1 Center for Power Electronics Systems A National Science Foundation Engineering Research Center Virginia Tech, University of Wisconsin - Madison, Rensselaer Polytechnic Institute North Carolina A&T State University, University of Puerto Rico - Mayaguez December 1, 2008 Future Electronic Power Distribution Systems – A contemplative view – Dushan Boroyevich Virginia Tech, Blacksburg, Virginia, USA Keynote presentation at: The 2 nd IEEE International Power & Energy Conference Johor Bahru, MALAYSIA PECon 2008 December 1, 2008 DB-1 Power Electronics Expanding and Emerging Applications Industry Automation Powering IT Alternative and Distributed Energy Systems Vehicular Power Systems Most of the Emerging Electric Power Technologies presume Most of the Emerging Electric Power Technologies presume Active Dynamic Control of the Electric Energy Flow (i.e. Active Dynamic Control of the Electric Energy Flow (i.e. Require the Use of Power Electronics Require the Use of Power Electronics)! )! Dushan Boroyevich: Future Electronic Power Distribution Systems Keynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
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Center for Power Electronics SystemsA National Science Foundation Engineering Research Center
Virginia Tech, University of Wisconsin - Madison, Rensselaer Polytechnic InstituteNorth Carolina A&T State University, University of Puerto Rico - Mayaguez
December 1, 2008
Future Electronic Power Distribution Systems– A contemplative view –
Dushan BoroyevichVirginia Tech, Blacksburg, Virginia, USA
Keynote presentation at:
The 2nd IEEE International Power & Energy ConferenceJohor Bahru, MALAYSIA
PECon 2008
December 1, 2008 DB-1
Power ElectronicsExpanding and Emerging Applications
Industry AutomationPowering IT
Alternativeand
DistributedEnergy
SystemsVehicularPowerSystems
Most of the Emerging Electric Power Technologies presumeMost of the Emerging Electric Power Technologies presumeActive Dynamic Control of the Electric Energy Flow (i.e. Active Dynamic Control of the Electric Energy Flow (i.e. Require the Use of Power ElectronicsRequire the Use of Power Electronics)!)!
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
2
December 1, 2008 DB-2
Power Electronics Future?
• Essential for societal energy needs from:
Retinal ImplantJ. G. KassakianIPEC, Niigata,
2005
organ implants
carbon-free energyto …
Source: Shell Global Scenarios
% of PrimaryEnergy
0%
20%
40%
60%
80%
Coal
Nuclear
Oil
Gas
Hydro
Traditional (Wood, etc.)
Wind, PV,other
renewables
1850 1875 1900 1925 1950 1975 2000 2025 2050Courtesy of GE Global Technology Center Source: Shell Global Scenarios
% of PrimaryEnergy
0%
20%
40%
60%
80%
Coal
Nuclear
Oil
Gas
Hydro
Traditional (Wood, etc.)
Wind, PV,other
renewables
1850 1875 1900 1925 1950 1975 2000 2025 2050Courtesy of GE Global Technology Center
December 1, 2008 DB-3
Electronic Focusof New Electric Power Systems
Emerging and future power systems will have all sources and loads interfaced through power electronics converters:
• IT Power: Portable, Server, Telecom, Data Center• More-electric aircraft, All-electric ship, Hybrid-electric car, • Sustainable energy, Distributed generation, Future power grid
Focus on: Electronic Power Distribution Systems (EPDS) .
The major opportunities and challenges for synthesis and integration of these systems are in:
• High-density power converter integration; • System-oriented modeling and analysis;• System architecture design and optimization;• Power management, control, and protection.
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
3
December 1, 2008 DB-4
Generator
480 V, 3Φ AC
Micro-Turbine
VSCFConverter
RenewableEnergy Source DC-AC
SWGRSWGR
Generator
Advanced (?) Electrical Power Systemof a Large Datacom Center
SWGR
120 V, 1Φ AC
Lighting
MotorMotor
CentralFan
120 V1Φ AC
480 V, 3Φ AC
HVAC System Pumps and Fans
… …
480 V, 3Φ AC
Com-pressor
SW GRSW GRSW GR SW GRSW GRSW GR
SWGR
SWGRSWGR SWGRSWGR
MotorMotor MotorMotor MotorMotor
ASDASD
ASDASD ASD ASD
ElectronicBallast
ElectronicBallast
ElectronicBallast
208 V3Φ AC
SWGR
Fan
SWBD
Analog
Telecom Power System
Battery
– 48 VDC
SWGR
PFCRectifier
PFCRectifier
...
