汽轮发电机失磁异步运行的耦合场有限元分析

为了准确模拟汽轮发电机失磁故障发生后的运行状态,建立了场、路、运动直接耦合的时步有限元分析模型,把电机的电磁场方程和定转子的等效电路方程进行联立求解,得到失磁故障过程中定子端电压、定子电流、转速、有功功率等变量随时间变化的波形,以及转子中涡流场的分布；通过间接耦合实现了失磁过程中转子的温度场计算.对1 000 MW汽轮发电机励磁绕组失磁进行了时步有限元分析,并通过转子温升计算和有功、无功功率波动结果可知：汽轮发电机失磁后,转差率、有功功率及转子铁心温度均在限定值内,但定子电流值过大,应采取及时的保护措施.

Coupled field finite element analysis for turbine generator under loss-of-excitation asynchronous operation

To accurately simulate the operating characteristics of turbine generator after loss of excitation, this work established a field-circuit-motion coupled time stepping finite element model, solved the electromagnetic field equations and the equivalent circuit equations in the stator and rotor windings, obtained the wareforms of the stator terminal voltage, stator current, speed, active power and other variables after loss of excitation, as well as the distribution of rotor eddy current; and achieved the temperature distributed in the rotor through indirect magnetic-thermal coupling model. A 1 000 MW turbine generator running under entire short-circuit loss of excitation and entire open-circuit loss of excitation were calculated respectively. The results of the rotor temperature rise as well as the fluctuations of active power and reactive power show that the slip, active power and rotor temperature are within the limited values, but the stator current is too large, so protective measures should be taken timely．