Improving detection sensitivity of an on-board radio interferometer system for locating partial discharge sources in propulsion coils of superconducting Maglev systems

The detection sensitivity of an on-board radio interferometer system for indicating abnormal propulsion coils in superconducting magnetic levitation (Maglev) systems was improved by shortening the antenna spacing from 1.0m to 0.5m and introducing the cross-correlation (CC) of dynamic spectra. Electromagnetic (EM) waves due to the occurrence of partial discharge (PD) pulses in an abnormal propulsion coil were received with the antenna-array consisting of four half-dipole antennas; dynamic spectra of the received signals were digitally calculated by using the in-place fast Haar wavelet transform (IP-FHWT) embedded in the radio interferometer system. The abnormal propulsion coil was indicated by combining the results of the PD location using the 625MHz-component and the relationship among the peak-to-peak amplitudes of the waveforms of the EM waves. From the viewpoint of receiving the EM waves with two or more antennas of the antenna-array, the detection sensitivity could be improved more than two times. The effects of frequency characteristics of the propagation paths could be removed by extracting only the 625MHz-componet from the CCs, i.e. this could reduce both errors in the time-delay estimation and in the PD location.