LED
AnalogICs
ASICs
MemIsolated POL
Converter
DigitalICs
DC-DCConverter
μP Non-IsolatedPOL Conv. ...
AC-DC
DC-AC
Battery
24 V, 1Φ AC
Fire Alarm System
SWGRSWGRSWGR
DC-AC
Battery
120 V, 1Φ AC
Emergency Lighting
SWGRSWGRSWGR
AC-DC
120 V1Φ AC
SWGR Computer Power System
ASICs
Mem
Fan
DigitalICs
LED
AnalogICs
DC-DCConverter
AC-DCFront-End
Server
48 VDC
Non-IsolatedPOL Conv.
μP
UPS
AC-DC DC-AC
Battery
120 V1Φ AC
...
• Inefficient• Expensive• Unreliable
Very colorful patchwork inherited from last century!
December 1, 2008 DB-5
Barriers/Challenge
• Complexity of traditional power systems:– Fully coupled dynamics of generation, distribution, and delivery.– System stability is enabled by imposing an overwhelming, slow,
electromechanical or electrochemical dynamics of the sources.
• Local focus of power electronics:– Concentrated on load dynamics– Evolving focus on source dynamics (UPS, distributed generation,
fuel cells, alternative energy sources)– Until now, only “fixing the problems” of power distribution
Challenge: Reduce system cost, increase efficiency and availability by decoupling the dynamics of energy sources, distribution system, and loads through the use of power electronics.
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
4
December 1, 2008 DB-6
Power-Converter-Based Power Systems Example: A Notebook PC
LCD Bias– 8 V
Backlight800 V
Memory1.8 V
Processor0.7-1.7 V
Logic
I /O DiskDrive
5 V Bus3.3 VBus
Peripherals
12 V
12-16 VPower
Management Battery90-260 V
50-60 Hz
19 VCharger AC
Adapter
Voltage Regulator
Voltage Regulator
CCFL Inverter
LCD Converter
LDO Regulator
Bus Converter
Bus Converter
Boost Converter
• Load converters: Meet dynamic energy requirements of the loads
REDUCECOST !
• Power Distribution Converters:– Increase peak-power efficiency ⇔ Improve power density– Increase light-load efficiency ⇔ Improve energy efficiency
• Source converters: Meet ac line standards; improve battery utilization
December 1, 2008 DB-7
More Electric Transportation
1. Variable frequency starter/generator
⇒ Eliminates Gearbox2. Variable speed drives
for ECS⇒ Eliminates Pneumatics3. High-frequency
voltage step-up/down⇒ Less Copper & Iron4. Electrical actuation⇒ Reduces Hydraulics
Similar approaches and advantages are being pursued in:1. Rail systems and vehicles (for long time)2. All-electric ships3. Hybrid electric cars, trucks, and buses
All electrical energy processed through electronic converters
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
1. Eliminates gear box and need for doubly-fed induction generator
2. Simpler transformer structure
3. Fully decouples wind and grid dynamics
Wind Energy:Evolution of Turbine Power Electronics
December 1, 2008 DB-9
Electronic Power Distribution System: Grid-interface for Offshore Wind Farms
AC Transmission for Offshore Energy HarvestingAC Transmission for Offshore Energy Harvesting
HVDC Transmission for Offshore Energy HarvestingHVDC Transmission for Offshore Energy Harvesting
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
6
December 1, 2008 DB-10
MixedAC / DC Power
Distribution
6 A
Servers1.5 kW
Charger2.8 kW
Transfer Switch
Inverter3 kW
6 A
25 A
100 A
60 A 60 A
25 A
Transfer Switch
Battery
Charger2.8 kW
6 A
LV DC Distribution48 V DC
1Φ AC Distribution120 V AC
CPES University Testbed: Hybrid Power System for Remote-site Datacom Centers
10 A
Cooling1.5 kW
Hybrid EnergyPower Sources
Telecom and ComputerLoads with HVAC
Similar tradeoffs in terms of size, efficiency, and power density for all power converters.
