电容分压电压互感器.pdf

国内图书分类号：TM451 学校代码：10213 国际图书分类号：621.31 密级：公开 工学博士学位论文 工学博士学位论文 电容分压型光学电压互感器研究 博 士 研 究 生：王红星 导师：蔡兴国 教授 申请学位：工学博士 学科：电力系统及其自动化 所在单位：电气工程及自动化学院 答辩日期：2010 年 12 月 授予学位单位：哈尔滨工业大学 Classified Index:TM451 U.D.C.:621.31 Dissertation for the Doctoral Degree in Engineering RESEARCH OF CAPACITOR DIVIDER OPTICAL VOLTAGE TRANSDUCER Candidate:Wang Hongxing Supervisor:Prof.Cai Xingguo Academic Degree Applied for:Doctor of Engineering Specialty Power System and Its Automation Affiliation:Dept.of Electrical Engineering Date of Defence:Dec.,2010 Degree-Conferring-Institution:Harbin Institute of Technology 摘 要-I-摘 要 光学互感器是智能变电站的关键基础设备。经过几十年的发展，光学电流互感器已经有了实用化的产品问世，而光学电压互感器由于受到测量精度低且抵御外界电场干扰能力差等因素的影响，其实用化进程相对缓慢。随着智能电网建设的全面展开，光学电压互感器的实用化研究已经迫在眉睫。在综合评述现有技术及应用成果的基础上，本文将电容分压型光学电压互感器确定为研究对象，针对其在实用化过程中所存在的主要问题，从高压电容分压器的分析设计、光学电压传感器的光路建模、光学电压传感技术以及互感器输出特性等几个方面对其展开了深入的研究。相间干扰电场对高压电容分压器的影响是电容分压型光学电压互感器外界电场干扰的主要来源，因而计及相间干扰电场的高压电容分压器的设计是非常必要的。本文结合电容分压型光学电压互感器的运行环境，从本相分压与相间干扰分压两个角度出发建立了高压电容分压器的数学模型，进而提出了高压电容分压器的设计方法，并通过实验手段验证了该方法的有效性。光路模型是分析光学电压传感器传变特性的有效工具，通常采用的正入射光学电压传感器的光路模型不能准确描述实际光学电压传感器的传变特性。计及双折射的影响，本文推导了关于任意起偏角的光学电压传感器的光路模型和基于该光路模型的双光路输出模型。所建立的光路模型具有一般理论意义，利用它们可以更准确的描述温度变化通过干扰双折射和晶体半波电压对光学电压传感器运行品质的影响。光学电压传感器测量精度的温漂问题是光学电压互感器测量精度低的主要原因，现有的提高光学电压传感器测量精度的方法一般是在传感系统的某一环节上采取措施，这不能彻底消除温度对测量精度的影响。本文着眼于光学电压传感器的系统结构，提出了自愈光学电压传感技术，使光学电压传感器能够自动适应环境温度变化。实验结果表明，该技术大幅度提高了光学电压传感器的测量精度。文章对采用了电容分压器的电容式电压互感器（CVT）、电容分压型电子式电压互感器（ECVT）、电容分压型光学电压互感器（OVT）的输出特性进行了比较分析，结果表明电容分压型 OVT 在稳态特性和暂态特性两方面都好于传统电压互感器。与 CVT 比较，电容分压型 OVT 不存在铁磁谐振和瞬变响应延迟的问题；与 ECVT 比较，电容分压型 OVT 不存在线路带滞留电荷重合哈尔滨工业大学工学博士学位论文-II-闸引起的较大暂态测量误差的问题。结合文中提出的高压电容分压器设计方法与自愈光学电压传感技术，研制出了课题组首台 0.5 级 220kV 电容分压型光学电压互感器样机。目前该样机已经完成了相关测试，并于 2010 年 5 月在实际电力系统中实现了挂网运行。测试结果和运行情况表明：本文所提出的提高光学电压互感器性能的方法是正确可行的，所研制的电容分压型光学电压互感器具有工程实用化前景。关键词：光学电压互感器；高压电容分压器；光路模型；输出特性 Abstract-III-Abstract Optical transformer is the key basis facility for building of intelligent electric substation.With several decades development,some practical product of optical current transformer has already launched,but the practical process of optical voltage transformer is relative slow due to its low measuring accuracy and poor resistance to outside electric field disturbance.With the overall development of the intelligent electric network construction,the utility research of optical voltage transformer has become imminent.On the basis of reviewing the existed technology and application,this paper treats the capacitor divider optical voltage transformer as the research object.Against the existing problem during the utility of the optical voltage transformer,the paper thoroughly research on the optimization of high voltage capacitor voltage divider,the optical circuit modeling of optical voltage sensor,the optical voltage sensing technology and the output characteristic of transformer.The outside electric field disturbance for the capacitor divider optical voltage transformer is derived from the effect of inter-phase electric field disturbance to the high voltage