Transcript Modification of Commercial Fault Calculation Programs for Wind

Activities of IEEE Power System
Relaying Committee WG-24:
Modification of Commercial Fault
Calculation Programs for Wind
Turbine Generators
WG Chair: Sukumar Brahma, New Mexico State
University
WG Vice Chair: Evangelos Farantatos, EPRI
1
PSRC WG C24 Scope
1) To survey WTG manufacturers to determine what
parameters they could provide that could be used by
steady state short circuit program developers in various
time frames.
2) Use the result of this survey to prepare a report that can
be used by steady state program developers to refine their
models.
2
Formation of WG C24
• This WG was formed as a result of the work
done in WG C17: Fault Current Contributions
from Wind Plants.
• WG was formed in September 2014. We have
had three meetings so far.
• Before talking about the activities of this WG,
a summary of the C 17 report is in order.
• Report can be found at http://www.pespsrc.org/Reports/Fault%20Current%20Contrib
utions%20from%20Wind%20Plants.pdf
3
Type 1 WTG
I2
I1
R1
V1
R2
jX1
IM
jXM
V0
jX2
R2 (1-s)/s
X '  X1 
 X m  X 2 
Vs
Xd’
Xm  X2
Figure ? Type 1 WTG with 1 cage Short Circuit Repres
Voltage source Vs in series with the direct-axis tra
reactance Xd’
• It was found that a conventional Thevenin
model with X’ as defined above is acceptable.
• Available commercial software often require
an equivalent sub transient reactance Xd’’, to
model as a synchronous generator.
4
Type 2 WTG
Vs
I2
I1
R1
V1
Xd’
Z’
R2
jX1
IM
jXM
V0
jX2
R2 (1-s)/s
Figure ? Type 1 WTG with 1 cage Short Circuit Represe
jX R  jX 
jX  R  jX 
Voltage source Vs in series with the direct-axis tran
m
2
2
reactance Xd’
1
m
2
2
Z '  R  jX  R1  jX 
• For higher operating slips, inclusion of rotor
resistance was found to provide more
accurate results.
• However, the maximum SC current would still
be close to that of Type 1 (small operating
slips means small external resistance).
5
Type III Responses – GE and EPRI
6
Vs
crowbar activated.
(a)
Xd”
Type 3 WTG
Figure ???a Type 3 WTG Short Circuit Representation
Is = 1.1 pu à 2.5 pu
crowbar not activated.
(b)
Figure ???b Type 3 WTG Short Circuit Representation
When the crowbar is active Voltage source Vs in
When the crowbar is not active then the current is
• series
Very
severe
faults
where
the
crowbar
is applied and
with the direct axis sub-transient reactance Xd”
limited and the short circuit representation is a
constant
current source
not removed, providing the fault current
performance
of a simple induction machine: Fig. (a).
• Faults of insufficient severity to cause crowbar
operation, for which injected currents are controlled
and performance is very similar to Type IV : Fig. (b).
• Faults of intermediate severity where the
nonlinearities of crowbar operation are critical, result
in complex behaviors.
7
Type 3 Model Suggestion From C17 Report
Maximum and minimum symmetrical short-circuit
current magnitudes a) one cycle, 2) three cycles after
fault application, as a function of residual MV bus voltage,
for an example Type III wind turbine generator. Considers
a range of pre-fault voltage Pre-fault power factor, and
8
pre-fault generated power.
Type IV Responses – C 17 Report
9
Type 4 WTG
Is = 1.1 pu
Figure ????
Type 4 WTGto
Short
Circuit
• Current is usually
limited
the
order of 1.1-1.5 per unit
Representation
of rated current and only provides balanced positive
current source limited
to 1.1 pu
postive
sequenceConstant
symmetrical
current
regardless
of the type of
sequence current
fault.
• Manufacturer may provide the impact of terminal
voltage on fault current contribution in a similar manner
as described for Type III machines – for multiple time
frames if applicable.
• Power factor is also required, because based on the
mode of control and terminal voltage, current
contribution can vary from purely active to purely
reactive.
10
WG C24 Activity
• We have had following presentations:
1. “Phasor Domain Modeling of Converter Interfaced
Renewables for Protection Studies”, by Dr.
Evangelos Farantatos, EPRI.
2. “Short-Circuit Behavior of Type III and Type IV
Wind Turbine Generators”, by Mr. Reigh Walling,
Walling Energy Systems Consulting.
3. “Simulating Wind and Solar Plants in a Short
Circuit Program”, by Dr. Sherman Chan, ASPEN.
4. “Modeling Wind Generation for Fault Analysis in
CAPE”, by Dr. Sandro Aquiles-Perez, Electrocon.
11
WG C24 Approach
• Decide as a group what is needed to accurately
model the voltage-controlled current source in
phasor domain at various time-frames?
• Send these requirements to generator
manufacturers and see if they are fine with
providing this information.
• Write a report on how to create phasor domain
models with this information.
12