The openWind user interface (left panel) shows various layers available within the workbook and workspace. The display window (right) shows one of six tabs within the layer properties of a met mast. Within the layer properties, there is info about the layer and displayed properties of items such as color, transparency, labels, and size. These can be changed, giving users a more flexible solution.
Stephanie Van Kempen, Senior Modeling Specialist, AWS Truepower
Nick Robinson, Director of openWind, AWS Truepower, www.awstruepower.com
OpenWind Enterprise is wind-project design and optimization software for professional wind developers. Comprehensive features in the software let users conduct wind-flow modeling, estimate energy yields, and calculate loss and uncertainty. Recent additions to the software, Time-Series Energy Capture, and refinements to the Optimization for Cost of Energy, further a developer’s capability to improve modeling accuracy and save time.
The openWind user experience begins with opening long-term adjusted wind data in the program. It lets users copy and paste the time-series data directly into the software, or import a CSV file from Windographer, a program which analyzes and formats wind resource data. Users can also import results from their own wind-flow models, or use the model in openWind. The geographic information systems (GIS)-based interface lets users drag and drop files and folders into the software.
Benefit from a GIS-based Interface
The software accepts a wide-variety of gridded data such as terrain, roughness length, and vegetation height. Within the GIS interface, users can convert satellite images to gridded data, edit attributes of vector layers, and convert vector layers into turbine-layout layers or environmental-sensor layers. There are also tools for clipping data, transforming raster layers, creating contours from elevation data, and buffering features. All these are useful when defining a buildable area for a project, among other tasks. Users can also edit layer attributes, and label and reorder objects.
Optimize a layout for cost of energy
The snapshot is of an optimized layout generated with the Optimization for Cost of Energy. A typical layer hierarchy appears in the workspace on the left. In the background, a sample turbine layout appears with access roads in red.
The Optimization for Cost of Energy tool optimizes for energy output while considering the incremental cost of adding an additional turbine. It takes into account road costs and constraints, collector-system cables, substation or grid-connection position, and simple financial assumptions to optimize a layout for both energy and constructability.
During optimization, the program generates an access-road layout and a collector-system layout for every set of turbine positions under construction. The Optimization for Cost of Energy leverages the full GIS capability of the software, letting it upgrade existing roads and factoring in costs of crossing water courses. If such information is available, the software can tap into the GIS data and assign a different cost for each geometry object. A simple collector-system optimizer also accesses GIS data layers to consider circuit limits as well as terrain and easements. For roads and the collector system, it is possible to define a buildable area in the same way as one would do for turbine placement.
Calculation of estimated energy yield
Several different wake models are available for use in openWind Enterprise. The most notable is the Deep-Array Wake Model (DAWM). This derivation of the Eddy Viscosity Wake Model better simulates wakes for larger arrays by taking into account changes in the boundary layer and roughness lengths. The DAWM will choose the results of either the Eddy Viscosity model or the DAWM when appropriate, so users need no aerodynamic experience with wake losses from large arrays.
Another software benefit is its ability to use turbine types with families of power curves and thrust curves at different air densities, as well as for different turbulence ranges. The program will choose the appropriate turbulence-intensity range of a power curve based on the per turbine total turbulence intensity.
The example attributes table is for a shapefile representing transmission lines. Users can set which field they would like to be used for the information and select functions as well as which field to use for object labels.
Time-series energy capture
A recent addition to the software is an ability to perform time-series energy capture. This can be used to generate energy production time-series or monthly diurnal energy matrices over any period with time intervals ranging from 1 to 60 minutes. The software takes a slightly different approach to that used in other programs. Instead of using a look-up table, it attempts to model the time-series energy capture from first principles, as if the era of wind-frequency tables never happened. This lets the software consider diurnally varying air density, temperature, and turbulence intensity. These can be switched off to perform a TAB-equivalent time-series energy capture, which uses wind-frequency tables instead of time-series data.
The addition of turbine scheduling lets users model environmental curtailments. For example, the user could specify that a turbine is switched off to avoid bats between certain times for certain days of the year, or to switch to a low noise power curve at night.
The GIS capabilities, Optimization for Cost of Energy, and Time-Series Energy Capture in openWind Enterprise can trim time off developing and proposing projects. Other features include sector-wise separation distances, shadow flicker, crane-pad checking, effective turbulence, gridded turbine layouts, spatially varying loss rasters, and wind-resource uncertainty. These features benefit users by letting them design a layout for a project and understand more of it than would otherwise be possible.
While openWind Enterprise is designed for power users that model large and complex wind projects, AWS Truepower plans to release a new version of the software aimed at developers and consultants with less demanding design requirements in November 2012. Among the differences, the new version will not have the cost-of-energy optimization tool or time-series energy capture, but it will calculate shadow flicker and sport openWind’s versatile GIS-style user interface.
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