Excerpt
2
The surge effects in the distribution networks are very
dependent on the lightning discharge current intensity, speed
of the return stroke and the point of impact, among others. The
two first parameters are relative to the lightning discharge
itself and, therefore, random; otherwise, the impact point is a
major influential factor for the calculation of the surges.
Table I show the peak induced surge voltages for lightning
discharges in a standard medium voltage distribution network
for the three phases. Each case represents a distance from the
network to the impact point of the lightning, where the first
case is closer and the last case is distant. It shows the little
influence of a three-phase over a single-phase analysis and the
influence of the distance in the induced surges.
TABLE
I
E
XAMPLE OF
S
IMULATION OF
O
VERVOLTAGE
'
S IN A
T
HREE
-P
HASE
C
IRCUIT
Induced Overvoltage's [kV]
Case
Phase A Phase B Phase C
1
49.60
48.80
49.60
2
24.70
24.50
24.70
3
15.00
14.60
15.00
4
9.12
9.00
9.12
5
5.58
5.52
5.58
6
2.88
2.88
2.88
7
1.74
1.56
1.74
8
0.78
0.72
0.78
9
0.48
0.48
0.48
10
0.18
0.18
0.18
Then, to reach a better analyses speed and minor modeling
complexity, a single-phase modeling of the circuits is used,
which is a valid approach that results in a faster analysis and
less time expensive process.
As well as to reach a balance between the model complexity
and the resulting error, it was adopted the use of a real
topology of the distribution network, using geographically
referenced database. In addition, to minimize the total error of
the simulations, many cases were simulated with the Monte
Carlo Method. However, some simplifications had to be taken
in order to reduce the complexity and the amount of
information required of the real topology.
For this reason, a plain area was adopted for the entire area
of the distribution network, that is, without any information
about topography or elevations. Also real elevated structures,
like towers, buildings and trees had not been considered
automatically; even so, they are simulated through the manual
inclusion of high points.
The adoption of these simplifications was mainly taken by
the difficulty and complexity of obtaining and dealing with
digital data about topography and elevated structures, since it
is necessary to implement the automated routines without
considering such simplifications.
Taking these simplifications led to a larger number of direct
interceptions from the lightning discharges for the distribution
networks, in other words, an overestimated result for the
worse case. However, through the manual inclusion of
elevated structures, some different cases can be simulated,
since a low natural shield for the network up to one high
degree of shielding, as a result of a larger number of induced
surges.
III. P
ERFORMANCE
S
IMULATIONS
Each performance simulation is executed in a great area,
covering the entire distribution network, however, not much
bigger than that, making possible to simulate a set of circuits.
It can deal not only with a typical urban network, more
uniform and with a greater network density, but also with rural
networks, more dispersed and non-uniforms, or even a mix of
both.
In this total area, and based on the number of discharges to
the ground by square kilometer per year (discharges/km²year),
adopted by the regional characteristic or an average, the
Monte Carlo Method is used to simulate 100 years or more of
lightning discharges. These simulations generate an enormous
mass of data that can be analyzed statistically, as a result
giving data that are more reliable for the studies.
The probable position of the discharge impact is defined
randomly within the total area, in the same way that the
current intensity, which follows a lognormal distribution with
an average of 31 kA, is random as also as the correlated speed
of the return stroke.
After these definitions, of the descending impact point and
current intensity, the verification of the attractiveness area is
initiated, following the Electro-Geometrical Model [1,10],
defining if that discharge will reach some structure, the
network or the ground.
With the impact point, current intensity and front time
defined for the lightning discharge, it is possible to calculate
the distribution network peak overvoltage. Leading to two
cases: When the discharge intercepts the network directly, the
peak overvoltage is calculated based on the parameters of the
traveling waves and surge impedance of the line. On the other
hand, when the lightning does not intercept the network, but
generates an induced surge, it is necessary to calculate the
distance from the impact point to the closer network point and
the electromagnetic fields, in order to verify the total
induction, as a result the surge peak overvoltage.
