Fault Diagnosis for Shielded Cable in EMUs Based on TLS-ESPRIT and 3D-BIS Images

Given the short daily maintenance time for electric multiple units (EMUs), it is essential to improve the diagnosis efficiency of the shielded cables in EMUs. Broadband impedance spectroscopy (BIS) is a promising technique for diagnosing these cables. However, the localization algorithms based on Fourier transform (FT) currently utilized in BIS have drawbacks such as the positioning resolution being strongly affected by the frequency bandwidth and test noise. Additionally, fault type identification in BIS faces challenges, including insufficient feature parameters, identification accuracy affected by tester experience, and demanding test requirements. In this article, we propose an efficient localization and type identification method to overcome the above problems. We employ the total least squares estimation of signal parameters via rotational invariance technique (TLS-ESPRIT) to improve positioning resolution and reduce positioning interference, and we extract image features from 3D-BIS data to distinguish between hard, low-resistance, and high-resistance faults. Furthermore, we propose a resonance counts calculation algorithm to further distinguish between the open-circuit and short-circuit faults. We compare positioning results for our method with traditional localization methods to demonstrate the utility of the approach, and we present laboratory data and field experimental results for EMUs to validate the proposed method.