Proceedings of the 14th International Middle East Power Systems Conference (MEPCON’10), Cairo University, Egypt, December 19-21, 2010, Paper ID 220.
A Combined MODELS-TACS ATPdraw General Model
of the High Impedance Faults in Distribution Networks
Kamal M. Shebl, Ebrahim A. Badran, IEEE Member, and Elsaeed Abdalla
Electrical Engineering Department,
Faculty of Engineering,
Mansoura University,
Mansoura, 35516, Egypt
eabadran@ieee.org
Thevenin-type and Iterated-type.
MODELS.
Abstract - The High Impedance Faults (HIF) are the faults
which are difficult to detect by overcurrent protection relays. In
this paper a generalized HIF arc model is presented. The
proposed model is based on the dynamic arc resistance. A
combination between MODELS and TACS as supported tools in
ATP will be used. The proposed arc model is validated by
comparing the simulated results with the published results. The
comparison shows a good agreement. Finally, the validated
model is used to analyse many fault scenarios on the IEEE 13node radial distribution test feeder. The outputs confirm the
presented model validity..
It is simulated using
In [7] and [8] the HIF is modeled using a series of two
variable resistors; a transient arc resistor and a steady-state
higher fault-path resistor. The two series resistors have been
controlled using TACS. In [1] the diodes and polarizing ramp
voltages are used to control arc ignition instants. The arc
model consists of linear resistance, nonlinear resistance, and
DC and AC sources. Whereas, in [2], [9] and [10] the arc
model is treated using anti-parallel diodes with non-linear
resistance and only DC source.
Index Terms - Modeling, Arc Model, HIF, Distribution Network,
ATPdraw.
In [11] a HIF model using two time-varying resistances is
presented using MODELS. Finally, in [3] a universal arc
model is introduced to represent the HIF arc fault’s feature.
This model is based on TACS.
I. INTRODUCTION
Detection of high impedance faults (HIF) still presents
important and unsolved protection problem, especially in
distribution networks [1]. When a conductor such as a
distribution line makes contact with a poor conductive surface
such as an asphalt road or a tree, the resulting level of fault
current is usually lower than the nominal current of the system
at the fault location. Therefore, the conventional protection
relay system will not be able to detect the HIF and/or trip the
appropriate protection relay [2].
In this paper the arc is proposed to be modeled using a
combination between MODELS and TACS in ATPdraw.
This will make a better utilization for the benefits of the two
tools in ATP. This can lead to generalization of the arc model
using ATPdraw.
II. THE PROPOSED HIF ARC MODEL
The arc of the HIF is proposed to be modeled using
MODELS in combination with TACS in ATPdraw. This
proposed strategy is more flexible and easy to use. It will
provide a general purpose icon in ATPdraw to represent the
HIF arc.
There are several models have been used for describing
the arcs. Most models are used for circuit breaker arcs and
several of them have been applied to long arcs or arcing faults
[3]. Furthermore, many software are used for analyzing this
phenomenon specially the transients programs.
The
ElectroMagnetic Transient Program (Alternative Version)
EMTP-ATP is used through many literatures' methods of arc
modeling.
The arc can be represented according to the principle of
thermal equilibrium using the following differential equation
[6]:
In [4] a realistic model of HIF incorporating non-linear
impedance, time-varying voltage sources and a controlled
switch -to yield the signal characteristics of arcing- is
presented. The main parts of this model were built using the
Transients Analysis Control System (TACS). Also, a digital
arc model which is derived from Hochrainer arc description is
used in [5]. It is based on energy balance in the arc. Whereas,
in [6], the arc is represented by two different components;
dg 1
= (G − g )
dt τ
(1)
i
(2)
G =
V arc
where g is the time varying arc conductance, G is the
stationary arc conductance, |i| is the absolute value of the arc
current, Varc is a constant arc voltage, and τ is the arc time
constant. The time constant can be given by;
527
τ = Ae Bg
It is evident that, the simulation time terminal is used to
enable the user to control the MODELS simulation time
regardless the overall ATP simulation step time. This makes
the MODELS solution very accurate.
Furthermore, a
feedback signal is used to update the arc conductance.
(3)
where A and B are constant parameters which represent
compromised values for positive and negative half cycles [3].
