Use of Phasors for Fault Location

Presenter: Armando Maldonado

Instructor: Dr. Mladen Kezunovic Ph.D.

Course: ECEN 679 Computer Relays

Single Ended ProtectionRelay Protection, voltage and current inputs at one end of transmission line.

• Fault type must be determined prior to fault location algorithm

• Algorithm calculates inductance from relay location to fault

• Fault Impedance = errors

• Load flow = errors

• Zero Sequence mutual coupling = errors

Single Ended ProtectionReduce the effect of fault resistance and load flow to combat errors.

• Voltage/Current phasors computed by Discrete Fourier Transforms

• Separate into real and imaginary components

• Multiply equations with

• Subtract real from imaginary equations and solve for “n”

Single Ended ProtectionVoltage and current phasors determined by fault type to properly solve for “n”

• AG Faults

• LL Faults

ZR1 = positive sequence impedance of the transmission line

ZR0 = zero sequence impedance of the transmission line

K0 = ratio of zero sequence impedance to positive sequence impedance of the line.

Two Ended ProtectionData needed for calculation of fault location

• Voltages

• Currents

• Time Stamps = Communication to central location for analysis

Method for location based on negative-sequence voltage profile along transmission line

k = line section

L or R = left or right junction

X or Y = terminal

Two Ended Protection Negative Sequence Voltage Magnitudes

• Voltage magnitudes indicate faulted line section

Two Ended Protection Algorithm estimates the distance to the fault on the homogenous line section.

• Use the equivalent negative sequence voltages and

• Voltage magnitudes at the fault location calculated form the two junctions should equal

• Algorithm solves “m” = distance to the fault

Comparisons Single Ended Fault LocationPros

• Only needs access to 1 terminal’s voltage and current values

• No communication to other terminals

Cons

• Nonhomogeneous systems

• Subject to errors from load flow mutual coupling

• Fault location approximation accuracy

Two Ended Fault LocationPros

• Algorithm not affected by fault resistance, load or zero sequence mutual coupling.

• Accurate fault locations

• Nonhomogeneous systems

Cons

• Communication to other terminals

• Needs accurate time stamps

• Data at both ends gathered at one location for analysis

References• J.M. Kennedy, General Electric, “Evaluation of a Phasor-Based Fault Location

Algorithm,”GE Protection and Controls, GER-3963.

• Yanfeng Gong, Mangapathirao Mynam, Armando Guzmin and Gabriel Benmouyal, Schweitzer Engineering Laboratories, “Automated Fault Location System for Nonhomogeneous Transmission Networks,” Boris Schulim, Orange and Rockland Utilities, 2012.

• Abdolhamid Rahideh, Mohsen Gitizadeh, Sirus Mohammadi, “A Fault Location Technique for Transmission Lines Using Phasor Measurements,” International Journal of Engineering and Advance Technology (IJEAT), ISSN: 2249-8958, Volume-2,Issue-1, October 2013

• IEEE Guide for Determining Fault Location on AC Transmission and Distribution Lines, IEEE Standard C37.114, 2004.

• S.M. Brahma, “New Fault Location Method for a Single Multi-Terminal Transmission Line Using Synchronized Phasor Measurements,” IEEE Trans. Power Delivery, Vol. 21-3, pp. 1148-1153, July 2006.

Thank you

Questions?