Methods of discriminating partial discharge and noise for power cable lines

This paper describes a new multiple means of discriminating partial discharge (PD) and noise for power cable lines, which is applied in some newly developed PD auto-measuring systems, not only for the PD measurement in laboratory, but also for the after-laying testing of power cable line on-site. Discrimination of PD and noise can be divided into two kinds of PD judgment. First, the judgment is executed automatically based on multiple logic gates: f-gate for frequency, n-gate for pulse count rate, q-gate for pulse magnitude, /spl phi/-gate for PD phase position, t-gate for continuous time, set logically in serial or in parallel. Second, the signals can be recognized by their pattern distributions: neural network recognition is based on the /spl phi/-q-n pattern; multiple frequency recognition is based on f-q-t pattern; and statistical source location pattern is based on x-q-t pattern. Satisfactory discrimination of high accuracy has been obtained through applying the measuring systems using the method in several PD measurements on-site.