Generator rotor turn-to-turn fault detection using fractional harmonics

A method of detecting a rotor fault condition using available electric power signals from an electric power generator with a rotor and a stator, the method comprising:

• receiving a current signal proportional to a current in a phase branch of the stator of the electric power generator;
• calculating a fractional harmonic of the current signal;
• comparing the fractional harmonic to a predetermined threshold;
• determining a rotor fault condition when the fractional harmonic exceeds the predetermined threshold for a predetermined time;
• determining a protective action when the rotor fault condition is determined;
• and,
• effecting the determined protective action

A device for protecting an electric power generator for generating electrical energy for an electric power delivery system using a stator and a rotor, the device comprising;

• a sensor component in electrical communication with an instrument transformer of the generator, the sensor component including a voltage signal output for providing voltage signals corresponding with the instrument transformer of the generator;
• a processor;
• a computer-readable storage medium in communication with the processor and the sensor component, comprising instructions that when executed by the processor cause the device to:
• calculate a fractional harmonic of the signal output using the voltage signals;
• compare the fractional harmonic to a predetermined threshold;
• determine a rotor fault condition when the fractional harmonic exceeds the predetermined threshold for a predetermined time;
• and,
• determine a protective action when the rotor fault condition is determined;
• and,
• an output in communication with the computer-readable storage medium for effecting the determined protective action.