Load flow Analysis (Gauss Seidel and Newton Raphson) using Powerworld
Aim: For the given 3 bus system obtain the bus voltages and line flows using
(a) Gauss Seidel Method
(b) Newton Raphson Method.
Note: Before doing the experiment, manually calculate all the bus voltages and line flows at the
endof first iteration using Gauss-Seidel Method
Result:
Find Out:
1. How Q limits of Generators are incorporated in load flow study?
2. What is the significance of generator capability curve of a synchronous generator?
Load Flow Analysis and Short Circuit analysis Using ETAP
Aim:
a) To find the bus voltages and line flows of given 3 bus system using ETAP. The line
impedances are marked in per unit on a 100 MVA base.
b) (i) Find the fault current in the above system when there is 3 phase to ground fault at
bus 2.
System Reactance data:
Generator at bus 1
Positive sequence reactance=0.1 pu
Negative sequence reactance=0.1 pu
Zero sequence reactance=0.05 pu
Generator at bus 2
Positive sequence reactance=0.2 pu
Negative sequence reactance=0.18 pu
Zero sequence reactance=0.1 pu
Transmission line Negative sequence Zero sequence reactance
reactance (pu) (pu)
1-2 0.025 0.075
1-3 0.05 0.15
2-3 0.025 0.065
Assume that all the generator neutrals are solidly grounded.
(ii) Find the fault current when there is a single line to ground fault at bus 2.
(iii) Find the fault current when there is a double line to ground fault at bus 2.
Short circuit Analysis using PowerWorld
Aim:
To determine the fault current in the given 4 bus system using PowerWorld for the
following cases
(i) A bolted three phase fault at bus 1
(ii) A bolted single line to ground fault at bus 1
(iii) A bolted line-line fault at bus 1
(iv) A bolted double line to ground fault at bus 1
Reactance data on a common base is as follows:
Item X1 X2 X0
G1 0.10 0.10 0.05
G2 0.10 0.10 0.05
T1 0.25 0.25 0.25
T2 0.25 0.25 0.25
Line 1-2 0.30 0.30 0.50
Note: Before coming to the lab calculate the theoretical value of fault current
Testing of Static Over Current Relay
Aim:
(i) To study the non-directional over current and earth fault relay model
MC12A
(ii) To conduct time over current pick up test at 50%, 100% and 150% of
normal current and determine percentage error.
(iii) To conduct instantaneous over current pick up test 2Is, 4Is, 6Is and 10Is
(iv) To obtain the operating time characteristics at TMS=0.5 and 1
Procedure:
(i) Time over current pick up test
IN=5A
Setting Range Constant, R= 5
Set current, IS=(0.1R+R∑ 𝑎) IN
Where ∑ 𝑎 depends upon the position of DIP switches
1. Do all the required connections
2. Adjust the position of DIP switches such that IS is equal to 50% of IN ( i.e
2.5 A).
3. Ensure that the current knob is at zero position. Switch on the current
injection unit and gradually increase the current.
4. The value of current at which the LED (Trip indication) begins to glow is
the pick up value
5. Reapeat the above procedure for 100% and 200% of IN
(ii) Instantaneous over current pick up test
High set value of current, IHS=(2+∑ 𝑏 )IS
Where ∑ 𝑏 depends upon the DIP switch positions
1. Do all the required connections
2. Adjust the DIP switch positions to make IHS = 5A
3. Turn on the high set enable switch
4. When a current corresponding to 95% of IHS is injected, the relay should
not trip.
5. When a current corresponding to 105% of IHS is injected, the relay should
trip
(iii) Operating Time characteristics
The relay is set for a 2.5A current. Obtain the trip time for current injections
of 2IS, 4IS, 6IS and 10IS. (Refer procedure to plot time current characteristics
of electromechanical over current relay)
Time over current pick up test
% of IN (A) DIP switch positions Set current Pickup % error
sw1 sw2 sw3 sw4 IS (A) current
(A)
50
100
150
200
Instantaneous over current pick up test
DIP switch High set current Pick up (Yes/ No)
positions IHS 95% IHS 105% IHS
(A)
5
10
Operating Time characteristics
IS=2.5A
2Is 4Is 6Is 10Is
C.T A.T C.T A.T C.T A.T C.T A.T
TMS =0.5
TMS= 1
Result:
