【作者】 邵霞；

【导师】 周有庆； 戴瑜兴；

【作者基本信息】 湖南大学 ， 电气工程， 2013， 博士

【摘要】 电子式电压互感器（EVT）具有体小质轻、无铁磁谐振、绝缘性能好、频率响应范围宽以及采用数字量输出等优点，被认为是传统电压互感器的替代产品，代表着高性能电压互感器技术的发展方向。虽然国内外研究人员在EVT的理论和应用研究方面已经取得了很大进展，但是目前EVT的技术尚不成熟，现场在运行的EVT普遍存在受温度和电磁干扰影响较大、故障率偏高等问题。本文以开发性能稳定可靠的EVT为目标，提出了直测电流型EVT的设计思想，围绕电流型EVT的组成原理及关键技术展开系统深入的研究，成功研制出110kV电流型EVT。本文完成的主要工作如下：（1）针对分压型EVT在传输分压信号过程中易受电磁干扰的问题，提出了一种通过直接检测电容电流实现一次电压传感和测量的电流型EVT构成方案。该方案利用电容传感头将待测高电压直接变换为电容电流信号，再进行信号还原从而实现电压测量。由于传输电流信号几乎不受电磁场干扰的影响，因此从传感机理上保证了电流型EVT良好的抗干扰性能。（2）高压电容传感头是电流型EVT实现信号传感的核心部件，针对常用的油浸式高压电容器易受杂散电容影响和介质损耗偏大的问题，提出了一种具有集中结构的独立式SF6同轴圆筒型高压电容传感头。建立了电容传感头的数学模型和电场模型，利用有限元法对其电场分布和受杂散电容的影响情况进行了仿真分析。系统地研究了SF6气体压力、温度、电极几何参数等因素对电容传感头性能的影响，并提出相应的改进方法。仿真分析及样机试验结果表明，SF6同轴圆筒型电容传感头受杂散电容影响小、介质损耗小、极间电场均匀、绝缘性能强。（3）信号积分是电流型EVT实现电压信号还原的关键环节，其工作特性直接影响EVT的稳态和暂态性能。针对常用积分电路不能兼顾宽频带响应特性和快速暂态响应的问题，提出了一种基于系统状态的自适应积分电路。自适应积分电路通过判别系统处于稳态或暂态情况，自动控制两种不同性能的积分器工作状态的切换，可以同时实现稳态宽频带响应性能和快速暂态响应性能，满足电流型EVT对信号积分电路在工频信号高精度测量、谐波测量和暂态性能等各方面的要求。仿真分析结果验证了自适应积分电路的正确性和有效性。（4）研究了提高电流型EVT工作稳定性的误差补偿方法。针对温度和SF6气体压力影响电容传感头测量精度和稳定性的问题，利用多传感器信息融合方法对电容传感头进行误差补偿。建立了包含温度、气体压力和电容传感头理想电容量的三元回归信息融合模型，采用最小二乘法获取最优的回归模型参数，计算电容传感头电容量的估计值，并利用该估计值对电流型EVT的输出电压进行修正，从而实现电容传感头的误差补偿，仿真结果验证了信息融合方法的有效性。针对模拟信号处理电路的温度漂移问题，建立了模拟信号处理电路的温度误差模型，提出了基于铂电阻的温度补偿方法，温度误差试验结果表明该方法能有效提高模拟信号处理电路的温度稳定性。（5）对电流型EVT的高压电容传感头和信号处理单元进行了设计；分析了变电站电磁干扰侵入电流型EVT的途径，研究了提高电流型EVT电磁兼容性能的措施，电磁兼容试验结果验证了所采取电磁兼容措施的有效性；对研制的110kV电流型EVT样机进行了多项试验，试验结果表明，电流型EVT样机的测量准确度达到0.2级，保护准确度达到3P级，而且符合EVT标准的其它相关性能要求。本文提出的电流型EVT采用基于直测电容电流进行高电压测量的传感原理和方法，具有抗干扰能力强、温度稳定性好、暂态性能好、带宽满足谐波测量要求的优点。本文的研究为EVT的实现提供了新的思路和解决方案，研制的电流型EVT整机性能指标达到了预期的设计目标，能够满足工程实用化的要求，具有广阔的应用前景。更多还原

