Partial discharge detection of generator stator winding helps to reflect the insulation condition of a motor and ensure the safe operation of a generator. The traditional pulse current method is susceptible to electromagnetic interference and cannot reflect the location of partial discharge in the stator winding in the field

while the fiber optic sensing adopts a fully insulated structure

which is resistant to electromagnetic interference and easy to be built-in

and has a high potential for application in partial discharge monitoring. Therefore

a detection method based on Michelson interference is proposed for stator bars

the sensing unit is optimized and tested

and its effect on the electric field at the end of the bars is investigated through simulation and experiment. On this basis

a test platform for partial discharge detection of generator stator bars is built

and tests are carried out on stator bars with different defects. The results show that the designed fiber-optic ultrasonic sensing system has a good detection effect on partial discharge at the stator bar end. The designed fiber optic ultrasonic sensing system has a good detection effect on the partial discharge of stator bars

and can detect the internal defect discharge of 30 pC. For discharges caused by three different surface defects

the lowest measurable discharge amount is 20 pC

and effective signals can be detected below a discharge amount of 60 pC

which is significantly better than traditional piezoelectric sensors. The peak frequency bands of ultrasonic signals of different defect types are consistent

but the components of each frequency band have obvious differences.