Part 2 Separation Effects Modeling
IEEE SPDC Spring Meeting, May 16
•
•
Christine Goldsworthy
•
Gerald Lee
Bonneville Power Administration (BPA)
Arrester Separation Distance – Considerations
Basic information for determining the arrester protective zone –
maximum separation distance for which the insulation coordination
requirements are met.
– Equipment to be protected - voltage withstand ratings:
• Self restoring insulation (switches) , non-self restoring (i.e. oilpaper -transformers, GIS-breakers, cables.
• Wave shape, magnitude and rate of rise (BIL, FOW, CW)
– MOSA protective level ratings for various equipment types and
relevant wave shapes
VTerminal ≤ 0.85 x VEquipwithstand
Arrester Separation Distance – Considerations
From C62.22: C.6.1 Calculated allowable separation
distances.
“Allowable separation distances between the arrester and the transformer
for the single-line, single transformer substation . . . for system voltages
from 69 kV through 765 kV based on the following:”
–
–
–
–
–
–
–
Typical values of BIL
Station class surge arresters
Minimum MCOV ratings
Maximum value for the 0.5 μs FOW protective level from Table 1
Surge arrester total lead length of 7.6 m
Incoming steepness of 1000 kV/μs
Protective margin of 15%
Clarify separation distance as used in C26
C62.22 Separation distances . . .
The allowable separation distances are given in Table 7 of 5.2.5.4.
Modeling a simplified 500 kV – 230 kV separation
distance case in ATP
• The Basic Model
–
–
–
–
–
–
–
Sources
Breakers
Bus
Lines
Transformer
MOSA
Other Circuit Elements
• Running Simulations
– Verifying Circuit Operation
– Analyzing Waveforms
– Tabulating Results & Conclusions
• Bibliography
The Basic Circuit – Normal one line diagram
PERL Sub
500 kV
SHER Sub
25 Ft Bus Sections
CVT
PCB
230 kV
Lines
PCB
Arrester Applied Here
AC Source
500 kV
Lines
PCB
17.3
Miles
MOV
34.5 kV
Direct
Stroke
Back
Flashover
Shield
Failure
Twr. 4
Twr. 3
Twr. 2
Bus
KEEL Sub
.25 Mile Line Sections
Twr. 1
The Basic Circuit/Model – in ATPDraw
Getting Started – Making the circuit model
• Start with simple circuits, verify operation, & build gradually
– Always check as you go.
• Use your own node names – For signal identification when
plotting and for troubleshooting in the .atp & .lis files.
• Add comments in the component attribute boxes for the
circuit elements.
Sources – AC sources
•
Default source frequency is 50 Hz
– change as needed (60 Hz)
•
If you want power flow in the
circuit use a phase angle between
sources
•
An accurate equivalent source
model requires a voltage source
plus a source impedance (R0, X0,
R1 & X1 & the Surge Impedance).
Example: ATPDraw “HELP” = ATP Rule Book Element
Definitions
Name : ACSOURCE - Steady-state (cosinus) function (current or voltage). 1 or 3 phase. Grounded or ungrounded.
TYPE 14 (+type 18 for ungrounded voltage source).
Card : SOURCE
Data : AmplitudeA = The peak value of phase A in [A] or [V] of the function. 3x1-phase source has also B and C.
Frequency = Frequence in [Hz].
PhaseAngleA= Phase angle in [deg] or [sec] for phase A. 3x1-phase source has also B and C.
StartA
= Starting time in [sec.] phase A. Add negative value to include in steady-state.
Source value zero for T<StartA. 3x1-phase source has also B and C.
StopA
= Ending time in [sec] phase A. Source value zero for T>StopA. 3x1-phase source has also B and C.
Current/Voltage: Select current or voltage source. Current source has rombe-shaped icon.
Single phase/3-phase/3x1-phase: 3-phase model assumes symmetrical source with equal amplitudes and start/stop times.
Positive phase sequence: Phase B shifted -120 deg., phase C shifted +120 deg.
