6. Multi-Voltage Level SystemA power system includes a generator (500 MVA, 13.8 kV, X'' = 0.2 pu), a transformer (500MVA, 13.8/138 kV, Z = 0.1 pu), and a transmission line (Z = 0.02 + j0.1 pu on 138 kV, 500MVA base). A load of 450 MW at 0.9 power factor lagging is connected at the end of thetransmission line.a. Convert all impedances to a common base of 500 MVA, 13.8 kV.b. Calculate the per-unit voltage at the load bus.

1. Transformer Per-Unit AnalysisA power system consists of a generator rated at 500 MVA, 20 kV, and a transformer rated at500 MVA, 20/230 kV with an impedance of 0.01 + j0.05 per unit on its own base. Thetransformer is connected to a transmission line with an impedance of 0.02 + j0.1 per unit ona 230 kV, 500 MVA base.a. Convert the transformer impedance to the generator base.b. Calculate the per-unit impedance of the transmission line on the generator base.c. Determine the total impedance of the system (generator, transformer, and transmissionline) in per-unit on the generator base.

A three-phase fault occurs at the end of a transmission line connected to a bus. The systemconsists of a generator (1000 MVA, 22 kV) with a sub-transient reactance of 0.2 per unit,and a step-up transformer (1000 MVA, 22/220 kV) with a per-unit impedance of 0.1 perunit on its own base. The transmission line has an impedance of 0.1 + j0.5 per unit on a 220kV, 1000 MVA base.a. Convert all impedances to a common base of 1000 MVA, 22 kV.

A single Phase 50kVA, 2400/240V, 60Hz distribution transformer is used as a step downtransformer at the load end of a 2400V feeder whose series impedance is (1.0 + j2.0) ohms. Theequivalent series impedance of the transformer is (1.0 + j2.5) ohms referred to the high voltage (i.e.primary) side. The transformer is delivering rated total power at 0.8 power factor lagging, and atrated secondary voltage. Neglecting the transformer excitation current, determine:(a) The voltage at the transformer primary terminals,(b) The voltage at the sending end of the feeder,(c) The real and reactive power delivered to the sending end of the feeder.Work in the Per Unit System, using the transformer ratings as base quantities

5. Transformer ConnectionA power system includes two transformers: T1 (100 MVA, 110/11 kV, impedance 0.05 pu)and T2 (100 MVA, 11/0.4 kV, impedance 0.06 pu). They are connected in series, with T1stepping down from 110 kV to 11 kV and T2 stepping down from 11 kV to 0.4 kV.a. Determine the per-unit impedance of each transformer on a common base of 100 MVA, 11kV.b. Find the equivalent per-unit impedance of the combined transformer system.c. Calculate the actual impedance in ohms on the 0.4 kV side

Given the normalised load impedance is zL  = 0.4+1.4j on a 50 Ω transmission line system (you may use Smith chart to answer the question):Select one:a.The load reflection coefficient is |ΓL| = 0.8 and theta =68 degb.The VSWR changes as we move along the line toward the generatorc.The voltage standing wave ratio is VSWR=2d.The voltage standing wave ratio is VSWR=5e.The load reflection coefficient is |ΓL| = 0.6745 and theta =26.5 deg