Partial Discharge Localization on Power Cables Using On-Line Transfer Function

An on-line method is proposed for cable transfer function (TF) identification. For a cable's TF identification with this method, no knowledge about the cable geometry and material specification is needed. Moreover, it does not require that the cable system go out of service. An identification signal is injected through a high-frequency current transformer (HFCT) to the shield of the cable. By measuring the injected signal via HFCTs clamped on the shield at two distinct locations along the cable, the TF of the cable can be identified. A novel partial discharge (PD) localization method is also introduced, which is based on asynchronous PD measurements. In this method, travel distance of the signal is estimated by the reconstruction of a reference signal from the measured signals, using the obtained cable TF. Reference signal refers to the typical waveform of PD signal at its source location. Both the cable identification and PD localization methods are validated using two experimental setups to simulate a diverse range of PD source distance. The test cables are a 666-m long, single-core, low-voltage (2 kV) signal cable with PE insulation, and a 51-km long, single-core, medium-voltage (24 kV) power cable with XLPE insulation.