【作者】 王莉；

【导师】 王博文；

【作者基本信息】 河北工业大学 ， 电气工程， 2012， 博士

【摘要】 随着电力系统容量的增长，继电保护系统的作用日益凸显，而电流测量是电力系统中继电保护、电能计量、系统监测、系统分析的关键，其测量精度与可靠性直接关系到电力系统的安全、可靠、经济运行。传统的电磁式电流互感器具有抗电磁干扰能力差、有油易燃易爆、绝缘结构复杂、造价高、动态范围小等缺点在一定程度上束缚了其发展和应用。光纤传感器具有尺寸小、重量轻、灵敏度高、抗电磁干扰能力强、集传感和传输于一体，易于制作和埋入材料内部，具有对结构应力、应变、温度和磁场进行高精度测量的优点。论文将具有磁致伸缩量大、响应频带宽、响应速度快的超磁致伸缩材料与光纤光栅相结合进行电流传感系统设计，建立系统模型，分析温度、预应力、偏置磁场对系统传感特性的影响，并对其进行了实验研究。1.根据超磁致伸缩材料的实验数据，对GMM的磁-力-热耦合特性进行详细的分析，从弹性Gibbs自由能出发，在Wiss铁磁理论、热力学关系与J-A模型的基础上，建立了能够描述超磁致伸缩材料磁-热-力耦合特性的非线性模型。该模型以显式的形式给出了磁致伸缩材料中磁致伸缩与磁场H、磁化强度M、应力、温度t之间关系，模型中所涉及的参数均可通过实验获得，模型能够准确地预测超磁致伸缩材料在不同预压力、温度影响下磁化强度、磁致伸缩、磁化率、压磁系数随外加磁场变化关系，并能够反映材料的饱和特性与不同应力影响下的“翻转效应”；可用于计算不同应力、温度影响下超磁致伸缩材料的磁致伸缩特性，在工程实际中有良好的应用前景。2.运用多参数磁测试系统对不同预应力、温度影响下Terfenol-D棒材的磁化特性与磁致伸缩特性进行了测试，结果表明预应力对材料的磁化过程与饱和磁致伸缩特性影响明显，预应力导致饱和磁致伸缩明显增加，温度对中低场区的磁化过程与磁致伸缩特性影响十分微弱，但对饱和磁化强度与饱和磁致伸缩值影响明显。通过实验结果与磁-力-热耦合非线性模型的计算结果的比较表明模型能够较好的预测应力温度影响下超磁致伸缩材料的磁致伸缩特性。实验结果对超磁致伸缩材料的理论研究、模型建立具有一定的指导意义，为以超磁致伸缩材料为核心的传感器、换能器的设计、优化以及应用提供依据。3.设计了基于磁致伸缩效应和光纤腔衰荡技术的高灵敏度电流传感系统。在Jiles-Atherton模型、二次畴转模型和光纤衰荡技术波长解调原理的基础上建立了电流传感器的数学模型，模型反映了电流-应变-光纤腔衰荡时间之间的耦合机制。对不同预应力作用下Terfenol-D棒的磁致伸缩输出应变、衰荡时间、系统灵敏度与磁场之间的变化规律进行了理论分析和仿真研究，结果表明，该传感器具有较高的灵敏度，可通过改变预应力实现不同量程范围内的电流或磁场测量，研究可为发展新型的高灵敏度电流传感器提供理论指导。4.设计了基于超磁致伸缩材料和光纤光栅的交流电流传感系统。在光纤光栅应变传感机理、超磁致伸缩材料磁-力-热耦合非线性模型、光纤M-Z干涉仪解调原理的基础上，建立了超磁致伸缩材料和光纤光栅的交流电流传感系统模型，模型能够反映电流-光纤光栅中心波长-光纤M-Z干涉仪输出光强之间的耦合机制。对不同偏置电流、预应力影响下交流电流传感系统的工作特性进行了理论分析和仿真研究，结果表明，偏置电流与预应力都将影响超磁致伸缩材料和光纤光栅交流电流传感器的工作特性，因此，在交流电流传感器具体设计与使用过程中需要综合考虑偏置电流和预应力的影响，合理选择偏置电流与预应力的值。更多还原