The steps of calculating of the arc conductance using
MODELS are arranged in the flowchart in Fig. 1. The
flowchart consists of; calculation of G, construction of the
main differential equation and its integration it. A feedback
signal is used in calculation to initiate the differential equation
solution. The arc conductance is updated at each time step of
solution. The arc resistance is modeled in power network
using TACS controlled resistance type 91 [12].
|i|
Varc
Simulation
Time
Measured
Current
Inputs
CTR
Rarc
HIF Arc
model using
MODELS
Outputs
RES
g
Measured
Fault
current
Feedback
G=| i |/Varc
Fig. 2: The ATPdraw HIF Arc Model using MODELS
III. VERIFICATION OF THE PROPOSED HIF ARC
MODEL
dg 1
= (G − g )
dt τ
Integrator
1/g
τ = Ae
The proposed HIF arc model is verified by comparing its
outputs with those published in [3]. The single line diagram
of the test system used for this verification is shown in Fig. 3.
The test system was picked from [3] and modeled using
ATPdraw as shown in Fig. 4 including the proposed HIF arc
model.
Bg
The test system operates at 20 kV. It consists of a 50 Hz
voltage source with 2.6% source impedance, Zs, and a 16
kVA, 0.234/20 kV transformer with 4.2% impedance, Ztr. A
capacitor divider of 100 pF and a calibrated resistance of
0.49 ohms are used with the system. For verification
purpose, the HIF is applied using the following fault
condition, Rtree=140.5 KΩ, A=5.6E-7, and B=395917 as
given in [3].
Arc resistance, Rarc
Fig. 1: The Flowchart of the Proposed HIF Arc Model
Fig. 2 illustrates the general view of the resultant
ATPdraw basic HIF arc model using MODELS. It consists of
five inputs; simulation time, the measured arc current, a
feedback signal (g) and two additional signals; CTR and RES.
CTR is a control terminal to enable the user to input any
additional control signal. RES is a reset terminal to enable the
user to coordinate with control signal. The outputs of the arc
model are time varying arc resistance, Rarc, and arc
conductance, g. The three input variables; Time, CTR, and
RES can be simulated using TACS to give the required signals
Zs
Ztr
I(t)
Rarc
G
Time
CTR
Thus, the proposed HIF arc model combines between the
simplicity of MODELS and the flexibility of TACS.
MODELS program is used in basic and iterative equation
processing. Whereas, TACS is used to enable the user to
input any type of control waveforms and/or reset signals.
This makes any type of faults, fault constants, and/or affected
power system constants can be manipulated through simple
terminals. So, the proposed model avoids the complexity of
existing TACS models and adds a flexible control to the
traditional black box MODELS subroutines.
RES
HIF Arc
model
using
MODELS
Rtree
Feedback (g)
Fig. 3: Single Line Diagram for the Test System Used for Validation of the
Proposed HIF Arc Model
Fig. 5a illustrates the ATPdraw-TACS model for the
required control circuit for generating CTR signal. This
signal represents the arc duration. Also, Fig. 5b shows CTR
528
output signal. Fig. 6a illustrates the ATPdraw-TACS model
for the required control circuit for generating RES signal. It
represents the duration of the insulation strength through the
arc. Also, Fig. 6b shows RES output signal
Fig. 7 introduced the comparison between the published
and simulated voltage and current at fault point. It is noted
that the peaks and the trajectories of both the voltages and
currents are similar. This figure ensures the validity of the
proposed model. It is clearly seen that the outputs of the
proposed model are in good agreement with that of the
published results.
Fig. 4: The ATPdraw Representation of the Test System Including the
Proposed HIF Arc Model
(a)
T
Published
200
CTR
Voltage ( x 0.1 KV )
150
100
50
a. TACS model for CTR
0
1.0
-50
0.8
-100
0.6
-150
Current (mA)
0.4
-200
0
0.0
0.00
0.02
0.04
0.06
0.08
0.02
0.04
0.06
0.08
[s]
(b) Simulated
0.10
(f ile arc 11.pl4; x -v ar t) t : C TR
b. CTR output signal
Fig. 7: Validation of the Voltage and Current of the Fault
Fig. 5: The TACS Representation of the CTR
IV. APPLICATION OF THE HIF ARC MODEL IN
GENERAL DISTRIBUTION SYSTEMS
T
To illustrate the general usage of the proposed HIF arc
model in distribution system analysis, a benchmark test
system is used. The IEEE 13 Bus test system is used in this
analysis [13]. The single line diagram of the system is shown
in Fig. 8.
