sadovic lighting performance computation
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EMTP-RV
USER GROUP MEETING
EMTP_RV MODELLING FOR THE TRANSMISSION LINE
LIGHNTING PERFORMANCE COMPUTATION
T. Sadovic, S. Sadovic
Dubrovnik 30.04.2009
BACK FLASHOVERS
SHIELDING FAILURES
INDUCED
I0, tf
I0, tfI0, tf
THE ANNUAL NUMBER OF LIGHTNING
OUTAGES PER 100 KM OF LINE LENGTH
LINE LIGHTNING PERFORMANCE
LINE BACK FLASHOVER RATE
THE ANNUAL OUTAGE RATE CAUSED BY A
FLASHOVER OF LINE INSULATION
RESULTING FROM THE STROKES TO THE
TOWERS AND TO THE GROUND WIRES
I0, tf
Back
flashover
LINE SHIELDING FAILURES
I0, tf
Shielding failure
Shielding failure
flashover
THE ANNUAL NUMBER OF LIGHTNING EVENTS
THAT BYPASS THE OVERHEAD GROUND WIRES
AND TERMINATE ON THE PHASE CONDUCTORS
THE ANNUAL NUMBER OF
FLASHOVERS CAUSED BY
SHIELDING FAILURES
Additional Shield Wires
Underbuilt Ground Wire
Line Surge Arrester
Increasing Insulation
Guy Wires
Foot_resistance
improvement
HOW TO IMPROVE LINE LIGHTNING PERFORMANCE?
1 LSA
per tower
2 LSA
per tower
LINE SURGE ARRESTER APPLICATION
123 kV Line Dubrovnik - Ston
U(t)
tt1
(U - t) Insulation characteristic(s1)
U0
(s2)
t2
U1
U2
ELECTROMAGNETIC TRANSIENTS SIMULATION
MODEL OF THE LINE INSULATION FLASHOVER
vl - Leader speed (m/s)
d - Arcing distance (m)
ll - Leader length (m)
u(t) - Applied voltage (kV)
E0 = 520 (kV/m)
Flashover models:
Constant voltage
Equal area
Leader propagation
Leader propagation model:
d lu(t)
)(
170
)( 0015,0
0d
tu
l
l eEld
tudv
1
))(( 0
0
k
DUtU k
t
t
gap
d Ugap(t)
dD
ddU
dUU
ddUU
dt
U
s
s
2045,0
822)2
710400(
4959,0
550)8
710400(
[IEEE] (kV) )710
400(
75,02
%500
75,0%508
75,0
U(t)
t ( s)2
U50%
8
U0
U2 s
D
EQUAL AREA FLASHOVER MODEL
dD
k
dU
2045,0
1
4950
EMTP_RV Model data:
[d - arcing distance in meters]
g
lci
I
I
RR
1
22 lc
g
gR
EI
Rlc – low current tower footing resistance ( )
Ri – tower footing impulse resistance ( )
I – impulse current (kA)
Ig – soil ionisation limit current (kA)
Eg – soil ionisation critical electric field (kV/m) – [Eg = 400 (kV/m)]
I
I (kA)
Ig
Linear Resistance
Non-Linear Resistance
U (kA)
ELECTROMAGNETIC TRANSIENTS SIMULATION
SOIL IONIZATION TOWER FOOTING RESISTANCE MODEL
hav
W
IC
Back
Flashover
QUICK BACK FLASHOVER RATE COMPUTATIONS
W - Line shadow width
A - Line attraction area
hav - Tower average height
IC - Back flashover critical current
W
100 km
A = 100 x W (km2)
Stroke current is changed until
flashover [IC obtained]
ANN
WA
bRW
hR
GL
a
ava
100
2
14 6,0
QUICK BACK FLASHOVER RATE COMPUTATIONS
W
100 km
A = 100 x W (km2)
)31
(1
1
6,2CI I
PC
ANN
WA
bRW
hR
GL
a
ava
100
2
14 6,0
CIL PNBFR 6,0
W - Line shadow width
b - Ground wire separation distance
NL - Number of strokes collected [str/100km/year]
NG – Ground flash density [str/km2/year]
BFR - Back flashover rate
0,6 > Takes into account strokes hitting shield wire
hav
W
IC
Back
Flashover
)24
(1
1
4SPS
IEEE DISTRIBUTION
i0 (t)
t ( s)
tf
I0
I0/2
tt
S (kA/ s)
IS PP
)31
(1
1
6,2IPI
0
ft
IS
CURRENT PEAK
STEEPNESS
Equivalent Front Time
Equal Probability
No DC Resistance
[Ohm/km]
Outside diameter
[cm]
x [m] y [m] y [m]
at midspan
1 0.1444 1.708 2.5 22.7 14.1
2 0.1444 1.708 -3 20.5 11.9
3 0.1444 1.708 3.5 18.3 9.7
4 0.4555 0.9 0 28.9 21.3
1
2
3
4
123 kV TRANSMISSION LINE DUBROVNIK STON
Un= 123 kV
Length = 46 km
Span = 200 m
L = ZT/v
v - velocity of light hT = 28,9 m
lprop = 20 m
ZT = 184
Propagation
element
L1 = 2,8 H
L3 = 1,37 H
L2 = 1,37 H
LINE SURGE ARRESTER
Current (A) Voltage (V)
1000 239000
2500 252000
5000 275000
10000 291000
20000 324000
40000 357000
Rated voltage: 123 kV
IEC Class II
Polymer housed
00km/year)(strokes/1 105215
(km2) 21210,0100100
(m) 210010522
(m) 1059,281414 6,06,0
ANN
WA
bRW
hR
GL
a
ava
123 kV TRANSMISSION LINE DUBROVNIK STON
Ground flash density: 5 strokes/km2/year
Length = 46 km
Using EMTP_RV find IC (Critical current)
)31
(1
1
6,2CI I
PC
CIPBFR 1056,0
AUTOMATIC BACKFLASHOVER COMPUTATIONS
EMTP_RV Line section model created
Netlist file obtained
AUTOMATIC BACKFLASHOVER SIMULATIONS
Tower Model> Sub circuits
Air gap model
Signal = 0: No flashover
Signal =1: Flashover
AUTOMATIC BACKFLASHOVER SIMULATIONS
Tool developed to run EMTP_RV in a loop
Initial stroke current Current step
AUTOMATIC BACKFLASHOVER SIMULATIONS
EMTP_RV is running in the loop until gap signal > 0
Flashover Tower 2
Phase conductor C
Stroke Sub circuit
AUTOMATIC BACKFLASHOVER SIMULATIONS
EMTP_RV is running in the loop until gap signal > 0
Critical current
Back flashover rate
FUTURE WORK > 3D EGM
WS - SIMULATED WIDTH
STRIKING DISTANCES
1. TO PHC & GW:
rS = A I B
[A=10, B=0,65]
2. TO TOWERS:
rTT = k rS
[k= 1 – 1,1]
3. TO EARTH:
span
rE
rT2
rT1
x0
y0
WS
DOWNWARD
LEADER
I0, tf
0,65
E vIEEE: r 3,6 1,7 ln(43 y ) I
rGW = rPHC = rNO = rS
GW
PHC
x0
dl
hl
rGW
rPHCrNO
WS/2 WS/2
NEARBY
OBJECT
DOWNWARD
LEADER APPROACHES
UNDER ANGLE
I0, tf
2cos2
f
FUTURE WORK > 3D EGM
FUTURE WORK > sigma slp like interface
EMTP_RV modeling and transients computation
Monte Carlo Statistical Study and 3D EGM
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