【Abstract】 Electronic Voltage Transformer (EVT) has a variety of advantages. It is small,light, non-ferroresonant, has a good insulation performance and a wide frequencyresponse range, as well as it can provide digital output. Therefore, EVT has beenconsidered as an appropriate substitute of the traditional voltage transformer and itrepresents the development trend of the high performance voltage transformertechnology. Many researchers from all over the world have made lots of progress inthe theories and applications of EVT. However, the techniques of EVT have not beenwell developed. The current operating EVTs have some common problems, such astemperature influence, electromagnetic interference, and high failure rate, etc. Aimedat the development of stable and reliable EVTs, this dissertation, firstly, bringsforward a design concept of the directly detecting current-based EVT, then, it studiesthe composition principles and key techniques of the EVT systemically andthoroughly, and finally researches and manufactures a110kV current-based EVTsuccessfully. The major achievements of this dissertation are described as follows:(1) To deal with the problems of the divider-based EVT’s electromagneticinterference during transmission of partial voltage signal, a current-based EVTscheme is proposed, which can realize primary voltage sensing and measurement bydirectly detecting capacitive current. Specifically, it, firstly, transforms the highvoltage, which needs to be measured, into capacitive current signal by usingcapacitive sensor, then re-transforms the current signal into voltage signal for voltagemeausurement. Since current transmission is hardly affected by electromagneticinterferences, a good anti-interference performance of the current-based EVT can beguaranteed from the sensing principles.(2) High-voltage capacitive sensor is a key component of the current-based EVTfor the signal sensing. This dissertation proposes a freestanding SF6coaxial cylinderhigh-voltage capacitive sensor with integrated construction, to deal with the problemsof being much affected by the stray capacitance and high dielectric loss of thecommon oil-immersed high-voltage capacitor. Here, the mathematical and electricfield models of the capacitive sensor are established, and the simulation analysis ofelectric field distribution and the stray capacitance influence are done by using finiteelement method. It also studies systemically the performance of the capacitive sensor as the change of parameters, including SF6gas pressure, temperature, and theelectrodes’ geometric parameter, then based on that, it introduces correspondingimproved methods. The results of simulation analysis and capacitive sensor prototypetests demonstrate that the proposed sensor is almost not influenced by straycapacitance, and has low dielectric loss, uniformity of electric fields between theelectrodes, as well as high insulation performance.(3) Signal integration is a key part of the current-based EVT to realize voltagere-transformation, whose operating characteristics have direct influence on the steadyand transient performances of the EVT. To deal with the problem that the commonused integral circuits cannot pay attention to both of the wide-band frequencyresponse characteristics and the rapid transient response characteristics, thisdissertation proposes a system state-based adaptive integral circuit. The circuit canidentify the steady and transient states of the power system, and then automaticallyswitch the working states of two integrators with different performances. The circuitcan achieve both wide-band frequency response characteristics in steady state andrapid transient response characteristics, so it can meet the requirements of thecurrent-based EVT on precise power-frequency signal measurement, the harmonicmeasurement and transient performances. The results of simulation analysis haveproved the correctness and effectiveness of the adaptive integral circuit.(4) The error compensation methods to improve the operation stability of thecurrent-based EVT are investigated in this dissertation. The multi-sensor informationfusion method is employed for error compensation of the capacitive sensor, to dealwith the problem that temperature and SF6gas pressure influence the measurementaccuracy and stability of the capacitive sensor. Firstly, the information fusion modelbased on the ternary regression analysis is established, which include temperature, gaspressure and ideal capacitance of the capacitive sensor. Secondly, the least squaremethod is used to get the optimal parameters in the regression model. Thirdly, theestimated capacitance value of the capacitive sensor is calculated. Finally, theestimated value is used to modify the output voltage of the current-based EVT,realizing the error compensation of the capacitive sensor. The simulation results haveproved the effectiveness of the information fusion method. To deal with thetemperature drift of the analog signal processing circuit, this dissertation establishesthe temperature error model of the analog signal processing circuit, and proposes atemperature compensation method based on the platinum resistor. The temperatureerror experimental results have demonstrated that this method can effectively improve the temperature stability of the analog signal processing circuit.(5) This dissertation designs the high-voltage capacitive sensor and the signalprocessing unit of the current-based EVT. The electromagnetic interference path tothe current-based EVT is analyzed, and the strategies to improve the EVT’selectromagnetic compatibility are studied. The effectiveness of the strategies isdemonstrated by the electromagnetic compatibility test results. Several experimentson the110kV current-based EVT prototype are conducted. The experimental resultshave shown that the EVT prototype assures0.2measurement precision class and3Pprotective class, as well as complies with other relevant performance requirements ofEVT standards.The proposed current-based EVT is based on the sensing theories and methodsfor measuring high voltage by directly detecting capacitive current. It has manyadvantages, among these are strong anti-interference performance, good temperaturestability, and good transient performance, and satisfactory bandwidth meeting therequirements of harmonic measurement. The research in this dissertation provides anew design idea and solution for realizing EVT. In addition, the researched andmanufactured current-based EVT has achieved the prospective design goals and canmeet the requirements of engineering applications, therefore, it has very promisingapplications in this field.更多还原