An advanced interface between the Lightning Induced ... - EMTP
Transcript of An advanced interface between the Lightning Induced ... - EMTP
An advanced interface between the Lightning Induced Overvoltage Code (LIOV) and EMTP-RV M. PAOLONE and F. RACHIDI ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE – EPFL SWITZERLAND A. BORGHETTI, F. NAPOLITANO and C.A. NUCCI, UNIVERSITY OF BOLOGNA ITALY
EMTP-RV European User Group Meeting April 3, 2012– Paris, La Défense, France
The problem
z'
H
IMMAGINE
dz'i(z',t)
R
R'
r
x
yZ
L
zz'
P(x,y,z)
Zo
Eh
E
r
zE
EEx
P(x,y,z)
φ
IMAGE
v
i(z’,t): lightning current; H: lightning channel height; v: lightning wave front speed.
Computation of overvoltages induced by electromagnetic fields produced by lightning return strokes nearby overhead lines.
Outline
¨ Introduction ¨ 2nd order FDTD for the solution of the Agrawal et
al. coupling model ¨ Boundary conditions
¤ Numerical treatment ¤ Structure of the interface
¨ Advantages of the proposed interface ¨ Comparison between experimental recordings and
simulation results ¨ Conclusions
Introduction
The evaluation of the lightning performance of overhead distribution lines has been the object of several studies e.g. : ¨ IEEE Std. Guide 1410; ¨ Joint Cigré-Cired WG C4.4.02;
The inherent complexity of distribution systems, namely: ¨ number of lines (main feeder with laterals) ¨ presence of power components (transformers, surge arresters, groundings, etc.) is well far from the straight line configuration generally adopted in these type of studies.
Introduction
Example: Influence of network topology on the indirect-lightning performance of distribution networks
0.0001
0.0010
0.0100
0.1000
1.0000
50 100 150 200 250Voltage [kV]
Ann
ual n
umbe
r of e
vent
s ex
ceed
ing
the
valu
e in
ab
scis
sa
straight lineH-shaped network (type 1)H-shaped network (type 2)T-shaped network
A. Borghetti, M. Paolone, C.A. Nucci, “Indirect-Lightning Performance of Overhead Distribution Networks With Complex Topology”, IEEE Trans. on PWRD, vol. 24-4, Oct. 2009, pp. 2206-2213.
Introduction
The contribution presents an improvement of the already developed LIOV-EMTP interface by introducing: ¨ improved boundary condition treatment of LEMP-illuminated lines (à time delays issues are fixed) ¨ integration of the LIOV code with the augmented nodal analysis technique implemented in the EMTP-RV.
Interface structure n-port (EMTP-RV)
LIOV-lines
Outline
¨ Introduction ¨ 2nd order FDTD for the solution of the Agrawal et
al. coupling model ¨ Boundary conditions
¤ Numerical treatment ¤ Structure of the interface
¨ Advantages of the proposed interface ¨ Comparison between experimental recordings and
simulation results ¨ Conclusions
2nd order FDTD for the solution of the Agrawal et al. coupling model
Agrawal et al. field-to-transmission line coupling model for a lossless single conductor overhead line
),,(),('),( thxEttxiL
xtxv e
x
s
=∂
∂+∂
∂
0),('),( =∂
∂+∂
∂ttxvC
xtxi s
∫−=+=ih
ez
si
ei
sii dztzxEtxvtxvtxvtxv
0
),,(),(),(),(),(
2nd order FDTD for the solution of the Agrawal et al. coupling model
⎟⎟⎠
⎞⎜⎜⎝
⎛Δ
−+−Δ−Δ−⎟⎟⎠
⎞⎜⎜⎝
⎛Δ−Δ−= −+−+−++
21111
2111 2
2''22' xvvv
xEhEh
CLt
xii
Ctvv
nk
nk
nk
nk
nk
nk
nkn
knk
⎟⎟⎠
⎞⎜⎜⎝
⎛Δ−+
Δ−+Δ+⎟⎟⎠
⎞⎜⎜⎝
⎛−
Δ−Δ−=
−+−+−++
tEhEhC
xiii
CLtEh
xvv
Ltii
nk
nk
nk
nk
nkn
k
nk
nkn
knk 2
'2''22'
