Seminar: Control for a Novel Compressed Air Energy Storage System for Wind Turbines

Abstract:

Wind is increasingly becoming an important source of energy around the world. Yet, the effective utilization of wind energy is hampered by wind’s intermittency and unpredictability, the temporal and geographic mismatch between the availability of wind and the demand for power. These characteristics make integrating wind energy into the electrical grid problematic. In addition, wind turbines typically have capacity factor of less than 40%, meaning that capitalization in electrical components are under-utilized. This is especially wasteful in the case of off-shore wind turbines as electrical connect and cabling represent a significant balance of plant cost.

These issues can be significantly alleviated if an energy storage system can be integrated with a wind turbine or a wind farm. It can store energy when there is excess power input, and supplement power when demand is larger than supply. Electrical system can also be downsized for mean rather than peak power. Compressed air energy storage (CAES) is a potentially cost-effective, scalable storage option. A novel compressed air energy storage concept has been proposed by our research group which does not require natural gas or depend on specific geographic locations (as needed in a conventional approach). The new approach relies on a near isothermal high pressure compressor/expander, and an “open accumulator” architecture that combines both the energy density advantage of hydraulics and the power density advantage of pneumatics.

This work involves heat transfer, fluid mechanics, machine design as well systems and control. In this talk, we will especially focus on how control is used to help overcome some key challenges. Three levels of control will be discussed: 1) at the compressor/expander level, optimal control of the compression/ expansion profile is used to significantly increase the efficiency and power density; 2) at the plant level, control is needed to maximize the wind energy capture, and the satisfaction of power demand while satisfying the components’ bandwidth limitation; 3) at the operational level, supervisory control is needed to determine the optimal strategy to maximize revenue for the wind turbine.

About the Speaker:

Perry Li is Professor of Mechanical Engineering at the University of Minnesota. His research interests are in design, control and sensing of mechatronics and fluid power systems. Current focus is on renewable energy capture/storage, hydraulic hybrid vehicles, hydraulic transformers, human interactive robots and underwater  vehicles. Until 2013, he was the founding deputy director for the NSF Engineering Research Center for Compact and Efficient Fluid Power (CCEFP). Prior to joining the University of Minnesota in 1997, he worked at Xerox research center. Dr. Li received his PhD in Mechanical Engineering from the University of California, Berkeley; his MS in Biomedical Engineering from Boston University; and MA in Electrical and Information Sciences from Cambridge University, England.

http://www.me.umn.edu/people/li.shtml

Hosted by Professor Junmin Wang