Wind Turbine and Plant Modeling:
Status and Needs
Robert Zavadil
Vice President & Principal Consultant
EnerNex Corporation
448 N. Cedar Bluff Road
Suite 349
Knoxville, TN 37923
Tel: (865) 671-6650
bobz@enernex.com
www.enernex.com
Why Models?
Computer models used in all phase of power system
engineering:
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¾
¾
¾
¾
Planning
Design
Maintenance and Operatios
Assessment and Forensic or Root Cause Analysis
Improvement and Enhancement
Engineering recommendations are based on specific results for
the system under consideration, not general rules
Primary Technical Tools
Power Flow
¾ Determines voltages, element loading for specified generation and deman
¾ Most basic power system engineering tool
¾ A variety of tools are used, but PSS/E and PSLF most common
Dynamic Simulation
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¾
¾
¾
Used to show how large power system moves from state to state
Requires detailed models of dynamic elements
Suitable for simulations of very large power systems
PSS/E, PSLF are the standards fro U.S. transmission entities
Electromagnetic Transients
¾
¾
¾
¾
Detailed studies of electrical, mechanical, and control interactions
Very detailed models of all power system elements
Detailed nature of modeling prevents application to large power systems
Examples: EMTP, ATP, PSCAD
Important Studies for Wind Generation
Power Flow
Transfer Capability
Transient Stability
Dynamic Stability
AGC/LFC/ED – Operations simulations
Chronological Production Costing
Specialized Studies (examples)
¾ Switching operations (cap bank switching, false breaker tripping)
¾ Sub-synchronous resonance
¾ Short-Circuit
ERCOT Model Development Project - History
Discussions of need for better wind plant models in
system studies at least as far back as August, 2001
¾ Ongoing issues with forced curtailment
¾ Recognition that curtailments have linkage to models
Project scope developed in early 2002
RFP issued April, 2002
Project awarded June, 2002
Project kick off August 1, 2002
Project completion September, 2003
Project Objectives
Develop models for four categories of commercial
wind turbines appropriate for:
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¾
¾
Steady state analysis (power flow)
Transient stability
Small signal stability
Stabilities studies including long and short-term dynamics
Validate models with available event data from field
measurements
Document and deliver as “User Models” for PSS/E
General Approach
1.
Develop detailed models for individual wind turbines in
PSCAD/EMTDC
2.
Execute cases with detailed models and analyze results
3.
Use simulation results to reduce the order of the turbine models for
the types of events to be studied
4.
Construct reduced-order models in PSS/E
5.
Compare PSS/E and PSCAD/EMTDC results; refine models if
necessary
6.
Validate PSS/E models against field measurements
GE Wind 1.5 MW – PSCAD/EMTDC Model
Id
BRK2 0.005
A
Vrbc
B
G5
2
G3
L5
2
G5
0.005
Ed
0.005
C
A
S4
B
S6
2
G4
L5
G2
2
G6
L3
L1
L3
L1
0.01
BRK3
Vrab
G3
2
G1
25000.0
G1
BRK3
DCBK
BRK2
DCBK
Timed
Breaker
Logic
Closed@t0
L2
2
G2
L2
L6
L6
L4
SBRK
Icr
Icrd
RPM
wm
Iar Ibr
G1
S5
S6
In2
Td
TE
G5
I2act
wm
G6
In1
Multimass
( IndM/c)
TL
Te Wpu
I2cmd
S3
Modulator
w/
I1actInterpolation S4
wm
G2
S2
G3
Gen-Side Ibrd
Converter
Icr Control
I1cmd
G4
Iard
Torque Td
Computer
Tact
Td
*
-1.0
0.001
Ilb
0.001
Ilc
a b c
IM
Te
Timed
Breaker
Logic
Closed@t0
Icr
Ics
W
Ibr
Iar
Iar
Vrab Vrbc
Iar
S1
Ila
L4
C
Ias
0.001
A
SBRK
A
Ias
B
Ibs
C
Ics
B
C
TL
N
GE Wind 1.5 MW
S tato r T erm inal V o ltage (L-G )
+3
V ta
Ia s
kV & kA
+2
+1
Stator Current
+0
-1
-2
-3 0
1
2
3
4
5
per-unit
G enerato r S peed
+ 1 .3
+ 1 .27 5
+ 1 .25
+ 1 .22 5
+ 1 .2
+ 1 .17 5
+ 1 .15
+ 1 .12 5
+ 1 .1
+ 1 .07 5
+ 1 .05
+ 1 .02 5
+1 0
wg p u
Generator Speed
1
2
3
4
5
E lectro m agnetic T o rque
per-unit
+0
E M T o rq ue
-0 .5
Generator Torque
-1
-1 .5 0
1
2
3
4
5
R eal and R eactive P o wer O utput
MW & MVAR
+2
+ 1 .6
P s tat
Q s ta t
+ 1 .2
+ 0 .8
+ 0 .4
Generator Real & Reactive Power
+0
-0 .4
-0 .8
-1 .2
-1 .6
-2 0
1
2
3
4
5
3
4
5
R o to r C urrent C o m m ands
kA (Rotor Circuit)
+1
+ 0 .8
IR D D
IR Q D
+ 0 .6
+ 0 .4
+ 0 .2
+0
-0 .2
-0 .4
-0 .6
-0 .8
-1 0
1
2
Tim e (s e c )
GE Wind 1.5 MW (cont.)
