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Reductions in the Cost Wind Generated Electricity: The Role of Power Conversion Systems
Reductions in the Cost Wind
Generated Electricity: The Role
of Power Conversion Systems
APEC 2006
William L. Erdman
BEW Engineering
San Ramo, Ca. Californias Wind Rush of 1980s
1970s OPEC
Embargo
1978 Passage of
PURPA
State Mandated SO-4
Power Purchase
Agreements
Combined Federal and
State Tax Incentives
First Laboratory for the Investigation of Large Scale
Transmission Connected Wind
17,000 Turbines Installed with a capacity of 1600 MW Current Capacity in the US
(AWEA - January 2006)
Numbers Shown in MW World Wide Installed Capacity as of
December, 2005 (MW)
18,428, 32%
10,027, 18%
9,149, 15%
4,430, 7%
3,122, 5%
1,717, 3%
1,353, 2%
1,260, 2%
1,231, 2%
1,219, 2%
7,368, 12%
Germany
Spain
US
India
Denmark
Italy
UK
China
Japan
NL
Rest of the world
60,000 MW Installed, 75,000 MW Projected by Dec. 2006
Source: Global Wind Energy Council Newly Installed Capacity
Jan Dec , 2005 (MW)
2,431, 21%
1,808, 15%
1,764, 15%
1,430, 12%
500, 4%
498, 4%
452, 4%
446, 4%
367, 3%
328, 3%
1,745, 15%
US
Germany
Spain
India
Portugal
China
Italy
UK
France
Australia
Rest of the world
Source: Global Wind Energy Council
3,000 MW Projected for US in 2006
950,000 MW Total US Generation) Turbine Ratings Over a Thirty Year Period
10
100
1000
10000
1980
1985
1990
1995
2000
2005
2010
Year
Tu
r
b
i
n
e
Ra
t
i
ng
,
k
W
Kenetech 56-50
Kenetech 56-100
Vestas V27
Enercon E-40
Micon 900
GE 1.5
Vestas V80
GE 3.6
Enercon E-112
Alstom Multi-brid
NEG-Micon 600
7.5 MW Offshore Turbines by 2010! Wind Generated Cost of Energy
COE Reduction Over 20 Year Period
38
32
26
20
17
14
12.5 9 8 5 4
0
5
10
15
20
25
30
35
40
1980
1985
1990
1995
2000
2005
Year
CO
E
-
C
/
k
W
h
Reduction in COE are result of Policy and Technology! Consortium Study of 1986
EPRI/US Windpower/PG&E
Study Objective How to make Wind Energy
Competitive with Fossil Fuels
One Important Conclusion Variable Speed
Operation
Increased Aero Efficiency Increased Energy
Capture
Structural Load Mitigation Reduced Capital Cost Constant Speed Vs. Variable Speed Turbines
Increased Energy Capture
TSR = K * RPM/ Wind Speed
Optimal TSR Requires Varying RPM Directly Proportional
to Wind Speed
8 15% Increase in Energy Capture!!!!! Time (Minutes)
PU Po
w
e
r
1.4 PU
1.05 1.1 PU
S
T
Constant Speed
(Induction Generator)
= Large
S
T
Variable Speed
(Arbitrary)
= 0
Constant Speed Vs. Variable
Speed Loads Reduction
Where
T: Generator Torque
S: Generator Speed Conventional Constant Speed
Turbine Architecture
Examples:
US Windpower 56-100
Many 1980s vintage Danish wind turbines
Padmount Transformer
480, 575 V Wye/
12,13.4 , 35. 4 kV Delta
Gearbox
Turbine
Pitch
System
Turbine
Rotor
Wind
T
AERO
T
GEN
Induction Generator
4 Pole, 1800 RPM, 60Hz
6 Pole, 1200 RPM, 60Hz.
Low Speed,
High Torque Shaft
High Speed,
Low Torque Shaft
Pitch
Angle
Power Factor
Correction Capacitance
Generator
Contactor
Pendant
Cables Full Conversion Early Architecture
Examples:
Kenetech KVS-33
Siemens (Bonus) 2.3 MW VS Doubly Fed Partial Conversion
System
Examples:
GE 1.5 MW
Gamesa G90
ENRON 750
Rotor
Inverter
Inverter
Control
AC Line
Filter
DC Link
AC Current
Fdbk
Voltage signals
for Synchronizing
Line
Inverter
Inverter
Control
Rotor
Position
Doubly Fed 6-Pole
Generator
Padmount Transformer
480 V, 575 V Wye,
12, 13.4, 34.5 kV Delta Full Conversion, Passive Generator
Rectifier
Examples:
Clipper C93
Enercon
Bergey Excel Power Quality on a 2.5 MW Split
Drive Train Full Converter System
Measurements Made on
NREL Dynomometer
Current THD 2.7%
650 kW
Unity
Power
Factor Future Work Medium Voltage
Converter Development
Reluctance to Move Towards Medium
Voltage Converters
Operational and Procurement History
Study Reveals Obvious Capital
Advantages
Retraining of Windsmiths and
Operational Procedures
Need for 10kV Power Semiconductors
Multi-Level Neutral Point Clamp Inverter
Current Source Technologies Wind Proportional
to the Length of
Vector
Blade Pitch Servos
60 kW of Position Servos on a 2.5 MW
Machine
Collective Pitch
Independent Blade Pitch Control (IBPC)
Cyclic Control Policy Based on Blade Azimuth
Blade Based Sensor IBPC to Minimize
Fatigue Loads on Blades
Use of IBPC, Torque and Yaw in Full State
Feedback Control Objective Function
Minimizes Linear Combination of Loads Independent Blade Pitch Control
Benefits
Blade Tip Deflections in 24 m/s Turbulence
-5
-4
-3
-2
-1
0
1
2
200
210
220
230
240
250
260
270
280
290
300
Time, seconds
B
l
ad
e T
i
p
D
e
f
l
e
c
t
i
o
n
s
,
m
Collective PID Pitch Control
IBPC Control Using Blade State Feedback Questions?