3x1-phase enables full control of all phase quantities.
Use this to allow external control via $PARAMETERS/Variables.
Degrees/Seconds: Unit of phase angle.
Peak L-G/RMS L-G/RMS-L-L: Amplitude multiplied by 1, sqrt(2), sqrt(2/3) respectively. Not used if Amplitude is a Variable.
Grounded/Ungrounded: ATP requires generally grounded sources.
Ungounded voltage sources handled via type 18 ideal transformers.
Ungrounded current sources handled by using two sources with opposite polarity.
Node :
AC= 1 or 3-phase node.
1. node = phase A, phase shift PhaseAngleA.
2. node = phase B, phase shift PhaseAngleB.
3. node = phase C, phase shift PhaseAngleC.
For trapped charge functions: Specify a current source, a very low frequency, Tsta=5432. and Tsto=0.
RuleBook: VII.C.4 + VII.C.7
Sources: Type 15 – Impulse function
Amp = Multiplicative number in [A]
or [V] of the function. Does not
represent peak value of surge.
T_f = The front duration in [sec].
Interval between t=0 to the time
of the function peak.
Tau = The stroke duration in [sec].
Interval between t=0 and the
point on the tail where the
function amplitude has fallen to
37% of its peak value.
Sources
– Heidler impulse model varying the rate of rise
Varying “n”, the factor determines the rate of rise of the function.
n=2
n=10
n=20
“n” = rate of rise increases
“n” = rate of rise decreases
Flashover Model
“Flash.sup” is a built-in
flashover model in ATPDraw
Breakers – 3-Phase Time-controlled switches
•
Breakers are modeled as switches
•
Some breakers may have transient recovery voltage (TRV)
capacitors that should be included for High frequency
modeling
Bus – Basics
•
Ex. Using a BRANCH card (LINEZT_3) to represent a
distributed parameters (Clarke) 3 phase. Transposed line
•
Use distributed parameter,
transposed line models (Clark)
•
Use non-frequency dependent
line models
Line model options . . . Non frequency
dependent
Generally used for steady
state modeling
Good for modeling lines that are
remote from the area of
interest, where line
characteristics have less effect
on the study area.
Line model options . . . Frequency dependent
Most users prefer and get the best results using J-Marti for modeling overhead lines
ALWAYS ( ) check this
box when performing
transient simulations as
opposed to SS or the case
will give you erroneous
data !
Lines - Basics
Lines – Modeling Basics
• The time-step must
coordinate with your line
models or ATP will crash.
The time step must be less
than the travel time of the
shortest line segment in
the model.
Lines - Flashover model configurations
Back Flashover:
Tower - Phase
Back Flashover:
A&C
Tower - Phase
Flashover:
Phase – Ground
For L=3m: Z= 200Ω,
& v=250M m/s
For L=3m: Z= 200Ω,
& v=250M m/s
Lines – Tower modeling example
For L=8m: Z= 200Ω,
& v=250M m/s
For L=8m: Z= 200Ω,
& v=250M m/s
,
0Ω
20
=
: Z m/s
2m
=1 50M
r L =2
Fo & v
Fo
rL
=
& v 12 m
=2 : Z=
50
2
M
m / 00 Ω
,
s
For L=4m: Z= 200Ω,
& v=250M m/s
For L=12m: Z= 200Ω,
& v=250M m/s
For L=4m: Z= 200Ω,
& v=250M m/s
Mini line models with surge
impedance, velocity and
length
Tower footing/grounding
equivalent
Transformers
Leaving out transformer capacitance
should provide the worst case voltage at
the teminal.
Distributed capacitance modeling . . .
More work is needed.
MOSA – Two Ways to Set Up Model
1.
Piecewise Non-linear resistor (series of
straight line resistors) - Type 92 (NLR92)
2.
Exponential Current Dependent Resistor
(Piecewise exponential) - Type 92 (MOV_3 or
MOV_1)
MOSA – Two Ways to Set Up Model
1.