capacitor voltage divider.The designed method for high voltage capacitor voltage divider considering the inter-phase electric field disturbance is very important.Combined with the practical operation environment of capacitor divider optical voltage transformer,a high voltage capacitor voltage divider mathematic model is built from the aspect of inner-phase and inter-phase disturbance voltage division.Furthermore,a method is proposed to design high voltage capacitor voltage divider with respect to the simulation software.The validity of the method is tested by experiment.Optical circuit model is an effective tool to analysis the transfer characteristic of the optical voltage sensor,the usually used normal incidence optical circuit model could not accurately describe the transfer characteristic of the optical voltage sensor.This paper derived arbitrary incident polarizing angle optical circuit model and dual optical circuit output model of the optical voltage sensor.The proposed optical circuit model has the general theoretical meaning,and it can accurately describe the effect of disturbing birefringence and the transistor half-wave voltage decided by the temperature variation to the operation quality for the optical voltage sensor.The temperature drift of measurement accuracy for optical voltage sensor is the main reason for the low measurement accuracy.The existing methods 哈尔滨工业大学工学博士学位论文-IV-improving the measurement accuracy of optical voltage sensor are usually to take measures on some aspect in sensor systems,and this can not eliminate the temperature effect to the measurement accuracy thoroughly.This paper presents a kind of self-healing optical voltage sensing technology by focusing on the optical voltage sensors system structure.This optical voltage sensor can adapt to the variety of environment temperature.The experiment result shows that the measurement accuracy is improved largely by adopting the technology.The output characteristic for three capacitor voltage of capacitor voltage transformer(CVT),Electronic Capacitor Voltage Transformer(ECVT)and capacitor divider optical voltage transformer(OVT)are compared and analyzed,and the result indicated that the steady-state characteristic and the transient-state of capacitor divider OVT are better than the traditional voltage transformer.Compared with the CVT,The capacitor divider OVT has no the problems of ferroresonance and transient response delay,and it also has no the problems of larger transient measurement error caused by the reclosing on a line with trapped charges versus to the ECVT.Combining the high voltage capacitor voltage divider designing method and the self-healing optical voltage sensor technology presented in the paper,A 220 kV,level 0.5 prototype of capacitor divider optical voltage transformer is developed.The relevant test of the prototype has already been completed,and the prototype has been operating in actual power system in since May 5th,2010.The test result and the operation