Single Enclosure,Self-Contained UnitPeak-powerEfficiency< 50 % !
December 1, 2008 DB-11
6 A
Servers1.5 kW
Charger2.8 kW
Transfer Switch
Inverter3 kW
6 A
25 A
100 A
60 A 60 A
25 A
Transfer Switch
Battery
Charger2.8 kW
6 A
LV DC Distribution48 V DC
1Φ AC Distribution120 V AC
10 A
Cooling1.5 kW
Electronic Power Distribution System (EPDS): An Integrated Testbed
Servers
DC-DC
HV DC Distribution300 V DC
Charger /Discharger RectifierRectifier
HVAC
System impact evaluation of integrated:• Active modules• Passive modules• Converters• Loads and converters
• Reduce number of converters by 30%
• Eliminate switchgear
• Improve availability
• Increase energy efficiency
Improved architectures:
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
7
December 1, 2008 DB-12
Characteristics of FutureElectronic Power Distribution Systems
• Power electronics converters are used for:– Source interface– Load interface (only “coffee makers” are still non-electronic loads?)– Power flow control and energy management
• Advantages:– High system controllability, flexibility, and responsiveness– Increased availability– Reduced size and weight– Increased energy efficiency
• Issues:– Subsystem interactions (power flow, power quality, EMI, thermal)– Complexity (not an issue if dynamics is understood & decoupled)– Reliability and lifetime (not protection)– Cost (not an issue if system and/or energy costs are reduced)
December 1, 2008 DB-13
Synthesis of DCElectronic Power Distribution Systems
Fan
SWBD
Analog
Telecom Power System
Battery
– 48 VDC
SWGR
PFCRectifier
PFCRectifier
...
LED
AnalogICs
ASICs
MemIsolated POL
Converter
DigitalICs
DC-DCConverter
μP Non-IsolatedPOL Conv. ...
Computer Power System
ASICs
Mem
Fan
DigitalICs
LED
AnalogICs
DC-DCConverter
AC-DCFront-End
Server
48 VDC
Non-IsolatedPOL Conv.
μP
...
System Integration is significantly hampered by:• Large number of different components • Many different manufacturers• Lack of knowledge of internal converter structures• Lack of information about internal converter parameters
Fan
LED
AnalogICs
DC-DCConverter
48 VDC
Fan
LED
AnalogICs
DC-DCConverter
48 VDC
48 VDC
Fan
SWBD
Analog– 48 V
DCPFC
Rectifier
PFCRectifier
...
LED
AnalogICs
Isolated POLDigital
ICs
DC-DCConverter
Fan
SWBD
Analog– 48 V
DC
Fan
SWBD
Analog– 48 V
DCPFC
Rectifier
PFCRectifier
...
