Research on Sensitivity Calibration Method for Flexible Ultrasonic Sensors in Partial Discharge Detection

This paper focuses on the calibration method for the sensitivity of flexible ultrasonic sensors for partial discharge detection of power cables. The traditional calibration platform，due to the mismatch between the acoustic impedance and the cables，causes the sensitivity of the calibrated flexible sensor not to accurately reflect its actual situation in the partial discharge detection of cables. In this paper，by constructing a new type of sensitivity calibration platform based on polyethylene plates，the calibration deviation problem of traditional steel plate platforms is solved thanks to the high similarity of the acoustic impedance characteristics of polyethylene plates to those of cable materials. The sensitivity calibration results of the flexible film sensor on the steel plate calibration platform and the polyethylene plate calibration platform are analyzed，finding that the peak sensitivity of the flexible sensor calibrated on the steel plate platform is only 53 dB，while the sensitivity calibrated on the polyethylene plate platform is increased up to 66 dB. The verification experiment of sensor sensitivity performed on the cables shows that the sensitivity calibrated on the polyethylene plate platform can accurately reflect the detection ability of the flexible sensor for the weak ultrasonic signal propagating on the cables. The new calibration platform set up in this paper can provide a basis and reference for the calibration of the sensitivity of flexible ultrasonic sensors.