Using optical couplers to monitor the condition of electricity infrastructure

Increases in renewable and distributed generation will change the operational characteristics of our ageing power networks. To cope with these changes improved monitoring of the performance of network infrastructure is needed. Defects developing in electrical plant give rise to partial discharge (PD) activity. This paper describes an on-line PD monitoring system based on electro-optic modulators. This technique does not require a power supply at the site of the sensors and the optical transmission of signal data is a significant advantage in electrically noisy environments. Laboratory based experiments and field trials are described, which show that this approach is feasible for HV transformers and underground cable. Intelligent filtering techniques have been developed to improve the sensitivity of detection and identify PD signals without assuming any knowledge of their characteristics.