11
211
2111
n n i v 0 0 , n k
n k i v max max ,
n k
n k i v ,
R 0
∫ h
e z dz t E
0 ) , 0 , 0 ( ∫
h e z dz t L E
0 ) , 0 , (
R L
) t , h , x ( E e x
n+1
n
n - 1
k k+1 k - 1 spatial discretization
time discretization
Outline
¨ Introduction ¨ 2nd order FDTD for the solution of the Agrawal et
al. coupling model ¨ Boundary conditions
¤ Numerical treatment ¤ Structure of the interface
¨ Advantages of the proposed interface ¨ Comparison between experimental recordings and
simulation results ¨ Application example: lightning-to-fault correlation ¨ Conclusions
Boundary conditions Numerical treatment
( ) ∫+Γ−=h
ez
n dztEiv0
000 ),0,0(
( ) ∫+Γ=h
ezkk
nk dztLEiv
0max ),0,(
maxmax
Problem: since the numerical solution of the internal FDTD nodes (k = 1,…, kmax-1) provided by the LIOV code is split from the one of the boundary conditions provided by EMTP-RV, explicit in a closed form the boundary conditions linking the voltages and currents at the terminal FDTD nodes is a non trivial task.
Scattered voltages
Boundary conditions Numerical treatment
Solution of the problem replace the spatial numerical discretization at the two line terminations (x=0 and x=L) by means of two Bergeron lines suitably extended to take into account the presence of the exciting LEMP: illuminated Bergeron Lines
utx =
ΔΔ
à Additional contraint to be applied to space (Δx) and time (Δt) integration steps which are correlated by means of the Courant stability condition:
Being u the propagation speed
Boundary conditions Numerical treatment
Bergeron equations (without external exciting LEMP) at the two terminations of a lossless line:
),(),(),0(),0( tttuZitttuvtZitv Δ−Δ−Δ−Δ=−
),(),(),(),( tttuLZitttuLvtLZitLv Δ−Δ−+Δ−Δ−=+
Where: ¨ v(0,t), i(0,t) and v(L,t), i(L,t) are the voltages and currents at the
beginning and at the end (L) of the LIOV line respectively;
¨ Z is the surge impedance of the line (assumed to be frequency independent).
Boundary conditions Numerical treatment
Bergeron equations in presence of external exciting LEMP at the two ideal line terminations:
∫Δ
−Δ−Δ−Δ−Δ=−tuex
ss dxthxEtttuZitttuvtZitv0
),,(),(),(),0(),0(
∫Δ−
+Δ−Δ−+Δ−Δ−=+L
tuL
ex
ss dxthxEtttuLZitttuLvtLZitLv ),,(),(),(),(),(
In the discretized form:
v0n+1 − Zi0
n+1 = v1n − Zi1
n − Δx2
Eh0n+1 + Eh1
n( )
vkmaxn+1 + Zikmax
n+1 = vkmax−1n + Zikmax−1
n + Δx2
Ehkmaxn+1 + Ehkmax−1
n( )
Boundary conditions Structure of the interface
( )00 iΓ
( )nn EhEhx1
102
+Δ +
( )hEzn ⋅+10
( )nk
nk EhEhx
11
maxmax2 −+ +Δ
( )hEz nk ⋅+1max
11
11 ,
++ nn iv 12
12 ,
++ nn iv 12
12 maxmax, +
−+
−nk
nk iv 1
111 maxmax, +
−+
−nk
nk iv
…… 1
01
0 ,++ nn iv 11
maxmax, ++ nk
nk iv
( )maxmax kk iΓ
Z Z Z Z
EMTP-RV EMTP-RV LIOV line
0G maxkG0'G max'kG
( )nnnnnn EhEhxZivZiv 11
0111
01
0 2+Δ−−=− +++
( )nk
nk
nk
nk
nk
nk EhEhxZivZiv 1
111
11maxmaxmaxmaxmaxmax 2 −
+−−
++ +Δ++=+
Boundary conditions Structure of the interface
The main system of equations in EMTP-RV is given by:
⎥⎦
⎤⎢⎣
⎡=⎥
⎦
⎤⎢⎣
⎡⎥⎦
⎤⎢⎣
⎡
v
n
V
n
dr
cn
vi
iv
VVVY
¨ Yn is the nodal admittance matrix; ¨ submatrices Vc, Vr and Vd are used to include non-nodal
type equations, such as branch relations (called voltage-defined equations), but can also use current coefficients;
¨ vn, iV unknown quantities (nodal voltages and branch currents);
¨ In current injections and vv voltage-defined equations.
