同步发电机偏心与绕组短路故障对磁场及电磁振动的影响

Effect of rotor eccentricity and stator short circuit faults on magnetic field and electromagnetic vibration characteristics of synchronous generator

以1台6 MW汽轮同步发电机为例,对转子静偏心、定子匝间短路及其联合故障下的磁场、电磁力和电磁振动进行研究。在气隙磁场不对称情况下,以等效电路为基础的经典算法将不再适用,为此建立发电机的有限元模型,基于瞬态磁场的计算结果,给出不同故障类型下的气隙磁场变化特征,并得到发电机不同运行状态下的径向电磁力及其与对应故障参数的变化关系。将电磁力作为载荷,对发电机的电磁振动进行研究,通过比较正常运行和故障运行状态下的位移曲线,定性分析不同故障对电磁振动的影响。研究结果表明:且该振动特征可以为发电机偏心和绕组短路故障诊断提供理论依据。

The magnetic field, electromagnetic force and vibration of a 6 MW synchronous generator were researched in cases of the rotor static eccentricity fault, the stator inter short circuit fault and the composite fault, respectively. The traditional calculation method based on the equivalent networks was invalid in the case of the inner asymmetric magnetic field. The finite element model of the generator was established and the variation characteristics of air-gap magnetic field in different fault types were analyzed based on the results of transient magnetic fields. Meanwhile, the change of electromagnetic force affected by corresponding fault parameters was studied under different operating conditions. The electromagnetic forces were taken as load condition, and curves of vibration displacement of the generator were obtained. The influences of different faults were analyzed qualitatively by comparing the curves of rated condition with that of faults. The results show that the radial vibration signal of generators can be used to detected air-gap eccentricity and winding faults.