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The National Wind Technology Center features three dynamometers that can perform research validation on wind turbine systems from 1 kW to 5 MW. The dynamometers replicate realistic operational conditions to assess drivetrain designs and increase the technical readiness of innovations.
Utility-scale wind turbines operate in dynamic flows that can vary significantly over timescales from less than a second to several years. To better understand the inflow to utility-scale turbines, two inflow towers were installed and commissioned at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with a combination of sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification to two utility-scale turbines. Herein, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation as well as persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results show that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence wind turbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from lower levels.
The National Wind Technology Center (NWTC) offers wind industry engineers a unique opportunity to conduct a wide range of tests. Its custom-designed dynamometers can test wind turbine systems from 1 kilowatt (kW) to 5 megawatts (MW). The NWTC's new dynamometer facility simulates operating field conditions to assess the reliability and performance of wind turbine prototypes and commercial machines, thereby reducing deployment time, failures, and maintenance or replacement costs. Funded by the U.S. Department of Energy with American Recovery and Reinvestment Act (ARRA) funds, the 5-MW dynamometer will provide the ability to test wind turbine drivetrains and connect those drivetrains directly to the electricity grid or through a controllable grid interface (CGI). The CGI tests the low-voltage ride-through capability of a drivetrain as well as its response to faults and other abnormal grid conditions.
This work discusses the dynamics of main bearing behavior in three-point suspension drivetrains for wind turbines. Three failure mitigation approaches and preliminary results are presented.
This overview fact sheet is one in a series of information fact sheets for the National Wind Technology Center (NWTC).
This year-long wildlife and vegetation study was conducted to update the National Wind Technology Center (NWTC) vegetation and wildlife baseline conditions. These updated baseline conditions will be used to support future National Environmental Policy Act (NEPA) analyses. NWTC is a laboratory center of the National Renewable Energy Laboratory (NREL), a national laboratory of the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, and operated by the Alliance for Sustainable Energy, LLC. The current effort involved conducting four seasons of vegetation and wildlife surveys beginning in July 2010 and ending in May 2011. This report presents the results of these surveys. Concurrent avian monitoring studies by Tetra Tech, Inc. were conducted beginning January 2010 to September 2011. The results of these surveys are presented in a separate report. Prior to the current study, Plantae (2000) completed a site characterization of vegetation communities and noxious weeds, Monahan (1996) conducted a raptor study, and Schmidt et al. (2003) conducted a bird and bat use and fatality study. More recently, Walsh conducted a bat study in 2010.
The U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) conducts a variety of research projects concerning wind energy research at the National Wind Technology Center (NWTC) located approximately 8 miles south of Boulder, Colorado, in northern Jefferson County. The NWTC provides a location with consistent winds and high speed gusts suitable for testing wind turbine technologies. Currently the NWTC houses a variety of structures on the 123 hectare (310 acre) site, including 13 operating turbines and 24 meteorological (met) towers. This report details the results of a migratory raptor field survey conducted at the NWTC during the month of April, 2010 as part of the larger study of site use by birds, and the site's effects on birds and bats.
The National Renewable Energy Laboratory (NREL) will work with Columbia Power Technologies [C-Power] to support work under US DOE DE-EE-0006399, “Build and Test of a Novel, Commercial-Scale Wave Energy Direct-Drive Rotary Power Take-Off Under Realistic Open-Ocean Conditions.” Work will include a review of their design for a novel wave energy direct drive generator. After review, the system will be prototyped and tested in the NREL National Wind Technology Center (NWTC) 5MW dynamometer and data will be recorded and analyzed. Conclusions from data analysis will be used to improve the design prior to completing a version of the system for ocean deployment. Additionally, NREL will work with Columbia Power Technologies [C-Power] to quantify the system levelized cost of energy (LCOE) and analyze the system in agreement with US DOE System Performance Advancement (SPA) goals 1 and 2.
As part of the five-year monitoring update of its natural resources, the National Renewable Energy Laboratory (NREL) contracted with ERO Resources Corporation (ERO) to conduct avian, small mammal, bat, carnivore, big game, amphibian, and vegetation surveys at the National Wind Technology Center (NWTC). This update to the baseline survey conducted in 2010-2011 will be used to evaluate and support National Environmental Policy Act (NEPA) analyses and assist in the management of natural resources at NWTC. NWTC is located on the boundary of Boulder and Jefferson Counties in Colorado (project area) and is part of the National Renewable Energy Laboratory (NREL), a laboratory of the U.S. Department of Energy (DOE). NWTC is operated by the Alliance for Sustainable Energy, LLC.
