March 11, 2005

Group 1 (Fuel Cell)

Adam Lint

Chris Cockrell

Daniel Hubbard

Group 2 (Flywheel)

Gavin Abo

Nate Stout

Nathan Thomas

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TABLE OF CONTENTS

1 Summary...... 1

1.1 Objectives...... 1

1.2 Significance of the project...... 1

1.3 Methods...... 1

2 Project Description...... 2

2.1 Objectives...... 2

2.2 Significance of Project...... 2

2.3 General Work Plan...... 3

2.3.1 Data and Characterization...... 3

2.3.2 Output Regulation...... 3

2.3.3 Inverting the DC Signal from the Fuel Cell...... 4

2.3.4 Simulation and Interfacing...... 4

2.4 Methods and Procedures...... 4

2.4.1 Data and Characterization...... 4

2.4.2 Output Regulation...... 5

2.4.3 Inverting the DC Signal from the Fuel Cell...... 5

2.4.4 Simulation and Interfacing...... 6

2.5 Additional Considerations...... 6

2.6 Technical Advisor...... 7

3 Bibliography...... 7

4 Credentials...... 8

5 Time Schedule...... 8

6 Budget...... 9

7 Safety...... 10

APPENDIX A: Credentials...... A1

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1 Summary

1.1 Objectives

One primary objective for this project is to interface an Avista SR-12 hydrogen fuel cell with the University of Idaho ECE department’s Analog Model Power System (AMPS). Team HydroFly will create a three-phase AC voltage from the DC output of the fuel cell in order to accomplish this goal.

The second primary objective is to implement a simulated design of a flywheel energy storage system and interface that system to the AMPS. This system will detect and correct voltage sags by temporarily providing power to the AMPS when needed.

1.2 Significance of the Project

The AMPS currently provides students with the opportunity to explore and understand a typical power transmission system. The ECE department wishes to expand and improve this system to include alternative energy sources and voltage sag correction. This will further facilitate the learning experience for students and enable them to experiment with new technologies in the power industry.

1.3 Methods

In order to accomplish the first objective, a DC to DC converter must be designed to regulate the fuel cell’s DC voltage to an acceptable level. This DC voltage must then be inverted to a 208V three-phase 60Hz signal and connected to the AMPS.

For the flywheel, Team HydroFly will implement a simulated design by Satish Samineni [1]. This implementation will use the AC voltage from the induction machine attached to the flywheel. This AC voltage will be transformed to DC via a voltage source converter then fed through a DC link filter. This filtered DC voltage will then be fed through another voltage source converter (DC to AC) and connected to the AMPS.

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2. Project Description

2.1 Objectives

Team HydroFly will regulate the unsteady output of the fuel cell to 24V DC, invert it to 24V three-phase 60Hz AC then step it to 208V line to line by using a 3-phase transformer connected in parallel. The fuel cell will be interfaced to the AMPS using this 60Hz AC output and will provide power to the system for use as an alternative source of energy. Power will only be allowed to flow in one direction and will be limited to 500 Watts peak because of the limitations of the fuel cell [2].

The flywheel energy storage system simulations will be implemented on the existing flywheel system with an AC drive to rotate the flywheel. Secondly, the AC voltage generated by the flywheel motor will be fed through a DC link in order to control its varying magnitude and frequency. The flywheel system will only be engaged when a voltage sag is simulated and detected on the AMPS; otherwise, it will remain charged and ready to respond to a voltage sag. The flywheel will be able to handle up to a 40% voltage sag by boosting the voltage up to a level within a 5% tolerance of the normal operating voltage.

2.2 Significance of the Project

In the mid 1990’s, the University of Idaho acquired the Analog Model Power System (AMPS) from Idaho Power [3]. The AMPS is located in the basement of the Buchanan Engineering Laboratory on the university’s campus in Moscow, Idaho. The purpose of the AMPS is to provide insight into the workings of a power transmission and distribution system. The main source of power is from the utility (Avista). Currently, a generator is also interfaced with the AMPS to provide additional flexibility for the system.

