Novel optical voltage transformer with double-light-channel temperature compensation

Abstract

The stability of optical voltage transformers has been the main obstruction to its practical application. An optical voltage sensor is the core of an optical voltage transformer. This paper proposed a novel reflection-type transverse modulation optical voltage sensor with double light channels temperature compensation. The sensor is based on the Pockels effect in a Bi<SUB>4</SUB>Ge<SUB>3</SUB>O<SUB>12</SUB> (BGO) crystal. The measured voltage is applied to the crystal along the &lt;001&gt; direction with light wave passing through the crystal along the &lt;110&gt; direction. Theoretical analysis shows that this is an optimum configuration for a reflection-type transverse modulation optical voltage sensor. The novel optical voltage sensor was employed to develop a novel optical voltage transformer (OVT) for 220 kV power systems. There isn't any capacitor divider in the OVT. The measured high voltage is applied to the optical voltage sensor directly. Experiments showed that the sensor has good double light channels temperature compensation characteristic and the stability of the OVT could reach +/- 0.4% during two weeks. The principle, structure and test results of the OVT are presented in this paper.