1000MW汽轮发电机三相短路后灭磁仿真

De-Excitation Simulation of 1 000 MW Steam-turbine Generator after Abrupt Three-phase Short Circuit

汽轮发电机机端发生三相短路后的灭磁,是属于灭磁的严重情况。这时如何适当配备灭磁器件的能容需要解决。本文通过对1台1000MW的汽轮发电机三相短路后灭磁的仿真,估计灭磁器件的能容。在仿真中除了转子上d轴磁场绕组,由转子锻件在d,q轴的阻尼作用外,还考虑了在q轴的第2个阻尼绕组。通常为正确估计灭磁时磁场能量,应考虑发电机空载特性饱和的非线性,但这里只计及了d轴的饱和,忽略了q轴的饱和,因此仿真出的交轴磁能偏大。仿真方法是利用Simulink积分算子构建解微分方程的多亇结构图,以某电厂1000MW汽轮电机额定负荷下突然三相短路,延时0.1s后灭磁进行仿真,得出可供参考的结果。

Fast de-excitation is one of main measures for protecting generators. De-excitation of steam-turbine generator after abrupt three-phase short circuit（ATPSC）is serious situation. It is important that how much capacity of varistor should be equipped properly. The aim of the paper is trying to estimate capacity of varistor of a 1 000 MW generator through simulation of it after ATPSC. In simulation, besides field winding, damping action of forge rotor in d,q axis, and second q axis damping winding were considered. In addition, non- linearity of d axis no-load characteristic（NLC）of generator was accounted. But the saturation in q axis of NLC was ignored, that is why magnetic energy obtained in q axis is a bit large. Structure schemes with integral operator 1/S for solving differential equation of Simulink were used. The example of simulation is about 0.1 second delay de-excitation ATPSC of a 1 000 MW generator with rated load. The results show that the simulation is successful .