离子流场模型中高压直流导线表面几何形态的表征方法研究

The geometrical morphology of the wires is the director factor, that influences the ion flow and the ionized electric field of the HVDC lines. The corona experiment is the main way to determine the roughness coefficient, that reflects the ion flow effect and the ionized electric field effect of the wires. The correlation model of the roughness coefficient and the surface geometrical morphology of the wires could not be provided in the existing research. By combining the corona experiments of the wires, the highly accurate measurement of the geometrical morphology, and the electromagnetic calculation, the correlation between the roughness coefficient and the surface geometrical morphology of the wires will be quantified, and the geometrical model of the roughness coefficient will be obtained in this project. This work could provide theoretical support and technical guidance for analyzing the ion flow and the ionized electric field and optimizing the geometrical morphology of the wires. The main research contents: (1) By combining the corona experiments and the highly accurate measurement of the geometrical morphology, the minimal scale for the surface geometrical measurement and modeling will be investigated. The multi-scale modeling method for the geometrical morphology of the wires will be investigated. (2) By comparing the corona experiments results of the smooth wires and the non-smooth wires, the roughness coefficient of the non-smooth wires will be obtained. The quantitative correlation between the roughness coefficient and the surface geometrical parameters of the wires will be extracted, and the geometrical model of the roughness coefficient will be built. (3) Based on the experiment and the mesurement, the geometrical model of the roughness coefficient will be extended for the wires with attached sand-dust by considering the influence of the physical properties. In Northern China, the influence of the sand-dust attaching to the wires on the ion flow and the ionized electric field will be analyzed with the numerical method.

导线的几何形态是影响直流输电线路离子流合成电场的直接因素，现有研究主要依靠电晕试验来确定反映导线离子流合成电场效应的粗糙系数，不能提供导线表面几何形态与粗糙系数的关联模型。本项目拟结合导线电晕试验、高精度几何形态测量和电磁场计算，量化导线表面几何形态与粗糙系数的关联关系，建立粗糙系数的几何模型，为离子流合成电场分析和导线几何形态优化，提供理论支撑和技术指导。主要研究内容：（1）结合几何形态高精度测量和电晕试验，研究导线表面几何测量和建模的最小尺度，研究导线表面几何形态多尺度建模方法；（2）对比非光滑导线与光滑导线电晕试验结果，获得非光滑导线的粗糙系数；提取粗糙系数与导线表面几何参数的量化关系，建立粗糙系数的几何模型；（3）基于试验测量并考虑物性影响，将粗糙系数几何模型推广用于沙尘附着导线情况，结合数值方法，分析我国北方地区沙尘附着直流导线后对离子流合成电场的影响规律。

近年来，我国投运了多个特高压直流输电工程。高压直流线路电晕放电会产生离子流、合成电场等电磁环境问题。线路电晕放电程度与表面粗糙度密切相关。导线表面粗糙度变化对直流电晕放电的影响规律，以及粗糙程度与粗糙系数的对应关系，目前仍缺少确切的结论。.本项目采用圆导线作为研究对象。首先对导线表面进行不同程度的磨制，利用触针法测量了这些导线的表面粗糙度。接下来，基于圆形电晕笼，测量了导线的起晕场强和粗糙系数。最后通过曲线拟合，获得导线表面粗糙度与正负极直流电压下粗糙系数的对应关系。.随着粗糙度的增大，导线起晕场强非线性下降，负极粗糙系数减小速度更快。随着表面粗糙度从0.5 μm增大到2.5 μm，正负极导线粗糙系数，即起晕场强分别下降了约13%和18%。表面粗糙度越大，粗糙度变化对粗糙系数的影响越明显。.该规律的意义在于，对导线表面几何形态进行直接控制，可对直流导线的起晕电压进行控制。