NOVATEUR PUBLICATIONS

International Journal of Research Publications in Engineering and Technology [IJRPET]

ISSN: 2454-7875
VOLUME 3, ISSUE 6, Jun.-2017
INVESTIGATION OF FAULT CURRENT LIMITING TRANSFORMER USING
VARIABLE REACTANCE
MR. KENDRE SOMNATH M.
ME (Power System) Scholar, Department of Electrical Engineering, GHRIET, Pune, India

PROF. LAKADE C.R.

Assistant Professor, Department of Electrical Engineering, GHRIET, Pune, India

ABSTRACT: beneficial effect of limiting the transformer current

To demonstrate experimentally the capability without dissipating energy.
of a reactive variable impedance transformer to limit The inductance is reliant on on the geometry of
the fault current and set a secondary voltage is the the core and the windings. The change in the dispersion
goal of this task. This transformer is capable of inductance is effected by the addition of an additional path
changing its leakage reactance using a shift of a mobile of the flow stream between the core legs. If the 100%
iron core block. It plays threerole that is voltage inductive differential transformers design, the transformer
transformation, fault current limiting and voltage will not burn, even after a short circuit in the secondary
regulation. A small test device was developed and winding. Design development approaches practically
tested almost these functions. Its features should go oriented as a transformer for application in which a
ahead and they also explained. variable current such as neon signs, gas discharge lamps,
KEYWORDS: Transformer, Faults, Variable Reactance, and laboratory test instruments, etc. In addition, the
Current Limiting Transformer etc. control arc welding sets, the average power control to
motor conductors extension of electricity generating
I. INTRODUCTION: systems and isolated connection in electrical
Our planet and our society evolve us, in many systemssource an increase in fault current. Although many
cases, evolving ever-changing environment and types of fault current limiters have been proposed and
illustrations, we are forced to advance. All this comes out some are ongoing, most only work for the current limit and
to fulfill the emergence of new desires emerging from this the high cost and space required for their installation are
variant, global and regional trends and new technologies. difficult problems. Moreover, a certain quantity of
What was able to come out dated as a rush, recently was connection, causing voltage variations in the system
contemporary. Development will change quickly need to standard voltage distribution system power quality.
recognize manufacturers to respond with new, advanced A solution in the middle of the supply line feed
products. Also when applied to product care, this is distribution system is the construction of a step voltage
mature, transformer etc. In this document, the influence on regulator (SVR), which nevertheless requires an additional
the major markets understands that the global trend is cost, which does not limit the accuracy of the fault current.
acknowledged in the era of the transformer, and currently These problems will be avoided by the introduction of a
includes innovative forerunner dry transformers and large development and distributed generation. We
distribution, including liquid filled. propose the leakage resistance of the transformer, which
Conventionally, the transformer in power system can be controlled by moving the core block. A capacitor
was passive system, become active elements of the connected in parallel, consisting mainly of voltage
network to interact vigorously in the future, network transformation and has three functions to limit the fault
capabilities, to ensure reliability and efficiency. In the new current, voltage transformation, and voltage regulation.
design specification, taking into account in the design Therefore, the additional fault current limit, the consumer
transformer has been improved in order to strengthen power system and the transformer can be replaced by a
regulation and stability. Current control, plays an essential transform substation to receive and SVR. In addition, it is
role in their own industrial units, variable current used to control the loop current limit fault, the expected
transformer rating. These transformers have been power flow. Create a small transformer to try to improve
distributed to the primary and secondary windings. The the performance and characteristics of the experiment.
primary coil A, B, C is in one half of the core, a, b, c are
positioned at the opposite end of the core. Another II.LITERATURE SURVEY:
keymodification in the conventional design is a change in Junji Kondoh and Itaru Ishii explained the fault
inductance characteristics. Leakage inductance has the current limiting transformer with variable reactance. They
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 NOVATEUR PUBLICATIONS
International Journal of Research Publications in Engineering and Technology [IJRPET]
ISSN: 2454-7875
VOLUME 3, ISSUE 6, Jun.-2017
investigated on transformer reactance for fault current Exciting circuit for the transformer is omitted from Fig.
limiting. Attest experimentally the proficiency of a 1(a).
transformer with variable reactance to restrict the fault
current and to regulate the secondary voltage [1].
S. Blair and brilliant team investigate the future
basic need to limit the fault current in the United
Kingdom’s electrical system and a part of the technical
implications of this change. It is expected that
approximately 300-400 electrical distribution substations
will be led to limit the fault current, especially in light of
the static evaluation of the alleged violation of the failure
level. A case study on distributed generation (DG) through
a superconducting fault current limiter (SFCL) is exploited
topotential guard and control problems. In particular, it
Fig. 1(b) VECTOR DIAGRAM FOR EQUIVALENT CIRCUIT
addresses DG fault ride-through, auto shut-off and the
current input of the adapter may be unacceptable for SFCL
The relationship of each voltage vector is shown in
that need recovery period[2].
Fig.1 (b). Impedance Zs of the transformer and transmitted
Professor KK. Kulkarni innovation introduced in
apparent power St are andimpedance angles ϕ and a
the varactor transformer (Variable reactance coil) recently
power-factor angle θ.
introduced VRT or power supplies. It has an irresistible
contact between primary and secondary. Host belongs to
B. FAULT CURRENT LIMITATION:
the DC link signal line can be considered the best core
A short-circuit in secondary side is considered and it is
saturation transformer is not the voltage control device,
presumed that V2 drops to zero. In this fault situation, the
however, no one can get secondaryside ampere.[3].
secondary current I2fc is greater than 10 pu in the case of a
conventional transformer, whose impedance ZS is set to
III. PRINCIPLE:
less than 0.1 pu in order to evade large voltage fluctuation
The principles of the three tasks (voltage
at the normal situation. On the other hand, I2fc may be set
transformation, limiting fault current and voltage
below a given level in the case of the transformer with
regulation) and the role of a capacitor connected in
variable reactance, since its minimum reactance Xsmin can
parallel are designated in this section with an equivalent
be selected much higher than ZS of a conventional
circuit for this system.
transformer because of the control function mentioned.
A. EQUIVALENT CIRCUIT:
C. ROLE OF PARALLEL-CONNECTED CAPACITOR:
Since the current flow to a power system is delayed, a
secondary V2 voltage is lower than V1R in general.
However, this can be changed to lead by connecting a
capacitor with an appropriate capacity. Under this
condition, V2 may be higher or lower than V1R.

