【作者】 王海明；

【导师】 郑绳楦； 毕卫红；

【作者基本信息】 燕山大学 ， 电路与系统， 2006， 博士

【摘要】 电子式电流互感器(ECT)具有高绝缘、无饱和等优良性能,被认为是传统电磁式电流互感器的替代产品,但迄今为止其研究领域依然充满难题,阻碍着电子式电流互感器的实用化进程,其中的主要原因是外界环境因素(如温度、电磁干扰等)对电流传感头的影响,使其无法满足电流计量精度以及连续稳定运行的要求。本论文的研究对象是电子式电流互感器的电流传感头。作为电子式电流互感器的理论基础,论文阐述了基于法拉第磁光效应和基于Rogowski线圈原理的电子式电流互感器的电流传感原理,阐述了不同类型电子式电流互感器的组成、结构及研究现状,揭示了目前电子式电流互感器电流传感头存在的主要问题。研究分析了基于Rogowski线圈原理的电子式电流互感器的组成结构。基于电磁场理论知识,系统地分析了圆形截面Rogowski线圈和矩形截面Rogowski线圈的电流传感原理,研究了自积分式电流传感头电路和外积分式电流传感头电路,分析了具有反馈环节的外积分器,从时域和频域两方面分析了电流传感头电路的工作原理。系统地建立了圆形截面、矩形截面、跑道形截面Rogowski线圈互感的数学模型。通过理论推导和实验的方法,研究了常规圆形截面线圈互感数学模型与新建互感数学模型之间的计算误差问题。针对IPEM片状结构矩形截面Rogowski线圈互感的计算问题,建立了求解矩形截面载流导体表面磁场的二重级数模型,给出了其互感数值求解方法,数据结果采用MATLAB和ANSYS仿真进行了验证。为了提高电流传感头灵敏度、同时保持线圈的必要带宽,论文分析了多Rogowski线圈串联组合式电流传感头的性能。研究分析了热膨胀效应对电流传感头Rogowski线圈的影响。提出并定义了Rogowski线圈热系数的概念,并根据线圈组成将该系数分为线圈绕组热系数和线圈骨架热系数。推导建立了计算圆形截面线圈和矩形截面线圈的四个热系数计算公式,建立了评价Rogowski线圈电流传感头热膨胀误差的数学模型,通过试验对理论分析结果进行了验证。本论文还分析了其它影响电流传感头性能的因素,分析了温度对传感头积分器电路的影响、Rogowski线圈接头匝工艺因素的影响、Rogowski线圈结构及其电磁参数的影响、外界电磁干扰因素的影响等。更多还原

【Abstract】 Being no saturation under fault current conditions and high level of insulation,Electronic Current Transformer (ECT) has been considered as the appropriate substituteof the traditional electromagnetic current transformer. However, the unsolved problemsare in the way to ECT’s practicality up to the present time. The major reason for this is theinfluencing factors, such as ambient temperature, electromagnetic interference, thatdecreasing the measurement accuracy and stability of ECT and baffling its application inpower industry. This dissertation focuses researches on electronic current transformer’shead.Being a foundation of electronic current transformer, the principles of ECT currentsensor based on Faraday mageto-optical effect and Rogowski coil theory are investigatedand described. The components, composite construction and present status of differenttypes of ECT’s development are summarized, which discovered the unsolved majorproblems existing in electronic current transformer’s head.A digital ECT based on Rogowski coils is studied on its elements and construction.The current-sensing theories of the Rogowski coil having a circular cross section and thecoil having a rectangular cross section are systematically investigated by use of theknowledge within electromagnetic field theory. An analysis of the circuits of currentsensor is presented in time domain and frequency domain, which includes aself-integrating circuit, an additional integrating circuit and an integrator with a feed backresistor.The mathematical models of Rogowski coil’s mutual inductance are systematicallybuilt, which is classified in terms of coil’s cross section in circular shape, rectangularshape and racetrack shape. The calculating difference between the conventionalmathematical model and the presented mathematical model of mutual inductance isdescribed and verified by an experiment on the coil with a circular cross section. Aparticular mathematical model is expressed as the double-layer series for solution ofmagnetic flux density surrounding a current-currying conductor with the cross section inrectangular shape, which provides a method for numerical solution of the mutualinductance of the coil in plate shape for IPEM. The resultant data on program MATLABare verified by a simulation on ANSYS. In order to increase the sensitivity and keep thebandwidth necessary, the performance of the Rogowski coil by integrating several subcoils is discussed in this dissertation.Due to an analysis of thermal expansion effect on Rogowski coil, a novel factordescribing the ratio error of induced voltage per unit rise in temperature is defined. Thefactor is classified further in terms of the coil’s component, wounding wire and former.Four equations are derived for calculation of novel factors describing the Rogowski coilswith a circular cross section and a rectangular cross section. A mathematical model is alsoproposed in order to evaluate the measurement error caused by thermal expansion effecton Rogowski coil;its numerical values from theoretical calculation are verified by anexperiment. The other influence factors on the coil are also discussed in this dissertation,such as the temperature variation of RC integrator, imperfect connect butt of winding,electromagnetic parameters related to coil’s structure, electromagnetic interference and soon.The problem involved in power supply for ECT transformer’s head is discussedfollowing description of three kinds of power, the power based on electromagneticinduction, the power based on laser and fiber and the power based on capacitor divider. Inorder to obtain the stability and an uninterruptible power supply, a new scheme of poweris proposed, which combines the application of Lithium-ion battery. The advantages ofthe Lithium-ion battery are discussed briefly according to its characters.The configurations are studied in this dissertation, which are mainly related tooptimization design of the electronic current transformer’s head. An assemblage gapfactor is proposed for description of the coil’s structure, technique, installation and design;the parameters describing the coil’s configuration and relations between the parametersare systematically discussed. The configurations of the Rogowski coils with thesingle-layer windings and the multi-layer windings are studied. In order to improve theperformance of Rogowski coil, a new mathematical model is developed for optimizationdesign of the coil’s configuration. The model is expressed as a computational processfinding the minimum of constrained nonlinear multivariable function. The coil’sreturn-loop for minimizing electromagnetic interference is discussed and the fulloptimization design is shown in a flow chart. All the calculation and simulation areprogrammed on MATLAB.Based on the previous analysis and experiment of the thermal expansion effect onRogowski coil, a new method called thermal expansion self-compensation is proposed tominimize the error caused thermal expansion, which is performed by using an embeddedcompensation ring in coil’s former. An analysis of the thermal compensation ring is givenand the compensation effect is examined by an experiment.更多还原