RES
a. TACS model for RES
2.0
*10 -6
1.6
1.2
0.8
0.4
0.0
0.00
0.1
Time (S)
0.2
0.02
0.04
0.06
0.08
[s]
0.10
(f ile arc11. pl4; x-v ar t) t: R ESS
b. RES output signal
Fig. 6: The TACS Representation of the RES
Fig. 8: IEEE 13 Bus Test Feeder System
529
The test system is supplied from 115 kV, 50Hz, with1100
MVA short circuit at 82 degree AC source. A 5 MVA,
115/4.16 kV, delta/wye grounded substation transformer, and
a 500 kVA, 4.16/0.48 kV in-line transformer are used. Many
lumped parameter and π-equivalent, single phase and three
phase over-head and under-ground lines are used to connect
the system parts. Loads consist of wye and delta connected
spot, unbalanced, and distributed loads. They are mixture of
constant kW, kVAR, and Z as given in the appendix. Also,
balanced three phase and single phase shunt capacitors are
connected.
Fig. 10b shows the waveform of the fault current for
single-phase to ground fault at bus 675. This bus is a threephase unbalance load with normal load current of 97 A, 30
A, and 108 A for phases A, B, and C, respectively. The fault
is applied on phase C. It is shown that the fault current is
20.5 mA. This value is very small current compared with the
rated current.
Fig. 10c shows the waveform of the fault current for
single-phase to ground fault at bus 652. This bus is a twophase load with normal load current of 40.5 A and 43.8 A for
phases A and C, respectively. The fault current is 18 mA. A
new fault current profile can be notable.
Fig. 9 illustrates the ATPdraw model of the test system
including the HIF arc model. The analysis will based on
single-phase to ground fault, that most of HIF are single
phase to ground faults [14]. Many points were selected at
different locations that represent many types of loads in the
test system. The fault was applied at 20 ms and cleared at 95
ms at bus 646, bus 652, and bus 675, respectively. The buses
were selected due to their load type variety.
20
[mA]
15
10
5
0
MODEL
dv
-5
F
-10
Gu
-15
58
F
F
-20
0.00
0.02
0.04
0.06
0.08
[s]
0.10
0.06
0.08
[s]
0.10
0.06
0.08
[s]
0.10
a. Bus 646
650
T
25.00
[mA]
18.75
645
646
632
V
12.50
6.25
I
634
633
0.00
-6.25
-12.50
-18.75
611
684
V
671
-25.00
0.00
0.02
I
b. Bus 675
692
652
0.04
20
675
[mA]
15
10
5
680
0
Fig. 9: The ATPdraw Model of the IEEE 13 bus test System Including the HIF
Arc Model
-5
-10
Fig. 10a shows the waveforms of the fault current for
single-phase to ground fault at bus 646. This bus is a singlephase load with normal load current of 72 A. It is shown that
the bus current does not largely change during the fault. It is
shown that the fault current is 20 mA. This value is small
enough such that the over current protection does not sense it
compared with the rated current.
-15
-20
0.00
0.02
0.04
c. Bus 652
Fig. 10: The HIF Current Waveform for IEEE Test System
530
[6] M. Kizilacy and P. La Seta, “Digital Simulation of Fault arcs in
Medium-Voltage Distribution Networks”, 15th PSCC, Liege,
22-26 August, 2005.
[7] S. R. Nam, J. K. Park, Y. C. Kang, and T. H. Kim, "A Modeling
Method of a High Impedance Fault in a Distribution System
using Two Series Time-Varying Resistances in EMTP", Power
Engineering Society Summer Meeting, IEEE-SM, Vol. 2, 2001,
pp. 1175-1180.
[8] F. M. Uriarte, “Modeling, Detection, and Localization of HighImpedance Faults in Low-Voltage Distribution Feeders”,
December 15, 2003, Blacksburg, Virginia, M.Sc. Thesis.
[9] S. R. Samantaray, P. K. Dash, and S. K. Upadhyay, “Adaptive
Kalman filter and neural Network Based High Impedance Fault
Detection in Power Distribution Networks”, Electrical power
and Energy System 31, 2009, pp. 167-172.
