International Journal of Electrical, Electronics and Data Communication, ISSN: 2320-2084
Special Issue, June-2015
SERIES COMPENSATED TRANSMISSION LINE FAULT LOCATION
USING GPS SYNCHRONIZED VOLTAGE MEASUREMENT
VINAY KUMAR SONI
IEEE Student Member,
Department of Electronics Engineering,
RITEE, Raipur, Chhattisgarh, India
[email protected]
Abstract — The transmission line faults are very
often occurred and destroy the quality of power being
transmitted through the transmission line. The
detection of faults in a transmission line using
measurement of voltage or current using current
transformers is very common but its efficiency is
limited by the efficiency of the current transformers
which seems very poor. In this paper a new algorithm
is presented for fault location in series compensated
transmission lines with Fixed Series Capacitor (FSC).
The time domain modeling of a transmission line and
FSC system are used in this proposed algorithm. The
series compensated lines have limitations with metal
oxide varistor (MOV) operation, prefault system
condition, and high resistance fault and shunt
capacitance. The measurement of voltages may be
done using GPS technology for accurate
synchronization. This paper gives a fault-location
method for transmission lines using only
synchronized voltage measurements at both ends of
the line which eliminates the inherent errors due to
current transformers. This method is applicable for
both transposed and un-transposed lines. This method
is tested using results from a steady state faultanalysis program and EMTP, and generated voltage
signals are preprocessed, and phasor are estimated
through DFT algorithm in the MATLAB.
Keywords - Fault location, bus impedance matrix,
EMTP, Fault analysis, Synchronized phasor
measurement, DFT, Series Compensation.
I. INTRODUCTION
The continuous supply of the electric energy is always
affected by the different types of faults in power
systems. This aspect is very important for the
electrical energy or power companies providing the
continuous power to the consumers. Therefore, the
correct detection of the fault points in a transmission
line is very important for such companies for finding
and repairing the problem with minimum
maintenance cost, time and effort. Different faults
occurring in a transmission line may be Line-to-Line
fault, Line-to–Ground Fault, Double line-to-Ground
fault etc. A fault locator is used for identifying fault
location in a power transmission line. In a
transmission line having the long length, error in the
location of the order of few kilometers may be
acceptable, but it will be would represent a long and
DIPESH KUMAR SHARMA
Associate Professor,
Department of Computer Science & Engineering,
RITEE, Raipur, Chhattisgarh, India
[email protected]
hard walk in rough terrain for repair.
Several fault location algorithms are designed for the
detection of faults in a transmission line. The
ooperative algorithms in fault locators can be
classified in two categories: the algorithms based on
the fundamental frequency component [1–4], and
second, the algorithms utilizing the higher frequency
components of the fault signals such as methods
developed based on travelling waves on the
transmission lines [5–10].
Also the fault location algorithms can be further
categorized based on the some other parameters like
required data from the line terminals. There are two
main categories of this parameter; in the first category
required data are provided only from one line end
[1,6,7,11]. In such schemes, the detected fault
location is not accurate or the determination of precise
fault location is difficult, hence the line repair time
may be long. In the second type, synchronized or nonsynchronized measured voltages and currents are
sampled at the both line terminals [2,3,5,12,&13].
These methods are generally more precise; however,
they need a communication channel to be placed
between the local and remote line terminals. Some
algorithms use the lumped model used for the
transmission line and the shunt capacitance of the line
is ignored which results significant error in fault
location estimation while some others use p model of
the linen[14]. These methods introduce small errors in
results for the short transmission lines but such errors
are not negligible for long transmission lines. More
accurate results can be achieved by using the
distributed line model [15]. It should be noted that the
fault location algorithms are rarely applied in
transmission lines compensated by FSC, and a few
algorithms applied in the lines with FSC are often
time consuming or need several cycles data of post
fault [16,17].
It is known that the FSC (Fixed Series Capacitor) &
TCSC (thyristor controlled series capacitor) are
important members of Flexible AC Transmission
System (FACTS) family; because they are capable of
changing the transmission line impedance and load
current continuously [18]. A typical TCSC module
consists of a series capacitor with a parallel path
thyristors valve in series with an inductor known as
the Thyristors Controlled Reactor (TCR). For
protecting these elements during the fault condition, a
Metal Oxide Varistor (MOV), an air gap and a
Series Compensated Transmission Line Fault Location Using GPS Synchronized Voltage Measurement
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International Journal of Electrical, Electronics and Data Communication, ISSN: 2320-2084
Special Issue, June-2015
breaker are installed in parallel with the capacitor and
a TCR. An FSC module consists of a fixed series
capacitor and a parallel with a MOV to protect this
element during a fault.
But the use of the series compensation creates certain
new problems for conventional fault locators and
protective relays in a transmission line compensated
by FSC & TCSC. FSCs have a complex transient
behaviour during the fault. The problem of fault
location in the series compensated transmission lines
has been considered in [23–25]. In that algorithm
requires synchronized voltage samples from both ends
of the transmission line. Two points for fault location
can be obtained, one in front and the other behind the
FSC. A new approach to identify the correct fault
point is proposed in this present paper applying an
impedance calculation technique for the calculation of
exact fault point.
following form:
II. FAULT LOCATION ON A TRANSMISSION
LINE USING SYNCHRONIZED PHASOR
MEASUREMENTS
In above figure the schematic diagram for series
compensated fixed capacitor type transmission line is
shown. As in equation (2) each element is a matrix of
dimension 3X3, the fixed capacitor injected to the line
has to be subtracted from actual impedance of the line
to get actual fault point of the system. But as shown in
the figure 3 the fault point is considered as a third bus.
So the new bus impedance matrix will be of
dimension 9X9. We are considering the third bus to
be faulted. Therefore change in the bus voltages on all
three buses due to the fault can be obtained by the
following equation:
The fault-location method considered here for
transmission lines uses only synchronized voltage
measurements at both ends of the line which
eliminates the errors due to CT [27]. The main
advantage of this method is that in this method
current-transformer
errors
in
the
current
measurements can be avoided. Since these errors can
be as high as 10%, the fault location is accurate with
this method and advantageous for long distances. The
transmission line for the study is shown in figure 1:
Fig.1. Transmission line considered for analysis.
Where Zs1abc and Zs2abc are three-phase source
impedance matrices (Ω) for bus 1 & 2 respectively.
And L is the length of the transmission line (km).
Zabc is the impedance matrix formed by self and
mutual impedances among phases (Ω/mile) and is
given by:
Now for a three-phase analysis, this line would be a
bus impedance/admittance matrix of the dimension
6X6. The bus admittance matrix will take the
Fig.2.A compensated transmission using FSC.
Where:
[0] is the Null matrix of dimension 3X1;
IFabc is three-phase fault current at the faulted bus
(i.e. bus 3) with direction as shown in Fig.2 having
dimension of 3X1; ∆Vi is the change in the threephase voltages at bus due to the fault at bus three and
its dimension is 3X1.
Zbusfault is the three-phase bus impedance matrix
with the fault considered at bus three. Its dimension is
9X9.
Now from equation (3), we can write:
In equation (4), Ybusfault is the three-phase bus
admittance matrix of dimension 9X9 and is equal to
the inverse of Zbusfault. It can be represented by
equation (5) given below. Each element of Ybusfault
Series Compensated Transmission Line Fault Location Using GPS Synchronized Voltage Measurement
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International Journal of Electrical, Electronics and Data Communication, ISSN: 2320-2084
is a matrix of dimension 3X3. Elements of the bus
admittance matrix Ybus (before fault) are known to
us. Using the connection of the system in Fig. 2, the
elements of Ybusfault can be related to the elements
of Ybus as shown in following equations (6)–(11):
Special Issue, June-2015
voltage ∆V3, L1 and L2. Thus the equations are
solved for L1 to get the fault location as:
Where P and Q are the vectors of dimensions 3X1 and
are given by:
Algorithm to for the Y bus (9x9) is as follow:
Fig.3.Transmission line with a fault.
In above equations (6)–(11), L1 and L2 are the
distances of the fault point from bus 1 and 2
respectively as shown in Fig. 2. ‘L’ is the total
length of the transmission line Zfabc is the threephase fault impedance matrix. Yabc is inverse of the
three-phase line impedance matrix per unit length,
i.e.
y abc   z abc 1 ____________(12)
So using equations (4)–(11), the following
equations can be formed:
033  Y11  y abc V1  y abc V1  yabc V3

