06-07 电力系统分析基础考试题A20061215.doc

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1、1.(20%)For a voltage source, its phasor representation is V = 120 -45o and its frequency is 60 Hz, (a)What is the instantaneous voltage V(t)?(b)Draw the phasor diagram of V = 120 -45o!(c)Plot the instantaneous voltage waveform for V(t). Make sure you label your graph properly!(d)This voltage source

2、is connected to a RL load with R = 10 ohms and L = 20 mH, what is the instantaneous current i(t)?(e)What is the power factor in part (d)? 2.(20%)A 200 kVA single phase transformer, 4,160 V/480 V, 60 Hz, has the following test results:Open circuit test:V=480 V is applied to the 480 V winding and 4,16

3、0 winding is opened, I = 10 A, P = 1000 W;Short circuit test:V = 208 V is applied to the 4,160 V winding, I = 48 A, P = 900 W;Find the equivalent circuit in ohms from the high voltage side.3.(20%)A 3-phase load has the following rated information: 250 kVA, 0.8 power factor leading at 480 V, Y-connec

4、ted. Do the following:(a)Find per phase impedance in ohms(b)Find per phase impedance in per unit using 250 kVA and 480 V as base value for 3-phase power and line to line voltage4.(20%)A fully transposed transmission line was constructed using ACSR conductor called “drake.” Bundle conductors are used

5、 and there are two conductors per phase and the distance between them is 0.4 meter. The three phase bundle conductors are placed horizontally with distance between the center of each phase conductor is 12 m.(a)Find the per unit length R, L, and C for this transmission line(b)Find the characteristic impedance Zc (c)If the length of this line is 180 km, what would be the most suitable per phase equivalent circuit for this transmission line?5.（30）已知两节点电力系统及其参数（标幺值）如图所示，计算系统潮流，求：（1）系统的节点导纳阵；（2）直角坐标形式的功率方程；（3）雅可比矩阵和修正方程式；（4）采用牛顿拉夫逊法第1次迭代求解的结果。第 2 页 共 2 页