The method adopted for the calculation of induced surges
was the LIOV-EFEI [13, 14], this is based on the LIOV Code
[3] (Lightning Induced Over-Voltage) developed at the
University of Bologna and adapted, with some simplifications,
by the High Voltage Laboratory (LAT-EFEI) of the Federal
University of Itajubá, Brazil.
For the performance simulation, three major cases were
simulated: one rural network, one flat urban network and an
urban network considering elevated structures. The simulation
results for the flat urban network and for the rural are very
close, with minimal differences.
Because of the bigger density of branches and lines by a
small area, the urban network simulations lead to the rise of
the number of interceptions by lightning discharges, not only
by direct interceptions but also by induced surges. However,
the statistical results in terms of current intensities and
overvoltage's are practically the same.
However, when the elevated structures are simulated, in
different sets, it is evident the decrease of the amount of
lightning intercepting directly the network. In fact, the
presence of closer high points to the networks exerts a greater
3
or minor degree of shielding of these to the direct
interceptions. In the case of metropolitan regions, which have
a bigger amount and concentration of high constructions,
towers, buildings as many other elevated points, the level of
direct interceptions of the network is extremely low.
A. Rural Simulation Results
The rural network, Fig. 1, by possessing a much greater area
than the urban, needed a large amount of lightning discharges
simulations. A total of 707,214 discharges were simulated,
equivalent to 364 years for the case of an average of
6 discharges/km²year and 323.85 km² of total area. From this
total, only 4.34% had directly intercepted the network, this is
caused by the sparse distribution of the circuit in a big area,
leading to a small probability of interception by the network of
a lightning discharge.
Fig. 1. Adopted rural medium voltage distribution network real topology.
For the 30,693 discharges of direct interception, the
histogram of the current intensities is shown in the Fig. 2.
From the fitted lognormal distribution, it was obtained the
current intensity value with 50% of probability: 40.24 kA;
with 90% probability: 16.66 kA and with 10% probability:
97.22 kA.
Fig. 2. Current intensity histogram for the lightning discharge direct
interception into the medium voltage rural distribution network.
Fig. 3. Induced overvoltage's histogram for the medium voltage rural
distribution network.
In the case of the discharges that had not intercepted the
network directly, that is, the remaining 676,521 occurrences,
they had generated the overvoltage histogram of the induced
surge, as it can be seen in the Fig. 3. In which it is possible to
see the low values found, that were caused by the general
great distances from the impact point to the network. From the
fitted lognormal distribution, it was obtained the value of
surge with a probability of 50% of occurrence: 6.46 kV; with a
probability of 90%: 1.28 kV and with 10%: 32.61 kV.
B. Urban Simulation Results
In the case of the urban network without the presence of
elevated structures, Fig. 4, it was simulated 286,237 lightning
discharges, what is equivalent to 2,141 years of lightning
discharges in the network. A number achieved by the total
area of 22.28 km² and the regional average of
6 discharges/km²year.
Fig. 4. Adopted urban medium voltage distribution network real topology,
without the presence of elevated structures.
From this total, 95,392 discharges intercepted the network
directly, where, by the fitted lognormal distribution, it was
obtained the current intensity with 50% of occurrence
probability: 38.14 kA; 90% of probability: 16.81 kA, and
10%: 86.53 kA, as it can be seen in the Fig. 5.
4
Fig. 5. Current intensity histogram for the lightning discharge direct
interception into the medium voltage urban distribution network, without
elevated structures.
The remaining 190,845 discharges that did not intercept the
network represent more than twice of the number of direct
interception. The Fig. 6 represents the overvoltage's
histogram, where the distribution identification could not fit
well, caused by the histogram non-uniformity.
Fig. 6. Induced overvoltage's histogram for the medium voltage urban
distribution network, without elevated structures.
As a result, the distribution that got optimum performance
in the test was the tri-parametric Weibull, in which it is
possible to obtain the overvoltage value with 50% probability
of occurrence that was 29.49 kV; the 90% probability:
6.46 kV and the 10% probability: 77.62 kV.