Piecewise Non-linear resistor (series of
straight line resistors) - Type 92 (NLR92)
2.
Exponential Current Dependent Resistor
(Piecewise exponential) - Type 92
(MOV_3 or MOV_1)
MOSA – Variations in ATP ZNO modeling calculations
Non Linear Resistance –
Note Straight Line
Segments
ZNO Fitter –Smoother
Exponential Segments
ZNO Modeling – High frequency models
• MOSA Characteristics – Using the ZNO Fitter card – The user modifies the “Type
92” card with the V-I characteristics
• Lead Inductance must be added as an external component to the model shown
below.
New proposed frequency-dependent
Model [R1]
Existing frequency-dependent Model in C62.22
Other Circuit Elements – Capacitive Voltage Transformer
Verifying Circuit Operation
• Do simple hand calculations to verify steady state voltages &
currents are what they should be
• Look at the ATP output files: .lis file shows the results after the
case has been run – Again check SS values, minimum & maximum
magnitudes – ARE they realistic (believable)?
• Use the .lis file to check/verify switches are closing and opening as
needed.
• When the run crashes - Use the .atp file to verify circuit
connections, verify that the various “cards” are being called.
Analyzing Waveforms
100 kA Lightning Surge at 1 Mile Out, Tower voltages after a direct stroke – showing wave propagation &
reflected wave
Analyzing Waveforms - A closer look at traveling waves
100 kA Lightning Surge at 1 Mile Out – from previous slide
Velocity of the positive sequence wave, conductor to conductor,
(sky mode) is faster than . . .
. . . The Velocity of the
zero sequence wave,
conductor to ground,
(ground mode) . . .
. . . The time delay
between sky and ground
mode traveling waves . .
.
Transient Analysis
100 kA Lightning Surge at 1 Mile Out, 396 kV MOSA on Bank
100 kA Lightning Stroke
100
Tow ers 1-4 Voltage, 100kA Stroke at 1 Mile Out,
5
[MV]
[kA]
4
80
3
60
2
1
40
0
20
-1
0
0.00
0.02
0.04
0.06
0.08
[ms] 0.10
0
2
4
6
(f ile PEARL_V6-MOSA-Separation_DistV3.pl4; x-v ar t) v :T500VA
(f ile PEARL_V6-MOSA-Separation_DistV3.pl4; x-v ar t) c:IMP -TWR
Transformer Voltage
1.00
-2
8
v :T500VC
[us]
10
t
Arrester Duty
2500
[MV]
v :T500VB
[J]
0.75
2000
0.50
0.25
1500
0.00
1000
-0.25
-0.50
500
-0.75
-1.00
6
8
10
(f ile PEARL_V6-MOSA-Separation_DistV3.pl4; x-v ar t) v :T500VA
12
v :T500VB
14
v :T500VC
[us]
16
0
0.00
0.02
0.04
(f ile PEARL_V6-MOSA-Separation_DistV3.pl4; x-v ar t) c:MOSAA -
0.06
c:MOSAB -
0.08
c:MOSAC -
[ms] 0.10
Transient Analysis
100 kA Lightning Surge at 1 Mile Out, 396 kV MOSA at HV Bushing vs 150 ft
Arrester at the Bank HV Bushing
Transformer Voltage
1.00
Arrester Duty
2500
[MV]
[J]
0.75
2000
0.50
0.25
1500
0.00
1000
-0.25
-0.50
500
-0.75
-1.00
6
8
10
12
(f ile PEARL_V6-MOSA-Separation_DistV3.pl4; x-v ar t) v :T500VA
v :T500VB
14
[us]
0
0.00
16
v :T500VC
0.02
0.04
(f ile PEARL_V6-MOSA-Separation_DistV3.pl4; x-v ar t) c:MOSAA -
0.06
c:MOSAB -
0.08
[ms] 0.10
c:MOSAC -
Arrester Located 150 Ft Away from Bank
Transformer Voltage w / MOSA at 150 Ft
1.2
2500
[J]
[MV]
0.8
2000
0.4
1500
0.0
1000
-0.4
500
-0.8
-1.2
6
8
10
(f ile PEARL_V6-MOSA-Separation_DistV3.pl4; x-v ar t) v :T500VA
