Big Wind Turbines Require Infrastructure Upgrades
National Wind Technology Center now home to three multi-megawatt wind turbines.
Understanding the system requirements and technical issues associated with operating utility-scale turbines is critical to NREL's interactions with the power industry as renewable wind power source applications grow rapidly. To that end, NREL has been completing electrical infrastructure upgrades to accommodate utility-scale wind turbines at the National Wind Technology Center (NWTC).
At one time, the NWTC was able to handle up to 7 megawatts (MW) of wind power, but the installation of NREL's first megawatt-scale turbine in the fall of 2009 necessitated infrastructure upgrades. Now the NWTC's electrical infrastructure can handle 10 MW, and three multi-megawatt turbines have been installed: the U.S. Department of Energy's (DOE)/General Electric's 1.5-MW turbine, Siemens 2.3-MW turbine, and Alstom 3-MW turbine.
NWTC Row 4 Infrastructure Upgrade Project
The megawatt-scale turbines reside in Row 4 at the NWTC, the eastern-most row on site. Interconnecting these large turbines required major electrical infrastructure upgrades, including road upgrades, installation of medium-voltage power for turbines, low-voltage power for data sheds, two new meteorology tower operations, telecommunication fiber optic cables, interconnection with grounding transformers and grounding reactors, and upgrades to utility interconnection switchgear. The last stage was interconnecting the Alstom 3-MW turbine to the main line along Row 4. Xcel installed a new circuit recloser—a self-contained device that automatically closes a breaker after it has been opened due to an electrical fault—on the distribution line serving the NWTC, providing improved circuit protection. This upgrade was needed to accommodate the addition of the new 3-MW Alstom wind turbine. Once the Alstom turbine is online, the aggregate generation capacity of the NWTC will be an impressive 9.2 MW (including 1 MW of photovoltaics). The project upgrades went so well, they won a Gold Hard Hat Award for Outstanding Industrial Project in October 2010 from McGraw-Hill Construction.
Interconnection and Power Purchase Agreement
DOE's Golden Field Office has an Interconnection Agreement for the NWTC with the local utility, Xcel Energy. This agreement, signed on December 20, 2010, is the culmination of nearly three years of negotiations with Xcel as well as an American Recovery and Reinvestment Act-funded design and construction project at the NWTC. December 20, 2010, also became the NWTC's "Initial Energy Delivery Date," the date DOE was eligible to receive credit for energy exported under a Power Purchase Agreement (PPA). The DOE wind energy "generating facility" currently has a capacity of 2.9 MW; the energy credit is $44.96/MWh. The Siemens 2.3-MW and Alstom 3-MW wind turbines are owned by these cooperative research and development agreement partners and are covered by other PPAs between those partners and Xcel.
The Bottom Line
The NWTC is home to the largest dedicated research and development fleet of utility-scale wind turbines being used for technical and operational analyses, enabling NREL to operate a realistic environment for research and analysis of renewable energy grid integration.
Learn more about NREL's wind research facilities.
Photo credit: Dennis Schroeder