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Material Type: Exam; Class: Power System Analysis; Subject: Electrical and Computer Engr; University: University of Illinois - Urbana-Champaign; Term: Unknown 1989;
Typology: Exams
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A generator bus (with a 1.0 per unit voltage) supplies a 150 MW, 50 Mvar load through a lossless transmission line with per unit (100 MVA base) impedance of j0. and no line charging. Starting with an initial voltage guess of 1.0 0 , determine the second iteration value of the load bus voltage (magnitude and angle) using the Newton- Raphson power flow method.
For the balanced, three phase network shown below assume that all data is per unit on a 100 MVA base except for the transmission line reactance. Assume a 20 kV voltage base for the generator and motor, and a 138 kV voltage base for the transmission line.
(9 pts) a) If the system is initially operating unloaded with all voltages at 1.0 per unit, what is the magnitude of the fault current (in amps) if a balanced, three phase fault occurs on the terminal of the generator on the left. You should neglect the dc offset current.
(8 pts) b) During the fault from part a, what is the per unit voltage magnitude on the terminal of the motor?
(8 pts) c) Repeat part a, except now assume that the generator is supplying 100 MVA with a 0.8 lagging power factor and a terminal voltage of 1.0 per unit.
( v(t) = 2 sin(t) volts ) and a switch. The switch, which is initially open, is closed at t = 0. Sketch the current through the circuit (as a function of time) for the first few cycles for t ≥ 0.