The maximum and minimum values had been similar to the
found ones in the previous rural case, however, as it can be
seen, the great majority of the cases of the surge for the rural
network stayed below 30 kV.
C. Urban with Elevated Structures Simulation Results
To make the simulated urban circuit better represents a real
case of an urban area, it is necessary to take into consideration
the presence of elevated structures, as trees, buildings, high
constructions, towers, among others. Thus, through the
inclusion of simulated elevated structures in the circuit, which
attracts the lightning discharges, diverting them from the
networks, it will supply a shielding effect.
Tests had been made with two configurations for the
simulations of elevated structures. Firstly, the structures are
enclosed with an average distance of 10 m from the network
and with 40 m between two consecutive structures. In this
configuration, a high index of network shielding was
achieved, proved by the index of 2.24% direct interception by
the network [5,7].
Secondly, the structures had been inserted with an average
distance of 5 m for the network and 80 m between two
consecutive structures, reaching a lower degree of network
shielding, with an index of 15.43% of direct interception of
the network [5,7].
These two previous simulations had shown a behavior of a
dense and a sparse urban region, simulating an urban zone of a
central region of a great city and a small town, respectively.
To simulate an average case, that could contemplate both the
situations, it was adopted the inclusion of elevated structures
with an average distance of 10 meters of the network and
70 meters between two consecutive structures, Fig. 7,
searching for an intermediate condition between the
previously simulated.
Fig. 7. Adopted urban medium voltage distribution network real topology,
with the presence of simulated elevated structures.
In this condition, 259,250 lightning discharges had been
simulated, or the equivalent to 1,939 years of lightning
discharges reaching this region. From these, only 2,938 had
been intercepted directly by the network. On the other hand,
an
elevated
structure
or
the
ground
intercepted
256,312 discharges, which is equivalent to 98.87% of the
cases. The shielding of the network was relatively high,
however, the study continued for the good statistical
representation of this case and by being a better study
condition for the induced overvoltages.
In the case of the direct interceptions, the Fig. 8 shows the
histogram of the found current intensities. The value of
discharge current intensity with a probability of 50% of
occurrence was obtained by the fitted lognormal distribution
and was 11.60 kA; for the case of probability occurrence of
90%: 5.29 kA, and for 10% probability: 25.44 kA. It is easy to
see the fall in the direct interception current intensities
observed, from 38.14 kA to 11.60 kA in the occurrence
5
probability of 50%. Due to the fact of the bigger intensity
discharges, by possessing a greater attraction distance, that
reaches firstly an elevated structure than the network
conductors.
Fig. 8. Current intensity histogram for the lightning discharge direct
interception into the medium voltage urban distribution network, with
simulated elevated structures.
The Fig. 9 shown the histogram of the induced
overvoltage's, in this figure is also difficult to identify the
distribution that can better fit, as a result it was used the one
that has the better adherence in the tests, which was the tri-
parametric Weibull distribution. Where can be obtained the
values of surge overvoltages with a probability of 50% of
occurrence: 31.45 kV; of 90% probability: 13.70 kV and of
10% probability: 72.20 kV.
Fig. 9. Induced overvoltage's histogram for the medium voltage urban
distribution network, with simulated elevated structures.
The increase in the found surge levels is notable, where the
maximum limit increased from 160 kV, in the case without the
presence of elevated structures, to 375 kV in this in case. It
was due to the high-intensity discharges that reach elevated
structures closer to the network. However, as in the previous
case, the biggest concentration was in the band of the 10 to
30 kV, what resulted in the values of probability very similar
between the two cases. Where for the 50% probability it was
increased from 29.49 to 31.45 kV, and 90% probability from
6.46 to 13.70 kV, however, the 10% probability had indeed a
small decrease from 77.62 to 72.20 kV.
IV. T
RANSIENT
S
IMULATIONS
Electromagnetic transitory simulations through the ATP
program had been executed to detail and analyze the dynamics
and distribution of the surge into the system and the response
from the installed equipment.
