Cancellation of continuous periodic interference for PD detection

Practical partial discharge detection is generally impeded by noise and interference. Especially in case of on-line detection in the field, the signal-to-noise ratio of the partial discharge pulses can be low. Primary disturbance sources include continuous periodic interference, such as amplitude modulated radio broadcasts. Typically, this type of interference is eliminated by digital notch filtering. Filters may introduce PD pulse shape distortion, which is generally not desired. As an alternative, adaptive interference cancellation is presented. Moreover, a mixed-signal implementation is proposed that enables interference rejection prior to digitization.