新型OVT内电场分析与传感头优化设计

发布时间：2018-04-30 05:27

本文选题：光学电压互感器 + 偏光干涉　；参考：《福州大学》2014年硕士论文

【摘要】：随着电力系统向高电压等级和大容量的不断发展,传统电压互感器因自身传感机理的缺陷,逐渐暴露出体积大、绝缘难度大、线性范围小、无数字接口等问题,无法适应电力系统智能化发展的要求。现有光学电压互感器(Optical Voltage Transducer,简称OVT)虽然能够克服上述缺陷,但仍存在许多问题没有得到解决,如测量范围小、受应力线双折射和温漂的影响严重等。近年来,双光路法、双晶体法等消除应力线双折射并进行温度补偿的研究得到广泛关注,但这些方法都未能从根源上解决问题。对于采用电光晶体Pockels效应的OVT,上述问题的症结在于偏光干涉测量模式的局限性。由于无法实现对晶体电光相位延迟的直接测量,通常采用偏光干涉测量模式,将相位延迟转变为光强调制,通过对光强的检测实现电压测量。这种测量模式反映光功率的大小,仅能近似线性地测量有限的电光相位延迟,其稳定性与可靠性受到温漂、晶体附加相位延迟、半波电压等问题的限制,无法满足电力系统的实用要求。因此,迫切需要设计一种能够对晶体电光相位延迟进行直接、线性测量的新型OVT,以解决半波电压限制、温漂等问题。本文分析了OVT偏光干涉光强调制测量模式的局限性,结合会聚偏光干涉原理设计了一种能够对晶体电光相位延迟进行直接、线性测量的新型OVT。该OVT将晶体电光相位变化转换为光斑图像的旋转角,通过测量光斑旋转角获得相位延迟。新型OVT测量模式与光强无关,可测量相位延迟为0-180。,电压测量范围不受晶体半波电压限制。文章在理论上分析推导了会聚偏光干涉图旋转角与晶体电光相位延迟角的线性关系,给出了光斑图像旋转角的读取方法,并通过实验验证了新型传感器能够测量的相位延迟角达到320°,线性度良好。此外,本文针对110kV电网,结合Ansoft Maxwell仿真进行新型OVT的结构设计,为样机的研制提供了参考依据。文章还分析了晶体形状以及外电场对电压测量的影响,并就横向调制模式提出在电光晶体上附加介质以改善晶体内电场分布的方法。通过对110kV电压等级OVT的仿真,证明了该方法能够改善电光晶体电场分布,减小光路偏移和干扰电场引起的测量误差,提高电压测量准确度和稳定性。
[Abstract]:With the continuous development of power system to high voltage level and large capacity, the traditional voltage transformer, because of its own sensing mechanism defects, gradually exposed the problems such as large volume, large insulation difficulty, small linear range, no digital interface and so on. Unable to meet the requirement of intelligent development of power system. Although the existing optical Voltage transducers can overcome the above defects, there are still many unsolved problems, such as the small measurement range, the serious influence of stress line birefringence and temperature drift, and so on. In recent years, the research of double optical path method and double crystal method to eliminate stress line birefringence and carry on temperature compensation has been paid much attention to, but these methods can not solve the problem from the root. For the Pockels effect of electro-optic crystal, the crux of the above problem lies in the limitation of the polarizing interferometry mode. Because it is impossible to measure the phase delay of crystal directly, the polarizing interferometry mode is usually used to change the phase delay into light intensity modulation, and the voltage measurement is realized by measuring the light intensity. This kind of measurement mode reflects the magnitude of optical power and can only measure the limited electro-optic phase delay approximately linearly. Its stability and reliability are limited by temperature drift, crystal additional phase delay, half-wave voltage and so on. Can not meet the practical requirements of the power system. Therefore, it is urgent to design a novel OVT that can directly and linearly measure the electro-optic phase delay in order to solve the problems of half-wave voltage limitation and temperature drift. In this paper, the limitation of OVT polarizing interference light intensity modulation measurement mode is analyzed, and a new type of OVT is designed which can directly and linearly measure the electro-optic phase delay of crystal based on the principle of convergent polarizing light interference. The OVT converts the phase change of the crystal into the rotation angle of the spot image, and obtains the phase delay by measuring the rotation angle of the spot. The new OVT measurement mode is independent of the light intensity, and the phase delay is 0-180.The voltage measurement range is not limited by the half-wave voltage of the crystal. In this paper, the linear relationship between the rotation angle of the convergent polarizing interferogram and the delay angle of the electro-optic phase of the crystal is derived, and the reading method of the rotation angle of the spot image is given. The experimental results show that the phase delay angle measured by the new sensor is 320 掳and the linearity is good. In addition, the structure design of a new type of OVT based on Ansoft Maxwell simulation is carried out for 110kV power network, which provides a reference for the development of the prototype. The influence of crystal shape and external electric field on the voltage measurement is also analyzed, and a method for improving the distribution of electric field in the crystal by adding medium to the electro-optic crystal is put forward for the transverse modulation mode. Through the simulation of 110kV voltage grade OVT, it is proved that this method can improve the electric field distribution of electro-optic crystal, reduce the measurement error caused by optical path deviation and interference electric field, and improve the accuracy and stability of voltage measurement.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM45

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