SYMMETRICAL FAULT DETECTION

2.  The system is aiming in keeping the power
system stability and continuity by regulating
the operation of distance relay during a power
swing and to mitigate the fault current with a
new improved FCL.

3.  Power swing is a common disturbance occurring in
power system.
 Undesired tripping of the distance relays should be
avoided during the power swing period.
 symmetrical fault at the time of power swing which
actually resembles the V & I of swing.
 Symmetrical fault during power swing can be
detected by Auto regression method and fault
mitigation can be achieved by SFCL

4.  The blocking of distance relays are actually making
large outages in power system.
 Large variations in voltage and current are having close
resembles with a symmetrical fault.
 Conventional methods are using wavelet transform,
Prony method, travelling wave analysis etc to identify.
 Symmetric nature of phase voltages and currents
during the swing makes this task tedious and become
inaccurate with these methods.

5. The method mainly aims at
• Analyzing the present situation.
• Executes the data obtained the data using auto
regression program.
• Predicts the future samples.
• Evaluating the results.
• Initiating the action on distance relay.

6. STUDY ON
POWER
SWING
SIMULATION
WITH
MATLAB -
SIMULINK
ANALYSIS OF
WAVEFORMS
CASE STUDY
ACTION ON
DISTANCE
RELAY
FILTERING
SYMMETRICA
L FAULT
COMPONENT
S FROM
POWER
SWING
APPLICATION OF
AUTOREGRESSIO
N
INTRODUCING
FAULT
MITIGATION
ANALYSIS
WITH
EXISTING
NETWORK
RESULT
ANALYSIS

8.  Auto regression is a special technique for
regression analysis.
 The technique models nth values of the system
as a function of K previous values.
 Higher values of K improves the system
prediction accuracy.

9.  The differential components of voltage and
current at any sampling instant of time are
calculated as follows:

10.  The rms values of differential voltage and
current are calculated over a period of one
cycle
Where N is the number of samples per cycle

11.  The differential power ΔP is calculated from
the rms voltage and current as

14. Load current

18. GENERATO
R
3 PHASE
FAULT
TRANSMISIO
N LINE
BUS LOAD
SFCL

19. ROLE OF SFCL
 SFCL possessing high stability margin and excellent mitigation
prior to conventional limiters .
 Ultrafast operation accomplished with automatic mode change.
 Using a superconducting FCL gives an economic advantage, if
technical problems can be solved at lower costs or if the usage of
a FCL makes savings in other equipment possible.
 This work deals with possible applications of a superconducting
fault current limiter in a high voltage transmission system
having a simulated power swing and fault.

22.  Provided with three fault current path with
internal select option.
 The MOV module is indented to work with
heavy fault currents.
 An associated spark gap with controlled
triggering is in gang operation with MOV.

23.  Virtually no voltage drop in steady state.
 Quick response times
 Effective current limiting
 Detection of fault current with in the first cycle
 No impact on voltage and angle stability
 No impact on normal operation of relays and
CBs
 Relatively low cost and maintenance

26.  The initial stage was going through the basic distance relay
mal operation and detection of symmetrical fault during
power swing.
 Auto regression based analysis is used to predetermine the
system behavior.
 SFCL based fault current mitigation is also inserted to
achieve a more stable network.
 The proposed scheme with and without SFCL have been
simulated with MATLAB-SIMULINK

27.  Detection of symmetrical fault during power swing is actually a
threat to power system protection.
 The initial stage was aiming at the auto-regression based study
of symmetrical fault components during the swing period.
 The thesis is thus proposing a SFCL fault mitigation scheme to
assure an improved reliability with the power system network.
 The simulated network shows clear role of SFCL in mitigating a
fault and there by improving the stability limits.

28.  [1] P. Kundur, Power System Stability and Control. New York: McGraw- Hill, 1994,
EPRI.
 [2] IEEE Power System Relaying Committee of the IEEE Power Eng. Soc., Power
swing and out-of-step considerations on transmission line. Rep. PSRCWGD6, Jul.
2005.
 [3] D. Tziouvaras, Relay performance during major system disturbances. 2006.
 [4] G. Benmouyal, D. Hou, and D. Tziouvaras, “Zero-setting power swing blocking
protection,” presented at the 31st Annu. Western Protect. Relay Conf. Washington,
DC, 2004.
 [5] B. Su, X. Z. Dong, Z. Q. Bo, Y. Z. Sun, B. R. J. Caunce, D. Tholomier, and A.
Apostolov, “Fast detector of symmetrical fault during power swing for distance relay,”
in Proc. IEEE Power Eng. Soc. Gen. Meeting, 2005, vol. 2, pp. 1836–1841.

29.  [6] H. Kazemi Karegar and B. Mohamedi, “A new method for fault
detectionNduring power swing in distance protection,” in Proc. IEEE
ECTICON,N2009, vol. 01, pp. 230–233.
 [7] X. Lin, Y. Gao, and P. Liu, “A novel scheme to identify symmetrical faults
occurring during power swings,” IEEE Trans. Power Del., vol. 23, no. 1, pp. 73–
78, Jan. 2008.
 [8] L. Xiangning, Z. Qing, L.Wenjun, W. Kecheng, and W. Hanli, “A fast
unblocking scheme for distance protection to identify symmetrical fault
occurring during power swings,” in Proc. IEEE Power Eng. Soc. Gen. Meeting,
2006, pp. 1–8.
 [9] L. Fu, Z. Y. He, R. K. Mai, and Z. Q. Bo, “Approximate entropy and its
application to fault detection and identification in power swing,” in Proc. IEEE
Power Energy Soc. Gen. Meeting, 2009, pp. 1–8.