气隙偏心下永磁风力发电机定子电磁振动特性分析

Electromagnetic Vibration Characteristics Analysis of Permanent Magnet Wind Generator Under Air Gap Eccentricity

永磁风力发电机定转子偏心会造成发电机气隙分布不均匀而产生磁场不平衡,使发电机振动加剧,严重时甚至引发转子扫膛,使发电机损坏失效。以某兆瓦级永磁风力发电机为研究对象,理论分析了气隙偏心对发电机气隙磁密和径向电磁力的影响,对于不同气隙偏心量下的风力发电机瞬态电磁场开展有限元分析,获得气隙磁密和径向电磁力分布特性变化规律,进而开展径向电磁力作用下定子谐响应分析,以掌握气隙偏心引起的定子振动响应特性。结果表明:随着气隙偏心量的增加,气隙最小处气隙磁密幅值增大,径向电磁力新增边带分量;发电机定子振动响应中工作频率的倍频幅值也随之增大,其中二阶径向模态响应幅值最大。所得结果可为发电机气隙监测方法研究提供一定的理论依据。

The rotor eccentricity of permanent magnet wind generator will cause uneven distribution of generator air gap and magnetic field imbalance, which aggravate the vibration of the generator, and even cause rotor scrapping in serious cases and result in generator damage and failure. Taking a MW-class permanent magnet wind generator as the analysis object, the influence of air gap eccentricity on generator air gap flux density and radial electromagnetic force is analyzed theoretically. Finite element analysis of transient electromagnetic field of wind generators under different air gap eccentricities is performed, and the distribution characteristics of air gap flux density and radial electromagnetic force under different air gap eccentricities are obtained. Harmonic response analysis of the stator under the radial electromagnetic force is conducted to obtain the response characteristics of the stator caused by air gap eccentricity. The results show that with the increase of air gap eccentricity, the amplitude of air gap density is increased, and new side band components of radial electromagnetic force appear. The amplitudes of harmonics of the operating frequency in the vibration response of generator stator also increase, and the amplitude of the second order radial mode response is the largest. The results can provide a certain theoretical basis for the research of generator air gap monitoring method.