In addition to the generator, the UI has obtained an Avista SR-12 500W fuel cell from Genesis Fueltech [2]. This fuel cell represents one of many alternative energy sources available in the 21st century; therefore, modeling this energy source on the AMPS would be a valuable learning tool for ECE students.

A flywheel will be used to correct voltage sags that can occur in AMPS. This models an alternative energy storage system useful for keeping the voltage on the system within given tolerances. This sag correction protects equipment that must operate within a very narrow voltage range.

2.3 General Work Plan

2.3.1 Data and Characterization

The first stage in completing this project will be to gather data for both the fuel cell and the flywheel. The fuel cell team will characterize the behaviors and functionality of the DC output of the fuel cell to determine its exact loading specifications and capabilities. Any difficulties in fuel cell operation will be discussed with Nathan Fletcher.

The flywheel team will review Satish’s simulations to better understand the capabilities of the flywheel system. They will also meet with Satish to discuss his design in detail and gather background information data about his project. Any difficulties in design of this system will be discussed with Satish.

2.3.2 Output Regulation

Because of drastic variations in the fuel cell output, Team HydroFly will first regulate the output of the fuel cell using a DC to DC voltage converter. This voltage converter will be a standalone component that doesn’t require any separate controls or user intervention.

Because of frequency variation and unsteady voltage levels, the flywheel output will be regulated using a DC link. This DC link must be able to control the voltage magnitude and frequency in order to synchronize to the AMPS. Two voltage converters and a DC link filter will be required for this task. To further control voltage magnitude, a series transformer will be connected on each of the three phases being connected to the AMPS.

2.3.3 Inverting the DC Signal from the Fuel Cell

The regulated output from the fuel cell will be inverted to a 24V three-phase 60Hz AC signal using a DC to AC voltage converter. The voltage will then be stepped up to 208V using parallel transformers.

2.3.4 Simulation and interfacing

When both systems have been characterized and enough data has been gathered to obtain all needed specifications, the systems will be simulated to aid in understanding, troubleshooting and further design. The fuel cell system will be simulated in a program such as Simulink, and the previous simulation of the flywheel system will be studied and modified to fit within the scope of this project.

2.4 Methods and Procedures

2.4.1 Data and Characterization

The behaviors and functionality of the DC output of the fuel cell will be characterized by loading the fuel cell with a resistor bank. If the resistor bank is unable to adequately load the fuel cell, a DC motor will be operated in parallel with the load bank to determine a max power output for the fuel cell is reached. If the fuel cell is overloaded, its internal circuitry will shut it down; therefore, “max power” output will be classified as the power that the fuel cell can provide while remaining operational for long periods of time (at least one hour).

By reviewing Satish’s simulation models, exact specifications for max power, voltage variation, current levels, and power quality will be found and recorded. A computer with MatLab and a FORTRAN compiler is required for the simulation process. Satish may also be able to assist with running the simulation models and determining the parameters of the actual system.

2.4.2 Output Regulation

The DC voltage from the fuel cell varies from 23V to 43V [2]. For this reason, it needs to be regulated to a steady 24V. This will be accomplished by using a DC to DC Buck-Boost converter. Alternatively, a Buck-Boost converter could replace the Buck converter to create a 12V output. This method, however, may lead to increased costs because of increased current flow through the converters. Either converter will need to accept a wide range of input voltages and output a steady signal with no more than  1V error. These converters should be able to handle 500 Watts peak power.

The frequency and voltage variation from the flywheel system will be controlled by using a DC link system. The two converters for this system will be purchased from a reputable electronics dealer and should be reprogrammable and have the ability to withstand about 500W peak power. After the DC link, a 3-phase series transformer or 3 single phase transformers will be used to step up the voltage to 208V AC.

2.4.3 Inverting the DC signal from the Fuel Cell

The DC to AC converter for this task will be purchased from a reputable electronics dealer and must have the capability of being reprogrammed to control frequency and voltage levels. This will aid in synchronization to the AMPS. Stepping up the voltage from 24V to 208V will require that three single phase transformers or one three phase transformer be connected in parallel with the AMPS.

