1. An 11 KV three phase transmission line has a resistance of 1.

5 Ω and reactance of 4 Ω per

phase. Calculate the % regulation and efficiency of the line when total load of 5000 KVA at
0.8 lagging power factor is supplied at 11KV at the distant end. Check the results obtained
using MATLAB.

2. Determine the Y bus matrix for the power system network given in Table and check the
results obtained in using MATLAB.
Bus code Line impedance (in p.u.) Half line charging admittance
1-2 0.05+0.25j 0.02j
2-3 0.04+0.15j 0.12j
3-1 0+0.15j 0.03j

3. An isolated power station has the following parameters

Turbine time constant, ƮT = 0.5sec ; Governor time constant, Ʈg = 0.2sec
Generator inertia constant, H = 5sec ; Governor speed regulation = R per unit
The load varies by 0.8 percent for a 1 percent change in frequency, i.e, D = 0.8. The governor
speed regulation is set to R=0.05 p.u. The turbine rated output is 250 MW at nominal
frequency 50 Hz. A sudden change of 50 MW occurs. Find the steady state frequency
deviation in Hz. Also obtain the time domain performance specifications and the frequency
deviation step response using MATLAB.

4. A 13.8 kV, 20 MVA, three phase generator have positive, negative and zero sequence
reactances of j0.25, j0.35 and j0.10 respectively. Determine the fault current and fault MVA
with zero fault impedance and prefault voltage of 1 V for the following faults.
i. A balanced three phase fault. ii. Single line to ground fault. iii. Double line to ground fault.

5. Determine Z bus matrix by bus building algorithm for the power system network shown in
Fig. Check the results obtained using MATLAB.

1 3

6. A 100 km long three phase 50 Hz transmission line has following line constants.
Resistance/ph/km=0.1Ω; Reactance/ph/km=0.5 Ω; Susceptance/ph/km = 10 × siemens.
If the line supplies load of 20 MW at 0.9 pf lagging at 66 KV at the receiving end. Calculate,
(1) Sending end power factor (2) Regulation (3) Transmission efficiency.
Check the results obtained using MATLAB.

7. Find the economic dispatch for the given problem: C1 =561+7.92P1 +0.001562P1 2 ;
C2 =310+7.85P2 +0.001940P2 2 ; C3 =78+7.97 P3 +0.004820P3 2 , where, P1, P2 and P3 are in MW.
Plant outputs are subject to the following limits:
150 MW  600 MW; 100 MW  400 MW; 50 MW  200 MW.
The real power loss is given by, P L=0.00003 P1 2 +0.00009 P2 2 +0.00012 P3 2 where, the loss
coefficients are specified in per unit on a 100 MVA base. The total system load is 855 MW.
Take tolerance value as 0.1. Check the results obtained using MATLAB.
1
8. Determine the Y bus matrix for the power system network shown in Table and check the
results obtained in using MATLAB.
Line no. Bus code Line impedance Line charging
(in p.u.) admittance
1 1-2 0.10+0.40j 0.015j
2 2-3 0.15+0.60j 0.02j
3 3-4 0.18+0.55j 0.018j
4 4-1 0.10+0.35j 0.012j
5 4-2 0.25+0.20j 0.030j

9. Determine Zbus matrix from Ybus matrix for the power system network given in Table. Check
the results obtained using MATLAB.
Bus code Line impedance Half line charging
(in p.u.) admittance
1-2 0.05+0.25j 0.02j
2-3 0.04+0.15j 0.12j
3-1 0+0.15j 0.03j

10. An isolated power station has the following parameters:

Turbine time constant, ƮT = 0.3 sec ; Governor time constant, Ʈg = 0.08sec
Generator inertia constant, H = 10 sec
Governor speed regulation = R per unit
Power system constant=120.
The load varies by 0.8 percent for a 1 percent change in frequency, i.e, D = 1. The governor speed
regulation is set to R=2.4 p.u. A sudden change of 50 MW occurs. Find the steady state frequency
deviation in Hz. Construct Simulink block diagram and also obtain the time domain performance
specifications and the frequency deviation step response using MATLAB.

