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-:Supervisor :- -: Submitted by :-
Md. Abul kalam Sushil kumar (070912094)
Upawan kishor (0709120096)
Harshit Sihna (0609120022)
ObjectiveIn this project a fuzzy logic based faults
protection scheme for a transmission line will be studied and the technique will be developed on the basis of extension simulation studies carried out on the transmission line using MATLAB for different fault operating condition.
IntroductionTransmission line system is a large, geographically wide
distributed system.Fault on the transmission line is generally higher than that on
other component. Line fault are the most common faults. Transmission line faults be identified and to be determined
accurately and reliably in quick time.
What is fuzzy logic?"Fuzzy Logic is basically a multivalued logic. It is a different way of looking at the world. It is a superset of Boolean logic! Allows intermediate values to be defined
between conventional evaluations like yes/no, true/false, black/white, etc.
Notions like rather warm or pretty cold can be formulated mathematically and processed by computers."
Why use fuzzy logic?Fuzzy logic is conceptually easy to
understand.Fuzzy logic is flexible.Fuzzy logic is tolerant of imprecise data.Fuzzy logic can be blended with conventional
control techniques.Fuzzy logic is based on natural language.
Foundations of Fuzzy LogicEverything is vague to a degree you do not
realize till you have tried to make it precise.Fuzzy Sets. If-Then Rules. Fuzzify inputs Apply fuzzy operator to multiple part antecedents Apply implication method.
Fuzzy logic process
Fuzzy control systemFuzzificationRule-evaluationDefuzzification
Power system model
Faults parameters line length = 300 km; source voltages: source 1: v1 = 400 kV; source 2: v2 = 400 δ kV, where δ is∠ the load angle; source impedance (both sources): positive sequence impedance = 1.31 + j15.0; zero sequence impedance = 2.33 + j26.6; frequency = 50 Hz; transmission line impedance: positive sequence impedance = 8.25 + j94.5; zero sequence impedance = 82.5 + j308; positive sequence capacitance = 13 nF /km; zero sequence capacitance = 8.5 nF/km.
The Fault CurrentThe characteristic features of different types
of fault are found out in terms ofΔ1,Δ2 andΔ3,
r1 = max{rms(Ia)}/max{rms(Ib)},r2 = max{rms(Ib)}/max{rms(Ic)}r3 = max{rms(Ic)}/max{rms(Ia)}where Ia, Ib and Ic are the post-fault samples
of the three phase currents.
the normalized values of r1, r2 and r3
r1n = r1/max(r1, r2, r3)r2n = r2/max(r1, r2, r3)r3n = r3/max(r1, r2, r3)Finally, the differences of these normalised
values are found out as follows.Δ1 = r1n − r2n, Δ2 = r2n − r3n, Δ3 = r3n −
r1n
Calculation program for characteristic of faults Ia =input('enter ia') Ib =input('enter ib') Ic =input('enter ic') R1 = ia / ib R2 =ib /ic R3 =ic/ia I =r1; if(r2>r1) I =r2; end if(r3>r1&&r3>r2) I =r3; end R1n =r1/i R2n =r2/i R3n =r3/i D1 =r1n-r2n D2 =r2n-r3n D3 =r3n-r1n
Faults Characteristic measurementsfor AB fault
Faults Characteristic measurementsfor BC fault
Faults Characteristic measurementsfor CA fault
Faults Characteristic measurementsfor AG fault
Faults Characteristic measurementsfor BG fault
Faults Characteristic measurementsfor ABG fault
Faults Characteristic measurementsfor BCG fault
Faults Characteristic measurementsfor ACG fault
Faults Characteristic measurementsfor ABC fault
fault classification approach
Fault classification approach Developments of rules base for phase (line to line) faults:-1. If (d1 is low) and (d2 is high) and (d3 is medium) then
(output1 is AB) 2. If (d1 is medium) and (d2 is low) and (d3 is high) then
(output1 is BC) 3. If (d1 is high) and (d2 is medium) and (d3 is low) then
(output1 is CA) 4. If (d1 is medium) and (d2 is low) and (d3 is high) then
(output1 is CA) Where for phase faults “low” means a value between -1 to -
0.1 “medium” means a value between -0.45 to 0.45 and “high” means a value between 0.1 to 1.
