Abstract:

Phase difference of a current sensor is susceptible to environmental impact. In order to improve
reliability and accuracy of the on-line insulation monitoring system, a phase difference measurement method
for current sensor on-line monitoring is proposed. In the method, independent component analysis (ICA) is
used to extract the test signal from the output of current sensor. An ICA model is established, and a method
given to compensate the number of observed signals and its components. To solve the problem that phase
errors are different in different test runs, an evaluation index of the mixing matrix is proposed to find the most
accurate result. Experimental results indicate that for a signal with SNR=10.9 dB, the percentage of phase
errors below 0.06± is raised form 51.4% to 81% by using the evaluation index.

Key words: phase difference, on-line monitoring, dielectric loss, independent component analysis (ICA), negentropy