汽轮发电机内部非线性特征的定量表述

为了建立汽轮发电机的精确的非线性模型，以有限元方法为工具，系统研究了汽轮发电机的3种非线性因素，即主磁通饱和效应、励磁电流漏磁通导致的转子轭部附加饱和效应及磁场畸变非线性。采用定、转子齿部磁压降及转子轭部磁压降在总的磁势中所占比例表示相关部分磁路饱和非线性，进而研究磁场畸变非线性的定量表示方法。提出用等效气隙长度相对于气隙设计长度的变化来描述磁场畸变非线性。在额定点附近，等效气隙长度达到设计值的1.4倍，而在临界失稳工况下，等效气隙长度达到后者的2倍以上。通过300 MW发电机实测数据与有限元计算结果对比，说明结果可信。该方法与传统方法相比，可以更准确地描述汽轮发电机非正常运行条件下的非线性程度。

The Quantitative Description of the Nonlinear Phenomena of the Turbo-generator

In order to establish a precise nonlinear model for turbo-generators,FEM was employed to study three nonlinear factors(including the main flux saturation,the rotor yoke saturation caused by excitation flux leakage and the magnetic field distortion).The core saturation was described by the ratios of stator and rotor tooth magnetic potential and rotor yoke potentials to total potentials.A quantitative method describing the magnetic field distortion was studied.The distortion was described by the difference between equivalent and designed length of air-gap.Near rated point,the equivalent length may be 1.4 times of the designed length,while in some abnormal states,the equivalent length may be 2 times of that.The measured data and computational results of FEM were compared to verify the conclusions in the paper.The result shows the proposed method could describe the non-linearity of turbo-generators more accurately than the conventional one.