Transformer test result is commonly influenced by its surrounding environmental interference. Based on the characteristics analysis of insect

bird

frog and automobile noises

three anti-interference methodologies are proposed in this paper

which are wavelet packet-spectral subtraction

short-time frame and filter design

respectively. Under the influence of insect

bird

frog and automobile noises with different signal-noise ratios

the anti-interference effects of the three methods are compared. Field test is conducted to verify the proposed methods. Finally

the application principle of the anti-interference methods is discussed. The result shows that wavelet packet-spectral subtraction and filter design methods will achieve better result than short-time frame method for different environmental interference types. However

better general applicability is found about the wavelet packet-spectral subtraction method for burst intermittent interference. In the field application process

proper method should be chosen according to actual demand. The result will provide critical reference for transformer noise test accuracy enhancement under complex environmental interference condition.