Using the bus impedance matrices determined in Problem 9.51, verify the fault currents for the faults given in Problems 9.10, 9.24, 9.25, 9.26, and 9.27.

Data From Problem 9.51:-

Compute the \(5 \times 5\) per-unit zero-, positive-, and negative-sequence bus impedance matrices for the power system given in Problem 9.8. Use a base of 100 MVA and \(15 \mathrm{kV}\) in the zone of generator \(\mathrm{G} 2\).

Data From Problem 9.8:-

Equipment ratings for the five-bus power system shown in Figure 7.15 are given as follows:

Draw the zero-, positive-, and negative-sequence reactance diagrams using a 100MVA, \(15-\mathrm{kV}\) base in the zone of generator G2. Neglect \(\Delta-\mathrm{Y}\) transformer phase shifts.

Problem 9.10:-

Determine the subtransient fault current in per-unit and in kA during a bolted threephase fault at the fault bus selected in Problem 9.9.

Problem 9.9:-

Faults at bus \(n\) in Problem 9.8 are of interest (the instructor selects \(n=1,2,3,4\), or 5). Determine the Thévenin equivalent of each sequence network as viewed from the fault bus. Prefault voltage is 1.0 per unit. Prefault load currents and \(\Delta-Y\) phase shifts are neglected.

Problem 9.24:-

Determine the subtransient fault current in per-unit and in kA, as well as contributions to the fault current from each line, transformer, and generator connected to the fault bus for a bolted single line-to-ground fault at the fault bus selected in Problem 9.9.
Problem 9.25:-

Repeat Problem 9.24 for a single line-to-ground arcing fault with arc impedance \(Z_{\mathrm{F}}=0.05+j 0\) per unit.
Problem 9.26:-

Repeat Problem 9.24 for a bolted line-to-line fault.

Problem 9.27:-

Repeat Problem 9.24 for a bolted double line-to-ground fault.

Transcribed Image Text:

Generator Gl: Generator G2: Transformer T1: Transformer T2: 50 MVA, 12 kV, X = X2 = 0.20, X0 = 0.10 per unit 100 MVA, 15 kV, X = 0.2, X2 = 0.23, X = 0.1 per unit 50 MVA, 10 kV Y/138 kV Y, X = 0.10 per unit 100 MVA, 15 kV A/138 kV Y, X = 0.10 per unit Each 138-kV line: X = 40 ohms, X = 100 ohms ==