Method for enhancement of a wind plant layout with multiple wind turbines

The present invention is directed generally to wind turbines, and more particularly to a method for enhancing an initial layout of multiple wind turbines in a wind plant.

Wind turbines are receiving increased attention as an environmentally safe and relatively inexpensive alternative energy source. With this growing interest, considerable efforts have been made to develop wind turbines and wind turbine plants that are reliable, efficient, and cost-effective.

Placement of wind turbines within a wind power plant has traditionally been performed with the single objective of maximizing overall energy production from the plant. For example, in designing the wind plant, wind turbines are initially placed at locations within the geographic boundaries of the plant having the highest winds based on a wind resource grid. A wind resource grid can be generated using commercially available wind resource assessment or modeling software such as WindPro™ (available from EMD International A/S, Aalborg, Denmark), WindFarmer™ (available from Garrad Hassan, Bristol United Kingdom), or WindFarm™ (available form ReSoft Ltd., Banbury, United Kingdom). Other design criteria or constraints, such as exclusion zones, minimum spacing constraints, noise restrictions, and the like, are then used to adjust the turbine layout.

Other wind plant design objectives, such as minimizing the cost of the wind plant, maximizing financial metrics, and minimizing noise, may also be taken into account in designing the plant layout. Various commercial software programs may be helpful in this regard. For example, to address cost, financial metrics, and noise constraints, software such as WindPro™, WindFarmer™, or WindFarm™ offer analysis modules that can be used to manually adjust the turbine layout as desired. In addition, these programs may offer a function or module allowing for the automatic maximization of energy production for a fixed number of wind turbines and a particular wind turbine model/configuration. Noise constraints and exclusion zones may also be considered in these programs. Even with the available software programs, additional analysis is needed before the turbine layout can be finalized, such as the calculation of the mechanical loads on each wind turbine to ensure that they are within the design limits of the wind turbine model(s)/configuration(s) of interest.

The published PCT application <patcit id="pcit0001" dnum="WO2008092462PCT"><text>WO 2008092462</text></patcit> describes a method for designing a wind plant wherein at least one group of wind turbines within the plant are selected to produce a non-optimal output as compared to another group of wind turbines for the same wind conditions in order to achieve a more even output for the entire plant. For example, a first group of wind turbines utilized in the plant are designed to produce a maximized output in a particular wind climate. This first group is supplemented by a second group of wind turbines that is specifically designed to produce a maximal power in lower wind speeds, and thus achieve their rated power in another window of the wind spectra as compared to the first group. The goal of the design is to increase the total power output of the plant across a broader spectra of wind conditions by having groups of wind turbines with rated power outputs at different wind speeds.

The commercially available wind plant programs, and the methodology described in the <patcit id="pcit0002" dnum="WO2008092462A"><text>WO 2008092462</text></patcit> publication, have the disadvantage that they view the wind plant as a single power producing unit subjected to an overall site condition, rather than a cluster of individual turbines subjected to unique wind conditions. The conventional design methodologies typically require an initial baseline layout wherein the types of turbines and overall site conditions are already established or assumed. Thus, the methodology is constrained from the very beginning. The conventional methods do not allow for consideration of the unique wind conditions experienced by each individual wind turbine within the plant, and thus do not consider that the individual turbine output can be increased by tailoring individual wind turbine characteristics, such as hub height, turbine types, and so forth, to the actual wind conditions experienced at each wind turbine location.

Another prior art example can be found in <nplcit id="ncit0001" npl-type="s"><text>Hans Georg Beyer: "Modelling Tools for Wind Farm Upgrading", Preceedings to EUWEC 1996 - Goteborg, Sweeden, 24 May1996</text></nplcit>.

Therefore, what is needed is a wind plant design methodology that maximizes the plant's annual energy production (AEP) by tailoring individual turbine characteristics to differing wind conditions that are experienced through the plant.

