Monitoring Method for an Unbalanced Three-Phase HTS Cable System via Time-Frequency Domain Reflectometry

In this paper, we propose a new time-frequency based analysis method that monitors the state of the high temperature superconducting (HTS) cable system in a real-time manner and detects the current imbalance of HTS cable system. The new time-frequency-based method utilizes the cross Wigner-Ville distribution to analyze the time-frequency localized phase difference of the reflected signal, which varies depending on the insulation characteristics of the HTS cable system. Also, a real-world AC 22.9 kV 50 MVA HTS cable system and a current source are used to validate the performance of the new monitoring method in order to detect current imbalance phenomenon.