Windward Engineering L.L.C., under contract with DOE as part of the Field Verification Program for Small Wind Turbines, has installed two small furling wind turbines (Whisper H40’s). One is located at the National Wind Technology Center (NWTC) near Boulder, Colorado and the other at our own test site in Spanish Fork, Utah. NREL has been responsible for testing at NWTC while Windward Engineering has been responsible for the testing at the Spanish Fork test site. Both turbines were installed and operating in early 2000 so we now have over one year of operational experience.

This project has two primary goals: 1) Determine and demonstrate the reliability and energy production of a furling wind turbine at a site where furling will be a very frequent event and extreme gusts can be expected during the duration of the tests, and 2) Make engineering measurements and conduct limited computer modeling of the furling behavior to improve the industry understanding of the mechanics and nature of furling. It is our hope that this project will broaden the understanding of furling wind turbine operation and performance as well as highlight the value, and the shortcomings of using computer models as a design tool for the small wind turbine designer.

This paper will present test data as well as general operating experience for the Whisper H40 located in Spanish Fork, Utah. These tests are monitoring basic performance (e.g. energy delivered to the inverter and to the grid, turbine power, wind direction, and wind speed). The turbine has operated without fault for over 15 months and has produced 1450 kWh. From this total 77% or 1111 kWh have been delivered through the battery/inverter system to the local utility grid. Four full quarters of 10-minute averaged data was collected and processed into a wind distribution and power curve. The power curve shows the Whisper H40 starts producing power at 3 m/s and reaches its peak power of 525 watts at 11.5 m/s. We are also continually monitoring and reporting important design parameters such as maximum rotor speed, maximum yaw rate, and maximum furling rate. This data has been used for validation of an ADAMS model. Preliminary modeling results show good agreement against test data although the yaw prediction needs improvement. Some model comparisons will be presented in this report.