For this reason, 45 cases of induced overvoltage's due to
lightning discharge had been simulated, plus 45 more
simulations for overvoltage's generated by direct impact
lightning discharge, totalizing 90 simulations. All of them
executed in an urban feeder, in which 36 of them, that is, 40%
had been executed in the presence of elevated structures. This
was done because of the fact that the results of an urban
network without the elevated structures possess similarity with
the results of a rural network, consequently we have that 54 of
the cases can be attributed to a rural or a low-density urban
network and the remaining to a dense urban region.
The simulations take into care the line surge impedance,
surge arresters, medium voltage transformers and its basic
insulation level, insulators and the line critical flashover
overvoltage for the entire distribution network under analyses.
The surge source was modeled with the 2-slope ramp
model, the lines with the lumped series R-L-C parameters
obtained from the Line Constants Routine. The transformers
with the high-frequency capacitive- model obtained from the
real transformers measurement with the Schering Bridge. The
flashover by voltage controlled switches and the surge
arresters by the pseudo-nonlinear resistance modeled by the
voltage by the current standard curve for gapped silicon
carbide (SiC) surge arresters, as shown in Fig. 10.
This was made necessary for the, up till now, great amount
of units installed in the field of surge arresters with the older
technology gapped silicon carbide, being then possible to
compare the results.
Fig. 10. Voltage by the current non-linear curve for a standard gapped silicon
carbide (SiC) surge arrester for medium voltage distribution system class
15 kV.
The Fig. 11 shows the histogram of the simulation results
for the current dissipated by the surge arresters under the
network direct interception lightning discharge. In this
histogram, it is possible to see that the majority of the surge
arresters dissipation stayed between 1.5 to 10 kA.
On the other hand, Fig. 12 shows the histogram of the
6
simulation results for the terminal overvoltage in the
transformers generated by network direct interception
lightning discharge. From this histogram, it is possible to
notice that the medium voltage transformer class 15 kV, are
receiving surges bigger than its basic insulation level, between
a 100 to 500 kV.
Fig. 11. Surge arresters current dissipation histogram for direct interception
of the lightning discharge.
Fig. 12. Distribution transformers, 15 kV class, medium voltage terminal
overvoltage's histogram for direct interception of the lightning discharge.
In the opposite case, when the surge arresters and
transformers are under induced surges, it is notable the lower
intensities. As it is possible to see in Fig. 13, all of the current
dissipated by the surge arresters are under one kA.
Also for the transformers overvoltage's, we can see in
Fig. 14 that all of them are under the minimum transformer
basic insulation level of 95 kV for the 15 kV class.
In other words, when the distribution systems are in a dense
urban region, with many elevated structures that can deviate
and dissipate the lightning discharge, there is no problem or
fault occasioned by the induced surges in the transformers or
even in the surge arresters. In fact, not even the insulators are
requested, because none of the cases provoked surges bigger
than the lines critical flashover overvoltage. In these cases, the
worse problem will be the transferred surge to the low voltage
circuit, which cannot deal with that amount of energy.
Fig. 13. Surge arresters current dissipation histogram for induced surge.
Fig. 14. Distribution transformers, 15 kV class, medium voltage terminal
overvoltage's histogram for induced surge.
However, if the distribution system was intercepted directly,
a common situation in rural or less dense urban regions, the
surges achieve high values that are capable of causing a
transformer, an insulator, or even a surge arrester to fail. Table
II shows the probability of a direct interception lightning
discharge to cause a failure in a transformer, according to its
basic insulation level for the 15 kV class, or to cause an
insulator flashover, according to the lines critical flashover
overvoltage.
TABLE
II
R
ESULT
S
UMMARY FOR THE
S
IMULATIONS OF
D
IRECT
L
IGHTNING
D
ISCHARGE
I
NTERCEPTION
Condition
Probability
> BIL 95 kV
80.0%
> BIL 110 kV
75.6%
> CFO 150 kV
46.7%
> CFO 175 kV
35.6%
> CFO 200 kV
26.7%
> CFO 225 kV
22.2%
Table III summarizes the occurrence probability of
transformers overvoltage and surge arresters current, obtained
from the fitted distribution from all the simulations.
