Sagnac型光学电压互感器传感单元非线性误差分析与抑制

Analysis and elimination of the nonlinear error in the sensing element for the Sagnac based optical voltage sensor

基于Pockels效应的Sagnac型光学电压互感器的传感单元是由法拉第准直旋光器和BGO晶体构成,其中由偏振串扰引入的非线性误差是影响互感器测量精度及稳定性的主要误差来源。为了抑制传感单元存在的非线性误差,从主要光路器件及器件间的耦合点中分析产生偏振串扰的非理想耦合点及耦合机理,并提取表征该耦合点的误差特征参量,建立各非理想耦合点的传输模型,由此推导由传感单元偏振串扰引入的非线性误差模型,数值仿真并实验验证非理想偏振耦合对互感器性能的影响。在此基础上,提出了由BGO晶体敏感环境振动、温度波动等产生的非线性误差的抑制方法,实验结果验证了抑制方法的有效性。

The sensing element of Sagnac based optical voltage sensor consists of the collimator-Faraday rotator and BGO crystal. The polarization cmsstalk induced nonlinear error significantly influences the measurement accuracy and the stability of the sensor. In order to suppress the nonlinear error presented in the sensing element, the imperfect polarization crosstalk is inves- tigated from the main optical components and their coupling points. And the transmission model is obtained with parameters characterizing the imperfect polarization coupling points. Then the nonlinear error is deduced. The numerical simulation and ex- periments are implemented to analyze the influences of the nonlinear error induced by the polarization crosstalk to sensor. Also, the scheme is proposed to eliminate the nonlinear error induced by the BGO crystal, environmental vibration and temperature fluctuations. The experiment results verify the feasibility of the proposed elimination scheme.