Parameter Free Identification of Fault Location in Multi-Terminal Power Transmission Lines

A method for use with a power transmission line having a first terminal, a second terminal, and a third terminal connected at a junction, wherein a first section connects the first terminal and the junction, a second section connects the second terminal and the junction, and a third section connects the third terminal and the junction, the method comprising:

• obtaining synchronized disturbance records from each of the first, second, and third terminals after a fault has occurred in the power transmission line;
• computing pre-fault voltage and current phasors and during-fault voltage and current phasors for each of the first, second, and third terminals based on the disturbance records;
• using an assumed faulted section from among the first, second, and third sections, computing values for a propagation constant of each section, a surge impedance of each section, and a fault location parameter, wherein the computing is based on simultaneously solving a plurality of pre-fault objective functions and during-fault objective functions for the assumed faulted section with the computed pre-fault voltage and current phasors and during-fault voltage and current phasors, and wherein the pre-fault objective functions and during-fault objective functions are formulated based on equating junction voltages determined from two of the terminals, conservation of charge at the junction, and equating fault location voltages determined from one terminal and the junction;
• and
• comparing the values determined for the propagation constant, the surge impedance, and the fault location parameter with predefined criteria.

A device for identifying a fault location in a power transmission line, the power transmission line having a plurality of terminals connected at one or more junctions, with at least a first terminal, a second terminal, and a third terminal connected at a junction, wherein a first section connects the first terminal and the junction, a second section connects the second terminal and the junction, and a third section connects the third terminal and the junction, the device comprising:

• a phasor computation module configured to obtain synchronized disturbance records from each of the plurality of terminals after a fault has occurred in the power transmission line and compute pre-fault terminal voltage and current phasors and during-fault terminal voltage and current phasors;
• and
• a fault location identification module configured to
• compute, using an assumed faulted section from among the first, second, and third sections, values for propagation constant of each section, surge impedance of each section, and a fault location parameter, wherein the computation is based on simultaneously solving a plurality of pre-fault objective functions and during-fault objective functions for the assumed faulted section with the computed pre-fault voltage and current phasors, during-fault current and voltage phasors, and line lengths of each section, and wherein the pre-fault objective functions and during-fault objective functions are formulated based on equating junction voltages determined from two of the terminals, conservation of charge at the junction, and equating fault location voltages determined from one terminal and the junction;
• compare the values determined for the propagation constant, the surge impedance, and the fault location parameter with predefined criteria;
• and
• determine a faulted section, the fault location, and the parameters for each of the first, second, and third sections, based on the comparison.

A device for use with a power transmission line having a first terminal, a second terminal, and a third terminal connected at a junction, wherein a first section connects the first terminal and the junction, a second section connects the second terminal and the junction, and a third section connects the third terminal and the junction, the device comprising:

• a processor;
• and
• a non-transitory memory coupled to the processor, the memory storing computer code that, when executed by the processor, causes the processor to:
• compute pre-fault voltage and current phasors and during-fault voltage and current phasors for each of the first, second, and third terminals based on synchronized disturbance records obtained from each of the first, second, and third terminals after a fault has occurred in the power transmission line;
• compute, using an assumed faulted section from among the first, second, and third sections, values for a propagation constant of each section, a surge impedance of each section, and a fault location parameter, wherein the computation is based on simultaneously solving a plurality of pre-fault objective functions and during-fault objective functions for the assumed faulted section with the computed pre-fault voltage and current phasors and during-fault voltage and current phasors, and wherein the pre-fault objective functions and during-fault objective functions are formulated based on equating junction voltages determined from two of the terminals, conservation of charge at the junction, and equating fault location voltages determined from one terminal and the junction;
• and
• compare the values determined for the propagation constant, the surge impedance, and the fault location parameter with predefined criteria.