1-4 training electrical engineers for renewable … electrical engineers for renewable energy...
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CoPEC
Training Electrical Engineers for Renewable Energy Challenges
Dragan MaksimovicECE DepartmentUniversity of Colorado at [email protected]
2IEEE PELS 2008 Symposium
CoPEC Background• Growing interest in Energy Engineering
Environmental and climate change concernsEnergy independence goalsA new frontier in Engineering: challenging problems, opportunities for innovation, entrepreneurship, and rewarding careers
3IEEE PELS 2008 Symposium
CoPEC Background• Growing interest in Energy Engineering
Environmental and climate change concernsEnergy independence goalsA new frontier in Engineering: challenging problems, opportunities for innovation, entrepreneurship, and rewarding careers
9,212 solar panels, 1,600 kW solar power system at the Google campus, Mountain View, CA
http://www.google.com/corporate/solarpanels/home
4IEEE PELS 2008 Symposium
CoPEC A New Frontier in Engineering• New Priorities: “for some job seekers, oil companies are out. Alternative-energy start-
ups are the place to be …” The Wall Street Journal, Oct. 29, 2007, p. R8 • “Greentech could be the largest economic opportunity of the 21st century,” KPCB
Venture Capital, http://www.kpcb.com/initiatives/greentech/index.html
5IEEE PELS 2008 Symposium
CoPEC Training of Electrical Energy Engineers
• Electrical Engineering started as electric power engineering; up to 1970’s EE curricula were dominated by traditional electric power topics
• Over the last 30-40 years, the traditional electric power theme has diminished in EE/ECE programs
Mature technologyFewer research funding opportunitiesFewer attractive engineering career optionsRapid emergence of many other EE and ECE areas
• Electrical Engineering is now at the core of many existing and emerging green energy technologies
How should we (re)organize EE programs to address the growing interests, as well as current and anticipated needs?
6IEEE PELS 2008 Symposium
CoPEC What is Electrical Energy Engineering?
• In the late 19th century Electrical Engineering started the revolution in generation, transmission and distribution of Electric Power
• In the 20th century, Electrical Engineering revolutionized Communication and Computing
Polyphase ac power distribution, and motors/generators based on rotating magnetic field
William Shockley, John Bardeen, Walter Brattain Transistor, Bell Labs, Dec 1947
2007 quad-core processor, more than 500 million transistors
Nikola Tesla
• 21st century Electrical Energy Engineering is all of the above, and more
7IEEE PELS 2008 Symposium
CoPECElectrical Energy Engineering program
at CU Boulderhttp://ece.colorado.edu/~ecen2060/energyprogram.html
ECEN2060Renewable Sources
and Efficient Electrical Energy
Systems
ECEN3170Energy
Conversion
ECEN4797/5797Intro to Power
Electronics
ECEN4517/5517Power Electronics and
PV Systems Lab
ECEN4167Energy Conversion 2
ECEN5807Model. and Control of
Power Electronics
ECEN5817Resonant and Soft
Switch Tech. in Power Electronics
ECEN5017Conventional
and Renewable Energy Issues
Sophomore Junior Senior Graduate
+EE/ECE fundamentals:Circuits and microelectronics, semiconductor devices, IC design, EM fields, programming, digital logic, embedded computing, communications/DSP, control systems
Faculty:Frank Barnes, Robert Erickson, Ewald Fuchs, Dragan Maksimovic, Regan Zane
8IEEE PELS 2008 Symposium
CoPECElectrical Energy Engineering program
at CU Boulder
• New introductory sophomore-level course, first offered in Spring 2008• Spring 2008 enrollment: 31 students, 2 non-credit continuing education• Minimal prerequisites, strong technical contents• Instructors:
Dragan Maksimovic, Robert Erickson, and Regan Zane
http://ece.colorado.edu/~ecen2060/energyprogram.html
ECEN2060Renewable Sources
and Efficient Electrical Energy
Systems
ECEN3170Energy
Conversion
ECEN4797/5797Intro to Power
Electronics
ECEN4517/5517Power Electronics and
PV Systems Lab
ECEN4167Energy Conversion 2
ECEN5807Model. and Control of
Power Electronics
ECEN5817Resonant and Soft
Switch Tech. in Power Electronics
ECEN5017Conventional
and Renewable Energy Issues
Sophomore Junior Senior Graduate
9IEEE PELS 2008 Symposium
CoPEC ECEN 2060 Objectives and OutlineIntroduction to Electrical Energy Engineering
Improve generation Reduce consumption
Transmission, Distribution, Conversion
and Storage
Energy EfficiencyRenewable Energy Sources
• Photovoltaic power systems
• Wind power systems