11. A two area system connected by a tie line has the following parameters on a 1000 MVA
base.R1 =0.05pu, R2 =0.0625pu, D1 =0.6, D2 =0.9, H1 =5, H2 =4; Base power1 =Base
power2 =1000MVA, TG1 =0.2s, TG2 =0.3s, TT 1 =0.5s, TT 2 =0.6s. The units are operating in
parallel at the nominal frequency of 50Hz. The synchronizing power coefficient is 2pu. A load
change of 200MW occurs in area1. Find the new steady state frequency and change in the tie
line flow. Construct Simulink block diagram and find deviation in frequency response for the
condition mentioned.

12. a. Calculate the inductance, capacitance and reactance of 3 phase 50 Hz overhead

transmission line which has conductors of 2.5cm diameter. Distance between conductors are
5m between A & B, 4m between B & C, 3m between C & A Assume conductors are
transposed regularly.
b. Calculate the inductance and capacitance of a 3 phase double circuit line if the conductors
are spaced 2m apart at the vertices of a hexagon and diameter of conductors is 2cm.

2
13. Determine the Y bus matrix for the power system network shown in Table and check the
results obtained in using MATLAB.
Line no. Bus code Line impedance Line charging
(in p.u.) admittance
1 1-2 0.2+0.8j 0.02j
2 2-3 0.3+0.9j 0.03j
3 2-4 0.25+1.0j 0.04j
4 3-4 0.2+0.8j 0.02j
5 1-3 0.1+0.4j 0.01j

14. Perform relay co-ordination study for the radial system shown below.

The relay make is as follows: Relay rated current = 5 Amps; Plug setting = 50% to 250% in
steps of 25%; Time setting multiplier = 0.05 to 1.0 in steps of 0.01;
Relay details
Relay name R1 R2 R3
Primary rating (1,2,3,4) 800 400 200
Secondary rating 5 5 5
Load current 800 400 200
Transmission line details on 100 MVA base
Bus code Impedance Line charging admittance/2
1-2 0.00+j0.1 0
2-3 0.00+j0.1 0
3-4 0.00+j0.1 0
Generator details: G1=100 MVA, 80 MW, 11 kV; Maximum fault level = 1000 MVA

15. Find the economic dispatch for the given problem:

C1 =561+7.92P1 +0.001562P1 2 ; C2 =310+7.85P2 +0.001940P2 2 ;
C3 =78+7.97 P3 +0.004820P3 2 , where, P1, P2 and P3 are in MW.
Plant outputs are subject to the following limits:
150 MW  600 MW; 100 MW  400 MW; 50 MW  200 MW.
The real power loss is given by, P L=0.00003 P1 2 +0.00009 P2 2 +0.00012 P3 2 where, the loss
coefficients are specified in per unit on a 100 MVA base. The total system load is 855 MW.
Take tolerance value as 0.1. Check the results obtained using MATLAB.

16. a. Calculate the inductance and capacitance of a 3 phase double circuit line if the conductors
are spaced 2m apart at the vertices of a hexagon and diameter of conductors is 2cm.
b. Calculate the inductance and capacitance of a conductor of a 3 phase system which has 1.2
cm diameter and conductors at the edge of an equilateral triangle of side 1.5m.

3
17. a. Calculate the inductance and capacitance per phase of a 3 phase double circuit as shown in
the figure. Diameter of each conductor is 1.5cm. Verify the results using MALAB program.

b. Calculate the loop inductance and capacitance of a single phase line with two parallel
conductors spaced 3.5 m apart. The diameter of each conductor is 1.5 cm.

18. Determine the Y bus matrix for the power system network shown in Table and check the
results obtained in using MATLAB.
Line no. Bus code Line impedance Half line charging
(in p.u.) admittance in p.u.
1 1-2 0.05+0.12j 0.025j
2 2-3 0.06+0.4j -
3 3-4 0.75+0.25j 0.02j
4 1-3 0.045+0.45j 0.015j
5 1-4 0.015+0.05j -

19. Determine Z bus matrix by bus building algorithm for the power system network shown in
Fig. Check the results obtained using MATLAB.

