cpes initiative on sustainable buildings and nanogrids
TRANSCRIPT
Center for Power Electronics Systems
CPES Initiative on Sustainable Buildings and Nanogrids
Bradley Department of Electrical and Computer EngineerungCollege of Engineering
Virginia Tech, Blacksburg, Virginia, USA
presentation to2011 APEC: Special Presentation Session on
Power Electronics and Alternative Energy
Igor Cvetkovic, Dushan Boroyevich, Fred C. Lee, Paolo Mattavelli,Dong Dong, Wei Zhang, Li Jiang, Pengju Kong, Bo Zhou
DC-based Nanogrid System
AC DISTRIBUTION
HYDRO
COMBUSTION
NUCLEAR
HYDRO
COMBUSTION
NUCLEAR
HVAC TRANSMISSION
HOUSEHOLD LOADS
Power Meter
Smart
microGRIDmicroGRID
acac--nanoGRIDnanoGRID PHEV
μC
dcdc--nanoGRIDnanoGRID
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Sustainable Buildings
ObjectiveApply power electronics to future residential and
commercial buildings to enable
major improvements in energy efficiency and sustainability
while minimizing cost and maximizing reliability.
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Mini-Consortium for Renewable Energy and Nanogrids (REN)Work Scope
•PV System
•Plug-in Hybrid Electric Vehicles / Battery Storage
•Wind Power
•Energy Management for the Nanogrid
•AC Nanogrid
•DC Nanogrid
•Solid State Lighting
Smart Appliancesand LightingSolar PV Wind Turbine
Plug-in Hybrid withBidirectional Converter
Grid Connection withBidirectional Converter
Heating, Ventilation,and Air Conditioning
Entertainment andData Systems
Electric EnergyManagement Hub
Current Principal Plus Members in this area:
Research Sponsors
ICTASIndustry Consortium
College of Engineering
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Work Scope:• Devices and Magnetics• Modeling and control (analog & digital)• 3D integration• High performance VRM/POL converters• DC/DC converters and Bus converters• EMI and PFC• Power architecture and management
Mini-Consortium Power Management Consortium (PMC)
(1998 –
present)
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Mini-Consortium for High Density Integration (HDI)
Work Scope:•
High-Temperature Integration Technologies
•
Components•
Module-Level Integration•
System-Level Integration
Research Sponsors
Industry Consortium
Current Principal Plus Members in this area:
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Sustainable Building Design Initiative Renewable Energy DC Nanogrid
ObjectivesObjectives–
DC-based power architecture (bus structure)
–
Decoupled dynamics from grid–
Islanded operation–
Bidirectional power conversion–
Zero-net annual energy cost–
Dispatchable generation / consumption
ChallengesChallenges–
Power management–
Wireless communication –
Integrated protection–
Breakerless system–
Grounding, EMI, & power quality–
Safety
PLUG-INHYBRID
ENERGYSTORAGE
WINDTURBINE
SOLARARRAY
GRID
Appliances: Washer, Dryer...
Appliances: Stove/Range...
DC bus
48 V
μC
M
μC
μC
Consumer el.: TV, Computer...
μCLED light
360 – 400 V
μC
ECC
Safe, Efficient, Convenient, Aesthetic, and Enjoyable Appliances and Ambient
Droop-based Continuous Power Sharing andAutomatic Prioritized Energy Use Optimization
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High power appliances:Wide input voltage range 100 V to 240 V AC(Japan to Europe)
Rectified max = 340 V DC PFC output ≈
380 -
390 V DC
Voltage Levels in the DC-Nanogrid System
Low power consumer electronics:
Low, safe touch voltage < 50 V DC…5 V,…19 V,…
24 V,…
48 V
Chosen is 380 V as the nominal voltage of the bus
Chosen is 48 V as the nominal voltage for the low
voltage local distribution
Standard - Standard -7
Sustainable Building Design Initiative Energy Control Center
FeaturesFeatures–
Large dc-link voltage variation–
Small dc-link capacitor–
Soft-start on both sides–
High performance PLL–
Fast dc voltage & ac current control–
Full EMI compliance on both sides–
Small CM voltage on both sides
Bi-directional Grid Interface Converter
360-400 V DC Bus with droop regulation and short-circuit current limiting
240 V, 60 Hz, 1Φ
Grid with dispatchable
active & reactive power and short-circuit
current limitingVDC
LAC1 LAC2
CAC
LDC
CDC
VACCLINK
Prototype of10 kW high power
density bi-directional grid interface converter
Two-stage converter usinglow-cost 3Φ
motor-drive IPM
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Generator
Control and drive Sensor
AC Grid
AC-DC converter DC-AC converter
Power Supply
SW1SW2
Generator
Control and drive
DC Bus
AC-DC converter
Power Supply
SW3SW4
Vertical-axis Cleanfield EnergyWind Turbine
Conventional structure:Two-stage power conversionAC-DC and DC-AC
New structure:AC-DC converter for the Nanogrid System
Sustainable Building Design Initiative Wind Turbine
FeatureFeatureAbility to regulate output voltage in stand-alone (islanded) operation
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Sustainable Building Design Initiative Plug-in Hybrid Electric Vehicle
Conventional structure:Two stage bidirectional power conversionDC-DC and DC-AC
Future plans:High Power Density Bidirectional DC-DC Converter
Dispatchable Active & Reactive power
Demonstrated V2G technology in an AC Nanogrid System
AC Grid DC Nanogrid10
Sustainable Building Design Initiative Battery Management System
GEM #6
GEM #5
GEM #4
GEM #3
GEM #2
GEM #1
BM C
External CAN Bus
+Battery
Management Module
Internal CAN Bus(Voltage,Current,
Temperature)
Dissipative
..