• Energy efficient lighting
• Drives in hybrid and electric vehicles
• Understanding of electrical engineering fundamentals in renewable sources and energy efficient systems
• Practical knowledge of engineering design issues in system examples• Background and motivation for follow-up studies
10IEEE PELS 2008 Symposium
CoPEC
• Introduction to electric power system
• Photovoltaic (PV) power systems
• Energy efficient lighting
• Wind power systems
• Hybrid and electric vehicles
ECEN 2060 Syllabushttp://ece.colorado.edu/~ecen2060
+
VDC
–
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ib(t)
ic(t)
Q1
Q4Q2
Q3
Q6
øa
øb
øc
3øacQ5
Permanent-magnet
synchronousmachine
IDC
vab(t)+
–vA0(t)
vB0(t) vC0(t)
0
A
C
n T
+–
B
11IEEE PELS 2008 Symposium
CoPEC ECEN 2060 Syllabus, Spring 2008• Electric Power System (4 lectures)
Electric utility industry, generation and consumption statistics, cost of electricity Overview of electricity generation: power plants and polyphase generators Transmission and distribution of electricity, the US electric power grids
• Photovoltaic Power Systems (16 lectures)The solar resource PV cell physics and efficiency limits, PV technologies, and PV cell electrical modelGrid-connected PV systems Power electronicsStand-alone PV systems and lead-acid batteries
• Energy Efficient Lighting (5 lectures)Lighting technologies, luminous efficiency and cost of lightingElectronic ballasts for discharge lampsSolid-state lighting and LED drives
• Wind Power Systems (10 lectures)The wind resource and efficiency limits, overview of wind turbinesWind turbine electrical systems: constant-speed and variable-speed architecturesAC machines3-phase power electronicsGuest lecture on wind turbine electrical systems and controls by Lee Jay Fingersh (NREL)
• Hybrid and Electric Vehicles (6 lectures)HEV power train architectures: series, parallel and series/parallelBatteries for HEV, PHEV and EVVariable-speed AC drivesOperation and sizing of system components
12IEEE PELS 2008 Symposium
CoPEC ECEN2060 topic example: PV systems
ACutilitygrid
iac
+
−
vac
+
−
VPV
IPV
PVarray
Single-phaseDC-ACinverter
+
−
VDCC
Inverter controller
DTs Ts
LiL
MPPT controller
Cpv
idc
vgate
it
vt
+
−
+ −vL
Grid-tie PV power system example
• What is it and how does it work?• Basic physics• Operation and engineering of system components• System engineering and economics
13IEEE PELS 2008 Symposium
CoPEC (1) Fundamentals of PV technology
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 500 1000 1500 2000 2500
Wavelength [nm]
Pow
er d
ensi
ty p
(lam
bda)
[W/m
^2/n
m]
AM1.5Ideal photovoltaic output
∫ ∫∞
===0 300
2max
W/m490)()(λ
λλλλnm
pvpvPV dpdpI
Photoelectric output power (ideal):
%49max ==S
PV
II
η
PV cell
+
_
Rs
RpVD
IDISCVPV
IPV
• Basic semiconductor and PV cell physics; limits of efficiency
• Overview of PV technologies, crystalline Si, thin film, etc
• PV cell circuit model and characteristics
Full sun: 1,000 W/m2
14IEEE PELS 2008 Symposium
CoPEC (2) PV modules and arrays
ACutilitygrid
iac
+
−
vac
+
−
VPV
IPV
PVarray
Single-phaseDC-ACinverter
+
−
VDCC
Inverter controller
DTs Ts
LiL
MPPT controller
Cpv
idc
vgate
it
vt
+
−
+ −vL
0 50 100 150 200 2500
1
2
3
4
5
6
7
8
9
10
Vpv [V]
Ipv
[A]
1
2
3
0 50 100 150 200 2500
200
400
600
800
1000
1200
1400
1600
Vpv [V]
Ppv
[W]
• Module and array characteristics
• Maximum power point (MPP)
• Effects of shading
Ipv [A]
Vpv [V]
Ppv [W]
1,000 W/m2
(uniform)
900 W/m2
(partial shading)
200 W/m2
(uniform)
Characteristics of an array of twenty 75 Wp modules (36-cell each) in series
Vpv [V]
15IEEE PELS 2008 Symposium
CoPEC
0 50 100 150 200 2500
1
2
3
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10
Vpv [V]
Ipv
[A]
1
2
3
(3) PV power electronics
ACutilitygrid
iac
+
−
vac
+
−
VPV
IPV
PVarray
Single-phaseDC-ACinverter
+
−
VDCC
Inverter controller
DTs Ts
LiL
MPPT controller
Cpv
idc
vgate
it
vt
+
−
+ −vL
• Basic operation of DC-DC converters and DC-AC inverters
• Overview of power semiconductor switches
• Basic averaged models and efficiency analysis
+
−
VPV
+
−
VDC
1−D : 1IPV IoutRL
Isw
Ipv [A]
Vpv [V]
Boost DC-DC converter averaged model
Boost DC-DC waveforms
Boost DC-DC efficiency analysis in
the PV system
Grid-tie PV system using Boost DC-DC MPP tracker
%96=boostη
%92=boostη
%92=boostη
16IEEE PELS 2008 Symposium
CoPEC (4) PV system controls
• Perturb and observe maximum power point tracking algorithm
• DC-AC inverter controls• DC bus voltage control• AC grid current shaping;
unity power factor
Initialize Iref, ΔIref, Pold
Measure Ppv
Ppv > Pold ?
