Partial Discharge measurements for failure diagnosis on an oil-filled high voltage cable

Summary

This paper reports about the experience with monitoring of partial discharges (PD) on an oil-filled high voltage cable which is part of the 110 kV distribution network in the city of Hamburg. The nearly 6 km long oil-filled cable system was switched off due to an internal electrical fault without breakdown. The fault did not cause any internal breakdown but partial discharge. Thus the fault localization using impulse reflection measurement was not possible. In order to detect the internal fault, resonant voltage tests with concurrent PD measurement were accomplished. Due to the length of the cable and the high attenuation of PD impulses in oil-filled HV cables it was not sufficient to only use one PD sensor at the cable termination. Thus, for fault detection, additional PD sensors were mounted at cable joints and along the cable by positioning inductive PD sensors between cable insulation and screen. The paper summarizes the experience with the PD measurements. Additionally, capabilities and limits of PD measurement on the described oil-filled cable are discussed. Also, the first experience using the PD measurement setup online with operating voltage instead of resonant voltage are reported.

Additional informations

Authors

Yang Liuqing, Fang Bing, Guo Peiqi, Zheng Bin