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Partial Discharge Characteristics of Typical Defects of High Voltage DC Cables

High Voltage Direct Current (HVDC) Cable is one of the most important components of the flexible DC transmission system, which shows outstanding characteristics of the new and renewable energy integration into power grid. Partial Discharge(PD) characteristics of the HVDC cable are different from High Voltage Alternating Current (HVAC) cables, and are with bigger challenge to be analyzed than PD of HVAC cables as there is no phase information of HVDC system. In this paper, PD characteristics of typical defects of the HVDC cables were studied. Firstly, four typical artificial defects of the HVDC cables were established in the lab and the PD testing system was presented. Secondly PD testing was carried out based on different types of the defects and the raw PD testing data was logged. Thirdly, PD transient pulses were extracted from the raw data, based on which the feature construction and statistical analysis of HVDC PD were carried out, in terms of the PD characteristics under different voltage and under different voltage polarity. Results shows that, PD pulses repetition of HVDC cable will increase with the testing voltage, and PD characteristic generated by different defects show a certain difference under positive voltage and negative voltage.