90

7.23

FIGURE 7.18

Single-line diagram for

Problem 7.21

A single-line diagram of a four-bus system is shown in Figure 7.18, for which Zaus is

given below:

ZBUS=j

CHAPTER 7 SYMMETRICAL FAULTS

Let a three-phase fault occur at bus 2 of the network.

(a) Calculate the initial symmetrical RMS current in the fault.

(b) Determine the voltages during the fault at buses 1, 3, and 4.

(c) Compute the fault currents contributed to bus 2 by the adjacent unfaulted buses 1,

3, and 4.

BUS 3

(d) Find the current flow in the line from bus 3 to bus 1. Assume the prefault voltage

Vy at bus 2 to be 1/0° pu, and neglect all prefault currents.

j0.25

j0.25

[0.25 0.2 0.16 0.14

0.2 0.23 0.15 0.151

0.16 0.15 0.196 0.1

0.14 0.151 0.1 0.195

ww

m 10.1

j0.2

BUS 2

0.125

BUS 1

j0.2

per unit

j0.4

(ground is the reference node)

ww

BUS 4

/0.1

SAUDA

10.2