DLL interface
DLL interface
Outline
¨ Introduction ¨ 2nd order FDTD for the solution of the Agrawal et
al. coupling model ¨ Boundary conditions
¤ Numerical treatment ¤ Structure of the interface
¨ Advantages of the proposed interface ¨ Comparison between experimental recordings and
simulation results ¨ Conclusions
Advantages of the proposed interface
Comparison between the previous LIOV-EMTP96 and LIOV-EMTP-RV interfaces
1000 m
10 m
1 cm
Zc Zc
50 m
Stroke Location
Side view
Top view
500 m
Observation point
Observation point
Lightning current (subs) ¨ 12 kA amplitude
¨ 40 kA/μs of max time derivative
¨ r.s. speed:1.3·∙108 m/s
¨ r.s. time-space distribution represented with the MTLE model
Advantages of the proposed interface
Comparison with Δx = 5 m, Δt = 1.66·∙10-8 s, Δx = 10 m, Δt = 3.33·∙10-8 s, Δx = 20 m, Δt = 6.66·∙10-8 s Line represented as a single straight line (1 section)
LIOV-EMTP96 LIOV-EMTP-RV
-10
0
10
20
30
40
50
60
70
0 2 4 6 8 10
Indu
ced
volta
ge (k
V)
Time (µs)
Δx = 5 m, Δt = 1.666E-8 s
Δx = 10 m, Δt = 3.333E-8 s
Δx = 20 m, Δt = 6.666E-8 s
-10
0
10
20
30
40
50
60
70
0 2 4 6 8 10
Indu
ced
volta
ge (k
V)
Time (µs)
Δx = 5 m, Δt = 1.666E-8 s
Δx = 10 m, Δt = 3.333E-8 s
Δx = 20 m, Δt = 6.666E-8 s
-10
0
10
20
30
40
50
60
70
0 2 4 6 8 10
Indu
ced
volta
ge (k
V)
Time (µs)
Δx = 5 m, Δt = 1.666E-8 s
Δx = 10 m, Δt = 3.333E-8 s
Δx = 20 m, Δt = 6.666E-8 s
Advantages of the proposed interface
LIOV-EMTP96 LIOV-EMTP-RV
Comparison with Δx = 5 m, Δt = 1.66·∙10-8 s, Δx = 10 m, Δt = 3.33·∙10-8 s, Δx = 20 m, Δt = 6.66·∙10-8 s Line segmented into 5 straight sections
-10
0
10
20
30
40
50
60
70
0 2 4 6 8 10
Indu
ced
volta
ge (k
V)
Time (µs)
Δx = 5 m, Δt = 1.666E-8 s
Δx = 10 m, Δt = 3.333E-8 s
Δx = 20 m, Δt = 6.666E-8 s
Outline
¨ Introduction ¨ 2nd order FDTD for the solution of the Agrawal et
al. coupling model ¨ Boundary conditions
¤ Numerical treatment ¤ Structure of the interface
¨ Advantages of the proposed interface ¨ Comparison between experimental recordings and
simulation results ¨ Conclusions
Comparison between experimental recordings and simulation results
Reduced scale model experiment Experimental data obtained by Piantini and Janischewskyj
A. Piantini, J.M. Janiszewski, “An experimental study of lightning induced voltages by means of a scale model”, Proc. of the 21st International Conference On Lightning Protection, Berlin, Germany, September, 1992.
