Question

A synchronous generator supplies a network through two transformers and a transmissionline, as drawn in

Figure 8.70. The generator is rated at 3 80 MVA and 22 kV with

a p.u. reactance of 1 .2 . The identical transformers are rated at 480 MVA with primary

and secondary voltages of 22 and 340 kV, respectively, and a 1 5 % reactance. The

transmission line is 45 miles long with an impedance of 0.07 + jO. 5 Q/mile. The transmission

line capacitances are neglected. The network voltage is 2 1 kV.

(a) Determine the transmission line, generator, and transformer parameters . Draw

the equivalent circuit. (b) Compute the generator excitation (induced) voltage at rated

load. Assume that the terminal voltage is the same as the rated voltage and the power

factor is 0 . 8 8 lagging. (c) Calculate the power transmitted to the network if the absolute

value of the excitation voltage is the same as the value found in part (b) , and the angle

between the network and generator excitation voltage varies . Plot the transmitted power

versus power angle and determine the power angle at 350 MW.

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Question & answer are in the graphics. Need to understand the process.