Development of Quench Detection Method Around the Joint Box for HTS Cable Using TFDR and EM Algorithm

A high-temperature superconducting (HTS) cable system requires cooling system to maintain a superconducting state. If a local fault occurs in the HTS cable, a fault current that causes heat can flow. This leads to a quench, where the superconductivity breaks down, inflicting critical damage on the HTS cable system. Conventional reflectometry method can detect the local quench point, but it is difficult to distinguish between a reflected signals from quench around the joint box and that from the joint box. In this paper, we propose two steps to solve this problem. 1) Anomaly detection step: we propose the integrating the autoencoder (AE) with time-frequency domain reflectometry (TFDR) to detect anomaly situation, and localize impedance mismatch point through time-frequency cross correlation (TFCC) function, which calculate the similarity between a reference signal and reflected signal. 2) Source separation step: If TFCC of signals overlap with each other, A expectation-maximization (EM) algorithm is used to separate each overlapped TFCC. The proposed method enables efficient monitoring of the HTS cable system by effectively detecting quench that occur around the joint box. We simulate the quench situation, and verify the proposed method through the simulation.