Non-dissipative
..IBat
IBat
SAFT Lithium Ion Battery System
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Sustainable Building Design Initiative Photovoltaic Management System
2nd
stage converterNon-inverting Buck-boost
Vs
DC bus360V ~ 400V
Ipv
Ps
Is1 Is2 Is3
Droop mode
MPPT mode
Current limit mode
Is
Vbus
3
10
Ipv
Vpv
Vpv
Ipv
Voc
=43.8V
Isc
=5.14A
(35.2V,4.83A)
Io
IoVo
Vlimit
=40V
Ilimit
=10A
MPP
MPPT range
Vo
Solarmagic Power optimizer
Smart PV panelPeak power tracking at the panel levelPeak power tracking at the system level20% more efficient than the centralized MPPT system
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2-stage MC3 LED Driver Schematic of proposed multi-channel constant current source
fs
LLC resonant topology
Multiple outputs current source
DC block cap balance the
current of two strings
Scalable for multiple LED
strings
Sustainable Building Design Initiative Solid State Lighting
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Integration of Technology into the Home Environment
Kitchen
Conference roomHallway
PC lab
Ceiling-based plug-and-playDC system
Source: www.energizer.com
Source: www.powermat.com
Source: www.duracell.com
Integration of existing technology
School of architecture + design, Virginia TechDesign by:
-
Synergy of power electronics and interior design
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Static (V-I) Characteristics of the System Components (dc-bus signaling technique*)
Ope
ratin
g ra
nge
Con
vert
er ra
ting
Act
ual
MPP
T
Con
vert
er ra
ting
Act
ual
MPP
T
Ope
ratin
g ra
nge
Con
vert
er ra
ting
Con
vert
er ra
ting
IpIg IwIs Ib
PLUG-INHYBRID
DC bus 360 – 400V
[*] J. Bryan, R. Duke, and S. Round, "Decentralized generator scheduling in a nanogrid using DC bus signaling," in Power Engineering Society General Meeting, 2004. IEEE, 2004, pp. 977-982 Vol.1.
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Static Operation of the DC-Nanogrid System
Iw Is
0Iw
+Is
= IL0= IL
Iw IsIg
Iw
+Is
−Ig
= ILIw
+Is
+Ig
= IL
IgIw Is
Iw
+Is
+Ig
+Ib
= IL
IwIb Ig IsIw Is IgIbIp
Iw
+Is
+Ig
+Ib
−Ip = IL
IL
Is Iw Ib Ip
LOAD
GRID
μC
IgIg
GRID
μC
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Optimization of the DC-nanogrid Operation
V [V]
0 Ig
400390380370360
Grid interface converter
A
IgA
A
IbA
Battery converter
IgB Ib
B
B B
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Power Socket/Plug for the High Voltage Disconnect
(+)(-)(PE)
dc-plugdc-outlet
+-Isolation
and control
(+)(-)
Cs Ds
Lc2rc2Lc1rc1
CL
RL
Disconnecting point
C E
v1
vCEv2
i2i1vb LL
An equivalent circuit of the system above:-
simulation results-
ideal disconnect-
high di/dt
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Building the Non-linear Static and Linear Dynamic Model
Load regulation static curve
Non-linear static model
Linear dynamic model
“AC-sweep point”
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Two port network behavioral model
+-v1
i2
v2
v1Goi2HiYi
Zo
i1
two-port network
~
~~ ~
~
~
dc-dc converter
⎥⎦
⎤⎢⎣
⎡⋅⎥
⎦
⎤⎢⎣
⎡ −=⎥
⎦
⎤⎢⎣
⎡
2
1
1
2~~
)()()()(
~~
iv
sHsYsZsG
iv
ii
oo
xXx ~+=
⎥⎦
⎤⎢⎣
⎡+⎥
⎦
⎤⎢⎣
⎡−−
⋅⎥⎦
⎤⎢⎣
⎡ −=⎥
⎦
⎤⎢⎣
⎡
1
2
22
11
1
2
)()()()(
IV
IiVv
sHsYsZsG
iv
ii
oo
Small-signal model:
Model containing DC operating point and the small-signal dynamics
expanded with the DC operating point
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48 V 8 V
A commercial60 W bus converter
100
0
-100
0.01
0.1
1
Mag
nitu
deP
hase
[°]
Frequency [rad/s]104 105 106
