The objective of this research is to develop an innovative integrated wind and energy storage system to support wind energy to achieve higher penetration in the electric utility grid. Energy storage can play a major role in improving the short-term and long-term dynamics, power dispatchability, and reducing voltage and frequency footprint of the wind energy.

The main intellectual merit of this project is to model, simulate, and characterize an integrated system of wind turbine generator hardware and controls with a new utility scale battery. The analysis from the modeling and simulation will be applied and a scaled down model of the system will be built, tested and characterized. The system developed in this project is capable of assisting in mitigating dynamic power intermittency, long term power smoothing and power shifting, regulating voltage, controlling power ramp rate, and frequency droop control.

The main broader impact is to provide quality integrated education, research, and engineering to meet the emerging workforce and needs of nation?s energy industry. The project team will promote education as an integrated part of this project. The results of this research will be integrated in workshops, short courses, and courses to be taught to undergraduate and graduate students and working professionals. Although there is a large population of minorities, including African-Americans and Hispanics, in the greater Milwaukee area, the percent of minority students at UWM is insignificant. One goal of this project is to include underrepresented minority and female students in this research.

Project Report

Project Outcome The current and anticipated growth of wind and solar energy will soon exceed the current capabilities of the electric grid to provide the integration services required for reliable system operation, and there is a need to explore innovative solutions for continuing reliable operation with the most efficient and economic integration of additional wind energy. Energy storage systems can provide support and enable higher penetration of renewable energy. In this project, we have integrated two types of energy storage systems, lithium-ion capacitors and zinc-bromide battery, with wind energy at turbine level to address the technical drawbacks of wind energy including limited power dispatchibility, voltage stability concerns, power variations, high power ramp rates, lack of frequency support, and loss of inertia. Lithium-ion capacitors’ high power capability complements zinc-bromide battery’s energy capability to perform this task. Both systems are integrated with the turbine electrical system at DC bus level to remove the need for additional power conversion circuitries. We have modeled the integrated system from wind to grid. The model includes the nonlinear mechanical model of a wind turbine, drive train, and electrical system. The models for energy storage systems are practical models derived from testing. We have installed and tested a 50 kWh zinc-bromide battery system in the lab create an electrical model for the system. We have also built and tested a 140-cell and a 240-cell ultracapcitor modules in the lab to derive its electrical model. A wind turbine emulator with a 50 kW synchronous and a 50 kW doubly-fed generator is also built. The power conversion circuitry is implemented to interface between two storage systems and the emulator. Our analysis indicates that the proposed storage system provides significant support for wind energy to smooth the power variations, shape the power ramp rates, and provide LVRT, inertia and frequency support. The results of the project have been presented and published in 13 journal and conference papers. Below is the brief list of the project outcomes: Built two detailed wind turbine models using Matlab/Simulink and ANSYS software which include all the energy conversion components from wind to grid. Created detailed electrical models for two types of energy storage elements, zinc-bromide battery and Li-ion capacitors, from test results. Integrated models of energy storage elements with wind turbine (both full conversion and doubly-fed induction generator) to create an integrated model. Modeled a wind farm, which includes detailed models of wind turbines integrated with energy storage, connected to the grid. Characterized energy storage power and energy capacity for power smoothing, power ramp rate control, inertia support, frequency support, voltage support, low-voltage ride-through (LVRT) support, and power shifting. Installed 50kWh, 25kW zinc bromide battery with energy conversion circuitry in the lab. Built two modules of Li-ion capacitors (360V and 720V) and tested in the lab. Built wind turbine emulator setup (50kW synchronous generator and 50kW DFIG) with energy conversion system. Connected zinc-bromide battery, Li-ion capacitors, and wind turbine emulator to create the integrated system, test, and characterize energy storage size and capacity. Published 13 papers from the research results of the project. Integrated research results in several courses (EE/ME 472: Introduction to Wind Energy; EE 478-Renewable Energy Systems; EE 471: Electric Power Systems; EE/ME 430: Energy Modeling; EE 572: Power Electronics; EE 890: Controls for Renewable Energy; EE 781-Advanced Synchronous Machinery; ; EE 890: Advanced Power Electronics). Gradated three Ph.D. students during the project. The students currently work for Eaton Corporation, Rockwell Automation, and Caterpillar. Trained four undergraduate students during the execution of the project. The main broader impact was to provide quality integrated education, research, and engineering to meet the emerging workforce and needs of nation’s energy industry. To conduct research on this project, team members including professors, graduate and undergraduate students, and industry experts have collaborated. The project team promoted education as an integrated part of this project. The PI and Co-PI at UWM involved undergraduate and graduate students in the project and used the results of the research in their courses (EE/ME 472: Introduction to Wind Energy; EE 478-Renewable Energy Systems; EE 471: Electric Power Systems; EE/ME 430: Energy Modeling; EE 572: Power Electronics; EE 890: Controls for Renewable Energy; EE 781-Advanced Synchronous Machinery; ; EE 890: Advanced Power Electronics) in order to prepare the next generation of workforce in the United States.

Project Start
Project End
Budget Start
2009-09-01
Budget End
2013-02-28
Support Year
Fiscal Year
2009
Total Cost
$316,249
Indirect Cost
Name
University of Wisconsin Milwaukee
Department
Type
DUNS #
City
Milwaukee
State
WI
Country
United States
Zip Code
53201