Although, as it considers half of the cases as a direct
interception and the other half as induced surges, it must be
properly pondered with the bigger probability of the induced
7
surges, which could indeed decrease the values shown. Since
there are 45 cases of direct interception, it should have
300 cases of induction, or 7 times more, considering a direct
interception probability of 15%.
TABLE
III
P
ROBABILITY
S
UMMARY FOR
A
LL OF THE
S
IMULATIONS
Probability
%
Transformer
Overvoltage
[kV]
Surge
Arrester
Current [A]
5
341.2
7,394.0
10
236.8
5,683.2
50
65.3
1,710.8
90
18.0
260.1
95
12.5
126.6
35
95.0
------
30
110.0
------
By doing a simply pondered adjustment of Table III, the
"corrected" values of Table IV are achieved.
TABLE
IV
P
ROBABILITY
S
UMMARY
:
A
DJUSTED
V
ALUES
Probability
%
Transformer
Overvoltage
[kV]
Surge
Arrester
Current [A]
5
116.21
4,612.70
10
90.79
2,514.12
50
38.00
39.94
90
15.91
0.001
95
12.43
0
9
95.0
------
5
110.0
------
V. F
IELD
V
ALIDATION
Through a research and development project in partnership
with AES Sul Brazilian utility, approximately 300 gapped
silicon carbide surge arrester unities had been removed from
the same distribution urban network of the simulations. These
units were submitted through an analysis technique for the
measurement of the bigger current intensity that the surge
arrester had discharged; this is done based on the electrodes
etchings measurement and comparison with laboratory made
marks. From this great data volume, the graph of Fig. 15 was
traced, in which it is possible to verify the great proximity and
similarity between the simulated and real measurement cases.
It is clearly in Fig. 15 that, mainly for the current intensities
with 50% probability or greater, both curves present a great
similarity, in fact, only below the 40% probability that the
curves diverge a little. From the graph, we can notice that the
occurrence of current intensities of 700 A or lesser possesses
probability equal or superior to 50%. For a 10% probability,
we have that the current intensity situates in the band of 5 to
6 kA, for a current intensity of 10 kA the probability will be
approximately 5%, and for a current intensity of 20 kA the
probability will be approximately 2%.
Fig. 15. Field fitted distribution vs. simulation fitted distribution comparison.
VI. C
ONCLUSIONS
The effect studies of the lightning discharges on the
electrical systems are complex and time demanding, because
they involve a lot of factors and modeling. The proper process
of the discharge is very difficult of being explained, for this
reason, generating a wide gamma of modeling possibilities,
each one adapted to the necessity of a specific study.
In addition, the simulation process of the effect of the
lightning in the distribution systems is sufficiently complex by
the great amount of influence factors, such as the network
topology, installed equipment, system shielding, installed
protection, elevated structures in the neighborhoods, amongst
others.
To avoid all these difficulties, some rational attitudes are
necessary to reach a simplified level in the process without
changing the simulation results from the practical values,
keeping it with an adopted tolerance. This implies in the
research and development of models that can reach a balance
between the modeling complexity and the results similarity,
further statistical simulations, through the Monte Carlo
Method, are made to reach a good response from the
simulations.
Through the development of many studies in the High
Voltage Lab. of the Federal University of Itajubá (LAT-EFEI),
Brazil, the LIOV-EFEI code is developed for the calculation
of induced overvoltages in distribution networks [2,3,13]. This
is based on the LIOV code developed at the University of
Bologna, however, adapted to the conditions in which it would
be used in the LAT-EFEI, generating an extremely practical
and efficient code.
Moreover, the development of a simulation routine became
necessary, which the use of the stochastic process. This
routine has as objective the effect simulation of the lightning
discharges on the medium voltage overhead distribution
systems, by the direct interception of it or through
electromagnetic induction. Thus an entire simulation program
was developed, which uses geographic databases with all the
pertinent information of the network, beyond user data and the
Monte Carlo Method.
