Advanced optical sensor performance in transmission and distribution applications

This paper reports on recent developments within research into optical fibre based voltage and current measurement equipment for metering and protection applications. Several parameters (thermal variations, intensity fluctuations due to mechanical disturbance, electronic noise) are known to influence the performance of these sensors and this paper summarises an analysis of the effect of such disturbances providing design criteria for the realisation of protection and metering class OCTs. Laboratory trials have shown that the compensation schemes devised reduce vibration errors by 20 to 30 dB and compensate for temperature induced drift to better than 0.1%. Extended engineering evaluation field trials of both OCT and OVT devices within a three-phase 132 kV installation have been undertaken over the past two years. Details of these trials are presented to provide an appreciation of the potential difficulties which may be encountered and the benefits which may be derived