基于零磁通原理的微电流传感器的研制

发布时间：2018-01-14 12:47

本文关键词：基于零磁通原理的微电流传感器的研制　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：高压电力设备的绝缘在线监测是确保电力系统安全运转的重要技术手段,其中高精度微电流传感器是实现电力系统绝缘状态在线监测不可或缺的工具。它涉及电气保护、电能计量、电控等相关领域,担负着采集信号的任务,是整个在线监测系统中的重要组成部分。因此,电流传感器的测量精度和工作可靠性与电力系统的安全运转直接相关。测量用电流传感器一般安装在高压开关领域,工作时容易受到强电磁场的干扰。并且,在电力线路或设备的绝缘在线监测中,需要测量的泄漏电流的数量级均在微安级,普通的小电流传感器难以满足需求。综上所述,设计一种测量精度高,灵敏度好,适用于强电磁场环境的微电流传感器对于电气设备绝缘状态的在线监测具有重要研究意义。本文基于零磁通原理研制了一种准确度可达到0.2级的微电流传感器。主要研究内容如下:首先,将单匝穿心式电流传感器作为研究对象。根据电磁感应原理建立了电磁式电流传感器的等效电路图并推导出误差公式,得出造成测量误差的主要原因是激磁电流。根据误差公式从电流传感器的磁芯结构参数、二次侧负载阻抗、二次侧绕组匝数、和磁芯材料等几个方面对影响误差的因素进行分析,设计了电流传感器的感应部分。为进一步减小误差,需增设外部补偿手段。首先阐述了有源补偿及无源补偿两种方法。在此基础上设计了基于零磁通原理的整体补偿方案。该方案将有源电子电路补偿方法与三次绕组并联阻抗的无源补偿方法结合,使磁芯达到“零磁通”状态,从而使得测量误差最小。为验证该补偿方案的正确性,基于Simulink建立了带有零磁通补偿的微电流传感器模型,并与传统电流传感器的模型进行对比性仿真实验。仿真结果表明带有零磁通补偿的微电流传感器较传统的电流传感器误差有所减小,提高了测量精度,证明了该补偿模型的正确性。设计了有源补偿的硬件电路以及信号处理电路。其中补偿电路实现的功能是将感应电压处理变换成补偿电流送入二次侧绕组,对输出电流进行相位幅值的补偿。信号处理电路主要对二次侧输出的微弱信号进行调理,方便后续处理及检测。以LabVIEW为软件平台设计了微电流传感器的误差测量程序,该程序可以实现数据采集、数字滤波、波形显示、比差及角差测量的功能。经实验室测试,该程序运行稳定、可靠、交互性强、显示内容丰富。在实验室环境下搭建测试平台,对微电流传感器的硬件、软件各个部分进行测试。通过对微电流传感器的误差测量结果表明,设计的微电流传感器可以测量μA~mA级的工频电流,增设的补偿电路可以有效的减小测量误差,提高测量准确度。整体运行稳定,各项指标达到设计要求。
[Abstract]:On-line insulation monitoring of high-voltage power equipment is an important technical means to ensure the safe operation of power system. High-precision micro-current sensor is an indispensable tool to realize on-line monitoring of power system insulation, which involves electrical protection, electric energy measurement, electrical control and other related fields, which is responsible for the task of collecting signals. Is an important part of the whole online monitoring system. The measuring accuracy and reliability of the current sensor are directly related to the safe operation of the power system. The current sensor used in the measurement is generally installed in the field of high voltage switch, and is vulnerable to the interference of the strong electromagnetic field. In the insulation on-line monitoring of power line or equipment, the order of magnitude of leakage current to be measured is in the microampere level, the ordinary small current sensor is difficult to meet the demand. In conclusion, a kind of measuring accuracy is high. Good sensitivity. The micro-current sensor suitable for strong electromagnetic field environment is of great significance for on-line monitoring of insulation state of electrical equipment. Based on the principle of zero flux, a micro-current sensor with accuracy of 0.2 grade has been developed in this paper. The main contents of the study are as follows:. First. Based on the principle of electromagnetic induction, the equivalent circuit diagram of electromagnetic current sensor is established and the error formula is deduced. According to the error formula, the structure parameters of magnetic core, the load impedance of secondary side and the turn number of secondary side winding are obtained. In order to further reduce the error, the inductive part of the current sensor is designed by analyzing the factors affecting the error in several aspects, such as magnetic core material and so on. Two methods of active compensation and passive compensation are introduced. On this basis, an integral compensation scheme based on the principle of zero flux is designed, which combines the compensation method of active electronic circuit with the third winding. The passive compensation method of parallel impedance is combined. In order to verify the correctness of the compensation scheme, a micro-current sensor model with zero flux compensation is established based on Simulink. The simulation results show that the error of the micro-current sensor with zero flux compensation is smaller than that of the traditional current sensor, and the measurement accuracy is improved. The correctness of the compensation model is proved. The hardware circuit and signal processing circuit of active compensation are designed. The function of the compensation circuit is to convert the inductive voltage into the compensation current into the secondary winding. The phase amplitude of the output current is compensated. The signal processing circuit mainly adjusts the weak signal output from the secondary side. Using LabVIEW as the software platform, the error measurement program of micro-current sensor is designed. The program can realize data acquisition, digital filtering and waveform display. Through the laboratory test, the program runs stably, reliably, interactively, and has rich display content. The test platform is built in the laboratory environment, and the hardware of the micro-current sensor is built. The error measurement results of the micro current sensor show that the designed micro current sensor can measure the power frequency current of 渭 AmA level. The additional compensation circuit can effectively reduce the measurement error and improve the accuracy of the measurement. The whole operation is stable and the indexes meet the design requirements.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212;TM855

【参考文献】