Tetra Tech EC, Inc. (Tetra Tech) conducted an avian monitoring and bird and bat mortality surveys at the National Wind Technology Center (NWTC) for NREL in 2010-2011. The purpose of the study was to quantify local avian use in the NWTC and vicinity and to estimate potential impacts to avian and bat species associated with the wind turbines and associated meteorological (met) towers at NWTC. Several different types of wind turbines are present on the NWTC with different capacities for energy production (1 kilowatt-3 megawatts [MW]; varying hub heights and turbine blade lengths) and met towers (guyed and unguyed) that vary in height (9.1-135 meters [m]). In a U.S. Department of Energy (DOE) review of three large turbine installations, DOE requested monitoring of avian and bat mortality be conducted, so that mitigation measures could be developed if needed.
This paper discusses the design, manufacturing, and planned testing of a scaled demonstrator turbine as part of the Segmented Ultralight Morphing Rotor (SUMR) project funded by the Advanced Project Research Agency - Energy (ARPA-E). The scaled demonstrator (SUMR-D) is based off of a downwind, 13.2 MW SUMR design. This scaled rotor will be tested on the CART2 turbine at the National Wind Technology Center to verify the scaling methodology and planned control scheme. The design was done in an iterative fashion among six teams focused on aerodynamics, structures, and controls. This process included extensive load analysis, modification for manufacturability, adaptations required for testing on the CART2, and ground proof loading. The details of this process are presented here, concluding with planned testing and expectations of performance.
An acoustical bat use survey was conducted at the NWTC from July 6, 2010 to November 7, 2010, using a passive acoustical method with AnaBat Systems Bat Detectors (Titley Electronics). The purpose of this survey was to obtain information about use by bats within the Project area. All data were collected from one bat detector. Bat activity was determined by the number of bat passes (number of echolocation calls recorded with = 2 chirps) per detector night. Species composition, temporal distribution (by month), and peak activity levels were analyzed. A total of 12,425 bat passes was recorded during the survey period for an index of activity of 99.40 bat passes per detector night. Of the 12,425 total bat passes, 8,772 passes could be identified to species (70.18 identified bat passes per detector night). Species identified included big brown bat, eastern red bat, fringed myotis, hoary bat, silver-haired bat, and Myotis bat group (which may include western small-footed myotis, western long-eared myotis, little brown myotis, and long-legged myotis). Most bats were detected in July (3,952 total bat passes) and August (5,058 total bat passes). The Myotis bat group was most the most frequently detected (4,373 identified bat passes). There were no peaks of activity during the monitoring period, but rather constant fluctuation. No Federally- or state-listed threatened, endangered, or candidate species or species of special concern were identified during surveys.
With increasing penetrations of wind power on electric grids, the stability and reliability of interconnected power systems may be impacted. In some countries that have developed renewable energy sources and systems, grid codes have been revised to require wind power plants (WPPs) to provide ancillary services to support the power system frequency in case of severe grid events. To do this, wind turbine generators (WTGs) should be deloaded to reserve a certain amount of active power for primary frequency response; however, deloading curtails annual energy production, and the market for this type of service needs to be further developed. In this report, we focus on the temporary frequency support provided by WTGs through inertial response. WTGs have potential to provide inertial response, but appropriate control methods should be implemented. With the implemented inertial control methods, wind turbines are capable of increasing their active power output by releasing some of their stored kinetic energy when a frequency excursion occurs. Active power can be temporarily boosted above the maximum power points, after which the rotor speed decelerates, and subsequently an active power output reduction restores the kinetic energy. In this report, we develop two types of models for wind power systems: the first is common, based on the wind power aerodynamic equation, and the power coefficient can be regressed using nonlinear functions; the second is much more complicated, wherein the wind turbine system is modeled using the Fatigue, Aerodynamics, Structures, and Turbulence Modeling (FAST) tool with several degrees of freedoms. A nine-bus test power system is built in Simulink and the Real-Time Digital Simulator, respectively, which are used to evaluate the frequency support performance of the WPPs. We implement two distinct types of inertial control methods in the modeled wind turbines: frequency-based inertial control (FBIC) and stepwise inertial control (SIC). We compare the performances of the two methods in terms of their frequency nadirs, rates of change of frequency, and recovery times. We conclude the results under various wind speeds and penetration cases, which provide insight into designing the inertial response of WTGs. Further, we discuss the impact of the parameters on the performance of the inertial control methods. We evaluate both the scaling factors for the FBIC method and the slope values for the TLIC methods. The simulation work shows the characteristics of different inertial responses compared to conventional synchronous generators. Based on the simulation results, we modify, improve, and test the inertial control methods under a more realistic wind turbine model based on FAST. We then validate the inertial responses under highly turbulent wind conditions generated by TurbSim, and we examine their influences on the turbine mechanical components. The extensive simulation proves the effectiveness of the proposed inertial control methods as well as the nine-bus test power system. We then reconsider the parameters. We rebuild the same test power system using Real time Simulator Computer Aided Design (RSCAD), and we implement the inertial control methods in the real Controls Advanced Research Turbine (CART3), which is prepared for the hardware-in-the-loop field-test simulation. After the setups for the hardware and software hybrid simulation platform are complete, the inertial response is further tested on a real wind turbine for the first time, in which CART3 release the controlled inertial response against the emulated frequency excursion, provided by the real-time simulated power system test bed in RTDS.
