EMI-based Diagnosis to Grounding Grids by Combining Ensemble Empirical Mode Decomposition and ICA

Grounding grids have been performed an essential role in electric transformer substations. The nondestructive diagnosis system applies transforms the condition of the undergrounding conductors to the surficial induced electric signal in sensing coil. However, the induced signal cannot be used directly to diagnosis due to the raw measurement is a mixture of responses from signal of interest, strong interference and other unknown noises. Therefore the separation of individual signatures from the mixture is posed as a blind source separation (BSS) problem. To extract the induced signal corrupted by noise, the independent component analysis (ICA) method is considered. By combining the EEMD and FastICA, the single-channel signal is decomposed into its ICs. The desired signal is then reconstructed to visualize the break point of the grounding grid. The results show this approach can be used to effectively diagnosis grounding gird in harsh electromagnetic environment.