一台100MVA、60Hz的三相同步发电机,由具有常值同步速度的原动机驱动,电机的电抗标值和时间常数如下 X" d =0.20p.u.,τ" d =0.04s X'=0.30p.u.,τ' d =1.0s X d =1.20p.u.,τ a =0.25s 电枢绕组初始时开路,调整励磁电压,使电枢机端电压为额定值(标值为1p.u.)。在转子交轴与a相磁轴重合即δ=π/2时,同步电机发生三相对称短路故障,试画出a相电枢电流的不对称波形。并求:
【单选题】A child who has once been pleased with a tale likes, as a
rule, to have it retold in almost the same words, but this should not lead
parents to treat printed fairy stories as formal texts. It is alw...
A.
they are full of imagination
B.
they just make up the stories which are far from the truth