【作者】 王鹏宇；

【导师】 鲁志伟；

【作者基本信息】 东北电力大学 ， 电气工程（专业学位）， 2019， 硕士

【摘要】 雷电是自然界固有的现象,输电线路遭受雷击严重的危害了电力系统的稳定运行,所以防雷击导线至关重要。随着我国社会经济的繁荣发展,土地利用率越来越高,提高线路利用率、稳定持续供电成为待需解决的问题。据长期的运行经验表明,同塔双回、多回输电线路回路数较多、档距长、杆塔高、遭受绕击的概率越来越高,特高压以及混合双压线路雷击跳闸的主因是绕击。所以精准的评估线路的绕击跳闸率对于指导输电线路稳定安全的运作具有重要的意义。电气几何模型（EGM）是最主要的计算输电线路绕击特性的方法,该方法将线路的几何参数,通过击距系数能够将雷电的放电特性与绕击性能联系起来,计算结果更加贴近线路真实状况,因而具有一定的准确性。但是传统的EGM模型,利用导线的平均高度,仅仅将雷电认为垂直向下,以此来估计输电线路的绕击性能会产生较大的误差。本文利用改进电气几何模型将雷击的方向扩至[-π/2,ψ_max],通过求出暴露弧、屏蔽弧不同雷电入射角下在地面上的投影,根据雷击入射角的概率分布得出绕击跳闸率。本文引进了三维电气几何模型,将输电线路的暴露弧面进行了三维的延伸扩展,计算了绕击跳闸率沿着档距内线路每一段与杆塔间长度的变化,通过沿着档距方向进行积分得出最终的绕击跳闸率。最后,通过实例的分析并借鉴相关文献计算方法进而验证本文计算的准确性。通过计及雷电入射角的三维电气几何模型分别计算了同塔单回、双回、四回输电线路不同地面倾角、保护角、杆塔高度和横担长度下的绕击跳闸率,分析各个因素对绕击跳闸率的影响,并为防雷电绕击提出指导建议。最后,对通化地区220kV输电线路进行绕击风险评估,进而给出防雷电绕击的改造方案。更多还原

【Abstract】 Lightning is an inherent phenomenon in nature.Lightning strike transmission lines seriously endanger the stable operation of the power system,so lightning protection is critical.With the prosperity and development of China’s social economy,the land utilization rate is getting higher and higher,and improving the utilization rate of the line and stabilizing the continuous power supply has become a problem to be solved.According to long-term operation experience,the probability of twin-circuit and Multi-circuit Transmission Lines with the same tower having more loops,longer spacing,higher pole and tower and being subjected to shielding failure is higher and higher.The main reason for lightning trip-out of UHV and hybrid double-voltage lines is shielding failure.Therefore,accurate evaluation of the lightning level of the line is of great significance for guiding the safe and stable operation of the transmission line.Electrical Geometry Model（EGM）is the most important method to calculate the transmission characteristics of transmission lines.This method can link the lightning parameters of the lightning to the performance of the lightning through the geometric parameters of the line.The calculation results are closer to the lines.The situation is therefore of certain accuracy.However,the traditional EGM model only considers lightning as vertical downward by using the average height of the conductor,so as to estimate the shielding failure performance of transmission lines,it will produce large errors.In this paper,the direction of lightning strike is extended to[π/2,ψ_max]by using the improved electrical geometry model.By calculating the projection of the exposed arc and shielding arc on the ground at different lightning incidence angles,the shielding trip probability is obtained according to the probability distribution of the pilot incidence angle.In this paper,a three-dimensional electrical geometry model is introduced to extend the bare arc surface of transmission line in three dimensions.The change of shielding trip rate along the length of each section of the line and the tower is calculated.The final shielding trip rate is obtained by integrating along the direction of the shied.Finally,the accuracy of the calculation is verified by the calculation of the example and comparison with other literatures.The three-dimensional electrical geometric model considering the incident angle of lightning is used to calculate the grounding trip angles under different ground inclination angles,protection angles,tower heights and cross-arm lengths of the single tower,double and four transmission lines on the same tower,and analyze various factors for the tripping of the bypass.The impact of the rate and recommendations for lightning protection.Finally,the risk assessment of lightning protection for 220kV transmission lines in TONGHUA area is carried out,and then the modification scheme of lightning protection and lightning protection is given.更多还原