Aspects and advantages of the invention will be set forth in part in the following description, or may be evident from the description, or may be learned through practice of the invention.

The present invention is defined by the appended claims.

Various aspects and embodiments of the present invention will now be described in connection with the accompanying drawings, in which: <ul id="ul0001" list-style="none"><li><figref idref="f0001">Fig. 1</figref> is a schematic view of a wind power plant according to aspects of the present invention;</li><li><figref idref="f0002">Fig. 2</figref> is a plan view of a wind power plant on a site deemed suitable for wind turbines according to aspects of the invention;</li><li><figref idref="f0003">Fig. 3</figref> is an overall process flow diagram according to a method embodiment of the invention;</li><li><figref idref="f0004">Fig. 4</figref> is a more detailed flow diagram of one of the process steps from <figref idref="f0003">Fig. 3</figref>;</li><li><figref idref="f0004">Fig. 5</figref> is a more detailed flow diagram of one of the process steps of <figref idref="f0003">Fig. 3</figref>;</li><li><figref idref="f0005">Fig. 6</figref> is a more detailed flow diagram of aspects of the flow process of <figref idref="f0003">Fig. 3</figref>; and</li><li><figref idref="f0006">Fig. 7</figref> is a more detailed flow diagram of aspects of the flow process of <figref idref="f0003">Fig. 3</figref>.</li></ul>

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the claims. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

As shown in <figref idref="f0001">FIG. 1</figref>, a wind power plant 200 includes a number of wind turbines 100. Each turbine 100 generally comprises a nacelle 102 housing mounted atop a tower 104. The nacelle 102 generally includes a generator, controller, and other associated equipment. The height of the tower 104 is selected based upon various factors, as described in greater detail below, and may extend to heights up to 60 meters or more. The wind turbines 100 may be installed on any terrain providing access to areas having desirable wind conditions. The terrain may vary greatly and may include, but is not limited to, mountainous terrain or off-shore locations. The wind turbines 100 also comprise a rotor 106 that includes one or more rotor blades 108 attached to a rotating hub 110. There are no specific limits on the number of rotor blades 108 required by embodiments of the present invention.

The plurality of wind turbines 100 are preferably controlled and/or monitored from a central controller 201. Signals 203 may be transferred to and/or from the wind turbines 100 to provide monitoring data and/or control signals. The number of wind turbines 100 in the plant 200 is not a limiting factor, but is generally dictated by a combination of considerations. The wind power plant 200 is arranged to provide a combined power output.

Referring to <figref idref="f0002">FIG. 2</figref>, a wind power plant is illustrated at a wind turbine site 300 bounded by boundary line 304. The site 300 includes a plurality of wind turbines 100 arranged therein. The site 300 includes one or more distinct regions. In the illustrated embodiment, regions A, B, and C are designated. The regions A -C may be defined by any combination of factors, but each region generally designates an area within the site 300 wherein a plurality of turbine locations are subjected to common wind conditions and constraints. Each of regions A - C includes a plurality of wind turbines 100 arranged on a variety of topography. The topography includes elevation contour lines 301 delineating changes in elevation within site 300 or a given region. The surface roughness is indicated by lines 302 and represents the ground cover and its influence on the wind conditions within the respective region A - C. An important topography consideration is the presence of significant dwellings or industrial buildings, such as a nearby city or residential area 305.

The site 300 may include any manner of exclusion zone 303, which may be a lake, unstable soil, inhospitable terrain, protected land region, or other area on which a wind turbine cannot be located for any reason. Further, the site 300 may include or be in close proximity to noise sensitive areas, such as the area 305, which may include homes, businesses, natural reserves, or other areas that are sensitive or intolerant to noise or close proximity to wind turbines 100. It should be appreciated that the exclusion zones 303, including noise sensitive areas 305, can include any area that is sensitive or intolerant to the presence of wind turbine 100s, the wind turbine structure (e.g., tower 104), or the associated structures or support components of a wind power plant (e.g., access roads or protective fences, migratory bird paths, habitat area reduction concerns for various animals, etc.), noise generated from a wind power plant, or any other factor related to the presence of a wind power plant.