conditions show that the presented method which can improve the optical voltage transformers performance is correct and feasible,and the developed capacitor divider optical voltage transformer has the prospects for practical applications.Keywords:optical voltage transformer,high voltage capacitor voltage divider,optical circuit model,output characteristic 目 录-V-目 录 摘要.I Abstract.III 第 1 章 绪论.1 1.1 课题研究目的与意义.1 1.2 新型电压互感器的分类.2 1.2.1 电子式电压互感器.2 1.2.2 光学电压互感器.3 1.3 光学电压互感器的基本原理.4 1.3.1 光学电压传感原理.5 1.3.2 电压信号检测方法.6 1.3.3 电压信号获取方式.8 1.4 光学电压互感器的研究现状.10 1.4.1 研究现状综述.10 1.4.2 存在的主要问题.13 1.5 电容分压型光学电压互感器.17 1.6 本文的主要研究内容.18 第 2 章 高压电容分压器的分析.20 2.1 引言.20 2.2 OVT用高压电容分压器的结构与特点.20 2.2.1 高压电容分压器的原理与构成.20 2.2.2 OVT用高压电容分压器的特点.21 2.3 高压电容分压器的数学模型.22 2.4 高压电容分压器的误差特性.23 2.4.1 杂散电容对电容分压器的影响.23 2.4.2 相间干扰对电容分压器的影响.26 2.4.3 温度变化对电容分压器的影响.29 2.4.4 其它因素对电容分压器的影响.30 2.4.5 高压电容分压器的误差综合.31 2.5 高压电容分压器的优化设计.32 2.5.1 高压电容分压器的有限元计算条件.33 哈尔滨工业大学工学博士学位论文-VI-2.5.2 杂散电容对电容分压器优化的影响.34 2.5.3 相间干扰对电容分压器优化的影响.35 2.5.4 精密高压电容分压器的设计.39 2.6 高压电容分压器的实验研究.41 2.6.1 电容分压器实际变比测定.41 2.6.2 邻近效应对变比影响的实验.42 2.6.3 温度变化对变比影响的实验.43 2.6.4 电压变化对变比影响的实验.44 2.7 本章小结.45 第 3 章 光学电压传感器的光路建模.46 3.1 引言.46 3.2 偏振光系统的琼斯矩阵分析法.46 3.2.1 偏振光的琼斯矢量表示.46 3.2.2 偏振器件的琼斯矩阵表示.47 3.3 光学电压传感器的理想光路模型.48 3.4 电光晶体元件的琼斯矩阵.51 3.4.1 电光晶体元件的干扰双折射.51 3.4.2 电光晶体元件的介电张量.52 3.4.3 电光晶体元件的琼斯矩阵.54 3.5 光学电压传感器的一般光路模型.56 3.5.1 一般光路模型的建立.56 3.5.2 光路模型的数学解析.58 3.6 光学电压传感器的双光路输出模型.60 3.7 光路模型的分析.61 3.7.1 光强的特性分析.61 3.7.2 光强的温度特性.63 3.8 本章小结.65 第 4 章 自愈光学电压传感原理及实现.66 4.1 引言.66 4.2 光学电压传感模型.66 4.3 自愈光学电压传感技术.68 4.3.1 光学电压传感的温度补偿.68 4.3.2 自愈光学电压传感原理.69 目 录-VII-4.4 自愈光学电压传感器.71 4.4.1 自愈光学电压传感器的可实现性.71 4.4.2 自愈光学电压传感器的实现.72 4.5 光学电压传感器的测试系统.74 4.6 自愈光学电压传感器的测试.75 4.6.1 常温下的精度测试.75 4.6.2 光强波动时的精度测试.76 4.6.3 循环温度下的精度测试.77 4.7 本章小结.78 第 5 章 电容分压型光学电压互感器的输出特性.79 5.1 引言.79 5.2 试验电路模型.79 5.3 稳态特性分析.81 5.3.1 准确度的理论分析.81 5.3.2 准确度的仿真分析.84 5.4 暂态特性分析.86 5.4.1 暂态性能技术指标.87 5.4.2 瞬变响应过程仿真.87 5.4.3 瞬变响应的理论分析.91 5.5 电容分压型OVT的性能优势.94 5.6 试验及挂网运行.95 5.7 本章小结.97 结论.98 参考文献.100 附录.111 攻读博士学位期间所发表的学术论文.114 哈尔滨工业大学博士学位论文原创性声明.115 哈尔滨工业大学博士学位论文使用授权书.115 致谢.116 个人简历.117 哈尔滨工业大学工学博士学位论文-VIII-Contents Abstract(in Chinese).I Abstract(in English).III Chapter 1 Introduction.1 1.1 Purpose and significance of the dissertation.1 1.2 Classification of new type voltage transformer.2 1.2.1 Electronic voltage transformer.2 1.2.2 Optical voltage transducer.3 1.3 Basic principle of optical voltage transducer.4 1.3.1 Principle of optical voltage sensor.5 1.3.2 Detection method of voltage signal.6 1.3.3 Access method of voltage signal.8 1.4 Present situation of research on optical voltage transducer.10 1.4.1 Summary of research present situation.10 1.4.2 Main problems on the research before.13 1.5 Capacitor divider optical voltage transformer.17 1.6 Main work of the dissertation.18 Chapter 2 Analyzation of high voltage capacitor voltage divider.20 2.1 Introduction.20 2.2 Structure and characteristic of high voltage capacitor voltage divider used in optical voltage transducer.20 2.2.1 