基于Kerr电光效应的变压器油中直流电场测量系统.docVIP

  基于 Kerr 电光效应的变压器油中直流电场 测量系统# 王鹏* 5 10 15 20 25 30 35 40 （清华大学电机系） 摘要：在直流电场下油纸绝缘系统中，空间电荷的存在会对系统的绝缘性能造成影响。通过 实时测量得到绝缘系统中的电场分布和电荷分布具有重要意义。Kerr 电光效应法因不会对 绝缘系统中电场分布造成影响而得到很多研究者的关注。由于实验系统中包含较复杂的光学 器件及微弱信号检测单元，其实现具有一定的难度。本文采用光电二极管作为光接收器件， 采用一种交流电压调制方法，结合锁相放大器实现了对微弱信号的检测；通过检测输出光强 中直流和所施加的交流信号分量，计算得到了待测直流电场的数值。试验结果表明该系统具 有较好的线性度。 关键词：绝缘系统 ；直流电场； 电光效应； 电场测量； 测量系统 中图分类号：TM854 A DC Electric Field Measurment System in Transformer Oil Based on Kerr Electro-optic Effect Wang Peng (Dept. of Electrical Engineering) Abstract: Space charge accumulation can seriously effect the insulation system under dc voltage. So the real electric field distribution or space charge distribution plays a significant role in the development of insulation system of power equipments. The electric field measurement method based on Kerr effect can not affect the electric field distribution under test and can obtain the electric field distribution on-line. For the small Kell constant of oil, ac modulation method is conducted during the measurement of dc electric field in oil in this paper. During the dc electric field measurement, a low ac voltage (about several hundreds voltage) are superimposed on the tested dc voltage. The dc electric field can be calculated using the dc and ac signal components through the optic intensity of the photodiode. During the measurement of electric field distribution based on Kerr effect, the output of the photodiode is connected to a phase lock amplifier, by which the dc and ac signal components needed to calculate the electric field are obtained. This method can get the final results of the dc and ac signal components. The validity of the measurement system is confirmed by the results. Key words: insulation system; dc electric field; electro-optic effect; electric field measurement; measurement system 0 引言 在高压装备绝缘结构（尤其是直流电场下）的设计中，空间电荷对电场分布的影响是 不能回避的重要问题[1]。空间电荷的存在，会畸变区域内的电场分布，导致绝缘水平下降。 此时，电场按泊松方程分布；若采用拉普拉斯方程进行求解将带来非常大的误差。因此，为 了优化绝缘结构设计，需要得到电极间的电场分布和空间电荷分布状况。在绝缘结构比较复 杂