In accordance with aspects of the invention, a methodology is provided for determining a wind turbine layout at a wind power plant site 300 wherein a plurality of wind turbines 100 generate a combined power output. Referring to the flow diagram of <figref idref="f0003">FIG. 3</figref>, the methodology includes identifying any manner of constraint on the power plant site at step 400. As discussed above, such constraints may include defined exclusion zones 303, noise sensitive areas, 305, and generally any area within or near the site 300 that is sensitive or intolerant to the presence of wind turbines 100.

<figref idref="f0004">FIG. 4</figref> represents a more detailed flow process of step 400 for identifying the constraints and exclusions of a particular power plant site, and presents a non-exhaustive list of factors that may be considered in identifying such constraints or exclusions. For example, step 402 represents consideration of any noise exclusion areas within or near the site 300. Step 404 represents consideration of topography and terrain constraints within the site 300 that may limit placement or grouping of wind turbines 100. Step 406 represents consideration of structures, buildings, residential neighborhoods, and the like that may prohibit placement of wind turbines 100. Step 408 represents consideration of any manner of land use constraints within or near the site 300.

Once the constraints of the plant site have been determined, at least one or more regions within the site are defined at step 450 (<figref idref="f0003">FIG. 3</figref>). As discussed above with reference to <figref idref="f0002">FIG. 2</figref>, these distinct regions A, B, and C may be defined by any combination of factors, with each region generally designating an area within the site 300 wherein a plurality of turbine locations are subjected to common wind conditions and constraints. It should be appreciated that the site 300 may include only one region, or may include a plurality of regions, as illustrated in <figref idref="f0002">FIG. 2</figref>. Each of the regions A-C includes a plurality of possible wind turbine locations arranged on the topography and terrain of the respective region.

At step 500 in <figref idref="f0003">FIG. 3</figref>, the wind state is determined for each of the identified regions. Referring to <figref idref="f0004">FIG. 5</figref>, any factor may be considered in predicting the anticipated wind state at the regions. For example, step 502 illustrates consideration of wind speed and direction at a particular region. Step 504 represents consideration of wind shear at the respective regions. Step 506 indicates consideration of air temperature and pressure at the particular regions. Step 508 represents consideration of extreme wind probabilities determined for the regions. It should be appreciated that the wind state at any given region, or the site overall, can be determined by any conventional method known and used by those skilled in the art, including the use of commercially available software programs, historical meteorological data, and any other type of tool or information available for developing an accurate wind resource assessment of the site 300 and distinct regions A-C in particular. It should also be appreciated that the steps and factor illustrated in <figref idref="f0004">FIG. 5</figref> are non-exhaustive, and that any number of additional factors or considerations may be taken into account in determining the wind state at the respective regions.

Referring again to <figref idref="f0003">FIG. 3</figref>, once the wind state at the particular region has been determined, the wind state is modeled with wake effects at the various turbine locations within each region. A wake modeling algorithm or program may be utilized to predict the cumulative wake effect experienced by the individual turbines within a given region. The wake effects are the result of cumulative placement of other wind turbines within the region at the various identified locations, and will affect the actual wind conditions experienced by a wind turbine 100 at any one of the respective locations. Initial modeling of the wake effects may be premised on a uniform rotor height for all of the turbines within the region. Wake modeling theories are known and used in the art, and include, for example, the Jensen Model and the Ainslie Model. WindFarmer™ incorporates an Eddy Viscosity wake model (based on the Ainslie Model), while WindPro™ utilizes the Park wake model (based on the Jensen Model). The wake modeling functions of these programs, or similar programs, may be used in practice of the present invention.

