In today circumstance, rapid development of power system network cause the fault current of the system increased greatly . The levels of fault current in many places have often exceeded the withstand capacity of existing power system equipment. As implication to this matter ; security , stability and reliability of power system will be negatively affected . Thus , limiting the fault current of the power system to a safe level can greatly reduce the risk of failure to the power system equipment due to high fault current flowing through the system. Because of that, there is no surprise to fault current limiter (FCL) become a most favourite research since this technology can limit the fault current .

2. Project Group Member
Name Enrollment No.
Jariwala Dhaval 090420109001
Topiwala Jaykumar 090420109010
Parmar Ronal 090420109031
Master Chirag 090420109062
Kulkarni Girishkumar 090424109403
Guided By
Prof . Rajesh Prasad

3.  INTRODUCTION :-
• In today circumstance, rapid development of power
system network cause the fault current of the system
increased greatly .
• The levels of fault current in many places have often
exceeded the withstand capacity of existing power system
equipment.
• As implication to this matter ; security , stability and
reliability of power system will be negatively affected .
• Thus , limiting the fault current of the power system to a
safe level can greatly reduce the risk of failure to the
power system equipment due to high fault current flowing
through the system. Because of that, there is no surprise to
fault current limiter (FCL) become a most favourite
research since this technology can limit the fault current .

4. In Present

5. • Let Assume 7500 KVA be the base KVA ,
• % Reactance of generator A on the base KVA = 7*7500/3000 = 17.5%
• % Reactance of generator B on the base KVA = 8*7500/4500 = 13.34%
• % Reactance of transformer on the base KVA = 7.5*7500/7500 = 7.5%
• Short circuit KVA = (7500 *1090 ) / 11.36 = 66,021 kVA
• Short-circuit current = ( S/C kVA) / (√3 * Voltage)
= 66,021 / (√3 * 3300 )
= 11.5506 kA
• Rating of C.B = 12kA , 66MVA

6. Single line diagram of system in figure without FCL
In Future

7. • Let Assume 7500 kVA be the base kVA ,
% Reactance of generator A on the base kVA = 7*7500/3000 = 17.5%
% Reactance of generator B & C on the base kVA = 8*7500/4500 = 13.34%
% Reactance of transformer on the base kVA = 7.5*7500/7500 = 7.5%
Short circuit kVA = 7500 * 100 / ( 7.3921 ) = 101,459.66 kVA
Short-circuit current = ( 55440) / (√3 * 3300 ) = 17.75 kA
Rating of C.B = 20kA , 100MVA

8. In Future With FCL

9. • Let Assume 7500 KVA be the base KVA ,
% Reactance of generator A on the base KVA = 7*7500/3000 = 17.5%
% Reactance of generator B & C on the base KVA = 8*7500/4500 =13.34%
% Reactance of transformer on the base KVA = 7.5*7500/7500 = 7.5%
Short circuit KVA = 7500 * 100 / (12.4362) = 60,307.81 KVA
Short-circuit Current = (60,307.81) / (√3 * 3300) = 10.55 KA
Rating of C.B = 12kA , 66MVA

10. IN PAST
WITHOUT
FCL
IN
PRESENT
WITHOUT
FCL
IN
PRESENT
WITH
FCL
CIRCUIT
DIAGRAM
SHORT
CIRCUIT
CURRENT(KA)
11.56 17.5 10.50
C.B
RATING 12KA ,66MVA 20KA , 100MVA 12KA , 66MVA

11.  At normal state the FCL is expected to :-
1. Have a low insertion impedance
2. Able to withstand distribution and transmission level
voltage and current rating
3. Have a low voltage drop
4. Have a low power loss

12.  In case of a fault, the FCL is required to :-
1. Be capable of limiting the first fault current peak
2. Large increase of impedance
3. Have an acceptable power loss
4. Tolerate the mechanical stresses
5. Endure the temperature rise
6. Withstand the fault condition for a sufficient time
7. Be capable of fast transition from normal to faulted
state and vice versa.

14. TYPES OF FCL :-
• Depending upon the method used to increase
the series impedance, the current limiters can
be broadly classified into the major types as,
1. Reactor
2. Super conductors (resistive)
3. Power electronic

15. Reactor Current Limiters
Bus-Bar
Reactor
G1 G2 G3
Feeder

16. Super Conducting Current limiters
• These types of current limiters are based on
super conducting materials (YBCO, NBCO etc). For
super conductors to remain in super conducting
state, the conditions to be satisfied include:
»The temperature is lower than the limit.
» The magnetic flux is lower than the limit.
» Current density is lower than the limit.
• When one or more conditions are not met then
the conductor comes out of super conduction
state and offers high impedance .

17. Advantages :-
• Distortion only during first cycle.
• Size may be small, because HTS performs
limiting action.
• Passive triggering
• Re-cooling required.
Disadvantages :-

18. Power Electronic Current Limiters
• These types of current limiters are based on the use of solid
state switches (SCR, GTO, IGBT etc) and are at present limited to
applications in low voltage and medium voltage systems.
• The basic principle is to turn off a series connected solid state
switch and increase the impedance of the network and
effectively limit the fault current.

