【作者】 吴昊；

【导师】 张黎；

【作者基本信息】 山东大学 ， 高电压与绝缘技术， 2016， 硕士

【摘要】 在能源问题日益严峻的形势下,风能逐步成为当今世界上发展最为迅速、应用最为广泛的可再生能源。风电机组作为风能资源开发利用的直接载体,由于其自身容量的增加和风电场的规模化和海洋化,风电机组自身和整体风电场的安全稳定运行日益成为风能资源发展面临的重要问题。雷电由于其强能量、高电压、大电流、高频率的特性,会对风电的有效利用和安全开发造成极大的威胁。特别是目前伴随着风电机组单机容量的提升,风机整体高度的增加,使其自身的引雷能力大大提高；另一方面,在海上风能大力开发的背景下,风机运行工作的环境日益恶劣,海洋大气环境潮湿多雨,雷暴现象相当频繁,也加大了风电机组遭受雷击的概率。在风电机组遭受到雷电袭击时,携带巨大能量的雷电流一般会在机组的桨叶顶端的接闪器(或机舱尾部的避雷针)注入,由桨叶内部设置的金属导体引流,再经机舱的导流路径进入塔体顶端,经过塔体进入风机的接地装置,最终泄流入大地。雷电流在整个风机上向下泄流的暂态过程中,一方面会导致风机各部位暂态电位发生变化,电位跃升现象的存在,有可能对设备造成反击或绝缘破坏；另一方面,将在风电机组的塔筒内部产生瞬态变化的电磁场,可能会对电力、信号线路和电子、控制系统内产生电磁干扰,进而威胁到风电机组的安全稳定运行。本文首先结合海洋接地环境的分层特性,建立了海上风机接地电阻模型,提出了海上风机接地电阻数值计算方法；本文根据海上风机桨叶旋转特性,建立了考虑叶片旋转因素的桨叶波阻抗模型,并利用圆锥天线理论推导了塔体波阻抗数值计算公式,进而提出了海上风机雷击暂态一体化模型。在研究雷电特性的基础上,本文选取了合适的雷电流模型,并利用软件ATP-EMTP搭建海上风机雷击暂态一体化模型,模拟雷电击中风机后的波过程,并探讨了各类影响因素(如雷击点位置、桨叶旋转位置、桨叶长度、塔体高度、雷电流参数等)对雷电暂态过程的影响规律。以风电机组塔筒内部电磁场为研究对象,通过对风机塔体部分利用基于有限元方法的Ansoft Maxwell软件对海上风电机组的塔简进行建模、仿真,计算了海上风机周围空间电磁场。对比分析海上风机上、下底所在两个平面的磁感应强度最大值的分布情况可知,海上风机周围空间磁场分布在水平方向上呈现对称性,强度反比于靠近塔壁的距离；在竖直方向上,磁场分布自风机塔筒顶端至塔筒底部,逐渐趋于均匀。更多还原

【Abstract】 Under the situation that energy problem is becoming more and more severe, wind power has become the fastest-growing and the most widely used renewable energy in the world today. Since wind turbine acts as a carrier invert wind energy into available energy, with the continuous increase of its capacity and the tendency of the large-scale and oceanic wind farm, it’s extremely important to keep the safe and stable operation of the wind turbine and the whole wind farm for the development of wind energy resources.Due to its strong energy, high voltage, high current, high frequency, lightning is a great threat for the effective development and safe utilization of wind power. Especially total height of the wind turbine increases with its increasing capacity, making it much more vulnerable to lightning strike; on the other hand, humid and rainy atmospheric environment with more frequent thunderstorm phenomenon on the sea makes the operation condition of offshore wind turbine more and more adverse, increasing the probability of a lightning strike. When lightning hits wind turbines, lightning current which carried huge energy usually strikes the arrester at the tip of the blade or the lightning rod. It flows along the conductor inside the blade or the cabin, and then it goes from the tower body into the grounding device, eventually drains into the earth. During the transient process that lightning current flows downwards along the wind turbine, on one hand, the transient potential along the current-flow path would rise which would do damage to the electrical equipment insulation; on the other hand, electromagnetic field inside the tower body caused by the lightning current is likely to result in electromagnetic interference within the power or signal lines and electrical control systems, which threatens the safe operation of wind turbines.Considering the layered characteristics of oceanic grounding environment, this paper established the grounding resistance model of the offshore wind turbine, and proposed a numerical calculation method of the grounding resistance. Wave impedance model of the blade was established according to the rotation characteristics of blades. By the theory of conical antenna, wave impedance numerical calculation formula the tower body was derived. Based on the above, lightning transient integration model of offshore wind turbines was put forward. Based on the research of the characteristics of the lightning, proper lightning model was selected for the simulation analysis. With the electromagnetic transient analysis software ATP-EMTP, the transient integration model above was established to simulate the lightning transient wave process on the wind turbine. Various factors, such as the lightning strike point, rotation position of blade, blade length, height of tower body and lightning current parameters, were changed to discuss their influence on the lightning transient process. Furtherly, electromagnetic field inside the tower body was calculated by using the Ansoft Maxwell software based on finite element method (fem). By contrastive analysis, we can conclude that the space distribution of the magnetic field inside the tower is symmetry in horizontal direction, and the maximum value decreases with the distance from the tower wall; In the vertical direction, the magnetic field distribution gradually tends to be more uniform from the top to the bottom of the tower.更多还原