Principle and construction of high voltage capacitor voltage divider.20 2.2.2 Characteristic of high voltage capacitor voltage divider used in optical voltage transducer.21 2.3 Mathematical model of high voltage capacitor voltage divider.22 2.4 Error characteristic of high voltage capacitor voltage divider.23 2.4.1 Effect of stray capacitance to high voltage capacitor voltage divider.23 2.4.2 Effect of interphase interference to high voltage capacitor voltage divider.26 2.4.3 Effect of temperature to high voltage capacitor voltage divider.29 2.4.4 Effect of other factors to high voltage capacitor voltage divider.30 2.4.5 Comprehensive analysis of errors of high voltage capacitor voltage divider.31 2.5 Optimal designing of high voltage capacitor voltage divider.32 2.5.1 Finite element calculation conditions of high voltage capacitor voltage divider.33 2.5.2 Effect of stray capacitance to the optimization of high voltage capacitor Contents-IX-voltage divider.34 2.5.3 Effect of interphase interference to the optimization of high voltage capacitor voltage divider.35 2.5.4 Designing of precise high voltage capacitor voltage divider.39 2.6 Experimental study of high voltage capacitor voltage divider.41 2.6.1 Determination of actual variable ratio of capacitor voltage divider.41 2.6.2 Effect of proximity effect to varable ratio.42 2.6.3 Effect of temperature to varable ratio.43 2.6.4 Effect of voltage to varable ratio.44 2.7 Summary.45 Chapter 3 Optical circuit modeling of optical voltage sensor.46 3.1 Introduction.46 3.2 Jones matrix analysis of polarized light system.46 3.2.1 Expression of Jones vector of polarized light.46 3.2.2 Jones matrix of polarized light devices.47 3.3 Ideal optical circuit model of optical voltage sensor.48 3.4 Jones matrix of electro-optical crystal element.51 3.4.1 Birefringence interference of electro-optical crystal element.51 3.4.2 Dielectric tensor of electro-optical crystal element.52 3.4.3 Jones matrix of electro-optical crystal element.54 3.5 General optical circuit model of optical voltage sensor.56 3.5.1 Establishment of the general optical circuit model.56 3.5.2 Mathematical analysis of the optical circuit model.58 3.6 Dual beam output model of optical voltage sensor.60 3.7 Analysis of optical circuit model.61 3.7.1 Characteristic analysis of light intensity.61 3.7.2 Temperature characteristic of light intensity.63 3.8 Summary.65 Chapter 4 Principles and realization of self-healing optical voltage sensor.66 4.1 Introduction.66 4.2 Model of optical voltage sensor.66 4.3 Sensoring technology of self-healing optical voltage.68 4.3.1 Temperature compensation of self-healing optical voltage sensor.68 4.3.2 Principle of self-healing optical voltage sensor.69 4.4 Self-healing optical voltage sensor.71 4.4.1 Realizability of self-healing optical voltage sensor.71 4.4.2 Realization of self-healing optical voltage sensor.72 4.5 Test system of optical voltage sensor.74 哈尔滨工业大学工学博士学位论文-X-4.6 Text of self-healing optical voltage