1. Tennesse Technological University
MODELING/SIMULATION OF COMBINED PEM FUEL CELL AND MICROTURBINE DISTRIBUTED GENERATION PLANT
Rekha .T. Jagaduri
Department of Electrical and Computer Engineering
Tennessee Technological University
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OUTLINE
Overview of Distributed Generation Plant.
Micro turbine as a DG.
PEM Fuel Cell as a DG.
Modeling of micro turbine.
Modeling of fuel cell.
Control Systems of micro turbine and fuel cell.
Grid connected micro turbine and fuel cell.
Simulation results.
Conclusion.
Future work.
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3. OVERVIEW OF A DISTRIBUTED GENERATION
Distributed Generation (DG) is the use of small-scale power generation technologies located close to the load being served.
It includes, for example, photovoltaic systems, fuel cells, natural gas engines, industrial turbines, micro turbines, energy-storage devices, wind turbines, and concentrating solar power collectors.
These technologies can meet a variety of consumer energy needs including continuous power, backup power, remote power, and peak shaving.
They can be installed directly on the consumer’s premise or located nearby in district energy systems, power parks, and mini-grids.
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4. ECONOMIC ADVANTAGES OF DG
Economic advantages include one or more of the following:
Load management
Reliability
Power quality
Fuel flexibility
Cogeneration
Deferred or reduced T&D investment or charge
Increased distribution grid reliability/stability
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MICRO TURBINE AS A DG
Micro turbine made its commercial debut in 1998.
Micro turbines belongs to an emerging class of small-scale distributed power generation
Basic components: compressor, combustor, turbine, and generator.
Typically in the kW size.
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MICRO TURBINE
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7. MODELING OF MICRO TURBINE
Mechanical Equations:
Electrical Equations:
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8. TWO AXIS MODEL OF A MICRO TURBINE
Phasor diagram of Micro turbine
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9. MICRO TURBINE CONTROLS
Overall block diagram of Micro turbine control
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10. FREQUENCY CONTROL OF MICRO TURBINE
Frequency control block
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11. VOLTAGE CONTROL OF MICRO TURBINE
Voltage control block
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FUEL CELL AS A DG
First fuel cell was developed in 1839 by Sir William Grove.
Practical use started in 1960’s when NASA installed this technology to generate electricity on Gemini and Apollo spacecraft.
Types of fuel cells: phosphoric acid, proton exchange membrane, molten carbonate, solid oxide, alkaline, and direct methanol.
Typically kW in size,
A number of companies are close to commercializing proton exchange membrane fuel cells, with marketplace introductions expected soon.
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13. BASIC PRINCIPLE OF A FUEL CELL
A fuel cell consists of two electrodes separated by an electrolyte.
Hydrogen fuel is fed into the anode of the fuel cell. Oxygen (or air) enters the fuel cell through the cathode.
With the aid of a catalyst, the hydrogen atom splits into a proton (H+) and an electron. The proton passes through the electrolyte to the cathode and the electrons travel in an external circuit.
As the electrons flow through an external circuit connected as a load they create a DC current. At the cathode, protons combine with hydrogen and oxygen, producing water and heat.
Fuel cells have very low levels of NOx and CO emissions because the power conversion is an electrochemical process.
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PEM FUEL CELL
Anode side reaction: H2 2H+ + 2e-
Cathode side reaction: 0.5O2+2H++2e-H20 +Heat
Overall reaction: H O2  H20 +Heat
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15. OVERALL CHEMICAL REACTION OF PEMFC
Component balance Equation
Energy balance Equation
Nernst Equation
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16. POWER CONDITIONING UNIT
AC Voltage of the fuel cell: Vac = m . VFC
where m is the modulation index,  is the firing angle
Block diagram of fuel cell with PCU
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FUEL CELL CONTROLS
Power Control scheme
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18. FUEL CELL CONTROLS Voltage Control Scheme
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19. INTERFACING DG WITH POWER GRID
The machine side characteristics of micro turbine are transformed to the system side frame of reference using the transformation matrix
The current injected into the system
I = Y. V
Which could be further written as
Ire+ jIim = (G + jB). Vre + jVim
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NUMERICAL ANALYSIS
Test System
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CASE STUDY
Case 1: Assuming 10% increase in input power of the micro turbine
Case 2: Assuming 20% increase in input power of the fuel cell
Case 3: Assuming a 10% increase in micro turbine power (with and without governor)
Case 4: Assuming a 1% increase in micro turbine voltage reference ( with and without voltage regulator)
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22. SIMULATION RESULTS – CASE 1
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23. SIMULATION RESULTS – CASE 2
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24. SIMULATION RESULTS – CASE 3
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25. SIMULATION RESULTS – CASE 4
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CONCLUSION
A combined micro turbine and PEM fuel cell plant connected to a power system was modeled and simulated.
Both the fuel cell and micro-turbine were assumed to be equipped with power and voltage control loops.
The micro-turbine was modeled using the d-q frame of reference and it was interfaced with the power system using transformation between this frame of reference and the system frame of reference.
A test system with typical numerical values was used to determine the accuracy of the model.
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FUTURE WORK
The same procedure may be extended to the case of several DG’s connected to a power system.
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THANK YOU
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