2.4.4 Simulation and Interfacing

The fuel cell interface design will require that the working DC to DC converter and DC to AC inverter be mounted on a panel to be interfaced to the inverter in a neat and organized fashion. A frequency feedback line will come from the AMPS to provide the instantaneous system frequency to the converter. The converter will be programmed to read the synchronous frequency and match it before switching online.

The flywheel design will require that the simulated design be constructed in a way that enables it to detect a voltage sag, synchronize with the AMPS and begin providing power within two cycles. However, the flywheel should only provide voltage to the AMPS when there is a voltage sag and should charge to full capacity when not in use. This system should be presented in an organized fashion similar to the fuel cell design.

2.5 Additional Considerations

In the future, fuel cells could be used as environmentally safe energy sources because the inputs are hydrogen and oxygen, and the only significant outputs are water, heat, and electricity. The flywheel is also an environmentally safe energy storage system. In addition, most components of the fuel cell and the flywheel can be recycled.

2.6 Technical Advisor

The technical advisors for this project are Dr. Herb Hess and Dr. Brian Johnson from the Department of Electrical and Computer Engineering at the University of Idaho in Moscow, ID. They will be providing support, when needed, in terms of opinions and thoughts on the designs for our project. They will also provide assistance with facilities and the transportation of equipment for our project. Their extensive experience with power engineering will be a great asset for our team. Members of our group will meet with Dr. Hess and Dr. Johnson each week to discuss our progress. At least once a month, our entire team will meet with Dr. Hess and Dr. Johnson for a more detailed progress report and discussion of our future plans for the project. They both will be receiving copies via email of important correspondence and paperwork with respect to our project.

3. Bibliography

[1] S. Samineni, B. Johnson, H. Hess, and J. Law, “Modeling and Analysis of a Flywheel Energy Storage System with a Power Converter Interface,” presented at the International Conference on Power Systems Transients (IPST), New Orleans, USA, 2003.

[2] N. Fletcher. (2002, Mar). Avista SR-12 PEM Hydrogen Fuel Cell. University of Idaho. Moscow, ID. [Online]. Available:

[3] AMPS User Guide. University of Idaho. Moscow, ID. [Online]. Available:

[4] Starting Procedure of TNA (Transient Network Analyzer). ECE 525. University of Idaho. Moscow, ID. [Online]. Available:

4. Credentials

See Appendix A.

5. Time Schedule

6. Budget

Flywheel Budget
Item / Price
Induction Motor Controller / $350
DC link / $4,000
3-phase transformer (500VA) / $125
Design Poster/Report Binding* / $15
Project Display Costs* / $35
Software Licenses* / $250
Miscellaneous / $300
Total / $5,075
Fuel Cell Budget
Item / Price
DC/DC Converter / $800
DC/3-Phase AC Converter / $2,000
Transformer / $125
Hydrogen / $45
Design Poster/Report Binding* / $15
Project Display Costs* / $35
Protection Circuitry / $100
Filtering / $50
Software Licenses* / $250
Miscellaneous / $300
Total / $3,720

*Costs shared between both groups

7. Safety

The AMPS system operates on a high voltage AC signal, and can drive high currents that may cause serious injury or fatality. Therefor, the AMPS should only be operated with two or more people in the lab. In addition, protective circuitry will isolate the flywheel and fuel cell from the AMPS and should remain well maintained to avoid system damage from voltage surges and current spikes on the AMPS. High voltage capacitors may be unenclosed and could be charged. People in the lab should be careful not to touch the capacitor leads. A shorting bar should be used to ensure that the capacitors are fully discharged before system maintenance is attempted. Since the fuel cell uses compressed hydrogen gas, open flames should not be present in the laboratory, and the main hydrogen valve should be turned off before leaving the lab. Because of poor ventilation in the lab, the doors should always remain open when the fuel cell is in operation.

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