不同模型的同步发电机失磁异步运行分析

Analysis on Asynchronous Operation without Excitation Field for Different Models of Synchronous Generator

建立了可以考虑磁场饱和、磁场畸变、谐波磁场以及集肤效应导致的实心转子涡流分布不均匀等因素的场路耦合时步有限元(T-S FEM)模型,并进行了试验验证。采用该模型对300 MW发电机稳态运行、励磁绕组开路及短路等失磁异步运行时的角速度、电磁转矩以及定子电流动态变化特征进行仿真,并与电力系统仿真软件PSD-BPA的仿真结果进行对比,结果表明:稳定运行时,2种模型计算的电磁转矩相差13.8%;失磁异步运行时,2种模型仿真得到的结果存在明显差别且有限元模型计算结果更接近实际情况,这主要是由于时步有限元模型能有效计及发电机内部多种非线性因素,故计算结果更为精确。本文研究成果为发电机设计及运行分析提供了理论支撑。

Field-Circuit Coupled Time-Stepping Finite Element Model （T-S FEM） is built, in which the magnetic saturation ＆ distortion, harmonic field and uneven distribution of eddy current caused by skin effect are considered, and the model is verified by testing. Angular speed, electromagnetic torque and stator current under steady-state operation, shorted and opened circuit of exeitation windings of a 300MW synchronous generator are ealeulated and compared through T-S FEM and PSD-BPA. The results indicate that the discrepancy of the electromagnetic torque calculated by two models is 13.8% at steady-state operation. With the asynchronous operation without excitation field, the obvious differences are derived based on the above two models and the calculation results obtained by T-S FEM is closer to the reality, since that T-S FEM can consider the non-linear factors inside the generator. The achievement in this paper provides theoretical basis for the design and operation of synchronous generator.