Q.1 A 220 kV, 50 Hz, three-phase, 60 km transmission line supplying a star-connected load of 240 MW with a power factor of 0.8 lagging is shown below. The line has the following parameters: • r = 0.15 Ω km -1 l = 1.4 mH km -1 Considering the line to be short, determine: a) the line impedance, Z b) the receiving end phase voltage (note: specified values of voltage and current are line values unless stated otherwise) c) the receiving end phase current d) the sending end line voltage e) the phasor diagram for the system. 一条220kV,50Hz,三相传输线,长60km,给一个星形连接的负荷供电。负荷吸收的(有功)功率为240MW,功率因数为 0.8 滞后,如下图所示。线路的参数如下: r = 0.15 Ω km -1 l = 1.4 mH km -1 把这条传输线当成短距离传输线,计算: a) 线路的串联阻抗, Z (Series impedance = Series Resistance + 1i * Reatance),结果以极坐标形式表示 b) 接收端的相电压 Vr,ph 或Vr,φ(注意,除非特别声明,电压、电流均为线电压、相电流),可用下标ph表示相 c) 接收端的相电流 Ir,ph d) 输送端的相电压 Vs,ph 或Vs,φ e) 画出