System and method for detecting, localizing and quantifying excess voltage drop in three-phase AC circuits

A method for detecting excess voltage drop (EVD) in an electrical distribution circuit, the method comprising:

• measuring three-phase voltages and currents provided to an electrical machine in the electrical distribution circuit by way of voltage and current sensors;
• causing a diagnostic system to calculate a fault severity index (FSI) based on the measured three-phase voltages and currents, wherein causing the diagnostic system to calculate the FSI comprises:
• receiving the measured three-phase voltages and currents provided to the terminals of the electrical machine;
• computing a positive, negative, and zero sequence voltage and sequence current from the three-phase voltages;
• determining a compensated negative sequence voltage from the negative sequence voltage component;
• determining a localization reference phase angle for each phase based in part on the three-phase currents;
• and
• calculating the fault severity index (FSI) in the electrical distribution circuit based on the compensated negative sequence voltage and the localization reference phase angles.

A diagnostic system configured to detect an excess voltage drop (EVD) fault in an electrical distribution circuit, the diagnostic system comprising:

• a processor programmed to:
• receive three-phase voltages and currents provided to terminals of an electrical machine connected to the electrical distribution circuit;
• compute positive sequence, negative sequence, and zero sequence voltage and current from the three-phase voltages and currents;
• determine a compensated negative sequence voltage from the negative sequence voltage component;
• determine a localization reference phasor for each phase based in part on the three-phase currents;
• identify an EVD fault in the electrical distribution circuit based on the compensated negative sequence voltage;
• and
• localize the EVD fault to one or more phases in the three-phase output based on a difference between a phase angle of the compensated negative sequence voltage and the localization reference phasors.