1 2

20. A two area system connected by a tie line has the following parameters on a 1000 MVA
base.R1 =0.05pu, R2 =0.0625pu, D1 =0.6, D2 =0.9, H1 =5, H2 =4; Base power1 =Base
power2 =1000MVA, TG1 =0.2s, TG2 =0.3s, TT 1 =0.5s, TT 2 =0.6s. The units are operating in
parallel at the nominal frequency of 50Hz. The synchronizing power coefficient is 2pu. A load
change of 200MW occurs in area1. Find the new steady state frequency and change in the tie
line flow. Construct simulink block diagram and find deviation in frequency response for the
condition mentioned.

21. a. Calculate the inductance, capacitance and reactance of 3 phase 50 Hz overhead

transmission line which has conductors of 2.5cm diameter. Distance between conductors are
5m between A & B, 4m between B & C, 3m between C & A Assume conductors are
transposed regularly.
4
 b. Calculate the inductance and capacitance of a 3 phase double circuit line if the conductors
are spaced 2m apart at the vertices of a hexagon and diameter of conductors is 2cm.

22. Determine Z bus matrix by bus building algorithm for the power system network shown in
Fig. Check the results obtained using MATLAB.
j0.25 2 j0.05
1 3
Element 2 Element 4
j1.0
Element 1 j1.25
Element 3

0
Ref.bus
23. Determine the Y bus matrix for the power system network shown in Table and check the
results obtained in using MATLAB.
Bus code Line impedance Line charging
(in p.u.) admittance
1-2 0.1+0.64j j0.006
2-3 0.15+0.58j 0
3-4 0.06+0.7j j0.004
4-1 0.08+0.45j j0.002
4-2 0.12+0.8j 0
3-1 0.04+0.22j 0

24. Using Gauss Seidal method, calculate the voltages, line flows and transmission loss for the
network given in Table. Take α=1.6, tolerance=0.5 and Base MVA = 100.
GENERATOR LOAD
BUS VOLTAGE Qmin Qmax
P Q REMARKS
NO. (p.u.) P (p.u) Q (MVAR) (MVAR)
(p.u) (p.u)
1 1.05 - - - - - - Slack bus
2 1.02 0.3 - - - -10 100 PV bus
3 - - - 0.4 0.2 - - PQ bus

BUS CODE ADMITTANCE

1-2 j0.4
1-3 j0.3
2-3 j0.2

25. Determine Zbus matrix from Ybus matrix for the power system network given in Table.
Check the results obtained using MATLAB.
Bus code Line impedance Half line charging
(in p.u.) admittance
1-2 0.05+0.25j 0.02j
2-3 0.04+0.15j 0.12j
3-1 0+0.15j 0.03j

5
26. a. Calculate the inductance and capacitance per phase of a 3 phase double circuit as shown in
the figure. Diameter of each conductor is 1.2cm. Verify the results using MALAB program.

b. Calculate the loop inductance and capacitance of a single phase line with two parallel
conductors spaced 3.8 m apart. The diameter of each conductor is 1.2 cm.

27. Find the economic dispatch for the given problem:

C1 =561+7.92P1 +0.001562P1 2 ; C2 =310+7.85P2 +0.001940P2 2 ; C3 =78+7.97 P3 +0.004820P3 2 ,
where, P1, P2 and P3 are in MW.
Plant outputs are subject to the following limits:
150 MW  600 MW; 100 MW  400 MW; 50 MW  200 MW.
The real power loss is given by, P L=0.00003 P1 2 +0.00009 P2 2 +0.00012 P3 2 where, the loss
coefficients are specified in per unit on a 100 MVA base. The total system load is 855 MW.
Take tolerance value as 0.1. Check the results obtained using MATLAB.

28. Analyze the performance of overcurrent relay for the system shown below.

The relay make is as follows: Relay rated current = 5 Amps; Plug setting = 50% to
250% in steps of 25%; Time setting multiplier = 0.05 to 1.0 in steps of 0.01; Primary rating of
relay =800; Secondary rating = 5; Load current=800 A; Impedance of transmission line (1-2)
= j0.1; Generator details: G1=100 MVA, 80 MW, 11 kV; Maximum fault level = 1000 MVA.