LED
AnalogICs
Isolated POLDigital
ICs
DC-DCConverter
LED
AnalogICs
Isolated POLDigital
ICs
DC-DCConverter
Isolated POLDigital
ICs
DC-DCConverter
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
8
December 1, 2008 DB-14
ioi
oi vivη
PJ⋅
=),(
Simplified Power Model of a Regulated DC-DC Converter
iiiv
orefV
iJ oE oi ov
[A]
[V]
10
20
30
40
50
0 5 10 15 20 25
Eo
io
Iomax
voltage regulation
mode
current limit
mode
Voref
Static Output Characteristic
[V]
10
20
30
40
50
0 40 60 80 100
1 kW
450 W
Vimax
Vimin
PoJi
vi
[A]
750 W
Static Input Characteristic
oorefooo iVivP ⋅≈⋅=
December 1, 2008 DB-15
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
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
12
December 1, 2008 DB-22
Generator
480 V, 3Φ AC
Micro-Turbine
VSCFConverter
RenewableEnergy Source DC-AC
SWGRSWGR
Generator
ACElectronic Power Distribution Systems
SWGR
120 V, 1Φ AC
Lighting
MotorMotor
CentralFan
120 V1Φ AC
480 V, 3Φ AC
HVAC System Pumps and Fans
… …
480 V, 3Φ AC
Com-pressor
SW GRSW GRSW GR SW GRSW GRSW GR
SWGR
SWGRSWGR SWGRSWGR
MotorMotor MotorMotor MotorMotor
ASDASD
ASDASD ASD ASD
ElectronicBallast
ElectronicBallast
ElectronicBallast
MTB Modeling of AC EPDS:• More difficult due to time-varying nature of steady-state• Large disconnect between system and converter modeling• Use of average models in system analysis is uncommon• “Constant-power loads” are being considered only recently • Small-signal frequency-domain modeling still in development
“Electronic”only recentlyin transportation and datacom centers.
December 1, 2008 DB-23
Stable Stable
AC Subsystem Interaction Example– small-signal and average modeling and simulation –
R50 Hz230 V
AC Generator PWM Boost Rectifier
600 VDC bus
Start-up to 135 kW
liv
)(sSZ )(sLY
( ))()()(
ssese
q
d Leig=⎥⎦
⎤⎢⎣
⎡
)()()( sss LS YZL ⋅=
• To avoid instability,
• Interface voltage is:
must not encircle –1 !
eigenvalues
the return ratio
ThLSli VYZIv ⋅⋅+= 1)( -
0-3
-2
0
2-1
-4
-2
0
2
4
0 2 4 6 8 10-1Real
Imag
inar
y
ed ( jω ) eq ( jω )
Generalized Nyquist Criterion
200
400
600
Cur
rent
[A]
0 0.1 0.2 0.3 0.4Time [s]
100200300400
Vol
tage
[V] vd
vq
id
iq
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
13
December 1, 2008 DB-24
200
400
600
Cur
rent
[A]
0 0.1 0.2 0.3 0.4Time [s]
100200300400
Vol
tage
[V] vd
vq
id
iq
AC Subsystem Interaction Example– small-signal and average modeling and simulation –
)(sSZ )(sLY
R50 Hz230 V
Unstable Unstable AC Generator PWM Boost Rectifier
600 VDC bus
-4
-2
0
2
4
0 2 4 6 8 10-1Real
Imag
inar
y
ed ( jω ) eq ( jω )
liv Start-up to 180 kW
Generalized Nyquist Criterion
December 1, 2008 DB-25
DC/AC
LV ACDistribution
LV AC Bus Voltage
Advanced Shipboard Electric Power Systems
• Increase in negative impedance loads produces oscillations.
• Further increase in negative impedance loads produces instability.
Active Filter
Using active filter to introduce damping at higher frequencies decouples the load from source dynamics; thence:
reduces complexity and stabilizes network !
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008
14
December 1, 2008 DB-26
Converter Controlled AC Distribution SystemFault Handling: One-Phase-to-Ground Short
2007300 MWACSarawak (Malaysia) – W. Kalimantan (Indo.)112012700 MWDCPeninsular Malaysia – Singapore72019300 MWACSabah/Sarawak (Malaysia) – Brunei Daruss.102008600 MWDCPeninsular Malaysia – Sumatra (Indonesia)6
ASEAN Centre for Energy
December 1, 2008 DB-31
A Dream of Electronic Energy Network
that will supplant Electric Power Gridto enable Carbon-Free Electricity by 2030
• All electricity could be generated carbon-free:Hydro Wind Solar Nuclear
• Today’s electric power grid cannot handle this due to:– No ability to absorb high % of distributed generation and storage– No adequate long-distance energy transport– No adequate energy storage
• Must use electronic networks for electric energy utilization!
• Save: bio fuels for some transportation fossil hydrocarbons for chemical products
Dushan Boroyevich: Future Electronic Power Distribution SystemsKeynote at PECon 2008, Johor Bahru, Malaysia, 1 December 2008