Download A CASE FOR MEDIUM VOLTAGE DIRECT CURRENT (MVDC

A CASE FOR MEDIUM VOLTAGE DIRECT CURRENT
(MVDC) POWER FOR DISTRIBUTION APPLICATIONS
IEEE-PES Power Systems
y
Conference and Exposition
p
Paper Session: Substation Innovations from Conventional Design
March 23, 2011 – Phoenix, AZ
Authors:
D Gregory
Dr.
G
Reed,
R d Dr.
D G
George K
Kusic
i – University
U i
it off Pitt
Pittsburgh
b
h
Dr. Jan Svensson, Dr. Zhenyuan (John) Wang – ABB Inc., R&D
Background, Motivation, and Introduction
2
A New Era of DC Power Systems
• Corporate research centers, universities, and industry are
beginning
g
g to (re)consider
( )
the premise
p
of DC power
p
in future
transmission and distribution system applications.
• Historically, AC has dominated the power industry
• W
Westinghouse,
i h
Tesla,
T l Edison,
Edi
and
d others
h
intensely
i
l fought
f
h the
h initial
i ii l
‘AC/DC Wars’ at the turn of 20th Century
• AC proved superior for all the right reasons at the time
• H
However, we continue
ti
ttoday
d to
t depend
d
d on a ‘legacy’
‘l
’ century-old
t
ld and
d
aging AC approach, concept, technology-base, and infrastructure
• What has changed for DC in the 21st Century?
• The era of Power Electronics Technologies
• Continued improvements and efficiencies in semiconductors, devices,
circuits, designs, systems, and applications scaled at all levels
• Consumer devices, emerging resources, energy storage, and other
systems operating at or supplying absolute DC power
3
DC Applications in Modern Society
• Rapidly Emerging DC Applications in the 21st Century
• Consumer Electronics
• Devices and Equipment Operated at Low-Level DC (Res/Comm)
• Renewable Energy Systems
• Generation Systems Producing DC Output Power (e.g.,
(e g Solar)
• Transportation Electrification
• Electric Vehicles Powered by DC
• Information Technology and the Internet
• Enhancement of Energy Efficiency via DC (e.g., Data Centers)
• Energy Storage Technologies
• DC O
Output and
d Integration
I
i through
h
h DC Interconnections
I
i
• Transmission and Distribution Infrastructure
• High Voltage Direct Current (HVDC) Systems (i.e., Transmission)
• What is Missing?
• Medium Voltage DC (MVDC) Distribution Infrastructure
4
Medium Voltage DC Networks
• MVDC Technology Development
• Benefits for installations of large
g and small scale wind / solar
farms, and other forms of bulk and distributed generation; as
well as for DC-loads, energy storage, EV integration, etc.
• Efficiency is expected to increase due to minimized power
conversions; but overall complexity may increase
• New technical requirements, standards, protective devices,
schemes, and other concepts require development / proof
• R&D is necessary for evaluating the MVDC potential
• High Voltage Direct Current (HVDC) Systems
• Proven benefits and merit over high voltage AC transmission
for long distance power delivery applications and recent offshore and other generation interconnections
• MVDC, however, is not a simple scaling of voltage level
• Focused research, development, and demonstration is needed
5
The MVDC Distribution Network Concept
6
Medium Voltage DC Network Concept
Existing AC
Infrastructure
AC Transmission
Supply
FACTS
Compensation
Future HVDC
Intertie
Fuel Cells
Non-Synchronous
Generation(Wind)
STATCOM / SVC
DC
DC
DC
DC
HVDC System
Photovoltaic
Generation
AC
DC
DC
DC
AC
DC
HVDC / MVDC
DC
DC
DC
DC
DC
DC
DC
DC
Distribution DC
Load Circuits
DC
DC
DC
AC
DC
AC
Electric Vehicle
Future DC
Industrial Facility
Future DC
Data Centers
DC
AC
Electronic and
AC Loads
Motor
Distribution Level
Sensitive Load
Storage
Variable
Frequency Drives
Control Algorithm
7
MVDC Network Applications
• Development Program Applications
• Renewable energy resource integration and end
end-use
use aspects:
• Solar energy – distributed, remote
• Wind energy – distributed, off-shore, remote
• Fuel cell integration
• Electric vehicle integration
• Variable frequency drives supply
• Sensitive
S
iti and
d electronic
l t
i load
l d supply
l
• Data centers – supply infrastructure
• Power plants – internal plant distribution systems
• Greenfield industrial parks
• Energy storage interconnection and control
• DC/AC power factor correction for distribution load circuits
• Dynamic voltage and VAR optimization
• High Voltage AC and DC transmission integration
Preliminary Work
Modeling, Simulation, and Analysis
9
Preliminary MVDC Development
– Subsystem 1
+
-
1.4 MW
Supply
Wind Turbine
MOD 2 Type
575 V / 14 kV
#1
#2
Six Pulse
Graetz
Bridge
AC/DC
Rectifier
Three Level
20 kV / 460 V
Neutral Point
IM
Clamp
#1 #2
Multilevel
Inverter
10 kW
Bidirectional
DC/DC
Converter
AC
C
Load
n=5
GRID
69 kV / 14 kV
#1
Transmission
Five Level 20 kV / 460 V
Neutral Point
IM
Clamp
#1 #2
Multilevel
I
Inverter
t
10 kW
#2
69 kV
20 kV
10
Research Objectives
– Subsystem 1
• Analysis conducted within the PSCAD simulation environment
• Evaluating
a uat g tthe
e pe
performance
o a ce o
of ttwo
op
practical
act ca topo
topologies
og es o
of
multilevel inverters which include the neutral point clamp
converter and flying capacitor circuitry.