IV.DESIGN METHODOLOGY:
A small trial apparatus was manufactured in order
to demonstrate experimentally the functions described in
Fig. 1(a) EQUIVALENT CIRCUIT OF PROPOSED TRANSFORMER
Section II.
REFERRED IN SECONDARY

Fig.1(a) shows the equivalent circuit of this

system, which is valued in secondary side of the
transformer. Turn ratio, voltage, current, resistance, and
leakage reactance are denoted by a, V, I, R and X and
subscripts 1 and 2 show the primary side and secondary
side, respectively. Symbols in Fig. 1(b) are defined as
V1r=V1/a , I1r=aI1 , Rs=R1/a2+R2, Xs=X1/a2+X2 The variable Fig.2 (a) STRUCTURE OF PROPOSED TRANSFORMER (LATERAL
range of the reactance Xsis represented as Xsmin≤ Xs≤ Xsmax. VIEW)

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 NOVATEUR PUBLICATIONS
International Journal of Research Publications in Engineering and Technology [IJRPET]
ISSN: 2454-7875
VOLUME 3, ISSUE 6, Jun.-2017
fixed iron core completely. A plan view of the mobile
portion of the actuator shown in the figure.2 (b).
The drive unit comprises of a settling positioning
mechanism and a protection mechanism. The position
adjustment mechanism is a linear variable direct current
(DC) power supply actuator and adjusted in position on a
moving block that is in the state. The control supply This
DC is provided by a DC source that is controlled by a
microcontroller. This supply is controlled by the fault
current level. When an overcurrent flows through the
transformer winding, the mobile block is strongly pulled to
Fig. 2 (b) STRUCTURE OF PROPOSED TRANSFORMER (TOP VIEW)
the right in Fig. 2 (b) with a linear actuator. This internal
operation of the mobile core and the inductive reactance of
A side view of the same shown in the figure. 2 (A).
the outer envelope acquire the change of the overcurrent
The moving iron core block and the magnetic track located
control.
between the two windings. There are two air spaces
V. MATLAB SIMULATION
between the core portion of mobile iron and the fixed iron
Fig. 3 (a) shows the simulation diagram of
core and the sum of them is defined as the total length (l g)
MATLAB. This simulation tries to implement a variable
empty. When it moves to lock moving core iron core in the
transformer resistor to limit current flow. Transformer
vertical position, as shown in Fig. 2 (a). The moving block
load resistance in this simulation varies depending on the
and fixed iron core stationary in the distance. The position
test and error. The inductance L varies in the test base and
of the mobile block is defined as X = 0 mm when the
the failure of the value change induction so that the total
mobile block is completely inserted in the fixed core and
faultcurrent enters the limit and the waveform input and
the total depth when the mobileblock is projected from the
output voltage and current characteristics are analyzed.

