电晕条件下特高压直流电气设备绝缘表面合成电场数值模拟方法研究

There is no efficeitve method to consider the influence of corona charge when calculating the total surface electric field on the insulation surface of ultra high voltage direct current（UHVDC）power transmission equipment. This lead to comparatively large errors in the design of external insulation structure of equitpment. In-depth study of the total electric field numerical calculation method for UHVDC equipment contribute to an accurate, rapid assessment for the total electric field around the equipment,and the optimization design of the UHVDC equipment. By research on corona mechanism of grading ring and shielding ball, the relationship between the corona onset electrical field strength and environmental and surface parameters, the prediction model which is fitting with simulation results according to experimental data will be given.The deficiency of Peek formula in the application of complex electrode structure is avoided, and hence the accuracy of total electric field is improved.By studying the accumulation and distribution law of the corona charges on the surface of insulating structure, based on the research foundation of insulation disk and single piece of insulator, the appropriate numerical simulation model will be proposed to solve the accumulation characteristics of charge emitted from coronating fitting in steady DC corona condition, which will be extended to complicated model with multi insulators,such as DC voltage divider. Through theoretical study and experimental verification, a system of calculation method of the total electric field around the UHVDC equipment will be proposed. The updating mode of charge density in air,and on the surface of insulation material is studied. The convergence and stability of the upstream finite element method is also studied as well when it is used in the complex model. The accurate solution of electric field on the surface of the power transmission equipment, space electric field and the ground ion flow field will be obtained, which is helpful to achieve the optimization design of the HVDC equipment.

针对特高压直流（UHVDC）电气设备绝缘表面合成电场计算问题，目前尚无有效的方法考虑空间电荷对合成电场的附加影响，使得设备外绝缘设计误差较大。研究空间电荷的产生、迁移以及对绝缘表面电场的相互影响特性，完善电晕试验和绝缘表面电荷测量平台。通过对环形、球形典型金具直流电晕机理的研究，分析金具起晕场强同环境和结构参数的关系，提取特征量，结合电晕模型试验结果，给出典型金具电晕起始场强预测值，弥补Peek公式在复杂电极结构应用中的不足，提高合成电场计算精度。以伞型绝缘圆盘表面电荷积聚试验为基础，拓展到多伞裙绝缘结构的电气设备，研究电晕电荷在绝缘结构表面的积聚规律和分布特性，建立模拟空间电荷在绝缘结构外表面积聚特性的数值模型。研究空气、绝缘表面电荷密度更新模式和方法，改进上流有限元法在复杂模型中的收敛性和稳定性，准确求解UHVDC电气设备绝缘结构外表面电位分布和合成电场，提高设备的外绝缘优化设计水平。

特高压直流电气设备绝缘表面合成电场计算问题是设备外绝缘设计的重要因素。本项目围绕绝缘表面合成电场数值模拟方法研究，从电晕起始特性、空间电荷在绝缘表面分布特性以及合成电场仿真计算方法三个方面展开。针对电晕起始特性，提出了臭氧检测法用于测量金具的电晕起始电压，开展了小尺寸球（棒）、大直径屏蔽球和均压环的电晕特性试验，获取了其电晕起始规律，能够为实际工程的电晕校核提供参考数据。提出了电晕起始电压（场强）预测模型，该模型依据静电场仿真计算获取电极附近的电场分布，定义并提取电场特征集，基于人工智能算法和已有电晕试验数据可准确预测相似环境下其他结构的同极性电晕起始电压。搭建了空间电荷在绝缘表面积聚和消散的试验平台，采用静电探头测量电晕后绝缘材料的表面电位，推导平面和曲面电荷反演算法，计算绝缘表面电荷分布。开展了环氧树脂、玻璃、硅橡胶、3D打印的光敏树脂、环氧树脂和硅橡胶伞裙切片、玻璃绝缘子、瓷绝缘子及喷涂有PRTV涂料的各类绝缘子的电荷积聚与消散试验，发现平板型绝缘材料表面电位呈现“钟形”或“马鞍形”分布，且在一定范围内，绝缘材料表面曲率越大，该处越容易积聚电荷；真型绝缘子表面电位呈现“勺子形”分布，表面电荷消散特性近似指数函数。基于瞬态上流有限元法模拟了电荷在空间中的运动过程，展示了电荷运动过程中空间合成电场的变化，建立了绝缘材料表面电荷面传导、体传导和空气中和三种消散模型，能够准确模拟平板型绝缘材料电荷消散特性。提出了绝缘材料表面电荷密度更新公式用于解决在合成电场计算中电位和空间电荷的相互影响、互相耦合的问题，实现了典型高压直流电气设备周围合成电场的数值计算，可为高压直流电气设备的外绝缘设计和结构优化提供参考。本项目共参与国际国内会议4人次，发表论文24篇，其中期刊论文19篇，SCI收录6篇，EI6篇，中文核心论文7篇，会议论文5篇，申请发明专利1项。共培养研究生10人，其中已毕业7人，在读3人。