1400 m
10 m
2 cm
Zc Zc
70 m
Stroke Location
Side view
Top view
700 m
Measurement point
Lightning current ¨ 27.5 kA amplitude
¨ Time to peak: 3.5 µs
¨ r.s. speed:0.33·∙108 m/s
¨ r.s. time-space distribution represented with the TL model
Ideal ground
Comparison between experimental recordings and simulation results
Reduced scale model experiment
-20
0
20
40
60
80
100
120
140
0 5 10 15 20
Indu
ced
volta
ge (k
V)
Time (µs)
MeasuredSimulated
Comparison between experimental recordings and simulation results
!
Full-scale experiment Experimental campaign carried out in 2003 at the (ICLRT [12-14]) operated by the University of Florida.
The facility consists of an experimental un-energized overhead multi-conductor power distribution line, illuminated by electromagnetic fields produced by artificially triggered lightning. The line is 0.75-km long, consisting of 4 conductors (3–phase conductors plus neutral, periodically grounded) and equipped with surge arresters.
Comparison between experimental recordings and simulation results
Full scale model experiment: models
Grounding has been modeled adopting a lumped-parameter approach by using the Rundeberg model and by segmenting the RLC network into 50 segments
R. Rudenberg, Electrical Shock Waves in Power Systems. Cambridge, MA: Harvard Univ. Press, 1968.
Comparison between experimental recordings and simulation results
Comparison between experimental and simulation results for the 6th return stroke of the lightning flash triggered 02 august 2003; induced-current flowing through the arrester located at pole 6 phase B
-50
0
50
100
150
200
250
0.E+00 2.E-06 4.E-06 6.E-06 8.E-06 1.E-05Time [s]
Indu
ced
Cur
rent
[A]
IBN6 SimulatedIBN6 Measured
M. Paolone, F. Rachidi, A. Borghetti, C.A. Nucci, M. Rubinstein, V.A. Rakov, M. Uman, “Lightning Electromagnetic Field Coupling to Overhead Lines: Theory, Numerical Simulations, and Experimental Validation”, IEEE Trans. on EMC, vol. 51-3, part 1, Aug. 2009, pp. 532-547.
Comparison between experimental recordings and simulation results
Comparison between experimental and simulation results for the 6th return stroke of the lightning flash triggered 02 august 2003; induced-current flowing through the grounding of pole 6
-400
-200
0
200
400
600
800
1000
1200
1400
0.E+00 2.E-06 4.E-06 6.E-06 8.E-06 1.E-05Time [s]
Indu
ced
Cur
rent
[A]
IG6 SimulatedIG6 Measured
M. Paolone, F. Rachidi, A. Borghetti, C.A. Nucci, M. Rubinstein, V.A. Rakov, M. Uman, “Lightning Electromagnetic Field Coupling to Overhead Lines: Theory, Numerical Simulations, and Experimental Validation”, IEEE Trans. on EMC, vol. 51-3, part 1, Aug. 2009, pp. 532-547.
Comparison between experimental recordings and simulation results
Comparison between experimental and simulation results for the 6th return stroke of the lightning flash triggered 02 august 2003; induced-current flowing through the grounding of pole 2
-500
0
500
1000
1500
2000
0.E+00 2.E-06 4.E-06 6.E-06 8.E-06 1.E-05Time [s]
Indu
ced
Cur
rent
[A]
IG2 SimulatedIG2 Measured
M. Paolone, F. Rachidi, A. Borghetti, C.A. Nucci, M. Rubinstein, V.A. Rakov, M. Uman, “Lightning Electromagnetic Field Coupling to Overhead Lines: Theory, Numerical Simulations, and Experimental Validation”, IEEE Trans. on EMC, vol. 51-3, part 1, Aug. 2009, pp. 532-547.
Comparison between experimental recordings and simulation results
Comparison between experimental and simulation results for the 6th return stroke of the lightning flash triggered 02 august 2003; induced-current flowing through the phase B at pole 6
-250
-200
-150
-100
-50
0
50
100
150
0.E+00 2.E-06 4.E-06 6.E-06 8.E-06 1.E-05Time [s]
Indu
ced
Cur
rent
[A]
IB6 Simulated
IB6 Measured
M. Paolone, F. Rachidi, A. Borghetti, C.A. Nucci, M. Rubinstein, V.A. Rakov, M. Uman, “Lightning Electromagnetic Field Coupling to Overhead Lines: Theory, Numerical Simulations, and Experimental Validation”, IEEE Trans. on EMC, vol. 51-3, part 1, Aug. 2009, pp. 532-547.
