戈宝军　周家驹　王立坤　陶大军　李梦乔　韩继超

摘要：为了研究发电机不同工况下转子槽楔涡流损耗，以1407MVA大型核用半速汽轮发电机为例，通过建立该发电机二维电磁场数学模型，基于时步有限元法计算发电机由负载不对称引起稳态负序运行时转子槽楔上感生的涡流损耗。建立动态分析的场—路耦合时步有限元模型，分别计算当发电机外部发生单相短路、相间短路、两相接地短路故障后瞬间和故障稳定后的转子槽楔涡流损耗，得到不同外部短路故障下转子不同位置的槽楔暂态和稳态涡流损耗分布。对比研究了发电机额定运行和空载运行时外部短路故障后槽楔涡流损耗的变化规律。分析结果表明外部短路故障后，负序电流会使发电机转子槽楔产生涡流损耗，威胁着发电机的安全运行，其中单相短路故障影响最为严重。

关键词：汽轮发电机；稳态负序；外部短路故障；场-路耦合；涡流损耗

DOI：1015938/jjhust201805010

中图分类号： TM311

文献标志码： A

文章编号： 1007-2683（2018）05-0054-08

Abstract：In order to study the generator rotor slot wedge eddy current loss under different conditions The 1407MVA turbo generator at half speed is researched as an example Mathematical model is established in 2D electromagnetic field Then the eddycurrent losses of the rotor slot wedge is calculated according to time step finite element method ，which is under the circumstance of generator steady negative sequence operation leaded by the asymmetrical load The fieldcircuit coupled timestepping finite element model is established for dynamic analysis In an instant and stability of the single phase shortcircuit fault， two phases to ground shortcircuit fault and the interphase shortcircuit fault， the eddycurrent losses of the rotor slot wedge is calculated Then the distribution of eddycurrent loss in transient and steady state of the different rotor slot wedge is revealed The changing rule of eddycurrent loss of the rotor slot wedge when external circuit happens in rated and noload operation condition

The analysis result shows that after external circuit， the eddycurrent losses are induced by the negativesequence current， which has great influence on generator steady operation The most serious impact happens in the single phase shortcircuit fault

Keywords：turbogenerator； steady negative sequence； external shortcircuit fault； fieldcircuit coupled； eddycurrent loss

0引言

隨着大型发电机单机容量的不断增大，使得发电机内磁、热负荷也随之提高，导致发电机电磁损耗也随之增大。在发电机运行过程中，由于负载不对称而引起稳态负序运行或者电机外部短路故障，会使电机处于不对称运行状态。此时，定子电流会产生负序旋转磁场，此磁场将会在转子表面以及槽楔中产生两倍频率的涡流，较大的涡流损耗必然导致发电机转子侧的温升相应增大。从国内外实际情况来看，负序电流过大烧伤转子的事例常有发生[1-2]，常常给发电机和电网造成不可逆转的损坏。……