[10] S. R. Samantaray and P. K. Dash, ''High Impedance Fault
Detection in Distribution Feeders using Extended Kalman Filter
and Support Vector Machine'', Euro. Trans. Electr. Power 2010,
pp. 382–393.
[11] Tao Cui, X. Dong, Z. Bo, A. Kilmek, and A. Edwards,
"Modeling Study for High Impedance Fault Detection in MV
Distribution System'', Universities Power Engineering
Conference, UPEC 2008, pp. 1-5.
[12] László Prikler and Hans Kristian Høidalen, "ATPdraw Version
5.6 for Windows 9x/NT/2000/XP/Vista - Users' Manual",
November 2009.
[13] IEEE Working Group on Distribution Planning, “Radial
Distribution Test Feeders”, Transactions on Power Systems,
Vol. 6, No. 3, August 1991.
[14] PSRC Working Group D15, "High Impedance Fault Detection
Technology", Report of PSRC, March 1, 1996.
The change of the influence of the fault current waveform
is notable. This is due to the change in fault location which
leads to change in the impedance angle between the source
and the fault point. This change in the influence of the
waveforms and the values of the fault currents confirm the
proposed model validity.
V. CONCLUSIONS
This paper introduces a generalized HIF arc model using
ATPdraw. The presented model is based on the dynamic arc
resistance. A combination between MODELS and TACS in
ATPdraw are used. The presented HIF arc model combines
between the simplicity of MODELS and the flexibility of
TACS. MODELS program is used in basic and iterative
equation processing. Whereas, TACS is used to enable the
user to input any type of control waveforms and/or reset
signals.
This makes any type of faults, fault constants,
and/or affected power system constants can be manipulated
through simple terminals. So, the proposed model avoids the
complexity of existing TACS models and adds a flexible
control to the traditional black box MODELS subroutines.
It is evident that, each part of the presented model can be
used separately in any other universal model. Also, the parts
of the model can be modified separately. So, the presented
model can be used as a generalized model for the HIF arc
using the ATPdraw.
The presented HIF arc model is validated by comparing
the simulated results with the published results. The
comparison has shown a good agreement. Finally, the model
is used to analysis the IEEE 13-bus radial distribution test
feeder through application of many faults scenarios. The
output waveforms of the analysis confirm the model validity.
APPENDIX
IEEE 13 Bus Test System Load Data
Node
634
645
646
652
671
675
692
611
REFERENCES
[1] M. Michalik, W. Rebizant, M. Lukowicz, S- Jae Lee, and S-Hee
Kang, “Wavelet Transform Approach to High Impedance Fault
Detection in MV Networks”, IEEE Power Tech., pp. 1-7, June
2005.
[2] T. M. Lai, L. A. Snider, E. Lo, and D. Sutanto, “Highimpedance Fault Detection using Discrete Wavelet Transform
and Frequency Range and RMS Conversion,” IEEE Transaction
on Power Delivery, Vol. 20, No. 1, January 2005, pp.397-407.
[3] Nagy I. Elkalashy, Matti Lehtonen, Hatem A. Darwish,
Mohamed A. Izzularab and Abdel-Maksoud I. Taalab,
“Modeling and Experimental Verification of High Impedance
Arcing Fault in Medium Voltage Networks”, IEEE Transaction
on Dielectrics and Electrical Insulation, Vol. 14, No. 2, April
2007, pp. 375-383.
[4] David chan, Tat Wai, and Xia Yibin, "A Novel Technique for
High Impedance Fault Identification", IEEE Transaction on
Power Delivery, Vol. 13, No. 3, July 1998, pp. 738-744.
[5] M. Kizilcay and T. Pniok, “Digital System Simulation of Fault
Arcs in Power Systems”, ETEP, Vol. 1, No. 1, January/February
1991, pp. 55–60.
531
Load
Ph-1
Model kW kVAr
Y-PQ
160
110
Y-PQ
0
0
D-Z
0
0
Y-Z
128
86
D-PQ
385
220
Y-PQ
485
190
D-I
0
0
Y-I
0
0
TOTAL 1158 606
Ph-2
Ph-3
kW kVAr kW kVAr
120
90
120
90
170
125
0
0
230
132
0
0
0
0
0
0
385
220
385 220
68
60
290 212
0
0
170 151
0
0
170
80
973
627 1135 753