Research on Time Saving and Accurate Testing Techniques for Frequency Domain Spectroscopy of Transformer Oil–Paper Insulation

Frequency domain spectroscopy (FDS) is a nondestructive insulation test method that has been widely applied to the insulation evaluation of power transformers. However, a major shortcoming of conventional FDS is the long test duration. Existing studies on accelerated FDS tests suffer from a lack of accuracy and are difficult to apply to field testing. To tackle this problem, a novel FDS test method (named iFDS) is proposed to reduce the duration and improve the accuracy of the oil–paper insulation test. Specifically, the test duration is reduced first by signal superposition and waveform prediction. Then, the test accuracy is improved from the aspects of the parameters design of excitation, the optimization of the test process, and time–frequency-domain data processing. Finally, a test platform is built based on the above methods to implement iFDS testing. To verify the effectiveness of iFDS, the dielectric parameters (tan
$\boldsymbol {\delta }$
and
$C\ast$
) of oil–paper insulation were measured using the iFDS platform and compared with that of the existing FDS methods in terms of duration and accuracy. Comparative experimental results show that iFDS is a superior method for saving time and accurate testing and has the potential to be versatile for evaluating more insulation objects.