Fig.3 (a) MATLAB SIMULATION MODEL OF PROPOSED TRANSFORMER

Fig. 3(b) WAVEFORM OF VOLTAGE BEFORE FAULT

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 NOVATEUR PUBLICATIONS
International Journal of Research Publications in Engineering and Technology [IJRPET]
ISSN: 2454-7875
VOLUME 3, ISSUE 6, Jun.-2017

Fig. 3(c) WAVEFORM OF CURRENT BEFORE FAULT

Fig.3 (b) and Fig.3(c) shows waveform of voltage and current before fault respectively. The phase voltage applied
is 210V, 50Hz.

Fig. 3(d) WAVEFORM OF VOLTAGE AFTER FAULT AT L=1H

Fig. 3(e) WAVEFORM OF CURRENT AFTER FAULT AT L=1H

Fig.3 (d) and Fig.3 (e) shows waveform of voltage and current after fault at L=1H respectively. Here L=1H is
transformer inductance at first and as seen in Fig 3(d), this waveform voltage deeps is very high after fault occurs. As seen
in Fig 3(e), this waveform current is extremely high after fault occurs.

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 NOVATEUR PUBLICATIONS
International Journal of Research Publications in Engineering and Technology [IJRPET]
ISSN: 2454-7875
VOLUME 3, ISSUE 6, Jun.-2017

Fig. 3(f) WAVEFORM OF VOLTAGE AFTER FAULT AT L=3.14H

Fig. 3(g) WAVEFORM OF CURRENT AFTER FAULT AT L=3.14H

Fig.3 (f) and Fig.5 (g) shows waveform of voltage REFERENCES:

and current after fault at L=3.14H respectively. Here 1) JunjiKondoh and Itaru Ishii, “Fault Current Limiting
L=3.14H is transformer inductance after fault and as seen Transformer With Variable Reactance,” IEEE
in Fig 3(d), this waveform voltage deeps is very low as TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY,
compared to L=1H after fault occurs as seen in fig.3(d). As VOL. 14, NO. 2, JUNE 2004.
seen in Fig 5(e), this waveform current is very low as 2) S. M. Blair; A. J. Roscoe ; C.D. Booth ; G.M. Burt ; A.
compared to L=1H after fault occurs as seen in fig.3 Teo ; C.G. Bright, “Implications of fault current
(e).Hence as a result it is determined that if inductance is limitation for electrical distribution networks,”
increased after fault then fault current can be restricted. Developments in Power System Protection (DPSP
2010). Managing the Change, 10th IET International
VI. CONCLUSION: Conference, ISBN: 978-1-84919-212-5DOI: 10.1049/
It is confirmed that the fault current limiting cp.2010.0355.
transformer with variable reactance has the following 3) Prof. S. M. Kulkarni, “VARIABLE REACTANCE
abilities: TRANSFORMER AN EMERGING TECHNOLOGY 1,”
 It transforms the voltage for wide extent of output National Conference on Recent Research in
current. Engineering and Technology (NCRRET -2015)
 It restricts the fault current enough because of high International Journal of Advance Engineering and
reactance without any action Research Development (IJAERD) e-ISSN: 2348 - 4470,
 The voltage is regulated by the reactance adjustment. print-ISSN: 2348-6406.

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