【Abstract】 With the growth of the capacity of the power system, the role of relay protection system hasbecome increasingly prominent, current measurement is the key to relay protection, energymetering, system monitoring, system analysis in the power system, the measurement accuracyand reliability is directly related to the power system safe, reliable and economic operation. Thetraditional electromagnetic current transformers have drawback of immunity to electromagneticinterference, oil flammable and explosive, insulation structure complex, high cost, smalldynamic range, which constrained their development and application to some extent. Fiber opticsensor has a small size, light weight, high sensitivity, immunity to electromagnetic interference,sensing and transmission at the same time, easy making and buried inside the material,high-precision measurement of structural stress, strain, temperature and magnetic field. In thispaper, a current sensing system based on giant magnetostrictive materials and fiber grating isdesigned and the system model is established too. The giant magnetostrictive materials havelarge magnetostrictive, wide frequency bandwidth, fast response speed. The influence oftemperature, prestress, bias field to the system’s sensing characteristics is analyzed, and theexperimental study of the sensing system is also carry out.The magneto-mechanical-thermo coupling characteristics of giant magnetostrictivematerials are analyzed according to the experimental data of the giant magnetostrictive material.A nonlinear magnetostrictive model which can describe the magneto-mechanical-thermocoupling characteristics of giant magnetostrictive materials has been proposed according toelastic Gibbs free energy, Wiss ferromagnetic theory, thermo-dynamics relations andJiles-Atherton model. The proposed model gives the mathematical relation among themagnetostriction, magnetic field, magnetization, stress and temperature for magnetostrictivematerial.The parameters referred to the model can be determined through experimental methods.The model can predict magnetization, magnetostriction, magnetic susceptibility, piezomagnetic coefficient curve with the applied magnetic field under different temperature and prestress, andcan also to reflect the saturation characteristics and “flip effect” under the influence of differentprestress. The proposed model can be used to calculate the magnetostrictive characterization ofgiant magnetostrictive materials in different temperature and under different prestresses. There isa good prospect in engineering practice.The magnetization and magnetostriction characteristics of Terfenol-D rods under differenttemperature and prestresses were tested by use of multi-parameter magnetic test system. Theresults show that the effect of prestress on magnetization process and the saturationmagnetostriction is significant, prestress causes the saturation magnetostriction increasesignificantly, and the effect of temperature on magnetization process and magnetostriction in thelow magnetic field is very weak, but significant in saturation field. The comparison between thecalculation results of the nonlinear model and the experimental results shows that the proposedmodel can be used to calculate the magnetostrictive characterization of giant magnetostrictivematerials in different temperature and under different prestresses. The experimental results havea certain significance of the theoretical study of the giant magnetostrictive material and providebasis for the sensor and transducer’s design, optimization and application.A high-sensitivity current sensor is designed based on magnetostriction effect and fiber-loopcavity ring-down technique. A mathematic model of the magnetic field sensor is presentedaccording to the Jiles-Atherton model, quadratic magnetic domain rotation model and thedemodulation principle of fiber-loop cavity ring-down technique. The model quantifies thecoupling mechanisms among the current，magnetic field, strain and the ring-down time of thefiber loop. The strain variation of a Terfenol-D rod, the ring-down time of the fiber loop and thesensitivity of the sensor with the magnetic field are analyzed and simulated under differentprestresses. Results show that the sensitivity of the sensor is very high and the measurementrange of the magnetic field sensor can be changed by changing the prestress. The study result canprovide a theoretical foundation for the development of new high-sensitivity current sensors.An AC current sensing system is designed based on giant magnetostrictive material andfiber Bragg grating.The model of AC current sensing system is presented according to strainsensing mechanism, nonlinear model of giant magnetostrictive materials, demodulation principleof fiber Mach-Zehnder interferometer. The model is able to reflect the coupling mechanisms among the current，the center wavelength of fiber Bragg grating and output intensity of fiberMach-Zehnder interferometer. For different bias current, the operating characteristics of ACcurrent sensing system under the influence of prestress are theoretically analyzed and simulated,results show that the bias current and prestress will affect the operating characteristics of ACcurrent sensing system based on giant magnetostrictive material and fiber Bragg grating,therefore, the influence of the bias current and the prestress needs to be considered in the designand application of AC current sensor and the suitable value of bias current and prestress shouldbe selected.更多还原