Once the wake effects have been modeled, an actual wind is calculated or determined for each of the turbine locations within a region at step 600 in <figref idref="f0003">FIG. 3</figref> and <figref idref="f0005">FIG. 6</figref>. The wake effects are applied to the determined wind state to predict the actual wind conditions at the respective turbine locations.

At step 650 in <figref idref="f0003">FIG. 3</figref>, once the actual wind at the respective turbine locations is calculated, individual wind turbine configurations and locations within the region are determined at step 650. At each identified wind turbine location within the region, a wind turbine configuration is selected to enhance output of a wind turbine at the location. This process includes selection of a turbine hub height that minimizes wake loss of the individual wind turbine at a particular location as a function of the actual wind conditions predicted for the turbine location. Because adverse wake effects are factored into the determination of actual wind conditions at the respective turbine locations, a turbine rotor hub height can be selected to minimize wake losses.

It should be appreciated that as turbine hub heights are selected for the various turbine locations within a region, the actual wind conditions at the remaining locations may vary as a result of changing wake effects. For example, the wake effects may have been initially modeled based on a uniform rotor hub height. As the hub heights change, so may the wake effects. Accordingly, it may be desired to model the wake effects for the remaining turbine locations after changing one or more turbine rotor hub heights. This process is illustrated by the arrow 655 in <figref idref="f0003">Fig. 3</figref>.

Referring to <figref idref="f0005">FIG. 6</figref>, it should be appreciated that any number of turbine configuration factors may be additionally considered. For example, step 652 represents required selection of a turbine rotor hub height to minimize adverse wake effects, as discussed above. Step 654 represents consideration of a minimum turbine spacing requirement within a particular region. Step 656 represents consideration of the power output required of the particular region, which will affect the size or number of turbines within the region. Step 658 represents consideration of the maximum number of turbines that can be located within any given region, which may be a factor of the minimum turbine spacing requirement of step 654 and power output per region of step 656. Step 660 represents consideration of noise exclusion areas that are near the region that may prohibit or limit placement of turbines of a particular size or power output. Step 662 represents consideration of cost and any other financial restraint that may affect the type, number, and configuration of turbines within the region. Step 664 represents consideration of the design load margins of any given wind turbine, and the combined affect of the load margins on satisfying the power output of the region. It should be appreciated from <figref idref="f0005">FIG. 6</figref> that any number or combination of factors may be considered in addition to selection of a turbine hub height that minimizes wake loss of an individual wind turbine in the final configuration of the respective turbines.

Referring again to <figref idref="f0003">FIG. 3</figref>, once all of the individual turbine configurations have been determined, an initial wind turbine layout plan is generated for the site 300 at step 700. This initial wind turbine layout plan thus treats each of the regions within the site as a cluster of individual turbines, with the configuration of each of the turbines determined to maximize the power output of the individual turbines as a function of actual wind conditions, including a particular rotor hub height that minimizes adverse wake effects.

At step 800 in <figref idref="f0003">FIG. 3</figref> and <figref idref="f0006">FIG. 7</figref>, the initial wind turbine layout plan generated in accordance with aspects of the present invention may serve as a final site plan, or may serve as the basis for further processes. For example, the initial plan generated herein may serve as the base plan for further utilization by one of the commercially available programs, such as the WindPro™, WindFarmer™, or WindFarm™ programs discussed above. Further enhancement may include consideration in step 802 of overall plant energy production needs, and an overall plant economic model in step 804. Customer design criteria may be considered in step 806, as well as any other design criteria in step 808. It should be appreciated that further enhancement of the initial wind turbine layout plan is not limited by any number or combination of criteria.

The present invention also encompasses a wind power plant wherein placement of the wind turbines and configuration of the wind turbines within the plant are accomplished with the methodology described herein. Thus, in this regard, the invention encompasses a wind power plant of the type illustrated in <figref idref="f0002">FIG. 2</figref> wherein at least one region within the site 300 is configured in accordance with the present methodology.

While the present subject matter has been described in detail with respect to specific exemplary embodiments and methods thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.