-:Supervisor :- -: Submitted by :- Md. Abul kalam Sushil kumar ( ) Upawan kishor ( ) Harshit Sihna ( )

Objective In 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.

Introduction Transmission 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 Logic Everything 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 system Fuzzification Rule-evaluation Defuzzification

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 = j15.0; zero sequence impedance = j26.6; frequency = 50 Hz; transmission line impedance: positive sequence impedance = j94.5; zero sequence impedance = j308; positive sequence capacitance = 13 nF /km; zero sequence capacitance = 8.5 nF/km.

The Fault Current The 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 measurements for AB fault

Faults Characteristic measurements for BC fault

Faults Characteristic measurements for CA fault

Faults Characteristic measurements for AG fault

Faults Characteristic measurements for BG fault

Faults Characteristic measurements for ABG fault

Faults Characteristic measurements for BCG fault

Faults Characteristic measurements for ACG fault

Faults Characteristic measurements for 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 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 faultsRange of membership function AB BC CA

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 “medium” means a value between 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 faultsRange of membership function AG BG CG

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 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 faultsRange of membership function ABG BCG CAG

Output for different faults d1d2d3Crisp outputType of fault AB BC AC AG BG CG ABG BCG ACG

Conclusion A 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 [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 [3] R. N. Mahanty, P.B. Dutta Gupta, “A fuzzy logic based fault classification approach using current samples only,” Electric power system research, , pp [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.

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