多工况背景下汽轮发电机不平衡电磁力的研究

发布时间：2018-03-27 08:42

本文选题：有限元　切入点：不平衡电磁力　出处：《华北电力大学》2015年硕士论文

【摘要】：转子偏心和励磁绕组匝间短路是汽轮发电机最为常见的故障形式,两种故障都会引起发电机内部磁场畸变,产生作用于转子的不平衡电磁力。不平衡电磁力是影响发电机机组振动的关键因素,当发电机运行工况改变时,不平衡电磁力也会随之发生变化。准确分析不平衡电磁力随发电机运行工况的变化特性,能够为通过调节发电机功率缓解机组振动提供理论支撑。本文的主要工作如下:(1)分析了励磁绕组匝间短路故障和转子偏心故障对发电机气隙磁密的影响。以QFSN200-2型汽轮发电机为研究对象,利用Ansys建立其有限元模型,分别设置不同的故障情况,计算得到了两种故障下发电机气隙磁密的分布,分析了气隙磁密随偏心程度、偏心方向、匝间短路程度、匝间短路位置的变化特性。(2)分析了偏心故障下不平衡电磁力随发电机运行工况的变化特性。给出了利用发电机气隙磁密计算转子所受不平衡电磁力的离散化公式,计算了存在偏心故障时发电机在多个运行工况下的不平衡电磁力,分析了偏心程度、偏心方向及运行工况对不平衡电磁力的影响,计算得到了理想并网发电机偏心故障下的不平衡电磁力随有功、无功调节的变化规律。(3)分析了发电机发生励磁绕组匝间短路故障后的电磁稳态特征,计算得到了匝间短路故障下不平衡电磁力随发电机功率调节的变化规律。基于转矩平衡,分析了励磁绕组匝间短路故障后发电机运行参数的变化情况,计算了故障后的不平衡电磁力,分析了匝间短路程度和匝间短路位置对不平衡电磁力的影响。计算了理想并网发电机励磁绕组匝间短路故障下的不平衡电磁力随有功、无功调节的变化规律。
[Abstract]:Rotor eccentricity and inter-turn short circuit of excitation windings are the most common fault forms of turbogenerator. The unbalanced electromagnetic force is the key factor to affect the vibration of generator unit. When the operating condition of generator changes, the unbalanced electromagnetic force is the key factor to affect the vibration of generator unit. The unbalanced electromagnetic force will also change with it. The variation characteristics of the unbalanced electromagnetic force with the operating conditions of the generator are analyzed accurately. The main work of this paper is as follows: 1) the influence of inter-turn short circuit fault of excitation winding and eccentric fault of rotor on the air gap magnetic density of generator is analyzed. The turbogenerator is the object of study. The finite element model of Ansys is used to establish its finite element model. The distribution of air gap magnetic density of generator under two kinds of faults is calculated, and the degree of air gap magnetic density with eccentricity, eccentricity direction and inter-turn short circuit is analyzed. The variation characteristics of unbalanced electromagnetic force under eccentric fault with generator operating condition are analyzed, and the discretization formula for calculating the unbalanced electromagnetic force of rotor by using generator air-gap magnetic density is given. The unbalanced electromagnetic force of the generator under several operating conditions is calculated, and the influence of eccentricity, eccentricity direction and operating condition on the unbalanced electromagnetic force is analyzed. The unbalance electromagnetic force under eccentricity fault of ideal grid-connected generator is calculated. The variation rule of reactive power regulation with active power and reactive power regulation is obtained. The electromagnetic steady-state characteristics of generator after inter-turn short-circuit fault of excitation windings are analyzed. The variation law of unbalanced electromagnetic force with generator power regulation under inter-turn short circuit fault is obtained. Based on torque balance, the variation of generator operating parameters after inter-turn short circuit fault of excitation winding is analyzed. The unbalanced electromagnetic force after fault is calculated, the influence of the degree of inter-turn short circuit and the position of inter-turn short circuit on the unbalanced electromagnetic force is analyzed, and the unbalanced electromagnetic force under the fault of inter-turn short circuit of excitation winding of ideal grid-connected generator is calculated. The changing law of reactive power regulation.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM311

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