On-line partial discharge (OLPD) insulation condition monitoring of complete high voltage (HV) networks in the oil & gas industry

The authors describe a new approach to on-line partial discharge (OLPD) insulation condition monitoring (CM) of complete high voltage (HV) networks (voltage range: 3.3 kV to 132 kV) in the oil & gas industry. The technique described is suitable for the condition monitoring of HV generators, switchgear, cables, motors and transformers. Comprehensive HV network OLPD condition monitoring coverage is achieved through the use of wideband, OLPD sensors and continuous monitors located at the central switchboards of the facility. The complete HV network condition monitoring system described in this paper is an extension of a CM system originally developed by the authors for remote OLPD monitoring of the stator winding condition of Ex/ATEX HV motors operating in hazardous gas zones. This technique utilises wideband, high frequency current transformer (HFCT) OLPD sensors located at the central HV switchboards to detect partial discharge (PD) signals that originate in remotely-connected HV plant and have propagated down the cable feeder circuit to the switchgear. This remote monitoring technique was presented by the lead author at the IEEE-PCIC 2012 [1] and IEEE-PCIC 2013 [2] for the application of OLPD condition monitoring of EX/ATEX HV motors, whilst avoiding the need to install sensors in the hazardous gas zone. In this paper, the authors describe how this remote OLPD monitoring technique can be extended to include the insulation condition monitoring of other HV assets including; generators, switchgear, cables and transformers, using the same wideband HFCT sensors attached to the HV cable terminations located at the central switchboards. The authors provide a number of case studies describing some past projects on the OLPD testing and monitoring of in-service HV generators, switchgear, cables, motors and transformers within the oil & gas industry. The applications knowledge obtained from these past projects on different plant types has been used by the authors in the development of this innovative, complete HV network condition monitoring solution.