L 
033  Y22  y abc
L

L1
L1
Start.
Read element data.
Step 1
Add element 1(ground as reference)
p=0, q=1.
{Zqi=Zpi,
Ziq=Zip,
Zqq=Zpq+Zpqpq}
Step 2
Add element 2
p=0, q=2
{Zqi=Zpi,
Ziq=Zip,
Zqq=Zpq+Zpqpq}
Step 3
Add element 3
p=1, q=2
{ Zli=Zpi-Zqi
Zil=Zip-Ziq
Zll= Zpl-Zql + Zpqpq
Modification of Zbus for elimination of lst node
Zbus(modified)=Zij(before
elimination)Zil*Zli*Zll-1
The above procedure from step 1 to step 6 is
same for zero sequence component of transmission
line.
Combination of both matrixes is 6*6 matrix.
Zabc =T-1 * Z012 * T.
Yabc = inverse of Zabc .
III. Modeling and simulation methodology
______(13)
y
y

V2  abc V2  abc V3
L2
L2

_______(14
Variables L1 and L2 are related as
L1  L2  L _______________(15)
Here equations (13) and (14) represent six complex
equations. Voltages at buses 1 and 2 are continuously
measured. So ∆V1 and ∆V2 are known. The unknown
parameters in the equations (13)–(15) are the fault
The simulation circuit diagram is shown in Fig. 4.
ATP (Alternate Transient Program) is a free version
of Electromagnetic Transient Program (EMTP) [28],
which is widely used to implement accurate and fast
electromagnetic
transient
simulation.
Time
synchronized samples are generated in ATP file. This
data is then processed in MATLAB. Algorithm for
fault location is implemented in MATLAB. The entire
implementation consists of two parts:
1. Simulation of power system in ATP.
2. Algorithm implementation in MATLAB.
Series Compensated Transmission Line Fault Location Using GPS Synchronized Voltage Measurement
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International Journal of Electrical, Electronics and Data Communication, ISSN: 2320-2084
IV. SIMULATION RESULTS
A 500-kV, 200-mile-long line, with fixed capacitor
and parallel connected MOV on source side was
chosen for simulation [27]. The parameters of this line
are in Appendix 1.
Fig.4. ATP model of the transmission line.
Algorithm applied for fault location of series
compensated line is simulated and the comparison is
shown in following Table 1, shows the results for all
types of fault at three different distances for two
different values of fault resistance. The percentage
error is calculated as:
% Error = Actual Location – Fault Location
Total Line Length
Special Issue, June-2015
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CONCLUSION
This paper presented an approach for locating the
fault in a transmission line using the synchronous
voltage measurement which also adopted the FSC. As
the errors in the case of current measurement
techniques may be very high for long distances which
will further reduce the quality of electrical power
therefore this technique will be very effective for fault
locations. GPS may be also adopted for synchronous
voltage measurement at both points of measurement.
Results showed that even for a long transmission line
the errors in the location are very small.
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