Iref = Iref +ΔIref
ΔIref = −ΔIref
Pold = Ppv
Continue in the same direction
Change direction
YES NO
0 1 2 3 4 5 60
50
100
150
200
250
300
350
400
450
500
Ipv = Iref
MPP
Ppv
17IEEE PELS 2008 Symposium
CoPEC (5) PV system design and economics
ACutilitygrid
iac
+
−
vac
+
−
VPV
IPV
PVarray
Single-phaseDC-ACinverter
+
−
VDCC
Inverter controller
DTs Ts
LiL
MPPT controller
Cpv
idc
vgate
it
vt
+
−
+ −vL
• Solar resource• System sizing and
basic economics• Example: a grid-tie
system in Boulder• Average of 5.5
hours or full sun • 1 Wp (Watts peak)
installed produces about 1.5 kWh per year
• Cost: about $8/Wp (excluding incentives)
kWhm2 day
US “hours of full sun” map
Insolation data: http://rredc.nrel.gov/solar/codes_algs/PVWATTS/
18IEEE PELS 2008 Symposium
CoPEC ECEN2060 observations
• Energy systems rich in EE contents (e.g. PV, Wind, Hybrid and Electric Vehicles) are great motivators for students in an introductory class
• This is not just a survey class: it is possible to introduce electrical energy engineering topics in significant technical depths even in an introductory class
Basic physics, materials and componentsPower electronics and electric machinesSystem controls, system design and economics
• Curriculum revisions are under way to open space for attractive introductory courses such as ECEN2060 at the sophomore level
19IEEE PELS 2008 Symposium
CoPECElectrical Energy Engineering program
at CU Boulder
• Major course revision in Spring 2008• Spring 2008 enrollment: 33 undergraduates, 11 graduate students• Objectives: hands-on design and project experience• Instructors:
Robert Erickson, Regan Zane and Dragan Maksimovic
http://ece.colorado.edu/~ecen2060/energyprogram.html
ECEN2060Renewable Sources
and Efficient Electrical Energy
Systems
ECEN3170Energy
Conversion
ECEN4797/5797Intro to Power
Electronics
ECEN4517/5517Power Electronics and
PV Systems Lab
ECEN4167Energy Conversion 2
ECEN5807Model. and Control of
Power Electronics
ECEN5817Resonant and Soft
Switch Tech. in Power Electronics
ECEN5017Conventional
and Renewable Energy Issues
Sophomore Junior Senior Graduate
20IEEE PELS 2008 Symposium
CoPEC
The course begins with basic experiments on:
• Photovoltaic power systems
• Power conversion electronics
The course then culminates in a design project involving photovoltaics and power electronics
A basic standalone PV power system in the ECEN 4517 laboratory
PV panels, battery, and inverter in the ECEN 4517 laboratory
PVPanel
85 W
Battery
Deep-dischargelead-acid
12 V, 56 A-hr
Inverter
120 V 60 Hz300 W
true sinewave
Charge control
DC-DC converterfor maximum powerpoint tracking and
battery charge profile
ACloads
DC loads
Digital control
ECEN4517/5517Power Electronics and PV Systems Lab
http://ece.colorado.edu/~ecen4517
21IEEE PELS 2008 Symposium
CoPEC ECEN4517/5517 Syllabus
1. Basic PV system elements (1 week)2. Basic converter control circuitry and pulse-width modulator
(1 week)PV
+
–
+
vbatt
–
Buck converter
Pulse-widthmodulator
High sidegate driver
ibatt+
vpv
–
Microcontroller
Sensors
Bootstrappower supply
Peak powertracking and
batterychargecontrol
C1
L1
C2
Batterycurrent and
