An introduction to the physics of wind turbines

Overview

Compared to other methods of power generation, wind turbines can seem relatively simple. While this is true for small generators, the size and complexity of commercial wind turbines make them subject to powerful physical forces—like gravity, yaw, and vibration—that must be factored into their design. This Plan looks at the complex physics and electronics behind commercial wind turbines, including an in-depth examination of the models and software engineers use to analyze their performance.

One of the most important properties of a turbine blade is its natural frequency, which can be calculated in multiple ways. The simplest method is the Euler beam equation, which uses a cantilevered beam to approximate the natural frequency of blades with uniform dimensions. Since most turbine blades are irregularly shaped, however, more complex models (such as the Myklestaad method) are then used to accurately determine the natural frequency. After this frequency has been determined, a spring-hinge model of the blade is constructed and analyzed to determine the effects that various environmental forces will have on the blade’s motion.

One of the primary ways that students learn about wind energy is through the Wind Energy Toolkit, a piece of software designed for use with the textbook Wind Energy Explained. During an internship at the Wind Energy Center at UMass Amherst, this Plan’s author was responsible for porting the software from Visual Basic to Python so that it could be available on more platforms.

Excerpts

“The environment for a working wind turbine has multiple layers of complexity. Even in relatively steady conditions, the effects of gravity, yawing, crosswinds, and the centripetal motions make it difficult to predict what will happen. Once you include forcing functions from the wind, even the simplest turbine blade is subject to chaotic motion.”

“Unlike the old visual basic interface, the Python version’s graphical environment attempts to bridge the gap between the different libraries. Instead of relying so much on screen input or reading from files one at a time, this graphical environment has a notion of working data sets that can be accessed from the top left window.”

Reflections