本文選題：有限元　切入點：不平衡電磁力　出處：《華北電力大學》2015年碩士論文

【摘要】：轉(zhuǎn)子偏心和勵磁繞組匝間短路是汽輪發(fā)電機最為常見的故障形式,兩種故障都會引起發(fā)電機內(nèi)部磁場畸變,產(chǎn)生作用于轉(zhuǎn)子的不平衡電磁力。不平衡電磁力是影響發(fā)電機機組振動的關鍵因素,當發(fā)電機運行工況改變時,不平衡電磁力也會隨之發(fā)生變化。準確分析不平衡電磁力隨發(fā)電機運行工況的變化特性,能夠為通過調(diào)節(jié)發(fā)電機功率緩解機組振動提供理論支撐。本文的主要工作如下:(1)分析了勵磁繞組匝間短路故障和轉(zhuǎn)子偏心故障對發(fā)電機氣隙磁密的影響。以QFSN200-2型汽輪發(fā)電機為研究對象,利用Ansys建立其有限元模型,分別設置不同的故障情況,計算得到了兩種故障下發(fā)電機氣隙磁密的分布,分析了氣隙磁密隨偏心程度、偏心方向、匝間短路程度、匝間短路位置的變化特性。(2)分析了偏心故障下不平衡電磁力隨發(fā)電機運行工況的變化特性。給出了利用發(fā)電機氣隙磁密計算轉(zhuǎn)子所受不平衡電磁力的離散化公式,計算了存在偏心故障時發(fā)電機在多個運行工況下的不平衡電磁力,分析了偏心程度、偏心方向及運行工況對不平衡電磁力的影響,計算得到了理想并網(wǎng)發(fā)電機偏心故障下的不平衡電磁力隨有功、無功調(diào)節(jié)的變化規(guī)律。(3)分析了發(fā)電機發(fā)生勵磁繞組匝間短路故障后的電磁穩(wěn)態(tài)特征,計算得到了匝間短路故障下不平衡電磁力隨發(fā)電機功率調(diào)節(jié)的變化規(guī)律。基于轉(zhuǎn)矩平衡,分析了勵磁繞組匝間短路故障后發(fā)電機運行參數(shù)的變化情況,計算了故障后的不平衡電磁力,分析了匝間短路程度和匝間短路位置對不平衡電磁力的影響。計算了理想并網(wǎng)發(fā)電機勵磁繞組匝間短路故障下的不平衡電磁力隨有功、無功調(diào)節(jié)的變化規(guī)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.
【學位授予單位】：華北電力大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TM311

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