Partial discharge location in power cables using a double ended method based on time triggering with GPS

Partial discharge (PD) diagnostics is the most widely used tool to assess the insulation condition of insulated power cables which facilitates informed maintenance planning leading to extended service life of ageing assets. Time domain reflectometry (TDR) using a single ended or double ended approach is the most widely used method for locating PD sources. The success of the single ended method is dependent upon cable network design. However, by monitoring PDs at both ends of the cable, i.e. double-ended PD monitoring, higher accuracy of PD location can be achieved with a higher success rate. The double ended method is not widely used due to its complex system design, time synchronization and communication requirement between measurement units. This paper proposes a double ended PD location system which triggers on the predefined one pulse per second (1PPS) signal obtained from a global positioning systems (GPS) using novel time based triggering logic (TBTL) implemented in field programmable gate arrays (FPGA). This system ignores non-useable (not synchronized) data caused by flywheel 1PPS from GPS receiver due to any short-term loss of satellite signals which eventually reduces the PD location accuracy. Furthermore TBTL also ignores spurious triggering pulses radiated from noise sources within the substation. With the use of a communication link between two ends of the cable provided via mobile broadband together with TBTL, eliminated the acquisition of non-useable(not synchronized) data. Based on laboratory tests and on-site measurements PD location accuracy of less than ± 10 m can be achieved. The system design, laboratory tests and on-site measurements are discussed.