12
v :T500VB
14
v :T500VC
[us]
16
0
0.00
0.02
0.04
(f ile PEARL_V6-MOSA-Separation_DistV3.pl4; x-v ar t) c:MOSAA -
0.06
c:MOSAB -
0.08
c:MOSAC -
[ms] 0.10
Transient Analysis
Arrester Circuit
Distance to
Transformer (ft)
Summary of studies involving 100 kA Direct Lightning Stroke at 1 Mile Out w/ a 396 kV MOSA at various locations
0
25
50
75
100
125
150
Direct Stroke to Phase Conductor 1 Mile out of Station
Voltages kVp
% PL
Protective Margin
MOSA
TRANSF Reduction
1300
1425
1550
696
819
0
59
74
89
689
905
11
44
57
71
682
1037
27
25
37
49
683
998
22
30
43
55
692
1026
25
27
39
51
692
1102
35
18
29
41
696
1149
40
13
24
35
1800
120
99
74
80
75
63
57
Peak MOSA and Transformer voltages do not occur at the same instant in time.
MOSA & Transformer Voltages Vs Circuit Distance
Under this condition: arresters
may be positioned between 75
and 150 circuit feet from the
transformer and still provide
adequate protection.
Voltage Stress at Transformer
& MOSA (kVp)
1500
1400
1300
1200
1100
1000
900
800
700
600
0
MOSA
25
50
75
100
125
Circuit Distance from Transform er to Arrester (ft)
Transf.
150
Transient Analysis
Arrester Circuit
Distance to
Transformer (ft)
Summary of studies involving 100 kA Back flashover at Station Entrance w/ a 396 kV MOSA at various
locations
0
25
50
75
100
125
150
Backflashover at Station (100 kA Stroke)
Voltages kVp
% PL
Protective Margin
MOSA
TRANSF Reduction
1300
1425
1550
789
1603
0
-19
-11
-3
788
1611
0
-19
-12
-4
790
1690
5
-23
-16
-8
797
2048
28
-37
-30
-24
793
2127
33
-39
-33
-27
798
2112
32
-38
-33
-27
811
2100
31
-38
-32
-26
1800
12
12
7
-12
-15
-15
-14
MOSA & Transformer Voltages Vs Circuit Distance
Under this condition: The
transformer is not adequately
protected no matter where
the arrester is located
Voltage Stress at Transformer &
MOSA (kVp)
2200
2000
1800
1600
1400
1200
1000
800
600
0
25
50
75
100
C ir c u it D is t a n c e f r o m T r a n s f o r m e r t o A r r e s t e r (f t )
MOSA
Transf.
125
150
Transient Analysis
Another example: 100 kA Direct Lightning Stroke at 1 Mile Out w/a different 396 kV MOSA at various
locations and J-Marti frequency dependent line sections. Using ATP “Comparison Case” to plot signals from
5 different cases in one master plot file.
These signals are all at the TX
terminal w/MOSA located @
different 25’ bus segments
Transient Analysis
Arrester Circuit
Distance to
Transformer (ft)
Summary of studies involving 33 kA Shield Failure at Station Entrance w/ a 396 kV MOSA at various locations
0
25
50
75
100
125
150
Shield Failure at Station (32 kA Stroke)
Voltages kVp
% PL
Protective Margin
MOSA
TRANSF Reduction
1300
1425
1550
754
981
0
33
45
58
758
1132
15
15
26
37
760
1188
45
9
20
30
764
1128
38
15
26
37
762
1277
56
2
12
21
759
1411
72
-8
1
10
765
1489
82
-13
-4
4
MOSA & Transformer Voltages Vs Circuit Distance
Voltage Stress at Transformer
& MOSA (kVp)
1500
Under this condition: arrester
must be located immediately
adjacent to the bank or up to
125 circuit feet away
1800
83
59
52
60
41
28
21
1400
1300
1200
1100
1000
900
800
700
600
0
MOSA
25
50
75
100
125
Circuit Distance from Transform er to Arrester (ft)
Transf.