voltageExperiment 3
3. Battery charge controller and PV peak power tracker using a DC-DC buck converter (3 weeks)
4. Inverter system (3 weeks)5. Project (6 weeks)
ECE Expo
12 VDC HVDC: 120 - 200 VDC
AC load120 Vrms60 Hz
Battery
DC-ACinverter
H-bridge
DC-DCconverter
Isolatedflyback
+–
d(t)
Feedbackcontroller
Vref Digitalcontroller
d(t)
+
vac(t)
–
Experiment 4
22IEEE PELS 2008 Symposium
CoPEC Portable PV carts• 85 W PV panel that can be
wheeled outside• Deep discharge lead-acid
battery and 300 W inverter to power test equipment
• Auxiliary DC power supplies for control circuitry
• One cart per bench, 10 total
PV panel85 Wpk
17.2 V at 4.95 AShell SQ-85P
Con
nect
ors
+
–
PVpanel
+
–
Battery
+
–
Isolateddc-dc
converters
+– 12V, 1A
+– 12V, 1A
+– 5V, 2A
Inverter60 Hz 300 W
120 Vrms
6 outletac power strip
AlarmBattery low voltage
VoltmeterBattery voltage
Batterycharger
Battery12 V
deep-discharge56 A-hr
Off cart:on stationary workbench
Ds
Cart schematic
PVPanel
85 W
Battery
Deep-dischargelead-acid
12 V, 56 A-hr
Inverter
120 V 60 Hz300 W
true sinewave
Charge control
DC-DC converterfor maximum powerpoint tracking and
battery charge profile
ACloads
DC loads
Digital control
23IEEE PELS 2008 Symposium
CoPEC Experiment 1, Jan. 22-24, 2008
24IEEE PELS 2008 Symposium
CoPEC ECE Expo, May 1, 2008
MPP tracker based on digitally controlled Cuk
DC-DC converter(April 26 College of Engineering Expo)
Electronic ballast for fluorescent lamps
Cascaded boost DC-DC
converter (battery to high-
voltage DC conversion)
20 projectsin power electronics
for PV or energy efficiency
25IEEE PELS 2008 Symposium
CoPECResearch Program
Colorado Power Electronics Center (CoPEC)
Energy Efficiency Power Electronics for
Renewable Energy
Energy Harvesting
Smart Power Electronics Technology
• Analog, mixed-signal and digital control techniques• Mixed-signal integrated circuits for power control• Converter modeling and design
Switched-mode power supplies
Lighting Power for RF systems
• PFC• Isolated DC-DC• POL DC-DC• Multi-phase• Low-power
Medical systems
• Ballasts• LED
drives
Ipv, Vpv
ConverterPV
ControllerIpv, Vpv
Ipv, Vpv
ConverterPV
ControllerIpv, Vpv
Ipv, Vpv
ConverterPV
ControllerIpv, Vpv
Ipv, Vpv
ConverterPV
ControllerIpv, Vpv
Ipv, Vpv
ConverterPV
ControllerIpv, Vpv
Ipv, Vpv
ConverterPV
ControllerIpv, Vpv
Inverter 60 Hz ACUtility
13 sponsoring companies, 25 graduate students, Faculty: R.Erickson, D.Maksimovic, Z.Popovic, R.Zane
26IEEE PELS 2008 Symposium
CoPEC Conclusions• Electrical Energy Engineering at CU Boulder
EE/ECE fundamentals + materials/devices + systems + economicsMore interdisciplinary than other EE areasEmphasis on technical and engineering fundamentals, even in introductory courses with minimum prerequisitesMotivated students
• Department strengths and new initiativesEnergy is a major area of emphasis in the ECE DepartmentCoPEC research program: very strong industrial supportRelated strengths in control systems, remote sensing, materials and devices, RF/microwave electronicsCU/CSU/CSM/NREL CREW: Colorado Renewable Energy Collaboratory Center for Research and Education in WindCampus-wide energy initiative