Experimental Study of PD Direction Finding Based on Stereo Ultrasonic Array Sensor of EFPI

The partial discharge ultrasonic array positioning technique combines the sensor array with the array signal processing method. In this paper, the Extrinsic Fabry-Perot Interferometric optical fiber ultrasonic sensor was used. It has the high sensitivity and is not affected by electromagnetic interference. And take full advantage of the EFPI sensor what can be placed in the oil to improve the array structure. First a four-element EFPI ultrasonic sensor array of regular tetrahedral structure was designed, which was placed in the fuel tank to detect the local ultrasonic signal. Then, the MUSIC algorithm was used to measure the local discharge source; and compared result with the 2×2 planar array. Finally, the correction is performed for the position error of the array element. The results show that the EFPI sensor stereo array can detect the partial discharge signal with high SNR in the oil, and has higher direction finding accuracy than traditional planar arrays. Especially in the aspect of array blind zone, the stereo array can effectively realize spatial multi-angle source direction finding. And TCT algorithm is used to correct the position error of the array element, which improves the direction finding accuracy, and satisfy the actual project needs.