sensor.75 4.6.1 Accuracy test under normal atmospheric temperature.75 4.6.2 Accuracy test with the fluctuating light intensity.76 4.6.3 Accuracy test at cycle temperature.77 4.7 Summary.78 Chapter 5 Output characteristics of capacitor divider optical voltage transformer 79 5.1 Introduction.79 5.2 Test circuit model.79 5.3 Steady state characteristics analysis.81 5.3.1 Theoretical analysis of accuracy.81 5.3.2 Simulated analysis of accuracy.84 5.4 Transient characteristics analysis.86 5.4.1 Performance specifications of transient.87 5.4.2 Simulation of trensient response process.87 5.4.3 Theoretical analysis of trensient response.91 5.5 Performance advantages of capacitor divider optical voltage transformer.94 5.6 Test and network operation.95 5.7 Summary.97 Conclusions.98 References.100 Appendix.111 Paper Published in the Period of Ph.D.Education.114 Statement of copyright.115 Letter of authorization.115 Acknowledgements.116Resume.117 第 1 章 绪论-1-第1章 绪论 1.1 课题研究目的与意义 高压电压互感器是电力系统中不可缺少的重要测量设备，它实现了一次与二次系统的电气隔离。一方面，当电力系统正常运行时，电压互感器把一次侧的高电压变换成适合于测量仪表和计量装置等工作的低电压；另一方面，当电力系统发生故障时，电压互感器能正确反映故障状态下电压波形，与继电保护和自动装置配合，对电力系统各种故障构成保护和自动控制。目前，在电网中大量投入使用的电压互感器大多数是常规的电磁式电压互感器(Potential Transformer，简称PT)和电容式电压互感器(Capacitor Voltage Transformer，简称CVT)。PT实际上是一台容量很小的变压器，它在较低电压等级中应用具有优势，但其存在铁磁谐振的隐患，且电压等级越高，绝缘越困难，造价也越高1。现在的高压电网中通常采用CVT，它由电容分压器和电磁部分组成，电磁部分也是一台变压器，只是一次侧电压是经过电容分压后的较低电压。与PT比较，CVT具有绝缘强度高、不与系统发生铁磁谐振、高电压下价格较低以及可兼作耦合电容器用于载波通信等优点2。但是，CVT暂态响应较差，电容与非线性补偿电感、变压器电感串联，设备本身有发生铁磁谐振的可能，这会威胁设备安全可靠的运行。此外，常规电压互感器还存在体大质重、容量有限、动态范围小、测量频带窄、抗电磁干扰能力弱、输出无法与计算机直接相连等问题3，这些都是它们的固有缺陷，无法根本消除。随着我国智能电网建设的全面展开，我国将加快建设以特高压电网为骨干网架，各级电网协调发展，具有信息化、数字化、自动化、互动化特征的统一的坚强智能电网4-6，这使得常规电压互感器因其自身传感机理的原因更加已难以适应现代电网建设的需要。因此，寻求能够克服常规电压互感器的上述缺陷并满足智能电网要求的新型电压互感器已势在必行。在当今世界，各大国都在逐步建立特大型电网，为了避免与 2003 年“8.14”美加大停电事故类似的破坏性电力系统灾难发生，人们正在构建突出自愈功能的电力系统安全防御体系。以相量测量单元PMU(Phasor Measurement Unit)为基础的提供电网准确动态过程测量数据的广域测量系统WAMS(Wide Area Measurement System)将成为电网安全防御体系的基础测量系统7-8。PMU不仅要求新型电压互感器具有高可靠性而且要求其既快速又高度准确的反映一次电哈尔滨工业大学工学博士学位论文 压，也就是说无论在稳态还是在暂态情况下，都要求新型电压互感器能够真实反映电压的频率、幅值和相位。因此新型电压互感器不是一般地对常规电压互感器的升级换代，而是现代化大电网安全稳定运行的需求。可见，研究与发展基于新原理的电压互感器对于保证日益庞大而复杂的电力系统安全可靠运行，并提高电网的自动化、智能化程度具有深远意义。新型电压互感器是智能电网建设所急需的更新换代产品，尽快将其实用化已成为电力系统发展的迫切需要。1.2 新型电压互感器的分类 具有实用化前景的新型电压互感器，在结构上基本都包括三个组成部分：电压传感部分、信号传输部分和信号处理部分。信号传输的光纤化和信息处理的电子化是所有新型互感器的共性，传感原理的不同，导致了新型电压互感器本质的不同。依据电压传感环节和传感原理的不同，新型电压互感器主要分为两种类型：采用分压原理的电子式电压互感器(Electronic Voltage Transformer，简称 EVT)和基于光学效应原理的光学电压互感器(Optical Voltage Transducer，简称 OVT)。-2-1.2.1 电子式电压互感器 电子式电压互感器依分压元件不同，主要分为电阻分压、电容分压和阻容分压等实现形式。电阻分压多用于 10kV和 35kV电压互感器9-12；电容分压主要用于中高压电压互感器13-16。目前，还出现了一种串联感应分压的应用17。电子式电压互感器的传感头就是由电阻/电容构成的分压器，如图 1-1 所示。被测电压信号由分压器从电网取出，其工作原理与 CVT 的电容分压器相似，不同的是其额定容量在毫瓦级(为一次侧电子电路供能)，输出电压一般不超过5V。因此，(或)应达到数百兆欧以上，而(或)在数十千欧数量级，为使分压比1R1CZ2R2CZK接近)/(2120RRRK+=或)/(211CCC+，要求负载阻抗(或)。同时分压所用电阻和电容在-40+80的环境温度中应阻值稳定，并有屏蔽措施，避免外界电磁干扰。2RZ 2CZ电子式电压互感器解决了铁磁谐振问题和磁饱和问题，提高了常规电压互感器的动态响应能力，但存在几个关键问题：（1）高压传感头必然是有源方式；（2）温度和电磁干扰的影响不能忽略；（3）受杂散电容的影响，测量精度难以保证。此外，电阻分压型电子式电压互感器因受电阻功率和准确度的限制而在超第 1 章 绪论 高压交流电网中难以实际使用；电容分压型