Surface charges greatly affect the discharge/flashover development process across an insulator. The relationship between surface charge distribution on insulating materials and measurement data based on Pockels techni...Surface charges greatly affect the discharge/flashover development process across an insulator. The relationship between surface charge distribution on insulating materials and measurement data based on Pockels technique is discussed, and an improved algorithm is built to calculate the real surface charge density from original data. In this algorithm, two-dimensional Fourier transform technique and Wiener filter are employed to reduce the amount of numerical calculation and improve the stability of computation, Moreover, this algorithm considers not only the influence of sample＇s thickness and permittivity, but also the impact of charges at different positions. The achievement of this calibration algorithm is demonstrated in details. Compared with traditional algorithms, the improved one supplies a better solution in the calibration of surface charge distribution on different samples with different thickness.展开更多
光学电压互感器(Optical Voltage Transducer,OVT)是重要的电力系统测量设备。在使用过程中,因碰撞、连接不稳定或温度变化等问题,会导致传感光路或内部锗酸铋(BGO)晶体发生微小偏移。当偏移为0.5°时,所引起的最大积分电压误差可达...光学电压互感器(Optical Voltage Transducer,OVT)是重要的电力系统测量设备。在使用过程中,因碰撞、连接不稳定或温度变化等问题,会导致传感光路或内部锗酸铋(BGO)晶体发生微小偏移。当偏移为0.5°时,所引起的最大积分电压误差可达0.1%,这对于0.2%的标准要求而言是不可接受的。为了减小偏移带来的误差,并改善BGO晶体内电场的均匀性,文中针对110 kV纵向调制型OVT提出了一种方解石介质分层和氮化铝包裹法,两端采用Φ10 mm×75 mm的方解石对BGO晶体进行分压,并覆盖一层0.5 mm厚的氮化铝来避免与SF6气体直接接触。该结构模型成功解决了其他方法无法解决的晶体或者光路偏移导致的积分电压误差问题。根据仿真结果可知,其偏移误差降低至0.008%以下,并且通过实验所得到图像的标准差提高了35%以上,光强的分布均匀性得到了提高。仿真和实验结果均表明,这种优化改进方案显著提升了OVT的性能和稳定性,为电力系统的精准测量提供了可靠保障。展开更多
基金supported in part by National Natural Science Foundation of China(Nos.50937004,50777051)
文摘Surface charges greatly affect the discharge/flashover development process across an insulator. The relationship between surface charge distribution on insulating materials and measurement data based on Pockels technique is discussed, and an improved algorithm is built to calculate the real surface charge density from original data. In this algorithm, two-dimensional Fourier transform technique and Wiener filter are employed to reduce the amount of numerical calculation and improve the stability of computation, Moreover, this algorithm considers not only the influence of sample＇s thickness and permittivity, but also the impact of charges at different positions. The achievement of this calibration algorithm is demonstrated in details. Compared with traditional algorithms, the improved one supplies a better solution in the calibration of surface charge distribution on different samples with different thickness.