With the use of the real data from the network, statistical
8
procedures and some approaches, the simulation routine
reached a high capacity of generating cases with an excellent
similarity with field results. Through these system
performance simulations for lightning surges, it is possible to
figure the improvement possibility of the system protection.
Where, for predominantly rural systems, the surges by
lightning direct impact stayed below 4% probability, with an
average current intensity of the order of 40 kA and
overvoltage of the order of 6 kV.
On the other hand, for the less dense urban network, that is,
small towns, where the number of elevated structures is small,
it has a direct impact index with 15% of probability. However,
for an urban network of the metropolitan region, with a higher
density of constructions, an index of only 2% of direct impact
was achieved. The result for an average case had presented
around 10% probability of direct interception by the
distribution system, with the average current intensity of the
order of 12 kA and average overvoltage intensity in order of
31 kV.
Consequently, it is thus evidenced the importance of the
system type to be analyzed, regarding the lightning discharges.
Therefore, systems in rural regions and different systems in
urban regions present very different results. However, it is
obvious the importance of better studies of the surges
provoked by electromagnetic coupling over the ones caused
by direct interception, where the average probability stayed
around 90% of the cases being by induction.
Analyzing the results of the electromagnetic transient
simulations it is possible to observe that, for induced surges:
none surge arrester dissipated current superior than 1 kA; none
transformer was submitted to an overvoltage superior to its
basic insulation level (BIL) and the occurrence possibility of a
flashover in the insulators only could be verified in 2 cases,
that is, 4%.
As this represented around 90% of the cases, it is evident
that the medium voltage overhead distribution systems would
not be subjected to failures or interruptions caused by induced
surges. However, to this be an absolute truth, the operational
condition of the surge arresters, insulators and the
transformers withstanding must be in satisfactory conditions.
Indeed, through laboratory tests on transformer unities, even
new ones, it was possible to notice that it is not true for the
majority of the cases.
It is also important to remind the necessity of the presence
of surge arresters in each medium voltage terminal of every
transformer installed in the system and even through the
network. A condition that, not rare, is verified inadequate or
for the lack of units or by miss-specification. As a result, we
have that the no observance of all the above requirements,
mainly for the transformers and surge arresters, let the system
into situations of failures, faults or interruption even in the
cases of the lightning-induced surge.
Although for the simulated cases of direct interception, the
situation becomes critical. Since it has that: the average
current dissipated by the surge arresters goes up for an average
of 9 kA; the transformers overvoltage's surpassed the
withstanding in 80% of the cases and the flashover probability
in the insulators was next to 50%.
Table V contains a summary of the electromagnetic
transient performance simulations of the system, in the cases
of surges by induction and direct impact.
TABLE
V
S
UMMARY OF THE
R
ESULTS OF THE
T
RANSITORY
S
IMULATIONS OF
E
LECTROMAGNETIC
Surge Arresters
Discharge Current [A]
Transformers
Overvoltage [kV]
Surge
Min.
Avg.
Max.
Min.
Avg.
Max.
Induced
22
283
892
10
27
53
Direct
Impact
680
4,779 48,412
39
214
2,173
It is possible to notice by the values presented in the Tables
II, IV, and V that for the condition of surge caused by direct
interception, the probability of failures and interruptions in the
system could be very high. In the surge arresters, the
dissipated current reached the mark of 48 kA, intensity
superior to the capacity of almost all of the surge arresters for
distribution networks class 15 kV. For the transformers, the
fault probability stayed between 70 and 80%, as the average
overvoltage value of 214 kV is very superior the biggest
standard BIL of 110 kV. As for the flashover probability in the
insulators, for the standard condition of 150 kV of critical
flashover overvoltage (CFO), it achieves 50%, however, this
value can be reduced to 20% with the increase of the lines
CFO to 225 kV. Therefore, for the direct interception surges in
the system, the possibility of an interruption is almost certain.
