Studies On Optical Voltage Sensor

In contrast to the conventional voltage or electric field sensor, the optical voltage sensor has inherent and advantageous features. Thus it has a very good application prospect. However, the optical voltage sensor has not widely applied in the electric voltage instrument due to its imperfect stability. This paper firstly summarized and analyzed the present and the prospective of optical voltage sensor. Then the paper presented a novel optical voltage sensor based on two BGO crystals and linear electro-optical effect, in order to improve the performance and stability of optical voltage sensor. Some major factors that affect the stability of the optical voltage sensor have been investigated and the solutions have been put forward. In order to evaluate the performance of the sensor in the operational environment, the accuracy test, temperature test and long-time test have been carried out. The analysis and test results show that the proposed sensor can be applied into the electric voltage instrument.The general design principle of optical voltage sensor based on the linear electro-optical effect was introduced. In order to improve the sensitivity of crystal, it is necessary to adequate selection of the material and the shape of the crystal. In order to increase the sensibility of the sensor, it is necessary to adjust the relative positions of the optical elements.The principle of the sensor based on reflective structure, transverse mode and two light paths compensation method has been analyzed in brief. The limitation of the sensor has also been introduced.A novel optical voltage sensor based on two BGO crystals, reflective structure and transverse mode has been presented. The structure and the mathematical model of the sensor have been introduced. In theory, the unwanted linear birefringence on the output of the sensor can be eliminated and the stability of the sensor is perfect. The major factors that affect the stability of the optical voltage sensor under practical condition have been analyzed. The influence factors include BGO crystal, collimator, half-wave plate, right-angle prism, reflection from the surface of the crystal, obliquely incident, light source and electronic circuit. The solutions according to the influence factors have been put forward.The output format of the proposed optical voltage sensor system is similar to that of the electronic voltage transformer. A calibration system for electronic voltage transformer has been developed. The test that estimates the performance of the calibration system has been carried out in National Center for High Voltage Measurement and the calibration system is approved for calibrating voltage transformers or optical voltage sensor system with precision class up to 0.2 at the industrial frequency.The performance of the optical voltage sensor in the operational environment should be tested before its actual application. A sealed cavity has been designed and used to simulate the real operational environment. The accuracy test, temperature test and long-time test have been carried out. The test results show that the optical voltage sensor based on two BGO crystals has higher accuracy and better stability than the sensor based on conventional sigle BGO crystal. The proposed sensor possesses good application prospect.