Coordinate Gauss-Boaga x [km]
Coo
rdin
ate
Gau
ss-B
oaga
y [k
m]
5080
5082
5084
5086
5088
5090
5092
2345 2347 2349 2351 2353 2355 2357
Coo
rdin
ate
Gau
ss-B
oaga
y [k
m]
Coordinate Gauss-Boaga x [km]
Comparison between experimental recordings and simulation results
Real network measurements
Comparison between experimental recordings and simulation results
LLS data summary: § period: March 2007–August 2008; § flashes: 569 flashes; § strokes: 851 strokes (778 negative and 73
positive); § 425 flashes (75% of the total) are
composed by only 1 stroke; § 82 flashes (14%) are composed by 2
strokes; § remaining 62 flashes (11%) are
composed by 3 or more strokes; § area: rectangular surrounding the
distribution feeder having a maximum distance of 2 km from the feeder extremities (in total:144 km2).
5080
5082
5084
5086
5088
5090
5092
2344.5 2346.5 2348.5 2350.5 2352.5 2354.5 2356.5
Coordinate Gauss-Boaga x [km]
Coo
rdin
ate
Gau
ss-B
oaga
y [k
m]
Return strokes Distribution network
Overvoltage measurement system data summary: § transients: more than 1700; § faults: 2 self-extinguishing and 4 causing circuit breaker opening.
2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 23565081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
Unit 3
Unit 2
Unit 1
substation
1
2 34
km
km
-5
-4
-3
-2
-1
0
1
2
3
4
0 10 20 30 40 50
Volta
ge (k
V)
Time (µs)
calcolate
10 Per. Media Mobile (misurate)
calculationsmeasurements
-4
-2
0
2
4
6
8
10
0 10 20 30 40 50
Volta
ge (k
V)
Time (µs)
calcolate
10 Per. Media Mobile (misurate)
calculationsmeasurements
Unit 1
LLS event nr: 30260-3 Current peak: -20.9 kA
Unit 3
Comparison between experimental recordings and simulation results
F. Napolitano, A. Borghetti, M. Paolone, M. Bernardi, “Voltage transient measurements in a distribution network correlated with data from lightning location system and from sequence of events recorders “, Electric Power Systems Research, vol. 81, Issue 2, Feb. 2011, pp: 237-253.
Outline
¨ Introduction ¨ 2nd order FDTD for the solution of the Agrawal et
al. coupling model ¨ Boundary conditions
¤ Numerical treatment ¤ Structure of the interface
¨ Advantages of the proposed interface ¨ Comparison between experimental recordings and
simulation results ¨ Conclusions
Conclusions
¨ A new interface between the LIOV code and the EMTP-RV has been developed in order to properly simulate the response of realistic distribution networks against external electromagnetic fields produced by nearby lightning.
¨ Compared to the already presented interface between the LIOV code and the EMTP96, the proposed one avoids the small time shift introduced between each illuminated LIOV-line and the boundary solution provided by the EMTP-RV.
Conclusions
¨ The proposed interface has been tested versus several experimental data sets, obtained by means of reduced scale models and triggered lightning à as expected, good agreement has been obtained.
¨ The proposed interface represent a powerful tool for the analysis of the distribution networks response against nearby lightning, insulation coordination studies, lightning-to-fault correlation, design and optimal placement of protection devices.
An advanced interface between the Lightning Induced Overvoltage Code (LIOV) and EMTP-RV M. PAOLONE and F. RACHIDI ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE – EPFL SWITZERLAND A. BORGHETTI, F. NAPOLITANO and C.A. NUCCI, UNIVERSITY OF BOLOGNA ITALY
EMTP-RV European User Group Meeting April 3, 2012– Paris, La Défense, France