The optic-voltage measurement system based on the ground potential crystal compensation

Voltage measurement is critical in power system and optic-voltage sensing is one of the promising ways. However, optical voltage sensors can be easily influenced by the environmental conditions in application, such as temperature, stress etc. In this paper, some methods to improve sensing stability are introduced and further challenges are analyzed. Thermal stress distribution in the sensing crystal when temperature changes and the phase retardation caused by the stress is analyzed. Then a novel optic-voltage sensing structure based on ground potential crystal compensation is proposed. In theory, the interference birefringence on the output of the sensor can be eliminated with this structure, so the sensor is sensitive to the measured voltage while insensitive to other environmental conditions. Experiments show the ratio error is −0.6%∼0.4% and the phase error is −60' ∼ 30' when the temperature changes from −25° C to 40°C.