19.  Solid state fault current limiter ( SSFCL ) :-
 Types of solid state fault current limiter :-
1. Resonant circuit current limiters
2. Resistance fault current limiter

20. 1. Resonant Circuit Current Limiters :-

21. 2. Resistance fault current limiter :-

22.  SSFCL advantage :-
• Limited fault current.
• Limited inrush current (soft start), even for capacitive loads.
• Repeated operations with high reliability and without wear-
out.
• Reduced switching surges.
• Improved power quality for healthy lines.

23. Fault-Current Limiter Applications :-
• Fault-current limiters can be applied in a
number of distribution or transmission areas.
1. Generator FCL
2. Feeder FCL
3. Bus-Bar FCL

24.  Generator FCL :-
• Advantages :-
1. The fault-current limiter FCL
protects the entire bus.
2. A larger transformer can be used to
meet increased demand on a bus
without breaker upgrades.
3. I2t damage to the transformer is
limited.
4. A large, low impedance transformer
can be used to maintain voltage
regulation at the new power level.

25. Feeder FCL :-
• Fault-current limiter in the
feeder position. The fault-
current limiter FCL protects an
individual circuit on the bus.
• The selective application of
small and less expensive
limiters can be used to protect
old or overstressed equipment
that is difficult to replace, such
as underground cables or
transformers in volts.

26.  Bus-Bar FCL :-
• Advantages :-
1. Separate buses can be tied together without a large increase in the fault duty on
either bus
2. During a fault, a large voltage drop across the limiter maintains voltage level on the
un-faulted bus
3. The paralleled transformers result in low system impedance and good voltage
regulation; tap-changing transformers can be avoided
4. Excess capacity of each bus is available to both buses, thus making better use of the
transformer rating

27.  Case-study from Iran Power Network :-
• The short circuit analysis of the power
network was done based on the actual and
future network specifications which have been
designed and published by Iran Generation
Transmission & Distribution Company.
• This method allows decreasing of 27% in fault
current amplitude.

28. • At the beginning, generating units were separated
from each other. But by increasing the electrical
demand and in order to increase the system stability
and reliability, they gradually became interconnected
and more generating units, substations, parallel
transmission lines, series and parallel capacitors were
installed.

29. • One of the problems related to the growth of the
transmission and distribution of electrical energy system is the
fast increase in the short circuit level that may cause the
following effects:
i. Overheating the series devices in the fault route.
ii. Producing very high mechanical forces in the
transformers, generators and reactors.
iii. Power system stability can be lost depending on the
fault current amplitude as well as its clearing time.
iv. Decreasing in reliability of electrical network.

30.  There are generally three solutions to remove
those effects:
1. To design power network in a way that
probability of occurring a fault be low enough.
2. Using applicable strategies in order to minimize
the network damage when a fault occurs.
3. Using fault current limiter depending short
circuit current level of each desired bus of power
system.

35. Economical observation
• For this observation, the high
voltage substation of
FirouzBahram was considered.
• In year 2011 due to increasing
short circuit current level, all
circuit breaker of this substation
must resize and again reinstall.
• Price of C.B of 50KA :-100,000$
• Price of C.B of 63KA :-165,000$
• Structure civil & reinstalling of
C.B = 3% of total fees
• All C.B replaced cost:- 1,700,000$
• Price of Plan = 850,000$

36. • the 850,000$ will be the
total price of plan which
contains any changing in
the actual circuit breakers
and using only the
combination method as
fault current limiter in the
best configuration such as
one presented in Fig.

37. • The price of basic components of this plan is as
follow as:
– two circuit breakers: 230,000$
– four sectionalizes; 80,000$
– three rectors and three capacitors; 400,000$
– three surge arrestors; 90,000$
• It shows a big benefit for this application. If the
substation had less than 12 circuit breakers this
benefit achieved to zero and it is more suitable to
change all circuit breaker with new ones.

38. Proposed scheme for Simulation and Hardware

39. Future Work :-
• We will simulate proposed scheme on
MATLAB.
• Later , implementation of Hardware will be
based on the simulation results.

40. References :-
a) Vibhor Chauhan, Rishi Pratap Singh and Seema Dhariwal ,
“Analysis of fault current limiter (FCL) for voltage sag
mitigation through MATLAB and simulink” , Journal of
Pune and applied science and techo , pp. 50-58 , Jan 2012 .
b) Hamid Javadi ,” Fault current limiter using a series
impedance combined with bus sectionalizing circuit
breaker”, Electrical power and energy systems , pp. 731-736
, Jan 2011
c) Vinod Gupta, U. C. Trivedi, N. J. Buch ,” Solid state fault
current limiter ” , National Power Electronic Conference
,IIT Roorke, 2010

41. d) Ram PARASHAR, Christian SASSE, Robin BANKS and
Leslie FALKINGHAM AREVA , “ Fault current
limiters for transmission & Distribution Network
” , T&D Technology Centre, United Kingdom , pp. 6-9 ,
June 2006
e) Michael Steurer , Klaus Frohlich , “Current limiter state of
art “, 15&16 July 1998