The Utility Wind Interest Group (UWIG) has undertaken a Distributed Wind Impacts project, which has produced software tools, application guides, and case studies to evaluate distributed wind projects. The project size may range from 1.5 to 15 MW, or higher in the near future. Given a number and size of available utility-scale wind turbines, and a candidate site, the evaluation process follows these high-level steps: 1. Capacity factor estimate from wind speed and other site characteristics. 2. Determine financing and power purchase agreement options. 3. Estimate the maximum feeder voltage change from full-on to full-off operation. 4. Electrical island evaluation from load and wind generation profiles; determine the need for transfer trip or other mitigation. 5. Flicker screening from the substation transformer size, type of line conductor, and distance from the substation. 6. Using a more detailed feeder electrical model: a. Estimate the loss of sensitivity in detecting ground faults with resistance. b. Check for proper coordination of the feeder overcurrent protective devices. c. Check for proper operation of utility tap changer and capacitor switching controls. 7. Design the interconnection, including transformer winding connections and wind turbine generator protection settings, to meet IEEE Std. 1547 and regulatory requirements. 8. Post-installation monitoring and evaluation, focusing on energy production and flicker. The methodology has been applied to several distributed wind projects, and these results are presented as case studies. The method is also presented at an annual workshop co-sponsored by National Renewable Energy Laboratory (NREL), American Public Power Association (APPA), National Rural Electric Cooperative Association (NRECA), and Western Area Power Administration (WAPA).
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