Tuesday, March 8, 2005
By Brent Summerville, NC Small
After leading a Small Wind
Energy workshop at the 2nd annual Southeast Student
Renewable Energy Conference in Knoxville this weekend, coworker, Mike Dooraghi, and I were approached by a gentleman from the audience.
He mentioned he had noticed there were basically two types of people in this field – wind people and solar people. The wind people, in his opinion, seemed more dynamic, like the wind.
That may be a little oversimplified but, indeed, this winter has been dynamic at the NC Small Wind
Initiative (SWI) Research & Demonstration Site on Beech Mountain. The winter months brought strong, cold winds, snow, sleet, and rime ice. The turbines were sometimes covered in ice, stalled until the next chance to thaw. At other times, the strong mountain winds pushed the turbines to the top of their power curves and beyond, fully exercising their various over speed protection methods.
All six wind turbines were brought online in December and through the TVA
Green Power Switch program, clean, green wind energy flowed onto the
Mountain Electric distribution grid - but not before a major upgrade to the site.
We often think of the grid as a steady constant, but it can also prove to be dynamic. The voltage from the utility was typically holding at 126V until our gridtie inverters attempted to sell the power back, at which time it rose to above
132V, causing the inverters to disconnect. This forced the wind turbine controllers to divert their power to diversion loads (heating elements).
In addition to the voltage fluctuation problem, the main electrical service supplied to the building was 480 feet of 60 amp service which was insufficient for the amount of power the site has the potential sell back. Working closely with
Richard Grubb of Mountain Electric, we installed a new 7200V primary line to our building, had a new transformer installed, and upgrade to 200 Amp service with
30 feet of 4/0 wire.
After some hard work in the trenches with a lot of good help, the new line was installed. The local inspector approved the work and we made the final connection. The new service was energized and after the pre-programmed 5 minute wait, all six turbines began selling power to the grid, including the Jacobs machine, which slowly ramped up to its maximum 20 kW! We monitored the grid voltage and it was holding steady at 126V with no problems.
The SWI team is currently setting up data logging equipment for the research portion of the project; configuring the power transducers, thermometer, barometer, anemometers, pyranometer, wind vanes, and digital decibel meter.
The instruments will stream data to a Campbell Scientific data logger for performing various studies including power curve verification, annual energy calculations, and acoustic measurements. We are also adding new pictures, video clips, and data to the website (wind.appstate.edu).
Working with small wind power has been challenging and very rewarding. When we are not installing or configuring equipment, we give tours to site visitors and lead workshops for the public. North Carolina has a myriad of renewable energy options and we are excited to be involved with small wind energy, which provides homes, businesses, and farms an option for producing their own clean energy.
Please the North Carolina Small Wind Initiative if you have any questions or would like to learn more about the program. (828) 262-7333. www.wind.appstate.edu
Source: NC Small Wind Initiative, Appalachian State University