To validate the simulations, a comparison of the results with
the current intensities dissipated by the gapped silicon carbide
surge arresters units removed from the field was made,
Fig. 15. In which, the similarity of the simulations with the
real cases can be verified, occurring a little distortion for the
probabilities lower that 40%, where the simulations had
presented bigger values than the real cases. These differences
could be attributed to the approach used and the
simplifications adopted, which tend to present a small error
regarding the physical event that they model, consequently,
the sum of these errors cause the verified discrepancy, indeed
leading to an overestimated result, the worse situation.
Finally, some best practices for the utilities are shown
below:
A. Surge Arresters
It is very important to attempt to the correct specification
and quality of the surge arresters, as well as searching for the
best cost versus benefit in its use (quantity and displacement
through the network). Where, through studies of insulation
coordination, it is possible to achieve the best distribution of
the units, reaching a balance between the maximum protection
and the minimum of units.
It was demonstrated that, for rural systems, the surge
arresters must have the capacity of withstanding the maximum
current of 40 kA. On the contrary, for urban systems, it is
more than appropriate to work with units that have a
maximum capacity of only 10 kA. Since the network is
entirely composed of overhead lines and the transformers has
9
an assured quality and withstanding capacity.
B. Insulators
It is evident that raising the insulators BIL, and
consequently the line CFO, is possible to reduce significantly
the possibility of flashovers and subsequent failures in the
occurrence of surges.
C. Transformers
To get the best protection condition of the transformers,
preventing failures by lightning discharges, it is essential that
they always were specified with the biggest BIL of its class.
Beyond always using surge arrester unities, correctly
specified, in each of its terminals.
It is recommended that regular statistical verification of the
new unities should be made, to certify and assure its quality.
One of the tests that can better assure the quality of a
transformer is the voltage impulse test.
A
CKNOWLEDGMENT
The authors gratefully acknowledge the support given by
the Prof. Carlo Nucci of the University of Bologna, Italy,
helping in the development of the LIOV-EFEI code. The
authors also gratefully acknowledge the support technically,
financially, and the supplied information by the AES Sul
utility, Brazil, special thanks to the M.Sc. Eng. Hermes R. P.
M. de Oliveira.
R
EFERENCES
[1] Marco A. M. Saran, "Lightning Overvoltage's in Medium Voltage
Lines", Master Thesis, Federal University of Itajubá, Brazil, Feb. 2009.
[2] Manuel L. B. Martinez, Pedro H. M. dos Santos, "Study of the Induced
Voltages in Distribution Networks, Guide for the Performance
Improvement of the Overhead Distribution under Lightning
Discharges", High Voltage Lab., Federal University of Itajubá, Brazil,
March 2004;
[3] Carlo A. Nucci, Mario Paolone, "Calculation of Induced Voltages in
Medium Voltage Overhead Systems due to Lightning Strokes Using the
LIOV Code", Report for the Second Phase of the R&D Project for the
AES Sul Utility, October 2003;
[4] Marco A. M. Saran, Rafael R. Bonon, Manuel L. B. Martinez, Hermes
R. P. M. De Oliveira, Carlo A. Nucci, Mario Paolone, "Performance of
Medium Voltage Overhead Distribution Lines Against Lightning-
Induced Voltages: A Comparative Analysis", GROUND'06 e 2nd LPE -
International Conference on Grounding and Earthing & 2nd
International Conference on Lightning Physics and Effects, Maceió,
Brazil, November, 2006;
[5] Marco A. M. Saran, Manuel L. B. Martinez, Hermes R. P. M. De
Oliveira, "Performance of Medium Voltage Urban And Rural
Distribution Lines Front Lightning Discharges And Induced Surges",
GROUND'06 e 2nd LPE - International Conference on Grounding and
Earthing & 2nd International Conference on Lightning Physics and
