Role of Power Electronics in
Power Systems
Ned Mohan
University of Minnesota
mohan@umn.edu
NSF-ECEDHA Energy and Power Summer Program
Atlanta, Georgia July 8-9, 2011
1
Power-Related Courses
Energy, Environment
and Society (3cr)
Power Systems (3cr)
Lab (1cr)
Power Systems (3cr)
Power Electronics
(3cr)
Lab (1cr)
Freshman
Electric Drives (3cr)
Lab (1cr)
Junior/
Senior
Senior Design
Project(3cr)
Senior
Power Electronics
(3cr)
1st Year
Graduate
Electric Drives (3cr)
Advanced Graduate
Courses
2
Role of Power Electronics in Power
Systems
•
•
•
Generation
Delivery
Efficient End-Use
3
Utilities Tomorrow versus Yesterday
Storage
EV
4
Power Electronics: An Enabling
Technology
Power Electronics
Interface
Converter
Source
Load
Controller
5
Device current [A]
Continuing Evolution of Power
Semiconductor Devices
104
Traction
103
102
101
HVDC
FACTS
Motor
Drive
Power
Supply
Automotive
Lighting
100
101
102
103
104
Device blocking voltage [V]
(a )
( b)
6
Controller ICs and Integrated Power
Modules:
7
Potentially Lower Cost
Power Semiconductor Price
Copper and Steel Prices
- Copper prices have gone up five fold
in three years
USD/A
0.7
1200 V
IGBTs
0.6
0.5
0.4
0.3
0.2
0.1
0
1990
1995
2000
2005
8
DOE Wind Research Consortium at UMN
Improving Reliability and Reducing
the Nacelle Weight by 20%
Open-end
Open-end
winding
windingac
ac
machine
machine
MC
MC
System
System
20
Utility
Utility
20
20
1800
High
Highfrequency
frequencytransformer
transformer
converter
convertersystem
system
1800
1800
High-Frequency
High-Frequency
Transformer
Transformer and
and
Converter
Converter
Stray Currents due to
Converter Switchings cause
Damage to Bearings
Heavy Cables
80-100 m
Light
Light Cable
Cable at
at 34.5
34.5kV
kV
Power Electronics
Converter with Large
Storage Capacitors
Converter
161kV
690V, 60-Hz
34.5 kV, 60-Hz Underground
Heavy Transformer
34.5
34.5 kV,
kV, 60-Hz
60-Hz Underground
Underground
690V
690V
690V
690V
60Hz
9
GE 1.5 MW Turbine
m/s
1 m / s 2.25 miles / hr
Source:
10
Power from the Wind
Source:
11
Role of Power Electronics in Wind
Power Electronics Interface
Gen
Conv1
Conv 2
Utility
12
13
Sodium Sulfur Battery Storage to Enable
Further Integration of Wind (Xcel Energy)
14
High Voltage DC Transmission – HVDC
(Current-Link)
AC1
AC2
15
HVDC (Voltage-Link)
16
Flexible AC Transmission Systems: FACTS
E1∠0
E2 ∠ − δ
jX
AC1
E1 E2
sin δ
P=
X
AC2
Control of X:
(a )
( b)
17
Voltage Control:
jX
Utility
STATCOM
(a )
(b)
(c )
Unified Control:
sub-station
E1
I
-
E3
+
E2
E2
1
2
E1
Shunt
converter
E3
(b)
Series
converter
P2 , Q2
P1 , Q1
(a)
18
Efficient End-Use
Electric Drive
Lighting 19%
Fixed form
IT
14%
Power
Processing
Unit (PPU)
Motor
Adjustable
Form
Electric Source
(utility)
speed /
position
Sensor
s
Power
Signal
Controller
HVAC 16%
Load
Motors 51%
Input command
(speed / position)
Adjustable Speed Drives
Figure 1-3 Block diagram of an electric drive system.
