Sensors placed on Sandia research turbines in Bushland, Texas, are providing researchers from the Labs and Purdue University enhanced capabilities to monitor and control wind turbines.
A team from both institutions presented research on the topic in a paper at the Windpower 2009 Conference and Exhibition in Chicago in early May.
“Excessive loads on wind turbines can cause damage to components, which can then lead to costly repairs or even catastrophic failure in some circumstances,” says Josh Paquette (6333), one of the Sandia engineers who worked on the project. “We are investigating how an accelerometer system can help determine blade motions and structural health, and allow for operational modifications to avoid damage.”
The accelerometer systems consist of sensors and software that constantly monitor forces exerted on wind turbine blades. They measure two types of acceleration: those due to varying winds and those caused by gravity and rotation. It is essential to accurately measure and separate both sources of acceleration to estimate forces exerted on the blades.
Purdue is under contract with Sandia to help develop the technology. In this particular research relationship, the two institutions are collaborating on an experiment using these sensors to monitor turbines in real time. The goal is to determine how the blades were actually being loaded and then eventually feed that information into a turbine’s control system.
The sensor research, says Jose Zayas, manager of Wind Energy Technology Dept. 6333, has been conducted on subscale experimental-size blades. The results will then be extrapolated to full-size machines.
“This work is important because as more wind power is deployed, it is essential to continue to develop innovations that improve the technology and protect the capital investments,” Jose says. “Each utility-scale machine costs in the range of $2 million to $4 million and damaged components could lead to the loss of entire machines.”
Wind power is becoming a more prevalent part of the US energy portfolio, Jose notes. At the end of 2008 some 25 gigawatts of wind energy had been installed nationwide. Also, in 2008 — for the second year in a row — wind energy accounted for approximately 40 percent of all new energy installed in the US.
A wind turbine’s major components include rotor blades, a gearbox, and generator. The wind turbine blades are made primarily of fiberglass and balsa wood or foam, and occasionally are strengthened with carbon fiber.
“The aim is to operate the generator and the turbine in the most efficient way, but this is difficult because wind speeds fluctuate,” says Doug Adams, a professor of mechanical engineering and director of Purdue’s Center for Systems Integrity. “You want to be able to control the generator or the pitch of the blades to optimize energy capture by reducing forces on the components in the wind turbine during low winds. In addition to improving efficiency, this should help improve reliability.”
Jose calls the joint research between Sandia and Purdue “a perfect partnership between a national laboratory and an academic institution.
“It shows how the two can work together and collaborate to improve industry,” he says.