Mechanical Torque
+1
Tmech
per unit
+0.8
+0.6
Mechanical Torque
+0.4
+0.2
+0 0
1
2
3
4
5
3
4
5
3
4
5
3
4
5
Blade Pitch
+49
beta
betastar
PitchComp
degrees
+39
Blade Pitch
+29
+19
+9
-1 0
1
2
Lambda (Tip-Speed Ratio)
+12
lambda
+9.6
+7.2
+4.8
+2.4
+0 0
1
2
Speed Error and Cp
+0.4
Cp
werr
+0.3
+0.2
+0.1
+0
-0.1 0
1
2
Time (sec)
PSCAD Results for Comparison w/ PSS/E
Terminal Voltage
+1.5
Real Power Generation
Vrms
+5
+1.4
+4.75
+1.3
+4.5
+1.2
+4.25
+1.1
+4
MVAR
per unit
+1
+3.75
+0.9
+3.5
+0.8
+3.25
+0.7
+3
+0.6
+2.75
+0.5 0
1
2
3
4
Pstat
+2.5 0
5
1
Reactive Power Generation
+4
Qstat
+1.25
+3.5
+1.24
+3
+1.23
+2.5
+1.22
+2
+1.21
per-unit
MVAR
+1.5
+1.19
+0.5
+1.18
+0
+1.17
-0.5
+1.16
1
2
Time (sec)
3
4
5
3
4
5
3
4
5
wgpu
+1.2
+1
-1 0
2
Rotor Speed
+1.15 0
1
2
Time (sec)
Prototype PSS/E Model Results
Validation of ERCOT Dynamic Models
Actual measurements are ultimate measure of model validity
Quantities of interest
¾ Terminal characteristics – voltage current, P, Q
¾ Mechanical – speed, pitch
¾ Wind speed
Challenges
¾ Both individual turbine and plant level measurements desirable for
computer model validation
¾ Not feasible to collect both here due to budget and logistical constraints
¾ Individual turbine measurement data hard to come by, even from vendors
Electrical data from interconnect bus best compromise in terms of
value and cost
Example Disturbance Data
king42 King Mountain - 5/10/2003 10:03:06.524
Min(Va)
Max(Va)
Avg(Va)
Min(Vb)
Max(Vb)
Avg(Vb)
Min(Vc)
Max(Vc)
Avg(Vc)
Min(Ia)
Max(Ia)
Avg(Ia)
Min(Ib)
Max(Ib)
Avg(Ib)
Min(Ic)
Max(Ic)
Avg(Ic)
Voltage (%)
100
95
90
85
Current (A)
800
700
600
0
EPRI/Electrotek
1
2
3
4
5
6
Time (s)
7
8
9
10
11
PQView®
Project Status
8 months of monitoring completed
Detailed PSCAD and reduced-order PSS/E single turbine
models completed for all 4 turbine types
Analytical validation of PSS/E turbine models against detailed
models completed for all 4 turbine types
ERCOT wind plant models completed with finalization of
TWPP remaining
Plant model validation against measurements completed
Presentation
Ongoing Needs
Model application expertise
Continuing model validation
Keeping up with new wind energy technology
developments
Addressing related issues
¾ Short-circuit behavior
¾ Advanced wind turbine technologies
¾ Advanced wind plant designs
Looking ahead…
Enlisting others in the process
¾ Other transmission providers, operators
¾ Turbine vendors / customers
¾ Industry working groups (e.g. IEEE PES)
Addressing other power system engineering needs related to
wind energy
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Short-circuit models
Operations models
Wind plant design
Turbine and wind plant requirements/standards
UWIG Role?