Control and Operation of Grid-Connected Wind Farms

From the point of view of grid integration and operation, this monograph advances the subject of wind energy control from the individual-unit to the wind-farm level. The basic objectives and requirements for successful integration of wind energy with existing power grids are discussed, followed by an overview of the state of the art, proposed solutions and challenges yet to be resolved.
At the individual-turbine level, a nonlinear controller based on feedback linearization, uncertainty estimation and gradient-based optimization is shown robustly to control both active and reactive power outputs of variable-speed turbines with doubly-fed induction generators. Heuristic coordination of the output of a wind farm, represented by a single equivalent turbine with energy storage to optimize and smooth the active power output is presented.
A generic approximate model of wind turbine control developed using system identification techniques is proposed to advance research and facilitate the treatment of control issues at the wind-farm level. A supervisory wind-farm controller is then introduced with a view to maximizing and regulating active power output under normal operating conditions and unusual contingencies. This helps to make the individual turbines cooperate in such as way that the overall output of the farm accurately tracks a reference and/or is statistically as smooth as possible to improve grid reliability.
The text concludes with an overall discussion of the promise of advanced wind-farm control techniques in making wind an economic energy source and beneficial influence on grid performance. The challenges that warrant further research are succinctly enumerated.
Control and Operation of Grid-Connected Wind Farms is primarily intended for researchers from a systems and control background wishing to apply their expertise to the area of wind-energy generation. At the same time, coverage of contemporary solutions to fundamental operational problems will benefit power/energy engineers endeavoring to promote wind as a reliable and clean source of electrical power.

About the Author: Dr. John N. Jiang is OGE Endowed Chair Professor in the School of Electrical and Computer Engineering in charge of electric power engineering program at the University of Oklahoma. Dr. Jiang has been involved in wind energy research since the early 1990s through a number of projects on technology research and development for utilization of wind power. Currently he is working with electric utility companies and research institutes on power system planning and operation issues taking into consideration of the uncertainties and risks from integrated variable renewable energy resources, market-based demand responses and stressed power system facilities. These researches are funded by federal agencies, local and regional power companies, including CAREER award from National Science Foundation.
Dr. ChoonYik Tang is an assistant professor in the School of Electrical and Computer Engineering at University of Oklahoma. Dr. Tang received the B.S. and M.S. degrees in mechanical engineering from Oklahoma State University, Stillwater, in 1996 and 1997, respectively, and the Ph.D. degree in electrical engineering from the University of Michigan, Ann Arbor, in 2003. Since 2006, he has been an Assistant Professor in the School of Electrical and Computer Engineering at the University of Oklahoma, Norman. His current research interests include systems and control theory, distributed algorithms for computation and optimization over networks, control and operation of wind farms, and computationally efficient digital filter design.
Dr. Rama Ramakumar is Regent Professor and PSO/Albrecht Naeter Professor and Director of the Engineering Energy Laboratory at the Oklahoma State University. Over his 41 year career in electric power engineering, Dr. Ramakumar has been primarily involved in renewable energy and energy systems research. He has authored a text book entitled "Engineering Reliability: Fundamentals and Applications" published by Prentice Hall and nearly 200 publications in various Journals, Transactions and National and International Conference Proceedings. He was named a Fellow of IEEE in 1994 for "contributions to renewable energy systems and leadership in power engineering education."