• PWM Techniques: Phase Disposition
Disposition, Phase Opposition
Disposition, and Alternate Phase Opposition Disposition
• Total Harmonic Distortion: THD appears to be the best metric for
g their performance.
p
evaluating
• Dynamic Performance Evaluation of Network
• Wind Speed Adjustments: Average wind speed will be modeled
initially without ramp and fluctuation effects in the wind source.
source
• DC Bus and Motor Faults: Analyze the effects of capacitor
balancing of the power electronic inverters and effects of motor
torque and speeds.
• Load Energizing: Impacts on THD distribution as certain loads
are connected in and out of the circuitry.
11
Preliminary MVDC Development
– Subsystem 2
60 0 [MVA]
60.0
230.0 [kV] / 20.0 [kV]
#1
#2
MW MVAR
60.0 [[MVA]]
575 [V] / 20.0 [kV]
#1
#2
12
MVAC System for Comparison
– Subsystem 2
60.0 [MVA]
230 0 [kV] / 20
230.0
20.0
0 [kV]
#1
#2
60.0 [MVA]
20.0 [kV] / 4.0 [kV]
60.0 [MVA]
5.0 [kV] / 20.0 [kV]
#1
#1
#2
#2
MW MVAR
60.0 [[MVA]]
20.0 [kV] / 5.0 [kV]
#1
#2
60.0 [MVA]
575 [V] / 20.0 [kV]
#1
#2
13
Factors for Comparison of MVDC/AC
– Subsystem 2
• Performance under the following conditions
• Loss of Generation
• i.e., PV Array is lost due to a fault, how does the system
react and recover from this loss?
• Dynamic Changes in Renewable Generation
• Similar to “loss of generation” but generation is not
completely lost
lost, only its voltage and thus power are altered
• Switch Misfiring
• If the power electronics do not react in an ideal manner
manner,
how is voltage and power flow affected?
Preliminary MVDC Development
– Subsystem 3
15
Research Objectives
– Subsystem 3
• DC Distribution for Future Industrial Facilities
• Manufacturing/Industry
• Direct DC Supply for VFDs, Industrial Automation and
Electronics Equipment
• Data Centers and IT
• Direct DC Supply for Computer, UPS and Battery Systems,
LED lighting
• DC Bus Architecture
• Easily incorporates on-site solar generation and hybrid
electrical storage options
Next Steps in MVDC Development
• Program Objectives, Goals, and Future Vision
• Complete the modeling,
modeling analysis,
analysis and verification of all
subsystems of the MVDC concept
• Integrate the various subsystems, resources, and loads into
one model for full-scale
full scale analysis
• Development and integration of control concepts
• Establish full verification of total system concepts, including
operation and control
• Model and test various improvements and enhancements for
parameter evaluation (e.g., advanced semiconductor
characteristics, optimized converter designs and control, etc.)
• Scaled proto-type development and testing
• Full scale deployment
p y
and demonstration
• Application for retrofit or green-field facility/site as a complete
DC-based network
Summary
18
Summary
• MVDC Technology Development Benefits
• Improved efficiency for renewable energy integration
• Support for the continued evolution of greater penetrations of
DC-based loads and resources
• Enhanced integration of energy storage systems and EVs
• Advancements in optimization, design, and applications of high
capacity power electronics converter technologies
• Advanced semi-conductor device developments
• Advanced smart grid methodology development for integrated
resource/load energy management and control
• Enhancement of existing interconnecting alternating current (AC)
infrastructure
p
of additional HVDC delivery
y infrastructure
• Enabled development
• Increased efficiency and lower operating losses in overall power
system delivery, generation, and end-use applications
Acknowledgments
The Commonwealth of Pennsylvania –
Dept. of Community and Economic Development,
Ben Franklin Technology Development Authority
University of Pittsburgh –
Electric
ect c Power
o e Research
esea c G
Group
oup Graduate
G aduate Students:
Stude ts
Brandon Grainger, Matthew Korytowski, Emmanuel Taylor
Q&A
THANK YOU