大气颗粒物对高压直流导线离子流场影响及应用研究

发布时间：2018-06-19 03:51

本文选题：特高压直流输电 + 大气颗粒物　；参考：《华北电力大学(北京)》2017年博士论文

【摘要】：电晕放电引起的离子流场是反映特高压直流输电线路电磁环境的重要参数,它与离子流密度、无线电干扰、可听噪声等物理量共同决定着输电导线的类型、对地高度、极间距、分裂间距与走廊宽度等线路设计指标。我国北方地区的特定季节出现了灰霾天气。灰霾中的大气颗粒物将因特高压直流输电线路的电晕放电而发生荷电,进而对输电线路离子流场和离子流密度产生影响。本文通过颗粒物存在时离子流场的建模计算,以及对直流导线离子流场的测量实验,研究了大气颗粒物的质量浓度、粒径、介电常数等物理量对离子流场的影响机理和规律。首先,研究了电晕放电产生的空间电荷对地面离子流场测量准确性的影响,以及直流电场仪探头对其周围离子流场的畸变规律。通过计算和测量获得了平行电极间离子流场、离子流密度、空间电荷密度的分布规律,得到了空间电荷对直流电场仪测量准确性的影响程度。提出了圆柱坐标系内离子流场的通量有限元方法,计算了离子流场在直流电场仪表面的分布,定量分析了直流电场仪对离子流场的畸变规律,并通过实验加以验证。提出了一种与电场仪配合使用的附加电极的设计方案,可明显抑制电场仪周围离子流场的畸变。通过理论计算和实验测量验证了附加电极的有效性。其次,分别提出了在平板电极和圆柱电极内的直流离子流场中测量大气离子迁移率的两种方法,并将所提方法应用于含颗粒物空气的等效离子迁移率的测量研究。建立了室内封闭实验室,在其中搭建平板电极的电晕放电实验平台,定量研究了燃香烟尘颗粒的质量浓度改变时,空气与燃香烟尘颗粒所组成的混合体系的等效迁移率的变化规律。再次,提出了计算离子流场的上流边界元方法,用来精确计算场域边界或电极表面的电场强度。使用边界单元和上流单元分别求解Poisson方程和电流连续性方程,迭代计算离子流场大小和空间电荷密度。通过离子流场的测量实验对所提计算方法的有效性进行验证。最后,在离子流场的上流边界元算法中计入颗粒物的场致荷电和扩散荷电效应,通过实验和计算获得了大气颗粒物的质量浓度、粒径、介电常数对高压直流导线离子流场的影响机理和规律。在室内封闭实验室中,测量了存在燃香烟尘颗粒时高压直流导线下方离子流场的分布,验证所提计算方法的有效性。通过测量和计算,获得了荷电颗粒物与空气中的小离子对总的空间电荷密度的贡献,以及荷电颗粒物对离子流场的贡献。针对±1100k V特高压直流输电线路的结构,计算了大气颗粒物的质量浓度、粒径、介电常数对输电线路下方地面处离子流场的影响规律。
[Abstract]:The ion current field caused by corona discharge is an important parameter to reflect the electromagnetic environment of UHVDC transmission line. It determines the type of transmission wire, ground height, polar distance together with physical parameters such as ion current density, radio interference, audible noise, etc. Line design index such as split spacing and corridor width. There is haze in the northern part of China during the special season. The atmospheric particles in the haze charge the corona discharge of the HVDC transmission line and then affect the ion flow field and ion current density of the transmission line. In this paper, the influence mechanism and law of mass concentration, particle size and dielectric constant of atmospheric particles on ion flow field are studied through modeling and calculation of ion flow field in the presence of particulate matter and the measurement experiment of ion flow field in direct current conductor. Firstly, the influence of space charge generated by corona discharge on the accuracy of surface ion flow measurement and the distortion of ion flow field around it by the probe of DC electric field instrument are studied. The distribution of ion current field, ion current density and space charge density between parallel electrodes are obtained by calculation and measurement. The degree of influence of space charge on the accuracy of DC field meter is obtained. The flux finite element method of ion flow field in cylindrical coordinate system is presented. The distribution of ion current field on the surface of DC field is calculated. The distortion law of ion current field is quantitatively analyzed and verified by experiments. A design scheme of the additional electrode used in conjunction with the electric field meter is proposed, which can obviously suppress the distortion of the ion flow field around the electric field meter. The effectiveness of the additional electrode is verified by theoretical calculation and experimental measurement. Secondly, two methods of measuring atmospheric ion mobility in DC ion flow field of flat electrode and cylindrical electrode are proposed, and the proposed method is applied to the measurement of equivalent ion mobility in air containing particulate matter. An indoor closed laboratory was established, in which the corona discharge experimental platform of flat electrode was set up, and the change of mass concentration of cigarette dust particles was studied quantitatively. The change of equivalent mobility of the mixed system composed of air and cigarette dust particles. Thirdly, an upper current boundary element method is proposed to calculate the electric field intensity of the field boundary or electrode surface. Poisson equation and current continuity equation are solved by boundary element and upper current element respectively. The size of ion flow field and space charge density are calculated iteratively. The validity of the proposed method is verified by measuring the ion flow field. Finally, the field charge and diffusion charge effects of particles are taken into account in the upper current boundary element algorithm of ion flow field. The mass concentration and particle size of atmospheric particles are obtained by experiments and calculations. The influence mechanism and law of dielectric constant on ion flow field of HVDC conductor. In an indoor closed laboratory, the distribution of ion flow field beneath the high voltage direct current conductor was measured in the presence of cigarette dust particles, and the validity of the proposed method was verified. Through measurement and calculation, the contribution of charged particles and small ions in air to the total space charge density and the contribution of charged particles to the ion flow field are obtained. According to the structure of 卤1100kV UHV HVDC transmission line, the influence of mass concentration, particle size and dielectric constant of atmospheric particles on the surface ion flow field under the transmission line is calculated.
【学位授予单位】：华北电力大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM75

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