Gold-Diaphragm Based Fabry-Perot Ultrasonic Sensor for Partial Discharge Detection and Localization

Acoustic measurement is the most widely used non-electric method to detect partial discharge (PD) signals by detect the ultrasonic waves arisen from partial discharge. To solve the shortages of low sensitivity and susceptibility to interferences, a gold diaphragm based Fabry-Perot interferometer ultrasonic sensor is proposed and experimentally demonstrated. Its high acoustic sensitivity and directional insensitivity shows great capability for PD detection and localization. Experimental results illustrate a well acoustic response from 20 kHz to 150 kHz when standard ultrasonic signals applied. The frequency range covers the acoustic frequencies derived from PD process. The ultrasonic signals from a discharge source is measured by the proposed fiber optic sensor with difference distances and incident angles. The output shows an attenuation of 1.32 dB/m and the sensor can detect weak signals as far as 3 m. The directional deviation coefficients are less than 10% for each measuring distance which exhibits directional independence. Two localization techniques with a sensor array (four sensors) are proposed and simulations are carried out to verify them feasible. The fiber-optic ultrasonic sensor may have a great potential in stability maintenance of electrical power systems due to its low cost, compact structure, environmentally robustness and simple manufacturing.