Range of universe of discourse of membership function assigned for crisp output
Types of faults Range of membership function
AB 0 - 10
BC 10 - 20
CA 20 - 30
Dovelopments of rules base for phase to ground (single line to ground) faults: 1. If (d1 is high) and (d2 is medium) and (d3 is low) then (output1 is AG) 2. If (d1 is high) and (d2 is high) and (d3 is low) then (output1 is AG) 3. If (d1 is high) and (d2 is medium) and (d3 is medium) then (output1 is AG) 4. If (d1 is low) and (d2 is high) and (d3 is medium) then (output1 is BG) 5. If (d1 is low) and (d2 is high) and (d3 is high) then (output1 is BG) 6. If (d1 is medium) and (d2 is medium) and (d3 is medium) then (output1 is
BG) 7. If (d1 is high) and (d2 is low) and (d3 is high) then (output1 is CG) 8. If (d1 is medium) and (d2 is medium) and (d3 is high) then (output1 is CG) Where for phase faults “low” means a value between -1 to -0.25 “medium”
means a value between -0.05 to 0.25 and “high” means a value between 0.05 to 0.8.
Range of universe of discourse of membership function assigned for crisp output
Types of faults Range of membership function
AG 35 - 45
BG 50 - 60
CG 65 - 75
Developments of rules base for phase to ground (double line to ground) faults:
1. If (d1 is low) and (d2 is high) and (d3 is medium) then (output1 is ABG) 2. If (d1 is low) and (d2 is high) and (d3 is low) then (output1 is ABG) 3. If (d1 is medium) and (d2 is low) and (d3 is high) then (output1 is BCG) 4. If (d1 is low) and (d2 is low) and (d3 is high) then (output1 is BCG) 5. If (d1 is high) and (d2 is medium) and (d3 is low) then (output1 is CAG) 6. If (d1 is high) and (d2 is low) and (d3 is low) then (output1 is CAG) Where for phase faults “low” means a value between -1 to -0.1 “medium”
means a value between -0.45 to 0.45 and “high” means a value between 0.1
to 1.
Range of universe of discourse of membership function assigned for crisp output
Types of faults Range of membership function
ABG 80 - 90
BCG 95 - 105
CAG 110 - 120
Output for different faultsd1 d2 d3 Crisp
outputType of fault
-0.9437 0.9973 -0.0536 5.1 AB
-0.0535 -0.9438 0.9973 20 BC
0.9973 -0.0535 -0.9438 24.9 AC
0.7482 0.2075 -0.9557 40 AG
-0.9557 0.7480 0.2077 55 BG
0.2076 -0.9557 0.7482 70 CG
-0.9375 0.9968 -0.0593 85 ABG
-0.0592 -0.9377 0.9968 100 BCG
0.9968 -0.0593 -0.9375 115 ACG
ConclusionA fuzzy logic based faults classification scheme is proposed to
identify all the ten types of shunt faults for the wide variation in operating conditions of a three phase transmission line.
The technique is developed on the basis of extensive simulation studies carried out on the transmission line using mat lab toolbox.
To apply the proposed technique three phase post fault current are measured(in R.M.S) at one end of the transmission line, generated for different of faults for a large number of test cases .In order to apply the technique features characteristic are extracted from the fault
References [1] Majid jamil , Md. Abul kalam and A. Q. Ansari, “fault
classification of three phase transmission line using fuzzy logic”, National conference on recent advances in electrical & electronic engineering (RAEEE-09), NIT Hamirpur , pp. 181-186.
[2] Huishing wang and W.W.L.keerrthibala “fuzzy- neuro approach to fault classification for transmission line protection,” IEEE transmission on power delivery, Vol. 13, no. 4,October 1998,pp. 1093-1102.
[3] R. N. Mahanty, P.B. Dutta Gupta, “A fuzzy logic based fault classification approach using current samples only,” Electric power system research ,77120073, pp. 501-507
[4] Jone Yen Rezalangari, “Fuzzy logic intelligence, control, and information”, Pearson Education.
[5] W.D. Stevenson, Jr. “ Elements of Power System Analysis”, Mc Graw Hill.
Thank you