Research Publication

During the summer of 2009, I had the opportunity to work at the National Renewable Energy Laboratory as a Department of Energy summer intern. During that time, I worked with Richard Osgood at the National Wind Technology Center conducting a full modal test of a Siemens 60 kW wind turbine. We wrote a paper together, and I presented our work at the International Modal Analysis Conference (IMAC) in Jacksonville, FL during February, 2010. For the full paper, you can download the attachment.

The test facilities at the National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory (NREL) include a three-bladed Controls Advanced Research Turbine (CART3). The CART3 is used to test new control schemes and equipment for reducing loads on wind turbine components. As wind turbines become lighter and more flexible to reduce costs, novel control mechanisms are necessary to stop high winds from damaging the turbine. However, wind turbines must also be designed to capture the maximum amount of energy from the wind, so engineers must devise new ways of achieving this while controlling wind loads that would cause the turbines to fatigue quickly. New control mechanisms and computer codes can help the wind turbine shed some loads in extreme or very turbulent winds. The special configuration of the CART3 allows researchers to analyze these diverse control schemes.

This paper reports on the initial results of a major full-scale modal testing campaign to validate and refine simulation models. One model is a tailored multi-body dynamic simulation model that will be used to develop an advanced controller designed to optimize power and minimize structural loads. Researchers would also like to tune Finite Element Models of the blades, nacelle and tower assembly to predict the higher order rotating modes of the wind turbine for a range of inflow conditions.

The paper will discuss an Experimental Modal Analysis approach where the wind turbine in parked condition is excited by shakers connected with cables. This approach will be compared to Operational Modal Analysis where the same structure is subjected to wind excitation without the shakers activated. These tests and data analyses will provide experience and increase confidence in the approach used for future tests in rotating conditions.

Heena Mutha,
Mar 28, 2010, 8:24 AM