Methods for Post-Processing and Trend Analysis of Conductivity Measurement Data

摘要

Material qualification for high voltage direct current (HVDC) transmission applications requires a robust and reproducible determination of conductivity. Addressing insulating materials for the use in HVDC cables, investigations on conductivity are closely related to low level measurements. It is found that noise reduction and material trend analysis can be enhanced significantly if besides commonly used moving average and median filters advanced methods are applied. Following the theory of ?₁ trend filtering, a noise reduction and the determination of piecewise linear material trends becomes possible. Subsequent, utilizing moving linear regression allows the determination of material dynamics over a predefined time window. Therefore, changes of the underlying material dynamics are revealed and allow a consideration for material analysis and modelling approaches. After a presentation of these post-processing methods, a comparison based on signal to noise ratio (SNR) using synthetically generated test data is carried out.