EV
19
Principle of Operation
conv1
conv2
utility
Load
controller
20
Step-Down (Buck) Converter
Filter
Vin
A
+
Vo
vA
−
d=
Tup
Ts
vA
vA
V A = Vo
V A = Vo = dVin
21
Realizing a Bi-Positional Switch in
A Step-Down Converter
q =1
iL
+
iL
Vin
+
Vo
−
−
)
q
(a)
+
iL
Vin
−
qA = 1
(b)
+
+
Vo
−
iL
+
Vo
−
Vin
−
qA = 0
(c)
22
Step-Up (Boost)
Converter
iL
Vo
C
q
vL
Vin
p
23
Bi-Directional Power Flow
Buck Boost
V1
iL
A
+
vA
−
+
V2
−
q
q − = (1 − q )
24
Synthesizing Sinusoidal
AC:
q =1
)
iL
q
vaN
Vd
0
vaN
vaN
0
0
vaN
ωt
Ts
25
Average Representation of the Switching Power-Pole
vaN = d aVd
ida = d a ia
ida
ida
+
a
Vd
+
ia
ia
+
Vd
vaN
vaN
−
−
−
N
1: d a
(a)
(b)
qa
26
Three-Phase Inverters
+
a
b
Vd
n
c
−
qa
N
qb
a
b
c
+
Vd
−
qc
N
1: d a
(a )
1: d b
( b)
1: d c
27
Interface for Wind
Generator
va (t ) ia (t )
−
+
AC motor
i A (t ) + e A (t )−
A
+
−
B
n
Vd
C
N
mot
motoring
Vd
v AN
v An
1
Vd
2
0
ωt
28
+
SV-PWM
ia
a
ib
b
Vd
c
ic
+v
b
vc
+
−v +
a
2
vsa (t ) = Vd ( qa e j 0 + qbe j 2π / 3 + qc e j 4π / 3 )
Basic Voltage Vectors
−
N
qa
qb
qc
Figure 7-1 Switch-mode inverter.
2
v2 (010)
2
v3 (011)
sector 2
2
vs
sector 3
2
v6 (110)
sector 1
2
v1 (001)
sector 4
sector 6
a -axis
2
2
vsa (000) = v0 = 0
2
2
vsa (001) = v1 = Vd e j 0
2
2
vsa (010) = v2 = Vd e j 2π / 3
2
2
vsa (011) = v3 = Vd e jπ / 3
2
2
vsa (100) = v4 = Vd e j 4π / 3
2
2
vsa (101) = v5 = Vd e j 5π / 3
2
2
vsa (110) = v6 = Vd e jπ
2
2
vsa (111) = v7 = 0
sector 5
2
v4 (100)
2
v5 (101)
29
30
Courses Developed
- Fundamentals-based;
integrated
- Using commonality, in-depth coverage of more topics
- Supported by state-of-the-art laboratories
P ow er E lectron ics
P ow er S ystem s
E lectric D rives
Bus-1
Features:
1
1
1
S w itching P ow er-P ole as
the B uilding-Block
Includes dc-dc C onverters
and dc-ac Inverters
Feedback control of
C onverters
Teaching M achines as a
subcom ponent of Drive System s
B us-2
Pe 2
fixe d
fo rm
Power
Processing
U nit (PPU)
M otor
Load
Pm 2
speed /
po si tion
a djus ta bl e
for m
Elec tric Source
(utility)
Sensors
m e asure d
sp ee d / p o siti on
Controller
inpu t com m and
(spe ed / po sition)
P owe r
S ign al
A pplications:
- H arnessing of W ind Energy
- E lectric and H ybrid-Electric V ehicles
S lides
S olutions
m anual
Includes Topics such as
-
-
Slides
Solutions
m anual
D S P -C ontrolled Lab
-
R enew ables/S torage
H VD C , FA C TS
V oltage S tability
T extbook
-
Textbook
H ardw are Lab
-
Pe1
E lectric
Dri ve
T extbook
-
Pm 1
B us-3
S lides
S olutions
m anual
S oftw are-based Lab :
- M A TL A B /S im ulink,
Pow erW orld, E M TD C
- C om plete Lab on C D
- 18 S hort V ideo C lips
-
31
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32
Increasing Student Enrollments
33
CUSP™
(www.doeconsortium.ece.umn.edu/cusp)
34