AStatistical MethodofImproving theResolution ofTime-delay ofUHFSignals forPD Location inTransformers
Zhiguo Tang, Beijing KeyLaboratory · 2005
It'simportant tomakean accurate PD location intransformers forfault diagnosis and maintenances ofpowersystems. Theoretically it's possible tolocate thePD sourcebymeasuring the differences inthearrival timeattheUHFsensor array. Thepropagation velocity ofEM waveinair is30cm/ns, whichisextremely fast, sotheresolution ofthetime- delay ofUHFsignals detected attheUHFsensor array isoneofthekeypoints tomakeanaccurate PD location. Here, we propose a mathematical method: cross-correlation-shifting-averaging algorithm that can improve theresolution oftheUHFsignal's time-delay byincreasing thesignal tonoise ratio andreducing the timedispersion caused bytherandom nature ofPD.The practical processing results ofexperimental datafrom ourlaboratory indicate that themethod canincrease the time-delay resolution bynano-seconds insomecases, whichimprove PD location accuracy bytensof centimeters.