345 kV substation optical current measurement system for revenue metering and protective relaying

The authors report for the first time on the performance of a 345 kV optical current sensor used for substation metering. The waveform quality of this sensor was compared to that of a conventional current transformer in both the time and frequency domains. The interfacing of this device with conventional 5 A protective relay systems using a pulse width modulation amplifier is discussed. The optical current sensor is based on the Faraday effect. This system was designed and developed to advance the state of the art in optical metering, relaying, and data acquisition. The decisions leading to the design of the optical metering system, the components of the system, the site installation, field test results, and recommendations for future work are discussed.>