, the physical phenomena behind noise generation are presented. The second section gives an overview of the key annoyance-related issues, including the roles played by the noise level, noise character, and atmospheric conditions. In Section 9.1, the currently used methods to model both noise generation and propagation are reviewed. In the penultimate section, before the summary, different methods to reduce wind turbine noise are reviewed, including the possibilities emerging during wind farm- and turbine-design processes and wind farm operation.
10 Bird and bat collisions at wind farms
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Wind energy is considered green as wind turbines do not produce pollutants during their operation. One drawback of wind energy is wind turbines' interaction with birds and bats, especially with those listed as endangered species or those protected by the Migratory Bird Treaty Act (MBTA). One way to live in harmony with nature is to study collision rates and develop mitigation techniques. This work describes various electronic monitoring techniques, collision models, and several mitigation techniques. All these approaches may not work 100 percent of the time, but at least they will reduce bird/bat mortalities with the wind turbines. This would be a win-win approach and living in harmony.
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Part IV The Intermittency Issue
11 Overview of state-of- the- art of wind power forecasting
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This paper is about the wind power forecasting is vital to the safe operation of the power grid and increased penetration of wind power. wind power prediction technology and its application have made significant progress in the areas of high penetrations of wind power, such as economic dispatch, unit commitment, and market trading. In terms of wind power forecasting accuracy, by improving core technologies of numerical weather prediction (NWP) and optimizing the wind power conversion model, the prediction error has been significantly reduced to ensure the balanced supply and demand of electricity. The prediction error of the wind power of the most advanced international level is as low as 2.5 percent. The forecast errors of different signs for different regions are mainly reduced by combining many wind turbines. In terms of prediction products, models of event forecasting, probabilistic forecasting, and clustering forecasting are derived by combining with extreme meteorological conditions such as high wind, low temperature, freezing rain, and haze. Consequently, forecasting products are becoming more diversified. In the aspect of prediction application and evaluation, the prediction evaluation index system has been significantly improved by combining with the requirement of economic dispatch and electricity market, which promotes the overall improvement of forecasting performance.
12 Storage-integrated wind farms
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This chapter develops a foundation for stability analysis of storage-integrated wind farms and delves into the concept of distributed control design to provide ancillary services to the grid using storage-integrated wind turbines. The stability analysis is performed for a double-fed induction generator (DFIG)-based wind turbine integrated with a stand-alone battery energy storage system (BESS). Dynamics of the induction generator, AC-side filters, phase-locked loop (PLL), rotor-side converter (RSC), grid side converter (GSC), and BESS controllers are considered. Eigenvalue analysis is performed to evaluate the stability of the integrated systems. A distributed controller is designed to provide active and reactive power-sharing and energy synchronization capabilities to the BESS units in an IEEE 14-bus system integrated with a wind farm composed of 10 storage-integrated wind turbines.
13 Current status of research on the design of hybrid wind and solar plants
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Due to the rapid depletion and significant environmental impact of conventional energy sources, research is being conducted worldwide to find out alternative energy sources. The use of renewable energy technologies is being explored around the world as an alternative to conventional sources. These sources are non-depletable and environment-friendly. They use natural resources like solar and wind to generate the required energy. They can be used as single sources or as a combination of more than one type of renewable energy source along with storage devices like battery or fuel cells. Renewable energy systems (RES) can be used as grid-connected or standalone systems. However, the unpredictable nature of these natural resources reduces their reliability to a great extent. Hence, proper selection and sizing of the sources are necessary to avoid excessive establishment and maintenance costs or compromised power reliability. This chapter discusses different methodologies available in the literature on optimum sizing of the renewable energy systems, including wind power plants.
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Part V Offshore Wind
14 Status of offshore wind farms in Europe: the case study of Galicia
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Maritime wind technology has had a great development in European countries for many years. This significant development is due to installing fixed wind platforms, such as monopiles, jackets, or tripiles in the North Sea. The offshore wind power sector can evolve into main spillways: designing, constructing, and R&D of new platforms at shipyards and installing offshore wind farms in specific locations.
Back Matter
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