Development of 220 kV self-healing optical voltage transducer

A self-healing optical voltage transducer (OVT) based on the Pokels electro-optical effect and capacitive divider of BGO crystal was developed to deal with temperature drift of voltage sensors. The sensor utilized a design of automatic calibrating reference source to solve the drift problem of measurement accuracy of an optical voltage sensor that was influenced by temperature. Using mathematic models of capacitive divider and sensors based on Pokels electro-optical effect, we explained the real-time correction principle of sensing channel parameters, put forward the structure design of optical voltage sensor, and tested the proposed optical voltage sensor based on IEC 60044-7 standard. The results showed that the magnitude error and the phase error were no more than 1% and 2', respectively, when 80%, 100% and 120% of the rated voltage were applied; the two errors were no more than 0.3% and 10', respectively, when 2% and 5% of the rated voltage were applied; and they were no more than 0.2% and 1', respectively when 150% of the rated voltage was applied. It is concluded that the developed OVT satisfies 0.1 level measurement requirements and the safety requirement higher than 3P level. Moreover, the OVT has magnitude error and phase error no more than 0.1% and 3', respectively, in the whole temperature range of circulating temperature tests, and it has also passed mechanical behavior tests.