Output Impedance Zo ( jω )
Input Admittance Yi ( jω )
0100
Frequency [rad/s]103 104 105 106
Pha
se [°
]
0.01
1
100
Mag
nitu
de
Current Back-gain Hi ( jω )
0.01
0.1
1
0-200
Frequency [rad/s]103 104 105 106
Pha
se [°
]M
agni
tude
Mag
nitu
de
0.01
0.1
1
Pha
se [°
]
0-200
Frequency [rad/s]103 104 105 106
Audio Susceptibility Go ( jω )Measured frequency response functions
Modular Terminal Behavioral (MTB) Low-frequency Model of DC-DC Converter
ii
ivoi
ovoZ
iYoi iH ⋅
io vG ⋅
“Black Box”Modeling Example
Curve-fitted,reduced order
transfer functions
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Obtaining un-terminated from the terminated transfer functions
+-v1
i1R i2
v2
v1Goi2HiYi
Zo
i1L
Vo
ZsIoYL
ip
Sourcetwo-port network
Load
Setup 1:
+-
~ ~
~~
~ ~
~
~
+-v1
v1Goi2HiYi
ZoVo
ZsIoYL
Setup 2:
+- ~ ~
~
i1~
v2
i2Ri2L
ip~
~
~ ~
two-port network
dc-dc converter
Source Loaddc-dc converter
1
1
1
2~~
)(,~~
)(visY
vvsG R
imom ==
Lim
Lom i
isH
ivsZ
2
1
2
2 ~~
)(,~~
)( ==
⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡
⋅
⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡
−−
−−
−=
⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡
im
om
im
om
rm
rm
gm
gm
rmgm
i
o
i
o
HZYG
TT
TT
TTHZYG
100010
010001
11
1
2~~
)(visTgm =
Lrm i
vsT2
1~~
)( =
22
System-level Model Verification (Sample System)
Ig2
Is2
Vbus1=Vg2
Solar Converter
Grid Interface Converter
Impe
danc
e In
terc
onne
ctio
n
DC/DC Bus conv. 1 LOAD 1
DC/DC Bus conv. 2 LOAD 2
ig2
is2
vbus1=vg2
Solar Converter
Grid Interface Converter
Impe
danc
e In
terc
onne
ctio
n
DC/DC Bus conv. 1 LOAD 1
DC/DC Bus conv. 2 LOAD 2
Vg2, Ig2Non-linear static model
Linear dynamic model
Vs2, Is2 Vbus2=Vs2
vbus2=vs223
System-level Model Verification (Sample System)
Ig2
Is2
Vbus1=Vg2
Solar Converter
Grid Interface Converter
Impe
danc
e In
terc
onne
ctio
n
DC/DC Bus conv. 1 LOAD 1
DC/DC Bus conv. 2 LOAD 2
ig2
is2
vbus1=vg2
Solar Converter
Grid Interface Converter
Impe
danc
e In
terc
onne
ctio
n
DC/DC Bus conv. 1 LOAD 1
DC/DC Bus conv. 2 LOAD 2
Vg2, Ig2Non-linear static model
Linear dynamic model
Vs2, Is2 Vbus2=Vs2
vbus2=vs2
Outpu
t cur
rent
[A]
Outpu
t cur
rent
[A]
Outpu
t volt
age [
V]Ou
tput v
oltag
e [V]
24
DC System Stability (example with low bus capacitance Cb )
Volta
ge [V
]C
urre
nt [A
]
100 1k 10kFrequency [Hz]
100k-200
0
100
-100
-20
20
40
0
Load
Load
Source
Source
|ZL||ZS|
ZS
ZL
GRID
LOAD 1 LOAD 2
Zc
Zwire Zwire
SOLARARRAY
CbCb
ZL
ZS
DC bus igvg isvs
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DC System Stability (value of Cb has increased)
GRID
LOAD 1 LOAD 2
Zc
Zwire Zwire
SOLARARRAY
CbCb
ZL
ZS
DC bus igvg isvs
0.085 0.09 0.095 0.1 0.105 0.11 0.115350
360
370
380
Output voltage
Time [s]
0.085 0.09 0.095 0.1 0.105 0.11 0.1150
5
10
15
Output current
Time [s]
Grid interface converterSolar converter
Grid interface converterSolar converter
vg,vs
is
ig
Mag
nitu
de [d
B]
Pha
se [d
eg]
-20
20
40
0
100 1k 10kFrequency [Hz]
100k-200
0
100
-100
|ZL|Load
Impe
danc
eIm
peda
nce
Load
Source
Source
|ZS|
ZS
ZL
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Thank You
The work and contributions are by many CPES faculty, students, and Staff.
Many global industrial and US government sponsors of CPES research are gratefully acknowledged.
Center for Power Electronics SystemsBradley Department of Electrical and Computer Engineerung
College of EngineeringVirginia Tech, Blacksburg, Virginia, USA
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