2. a) Considering how the different phascs are affected during a power system fault, what are the two main categories of faults in power systems? How are they different?
Which method can be used for analysing them?
b) The single line diagram of a power system is shown in Figure Q2.1 including
generator and transformer winding connection and earthing details. The parameters
for this system have been calculated on a common 100 MVA base and are given in
Table Q2.1. All resistances and shunt susceptances are neglected. This system
experiences a single line to ground fault at a point F on line L1. The point F is at a
distance d from Bus 4 along the line L1. The total length 1 of the line Li is 50 km.
Note that the location of d is not drawn to scale in Figure Q2.1. The fault current at
the fault point F is measured to be 6.106 kA.
G1
3
40
AL
T3
5
L1
-a
(2 d)
يطي
G2
2
T2
Figure Q2.1
Table 02.1
G1
G2
Ti
T2
T3
L1
Rated voltage
(kV)
20
20
20/33
20/33
33/11
11
Zero sequence
Positive sequence Negative sequence
reactance Xo (p. u.) reactance X1 (p. u.) reactance X2 (p. u.)
0.20
0.30
0.35
0.15
0.25
0.30
0.12
0.12
0.12
0.20
0.20
0.20
0.20
0.20
0.20
1.20
0.50
0.50