Advanced Energy Systems (AES) Inc. conducted a conceptual study of independent pitch control using inflow angle sensors. The control strategy combined input from turbine states (rotor speed, rotor azimuth, each blade pitch) with inflow angle measurements (each blade angle of attack at station 11 of 15) to derive blade pitch demand signals. The controller reduced loads sufficiently to allow a 10% rotor extension and to reduce cost of energy 6.3%. iv ACKNOWLEDGMENTS This study was performed by a team of wind energy consultants, including Tim Olsen of Advanced Energy Systems (project manager), Eric Lang of E3-Design (principal investigator), Craig Hansen of Windward Engineering, Marvin Cheney of PS Enterprises, John VandenBosche and Terrance Meyer of Chinook Wind, and Gene Quandt. Technical and management support were provided by a National Renewable Energy Laboratory (NREL) technical review team, led by Alan Wright and Dave Simms (technical monitors), with Neil Wikstrom serving as contract administrator. David Malcolm and Dayton Griffin of Global Energy Concepts also provided substantial support in establishing and understanding the WindPACT baseline turbine and its associated design and analysis tools. Funding was made possible through the NREL Low Wind Speed Turbine Project, subcontract number RAM-2-31235 (84%), and cost-sharing by the project team members (16%). v

Price: Microfiche A01Printed Copy A02Codes are used for pricing all publications. The code is determined by the number of pages in the publication. Information pertaining to the pricing codes can be found in the current issue of the following publications which are generally available in most libraries: Energy Research Abstracts (ERA); Govern ment Reports Announcements and Index ( GRA and I);

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or DOE Information Bridge http://www.doe.gov/bridge/home.html Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste FOREWORDThe National Renewable Energy Laboratory's (NREL's) National Wind Technology Center is supporting the efforts of its industry partners to develop advanced, utilityscale wind turbines. Part of the research being conducted focuses on innovative components and subsystems that eventually may be incorporated into these advanced turbines. PS Enterprises, Inc. (PSE) chose to investigate a flexible, downwind, free-yaw, five-blade rotor system employing pultruded blades.Studies conducted by PSE showed that, for a given rotor solidity, increasing the number of blades reduced the rotor weight. And from previous experience with both helicopter and wind turbine rotors, it was known that the pultrusion process resulted in blades having a very low cost-per-unit-weight. Indeed, pultruded blades were employed on wind turbines by StormMaster, Windtech, Dynergy, and Bergey Windpower. However, in some cases, problems were reported with yaw instability and occasional tower strikes. Furthermore, because pultruded blades are constrained to constant cross sections, without taper or twist, they are known to suffer a degradation in aerodynamic performance. So the challenge of the PSE project was to design and test a dynamically-and structurally-stable rotor that demonstrated the anticipated weight and cost savings while maintaining reasonable aerodynamic performance.PSE assembled a diverse group of consultants from around the United States to work on the project. The expertise of the project participants included aerodynamics, mechanical design, structural dynamics and testing. They worked closely with NREL to accomplish design reviews, modal tests, blade structural tests and field tests. This approach had the effect of adding logistics challenges to the acknowledged technical difficulties.It can be said with virtual certainty that engineering projects of this nature always encounter unexpected difficulties and frequently fall short of the original goals and objectives. In this project, a gearbox failure and subsequent runaway led to an early curtailment of the field-test program. Nevertheless, PSE and its consortium of consultants, completed an exceptional amount of work, the results of which demonstrate great promise for the proposed rotor concept. And to their credit, it was completed within the negotiated budget. PREFACEThis project, supported by NREL under Subcontract No. AAA-4-12272-04, was undertaken to assess the feasibility of using pultruded blades for wind turbine rotors. It represents a more rigorous engineering investigation of pultruded wind turbine blades compared to that performed on the initial rotors using this technology. The early operating experience of these rotors, although it showed pultrusions as a promising new blade technology, was plagued with design and quality control problems. Adequate engineering analysis and component testing had not been performed du...

. It provides additional information on the wind resource, economics, and operation of the DOE wind turbines installed recently in conjunction with the existing diesel power grid for the Naval Auxiliary Landing Field, San Clemente Island (SCI), California, project.The purpose of this report is to evaluate the wind power benefits and impacts to the SCI power system, including energy savings, emissions reduction, system stability, and decreased naval dependence on fossil fuel at the island. The primary goal of the SCI wind power system has been to operate with the existing diesel power plant and provide equivalent or better power quality and system reliability than the existing diesel system. The wind system is intended to reduce, as far as possible, the use of diesel fuel and the inherent generation of nitrogen oxide emissions and other pollutants.The first two NEG Micon model NM 225/30 225-kilowatt (kW) wind turbines were installed on February 5, 1998, and commissioned March 31, 1998. A third turbine of the same design was installed July 5, 1999, and commissioned October 22, 1999. This report describes the SCI wind resource and operational data gathered from January 1999 through June 30, 2000, as well as the ongoing cost of energy provided by the wind turbines on SCI. Earlier data from 1995 through 1998 are presented in NREL/SR-500-24663, cited above. In support of this objective, several years of data on the wind resources of SCI were collected and compared to historical data. The wind resource data were used in economic and feasibility studies for a wind-diesel hybrid installation for SCI.Because of their success with the current 675 kW wind turbine installation and subsequent receipt of the 2000 Federal Energy and Water Management Award, the Navy is considering future expansion of the SCI wind farm. iv AcknowledgmentsThe authors wish to extend special thanks to the following major contributors to the success of this project: The long-term objectives of the U.S. Navy for San Clemente Island (SCI) are to install about 8 megawatts (MW) of wind capacity and to develop a pumped-hydroelectric storage system. San Clemente Island's electrical system is powered with diesel generators, using wind energy to reduce the overall diesel-system operating costs and emissions.To accomplish this mission, the National Renewable Energy Laboratory (NREL), with the aid of the Naval Facilities Engineering Service Center (NFESC), was charged with collecting wind resource data, and then installing the wind turbine system. The first two wind turbine installations were funded through the U.S. Department of Energy (DOE)/SERDP; the third wind turbine was funded by DOE's Federal Energy Management Program (FEMP). This report summarizes the results of those tasks and the operational data acquired to date.The annual average wind speed measured from August 19, 1995, through July 30, 2000 at the SCI wind turbine site is 6.0 meters per second (m/s) (11.7 knots). The National Renewable Energy Laboratory and NFESC take these readings from a 42.7-m...