气隙静偏心与转子匝间短路下电磁转矩特性区分

Electromagnetic torque characteristic identification among static air-gap eccentricity and rotor interturn short circuit

对发电机气隙静偏心、转子匝间短路及其复合故障前后的电磁转矩进行了分析。首先,通过理论推导了各运行状态下电磁转矩表达式;然后,利用有限元软件Ansoft建立了模拟发电机仿真模型,并计算了对应的电磁转矩;最后,对模拟发电机进行了实测,三者所得结果基本吻合。结果表明:正常运行与转子匝间短路下,电磁转矩为常值,不存在谐波成分,且随着短路程度的加剧,均值不断减小;气隙静偏心使电磁转矩产生二倍频成分,偏心程度加剧时,均值与二倍频幅值增大;复合故障下,电磁转矩产生一倍频和二倍频成分。当仅短路程度加剧时,一倍频幅值增大,均值和二倍频幅值减小;当仅偏心程度加剧时,均值、一倍频和二倍频幅值增大。

This paper investigates the electromagnetic torque characteristics under static air-gap eccentricity(SAGE),rotor inter-turn short circuit(RISC),and the SAGE and RISC composite faults,respectively.Firstly the electromagnetic torque expressions under different running conditions are deduced.Then the generator modeling and the corresponding simulation under different conditions are accomplished with the finite element software Ansoft.Finally,experiments are taken on a simulating generator to verify the theoretical analysis and simulation results.It is shown that the electromagnetic torque only has DC component under normal condition and RISC,in which the DC component amplitudes will decrease as the short circuit degree develops.The electromagnetic torque has 2nd harmonic component under SAGE,in which the 2nd harmonic amplitudes will increase as the eccentricity degree develops.When under the composite faults,the 1st and 2nd harmonic component will be induced.As the short circuit degree develops,1st harmonic amplitude will increase while the DC component and 2nd harmonic amplitude will decrease.Besides,the increment of the eccentricity degree will increase the DC,1st and 2nd harmonic amplitude.The simulation and experimental results comply with the theoretical analysis.