With the same transformer banks as in Problem 3.47, Figure 3.41 shows the oneline diagram of a generator, a step-up transformer bank, a transmission line, a step-down transformer bank, and an impedance load. The generator terminal voltage is \(15 \mathrm{kV}\) (line-to-line).

(a) Draw the per-phase equivalent circuit, accounting for phase shifts for positive-sequence operation.

(b) By choosing the line-to-neutral generator terminal voltage as the reference, determine the magnitudes of the generator current, transmission-line current, load current, and line-to-line load voltage. Also, find the three-phase complex power delivered to the load.

Problem 3.47

Consider the oneline diagram shown in Figure 3.40. The three-phase transformer bank is made up of three identical single-phase transformers, each specified by \(X_{1}=0.24 \Omega\) (on the low-voltage side), negligible resistance and magnetizing current, and turns ratio \(\eta=N_{2} / N_{1}=10\). The transformer bank is delivering \(100 \mathrm{MW}\) at 0.8 p.f. lagging to a substation bus whose voltage is \(230 \mathrm{kV}\).

Transcribed Image Text:

Generator T ZLine =j100 9 Transmission line AY Step-up transformer bank T ZLoad=5+j1 YA Step-down transformer bank