Effects, Maceió, Brazil, November, 2006;
[6] Marco A. M. Saran, Rafael R. Bonon, Manuel L. B. Martinez, Hermes
R. P. M. De Oliveira, Carlo A. Nucci, Mario Paolone, "Performance of
Medium Voltage Overhead Distribution Lines Against Lightning
Discharges", International CIGRÉ Symposium TPLEPS Transient
Phenomena In Large Electric Power Systems, Zagreb, Croatia, April
2007;
[7] Marco A. M. Saran, Manuel L. B. Martinez, Hermes R. P. M. de
Oliveira, "Performance of Medium Voltage Urban and Rural
Distribution Lines Front Lightning Discharges and Induced Surges",
15th International Symposium on High Voltage Engineering, Ljubljana,
Slovenia, August 2007;
[8] Marco A. M. Saran, Manuel L. B. Martinez, Carlo A. Nucci, Mario
Paolone, Hermes R. P. M. de Oliveira, "Performance Analysis of
Medium Voltage Overhead Distribution Line Against Lightning", 19th
CIRED, International Conference on Electricity Distribution, Vienna,
Austria, May 2007;
[9] Marco A. M. Saran, Manuel L. B. Martinez, Carlo A. Nucci, Mario
Paolone, Hermes R. P. M. de Oliveira, "Comparative Performance of
Medium Voltage Overhead Distribution Lines Designs Submitted to
Induced Voltages", Power Tech, Lausanne, Switzerland, July 2007;
[10] IEEE Guide for Improving the Lightning Performance of Electric Power
Overhead Distribution Lines, IEEE Std 1410-2004, T&D Committee,
IEEE Power Engineering Society;
[11] John G. Anderson, Thomas A. Short, "Algorithms for Calculation of
Lightning Induced Voltages on Distribution Lines", IEEE Transactions
on Power Delivery, Volume 8, Number 3, Pages 1217-1225, July 1993;
[12] Parameters of Lightning Strokes: A Review, Lightning and Insulator
Subcommittee of T&D Committee, IEEE Transactions on Power
Delivery, Vol. 20, No. 1, January 2005;
[13] Pedro H. M. dos Santos, "Performance Analysis of Medium Voltage
Circuits Front Induced Lightning Impulses", Master Thesis, Federal
University of Itajubá, Brazil, March 2007;
[14] Ricardo G. de Oliveira Jr., "Induced Voltages in Medium Voltage
Lines", Master Thesis, Federal University of Itajubá, Brazil, August
2008;
[15] Andrew R. Hileman, "Insulation Coordination for Power Systems",
Marcel Dekker Inc., 1999;
[16] G. Vernon Cooray, "The Lightning Flash", IEE Power Series, Volume
34, 2003;
[17] Lou van der Sluis, "Transients in Power Systems", John Wiley & Sons,
2001;
[18] Mustafa Kizilcay, "Power System Transients and Their Computation",
Osnabrück University of Applied Sciences, Germany, 2000;
[19] Protection of MV and LV Networks against Lightning, Joint CIGRE-
CIRED Working Group C4.4.02, 2005;
Marco Aurélio M. Saran received his B.Sc. and M.Sc. degrees in electrical
engineering from the Federal University of Itajubá, Brazil.
Currently, he is a Consultant and Researcher of the High Voltage Lab. of
the same university, dealing with research and development projects, tests on
electrical equipment, among other activities. He is involved in the electric
power system area, especially insulation coordination, reliability and
distribution systems. He is author or co-author of several papers and technical
reports.
Manuel Luiz B. Martinez received his B.Sc. and M.Sc. degrees in electrical
engineering from the Federal University of Itajubá, Brazil and his Ph.D.
degree in electrical engineering from the São Paulo University, Brazil.
Currently, he is Full Professor in power systems of the Federal University
of Itajubá and the Main Professor of the High Voltage Lab. at the same
university. He is involved with the electric power system area and his research
interests include high voltage, electromagnetic compatibility, power systems
transients, reliability, insulation coordination, electrical distribution,
transmission and energy efficiency. He is author or co-author of several
papers, technical reports and journal publications.
Excerpt out of 9 pages
- Quote paper
- Marco Saran (Author)Manuel Martinez (Author), 2009, Analysis of Overhead Distribution Lines Performance under Lightning Surges, Munich, GRIN Verlag, https://www.grin.com/document/338848
Similar texts
Publish now - it's free
✕
Excerpt from
9
pages
Comments