Practical location method of transformer partial discharge

Ultrasonic method is applied through calculating the time differences that the signal reaches different sensors, something like passive sonar locating, to locate the signal origin. So far, though numerous scholars have been trying to complete the approach theoretically or practically, the achievements are far from satisfactory. In the paper three aspects affecting partial discharge positioning are addressed, i.e. relative time differences among the sensors, algorithm of positioning, and propagation path of ultrasonic wave. From a comprehensive view, an sound-sound locating method with great practical value is put forward in the paper. In order to precisely locate the positions where ultrasonic signal is accessible from the outside of the tank, a repeated process of testing is necessarily required. Meanwhile, the sequential locating method is applied to preliminarily point out the discharging origin. Then, the ultrasonic signal representing the cross correlation function between the base sensor and the other ones. Then, as has been known, the discharge area can be assumedly divided into module (spatial position cubes). For any cube, that ultrasonic signal reaches different sensors can be calculated, with reference of generalized correlated function curve and add all the values together to make the generalized correlated function value. The maximum value of the generalized correlated function values of all the cubes is positively that of the discharge cube. Featuring avoiding direct calculation of the time differences of the ultrasonic signal, the method mentioned in the paper improves the precision of the positioning and effectively constrains divergence of discharge detection. The vitality of the method is supported by laboratory tests.