To locate the partial discharge（PD） source in a transformer

an ultrasonic localization method by time difference screening（TDS） and artificial bee colony（ABC） secondary optimization is proposed. Firstly

the time difference of received signals is estimated by the generalized cross-correlation method. On this basis

the time-difference screening link based on spherical equations is added to eliminate the time-difference with large errors. Secondly

the constrained optimization model of spatial localization is set up according to the effective time-difference and solved by ABC algorithm. The K-Means clustering analysis is carried out for some localization results. Finally

the ABC algorithm is used to optimize the minimum point of the sum of distance clustering centers

and the localization result with large error is corrected. The simulation results show that the localization error of the method in this paper is more negligible than that of the traditional method

and the localization error is less than 5 cm in the field experiment.