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Fault Location EE 526 Venkat Mynam Senior Research Engineer Schweitzer Engineering Laboratories.

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Presentation on theme: "Fault Location EE 526 Venkat Mynam Senior Research Engineer Schweitzer Engineering Laboratories."— Presentation transcript:

1 Fault Location EE 526 Venkat Mynam Senior Research Engineer Schweitzer Engineering Laboratories

2 Accurate Fault Location is Critical Expedite Service Restoration Reduce outage times Identify insulator problems Prevent potential recurring faults Verify Protective Relay Performance

3 Permanent Fault Need Immediate Attention We need accurate fault location

4 Temporary Faults Needs Attention Too Identify & Fix Damaged Insulators-Minimize Fault Recurrence

5 Hard to Find a Flashed Insulator

6 Finding Faults

7 Visual Methods

8 Estimate Location From Current “JM Drop” circa 1936 Approximate fault location was calculated based on system and line parameters

9 Methods in Use Line impedance Based ♦ Measure impedance to fault ♦ Compare it to the actual line impedance Traveling Wave Based ♦ Measure wave arrival time

10 System One-Line and Circuit Representation of System Fault

11 Modified Takagi Method-Single Ended (Negative Sequence) Multiply by I 2 and save Imaginary part Zero For: Rf=0 or system is homogeneous

12 IEEE Guide Defines Homogeneous System “A transmission system where the local and remote source impedances have the same angle as the line impedance”

13 Single End Impedance Method Fault resistance System nonhomogeneity Accuracy of measurements Accuracy of positive-sequence line impedance Accuracy of zero-sequence line impedance Effect of zero-sequence mutual coupling from parallel lines Time synchronization Communication Radial topology      

14 SE Impedance Fault Location Phase-Ground Faults

15 SE Impedance Fault Location Multi-Phase Faults

16 Fault Loop Selection and Reporting Select appropriate Fault Loop Report a single fault location value ♦ Select a window of data from the fault data ♦ Provide the average value of fault location computed from the selected window

17 Modified Takagi Method-Multi Ended (Using Remote terminal current) Multiply by I 2 and save Imaginary part THIS IS ZERO

18 Multi-End I2 Total Current Fault resistance System nonhomogeneity Accuracy of measurements Accuracy of positive-sequence line impedance Accuracy of zero-sequence line impedance Effect of zero-sequence mutual coupling from parallel lines Time synchronization Communication      

19 ME_I Impedance Fault Location Phase-Ground Faults

20 ME Impedance Fault Location Multi-Phase Faults

21 V2F + ref Multi Ended Negative Sequence Using Remote terminal voltage and current

22 Use Synchronized Measurements to Calculate Voltage at Fault Point

23 Double End With V2 and I2 Fault resistance System nonhomogeneity Accuracy of measurements Accuracy of positive-sequence line impedance Accuracy of zero-sequence line impedance Effect of zero-sequence mutual coupling from parallel lines Time synchronization Communication    

24 Multi-End Fault Location That Does Not Require Data Alignment Each Relay Receives: ♦ Magnitude and Angle of Z 2R ♦  I 2R 

25 Local and Remote Data Necessary for Fault Location Rearrange Above Equation to Form a Quadratic Equation Solve Quadratic for Fault Location m Download Paper

26 Multi-End Methods Needs Time Synchronized Data Synchrophasors Synchronized samples ♦ Devices with data acquisition synchronized to a common time source ♦ Fixed sampling rate

27 Series Compensated Lines Line Side PT Bus Side PT Challenges Steady State Transient (phasor estimate is not stable) Subsynchronous MOV and bypass breaker switching Download Paper

28 Three-Terminal Line

29 Reduce From Three-Terminal Line to Two-Terminal Equivalent V 2_SP = V 2S – Z 2L_SP I 2S V 2_TP = V 2T – Z 2L_TP I 2T V 2_UP = V 2U – Z 2L_UP I 2U Same Result

30 Use Two-Terminal Equivalent to Solve for m I 2_Eq = I 2T + I 2U V 2_Eq = V 2_TP Solve for m using SE or Multi-terminal (ME_I, ME) ME_I

31 Mutually Coupled Lines Download Paper

32 Composite Lines Identifies faulted line section Calculates distance to fault

33 Intersection of Voltage Profiles Identifies Faulted Section

34 Calculate Distance to Fault Within Faulted Section using ME method Download Paper

35 Impedance Method Approach Summary Measure VA, VB, VC, IA, IB, IC Extract fundamental components Determine phasors and fault type Apply impedance algorithm

36 Impedance Fault Location Methods Multi-End Method using local and remote voltage and currents Multi-End Method using local voltage and currents, and remote currents Single-End Method using local voltage and currents SE MEI ME

37 Some of the Challenging Situations for Z based Fault Location Methods Short faults: faster relays and breakers- phasor estimate is not stable Faults associated with time-varying fault resistance-phasor estimate is not stable Series compensation

38 Short Duration Faults Raw-Blue, Cosine Filtered-Green Magnitude of Filtered Quantity-Red

39 Lightning and Faults Launch Traveling Waves tLtL tRtR Download Paper

40 Double Ended TW Fault Location

41 Single-End TW Fault Locator

42 Results From Field 117.11km, 161 kV line 18 sections with 4 different tower configurations Challenges with existing impedance based fault location methods Image courtesy of Google

43 FaultTWPatrolSE_ZME_Z_IME_Z CG109.74109.29105.44106.24106.56 BG 61.12 61.4154.7560.6960.70 BG108.23107.60101.59106.43 BG 98.85 98.9895.2098.37 Fault Location Results (161kV, 117.11km long line)

44 Temporary Fault Due to Insulator Flashover

45 Insulator Flashover


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