Abstract not provided
New test facility will be used to accelerate the development and deployment of next-generation offshore and land-based wind energy technologies.
This report documents the torsional drivetrain dynamics of the NWTC's 2.5-megawatt dynamometer as identified experimentally and as calculated using lumped parameter models using known inertia and stiffness parameters. The report is presented in two parts beginning with the identification of the primary torsional modes followed by the investigation of approaches to damp the torsional vibrations. The key mechanical parameters for the lumped parameter models and justification for the element grouping used in the derivation of the torsional modes are presented. The sensitivities of the torsional modes to different test article properties are discussed. The oscillations observed from the low-speed and generator torque measurements were used to identify the extent of damping inherently achieved through active and passive compensation techniques. A simplified Simulink model of the dynamometer test article integrating the electro-mechanical power conversion and control features was established to emulate the torque behavior that was observed during testing. The torque response in the high-speed, low-speed, and generator shafts were tested and validated against experimental measurements involving step changes in load with the dynamometer operating under speed-regulation mode. The Simulink model serves as a ready reference to identify the torque sensitivities to various system parameters and to explore opportunities to improve torsional damping under different conditions.
Construction activities at most large-scale ground installations of photovoltaic (PV) arrays are preceded by land clearing and re-grading to uniform slope and smooth surface conditions to facilitate convenient construction access and facility operations. The impact to original vegetation is usually total eradication followed by installation of a gravel cover kept clear of vegetation by use of herbicides. The degree to which that total loss can be mitigated by some form of revegetation is a subject in its infancy, and most vegetation studies at PV development sites only address weed control and the impact of tall plants on the efficiency of the solar collectors from shading.This study seeks to address this void, advancing the state of knowledge of how constructed PV arrays affect ground-level environments, and to what degree plant cover, having acceptable characteristics within engineering constraints, can be re-established.
Southwest Windpower, Inc. (SWWP) has been designing and distributing small wind turbines for more than 22 years and is the recognized global leader in the design, manufacturing and distribution of small wind systems (400-3000 watts). The company has been a pioneer in the development of wind technology and has built and shipped more than 170,000 wind turbines to over 120 countries worldwide. Headquartered in Flagstaff AZ, SWWP has sales representatives in over 88 countries. Applications for SWWP systems include residential homes, commercial properties, micro grids, remote cabins, telecom transmitters, offshore platforms, water pumping and sailboats. In addition, U.S. Department of Defense uses SWWP’s products in Forward Operating Bases (FOB’s), USGS uses them for remote monitoring of glacier movements and the CIA uses them to provide power seismic monitoring. Today, SWWP plans development of new technologies to address distributed energy market needs and become even more aggressive in international markets. This strategy includes extensive Research, Development, Demonstration & Deployment (RDD&D) activities to improve existing production line into more simple, reliable, and cost-effective wind turbine systems. Important part of such activities is the field testing of the new systems, which should provide: (i) validation of the reliable operation of hardware and software; (ii) validation of numerical models of the system and its components; (iii) field comparison of various control and optimization strategies; (iv) customized reliability testing; (v) customized monitoring and analysis testing; and (vi) IEC certification testing (vii) filed demonstration of system performance and reliability. Such field testing facility should encompass multiple towers and appropriate data acquisition systems. SWWP is exploring to move part of the engineering department to Colorado, and execute its RDD&D strategies in this new location. Partnership with NREL will provide great insights into SWWP’s RDD&D processes and more efficient commercialization by utilizing NWTC as the field testing site, and working close with NREL personnel. NWTC is ideally suited to strain the design. NREL is very experienced with customized and IEC testing. During this project, Southwest Windpower aims to improve the value proposition of distributed renewable energy, and make it a competitive choice in the energy markets. As of today, more then 170,000 small wind turbines, manufactured in the U.S., are installed in more then 180 countries. With the improved value proposition, Southwest Windpower wants to create and address new market needs, substantially increase its sales domestically and internationally, which should have positive impact on the creation of American jobs, competitiveness of U.S. economy, export or U.S. products, and the use of renewable energy.