150
Transient Analysis
Arrester Circuit
Distance to
Transformer (ft)
Summary of studies involving 33 kA Back flashover at Station Entrance w/ a 396 kV MOSA at various locations
0
25
50
75
100
125
150
Backflashover at Station (33 kA Stroke)
Voltages kVp
% PL
Protective Margin
MOSA
TRANSF Reduction
1300
1425
1550
706
1077
0
21
32
44
706
1132
5
15
26
37
706
1090
1
19
31
42
708
1130
5
15
26
37
706
1180
10
10
21
31
711
1181
10
10
21
31
716
1182
10
10
21
31
MOSA & Transformer Voltages Vs Circuit Distance
Voltage Stress at Transformer &
MOSA (kVp)
1300
Under this condition:
Arresters must be carefully
positioned for transformers
w/ 1300 and 1425 kV BIL.
1800
67
59
65
59
53
52
52
1200
1100
1000
900
800
700
600
0
25
50
75
100
C ir c u it D ist a n c e fr o m T r a n sfo r me r t o A r r e st e r (ft )
MOSA
Transf.
125
150
Bibliography
1.
Numerical modelling of metal oxide varistors,
Proceedings of the XIVth International Symposium on High Voltage Engineering,
Tsinghua University, Beijing, China, August 25-29, 2005
Boris Žitnik1*, Maks Babuder1, Michael Muhr2, Mihael Žitnik3 and Rajeev Thottappillil3
1 Milan Vidmar Electric Power Research Institute, 1000 Ljubljana, Slovenia
2 Institute of High-Voltage Engineering and System Management, Graz, Austria
3 Division for Electricity and Lightning Research, Uppsala University, Sweden
2.
Simulation of metal oxide surge arrester dynamic behavior under fast transients
The international Conference on Power Systems Transients -IPST 2003 in New Orleans, USA
A. BAYADI1, N. HARID 2, K. ZEHAR 1, S. BELKHIAT 1
(1) Université Ferhat Abbas Sétif, Faculté des sciences de l’ingénieur, Département d’électrotechnique
Algeria (e-mail : [email protected], [email protected])
(2) Cardiff School of Engineering, Engineering Electrical Division Cardiff, United Kingdom
3.
Alternative Transients Program - Comparison of transmission line models
Orlando P. Hevia
Bibliography
4.
Parameters Affecting the Back Flashover across the Overhead Transmission Line
Insulator Caused by Lightning
Proceedings of the 14th International Middle East Power Systems Conference (MEPCON’10), Cairo
University, Egypt, December 19-21, 2010, Paper ID 111.44
Ossama E. Gouda Adel Z. El Dein Ghada M. Amer
Department of Electric Engineering Department of Electric Engineering Department of Electric Engineering
Faculty of Engineering High Institute of Energy High Institute of Technology
Cairo University, Giza, Egypt South Valley University, Aswan, Egypt Benha University, Benha, Egypt
5.
AN EFFICIENT MODELING OF TRANSMISSION LINES TOWERS AND GROUNDING
SYSTEMS FOR LIGHTNING PROPAGATION STUDIES
IX International Symposium on Lightning Protection 26th-30th November 2007 – Foz do Iguaçu,
Brazil
João Clavio Salari Carlos Portela Rogério M. Azevedo CEPEL Electric Power Research Center COPPE / UFRJ
Federal University of Rio de Janeiro CEPEL Electric Power Research Center
[email protected] [email protected] [email protected] P.O. Box 68007 – Zip Code: 21941-911 – Rio de Janeiro –
RJ – Brazil – Tel: (21) 2598-6223