【作者】 李云伟；

【导师】 王泽忠；

【作者基本信息】 华北电力大学（北京） ， 电工理论与新技术， 2008， 博士

【摘要】 随着电网向特高压、集约化方向发展和微电子技术在二次设备中的广泛应用,变电站电磁环境日趋恶化,二次设备的电磁兼容问题日益突出,研究变电站开关瞬态场及其对二次电缆的耦合机理具有重要的理论意义和应用价值。本论文基于时域有限差分(FDTD)方法,研究了变电站开关瞬态场的时域仿真方法,变电站土壤中和电缆沟内的瞬态电磁场分布,有界波电磁脉冲(EMP)模拟器的传输线设计,近场对有限长线缆的耦合机理,以及瞬态电磁场耦合电缆的数值计算方法。论文主要研究成果如下:1.建立了变电站开关瞬态场的时域仿真模型,基于火花放电理论,提出了隔离开关操作时电弧放电通道的时变电阻和电感公式。通过拟合典型变电站开关瞬态场实测数据获得了开关电弧放电通道时变电阻的变化范围。基于该模型研究了影响开关瞬态场强度和上升时间的多种参数,为超高压和特高压变电站开关瞬态场研究提供了理论基础。2.针对变电站电缆沟内瞬态电磁场分布,提出了非均匀网格FDTD法,获得了变电站土壤中和电缆沟内不同截面上的开关瞬态场分布规律。深入研究了盖板参数对电缆沟内开关瞬态场强度的影响,为电缆沟设计和二次电缆布线提供了理论依据。3.针对变电站电磁脉冲(EMP)模拟技术,首次研究了有界波EMP模拟器的传输线部分的长度、宽度以及有耗大地介电常数、电导率对其工作区间内电磁波传播模式的影响,结果表明传输线宽度是主要影响因素。该结论可指导有界波EMP模拟器传输线设计。4.提出了近场对有限长线缆耦合的时域计算方法,系统地推导了与多种细导线相交的网格面上的电磁场分量的FDTD差分方程,该方法的优点是直接在时域内对近场和传输线进行整体建模计算。本论文比较了研究场线耦合问题的时域近场方法和远场方法。基于该方法研究了电场分量和磁场分量对线缆的耦合机理和不同回路间的串扰问题。5.提出了瞬态电磁场对电缆耦合的区域分解时域有限差分(DD-FDTD)计算方法,基于法拉第定律的积分形式推导出了圆柱坐标系下三角形网格内磁场分量的FDTD差分方程。初步研究表明快速瞬态电磁场难以透过电缆屏蔽层耦合电缆芯线,缝隙耦合可能是瞬态电磁场耦合电缆的主要途径。更多还原

【Abstract】 With the grid is developing for UHV/compactness and microelectronic technology is used in secondary equipment, transient electromagnetic environment is becoming more and more complex, and electromagnetic compatibility problem of secondary equipment is more and more severe in substations. It is provided with important theoretical meaning and applied value to investigate switching transient field and the mechanism of it coupling to secondary cable. In this paper, on the base of finite-difference time-domain (FDTD) Method, time-domain simulating method of switching transient field is investigated, transient electromagnetic environment in the soil and in the cable tunnel is analyzed, the design of the transmission line of bounded-wave electromagnetic pulse simulator, coupling mechanism of near-field to finite-length wire and cable, and computing method of transient electromagnetic field coupling to shielding cable are investigated. The main achievements are as follows:1. Time-time model of simulating switching transient field is founded, according to the theory of spark discharge, time-dependant resistance and inductance expression of arc discharging channels are put forward while the insulating switch is operated. The range of time-dependant resistance is achieved by fitting the measured datum of switching transient field in typical substations. Using the founded model, the factors of influencing switching transient field are studied, which can be used to investigate switching transient field in EHV/UHV substations.2. Aiming at the distribution of transient electromagnetic field in the cable tunnel, uneven mesh FDTD Method is put forward. The switching transient field is systematically analyzed in the soil and in the cable tunnel in substation, and distribution rule is achieved. The factors of cover board which influence the distribution of switching transient field in the cable tunnel are analyzed, which supply the qualification of designing the cable tunnel and laying secondary cable.3. Aiming at simulating technology of EMP in substations, the influencing parameters of transmitting mode of electromagnetic wave in the workroom of bounded-wave EMP simulator are investigated, including the width and length of the transmission line of bounded-wave EMP simulator、the dielectric constant and conductance of the soil, the results indicate the width of transmission line is primary parameter, which can be used to help design the transmission line of bounded-wave EMP simulator. 4. Time-domain method of near-field coupling to finite length thin wire is put forward, the FDTD discrete equations of electromagnetic fields on the surface of the mesh which intersect the different thin wires are deduced, the merit of the time-domain method is that near-field and thin wire are regarded as one whole to be directly computed in the time-domain. In this paper, near-field method and far-field method for investigating the field-to-wire coupling are compared. Using the time-domain method, coupling mechanism of field-to-wire is investigated, and mutual interference of different loop is also investigated.5. Domain decomposition FDTD algorithm is firstly put forward which be used to investigate transient electromagnetic field coupling to shield cable, on the base of integral expression of Faraday law, FDTD discrete equation of magnetic component in triangle mesh is deduced. Elementary investigation indicates that fast transient electromagnetic field is difficult to penetrate the shield of the cable; aperture is primary possible pass of transient electromagnetic field coupling to the core of the cable.更多还原