Master of Sciences (Engineering), Case Western Reserve University, 2017, EECS - System and Control Engineering

Individual pitch control is a new technique in the field of wind turbine control, used to reduce the asymmetric mechanical loads on the blades of multi-megawatt turbines. Therefore, the mechanical fatigue is reduced and the lifetime of the turbine is extended. In this work, an individual pitch controller is developed for the National Renewable Energy Laboratory's (NREL) 5 MW reference wind turbine. The individual pitch controller works along with a collective pitch controller, designed using the Quantitative Feedback Theory Control Toolbox in Matlab. The individual and collective pitch controllers are simulated using NREL's computer-aided engineering tool for horizontal axis wind turbines, FAST. Simulations show that the addition of the individual pitch controller reduces the loads on the tilt and yaw turbine components (the nacelle and tower) at the 1p and 3p frequencies by half, and the loads on the blades at the 2p harmonic frequency, by almost half.

Committee: Mario Garcia-Sanz Ph.D. (Advisor); Kenneth Loparo Ph.D. (Committee Member); Sree Sreenath Ph.D. (Committee Member); Roberto Fernández Galán Ph.D. (Committee Member) Subjects: Energy; Engineering

Master of Science (MS), Ohio University, 1998, Electrical Engineering & Computer Science (Engineering and Technology)

On the design of nonlinear gain scheduled control systems

Committee: Douglas Lawrence (Advisor) Subjects:

Master of Science, University of Akron, 2012, Electrical Engineering

This thesis presents a study to understand how the features of the communication protocol used to transmit feedback information on a discrete-time position control system feedback channel affect the overall quality of control. The features of several industrial standards for the transmission of feedback position information by absolute position encoders in a position control system have been identified. The communication channel used to feed back digital position information and the identified parameters are modeled and simulated to determine how the communications affects the performance of the control system, especially while communicating via long cables in the presence of noise. So, a framework has been developed in order to simulate combined operation of the communication channel and the control system. In this work, a series of simulations are performed for an example scenario of a blade pitch position control in a wind turbine. The quality of control is studied for this application when various error checking strategies are used, in systems with different cable lengths and different levels of noise. The results show that for systems communicating via longer cables, error checking is essential to achieve a high quality of control. For control systems that require fast sampling, a trade-off must be made between the bit rate, which determines the sample rate, and the degree of error checking. Recommendations for choosing which features to use are made based on the expected level of noise and cable length.

Committee: Joan E. Carletta Dr. (Advisor); Kye-Shin Lee Dr. (Advisor); Robert J. Veillette Dr. (Committee Member) Subjects: Electrical Engineering