Laboratory report 2
MECE-608: Power System Analysis
Department: Electrical and Computer Engineering
By: Mohammad Jawid Ahmadi
ID: 202115365
Objectives
The purpose of this lab is to investigate how changing transmission line characteristics affects
power flow in a distribution grid. The research will be carried out using the PowerWorld
Simulation system.
Section I
Procedure
PowerWorld was used to construct a circuit with two generators, three buses, transmission lines,
two loads, and one shunt capacitor as the first step in the lab exercise. All transmission lines had
their "per unit impedance parameters" adjusted to 0 as recommended by the Laboratory Manual.
All lines have 250,000 MWA ratings applied to them. After that, we simulated this power grid
using the predefined settings and monitored the resulting power flow and losses.
Figure 1. PowerWorld network created using default settings.
As can be seen, all transmission lines have zero power losses, with the exception of the line
connecting buses 4 and 5, where a reactive power loss of 0.0002 Mvar exists. The per-unit
impedances of all transmission lines were all set to 0, but the series reactance was always set by
the tool to 0.000010. This is why. Hence, some neglectable Mvar losses (which may be
approximated to zero) can be detected at this line. Because the per-unit parameters are 0, the
transmission lines’ losses are likewise 0.
The top generator's numbers started out at 60 MW and 20 Mvar, but during the run, they dropped
to 20 MW and 16 Mvar, while the bottom generator showed 40 MW and 5 Mvar. The 40 MW,
20 Mvar, 20 MW, and 10 Mvar loads as well as the 9.3 Mvar shunt capacitor are to blame. In
response to the load consumption, both generators provided a total of 60 MW and 21 Mvar,
which is the same as the load consumption. The shunt capacitor reduces the reactive power that
the top generator produces.
Figure 2. The concise list of power flow for the first circuit.
Section II
Procedure
To ascertain the impact of increasing load consumption on the power flow and losses, the identical
circuit utilized in the first section of the laboratory study was employed in the second section.
According to Table 1, the load consumption values for the two loads were set to various levels.
The simulation of this power network was then conducted using both the default and modified
settings, and the power flow and power losses were recorded.
Figure 3. Power network with the increased load consumption: 30MW and 50 MW.
Figure 4. The circuit's rapid power flow list with the higher load consumption.
Figure 5. Increased load demand on the power network: 40 MW and 60 MW.
Figure 6. The circuit's rapid power flow chart with the rising load consumption.
Test
Table 1. The transmission line losses according to the increased load consumption.
The
load 1
values
The load
2
values
Transmission
line losses for
1-2, 2-3
Transmission
line losses for
1-5
Transmission line
losses for line 45
MW Mvar
MW
Mvar
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
Total network
losses
1
20
10
40
20
0.000
0.000
0.000
0.000
0.000
0.0002
0.000
0.0003
2
30
10
50
20
0.000
0.000
0.000
0.000
0.000
0.0002
0.000
0.0003
3
40
10
60
20
0.000
0.000
0.000
0.000
0.000
0.0002
0.000
0.0004
4
50
10
70
20
0.000
0.0001
0.000
0.000
0.000
0.0002
0.000
0.0005
5
60
10
80
20
0.000
0.0001
0.000
0.000
0.000
0.0002
0.000
0.0006
As can be seen, all transmission lines have zero power losses, with the exception of lines 1-2 and
2-3 and the line connecting buses 4-5, which occasionally have reactive power losses of 0.0002
Mvar and 0.0001 Mvar, respectively. Again, this is because all of the transmission lines' per-unit
impedances were set to 0, but the tool itself always sets the series reactance to 0.000010. As a
result, along this line, there are some Mvar losses that may be neglected and are about equal to
zero. Since the per-unit parameters are zero, the losses on the transmission lines are also zero.
While the reactive power and real and reactive powers of the bottom generator remained
constant throughout the simulation, the top generator's real power values changed:
1𝑠𝑡 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 40 MW, 5 Mvar for bottom generator; 20 MW, 16 Mvar for top generator;
2𝑛𝑑 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 40 MW, 5 Mvar for bottom generator; 40 MW, 16 Mvar for top generator;
3𝑟𝑑 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 40 MW, 5 Mvar for bottom generator; 60 MW, 16 Mvar for top generator;
4𝑡ℎ 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 40 MW, 5 Mvar for bottom generator; 80 MW, 16 Mvar for top generator;
5𝑡ℎ 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 40 MW, 5 Mvar for bottom generator; 100 MW, 16 Mvar for top generator;
It can be observed that both generators’ supply is controlled according to the load consumption:
for example in the 2nd iteration, the total power supply by both generators were 80 MW (40 MW
for top and 40 MW for bottom generator) and 21 Mvar (16 Mvar and 5 Mvar) Despite the fact that
the overall load consumption parameters were 80 MW (30 MW for the first load and 50 MW for
the second load) and 30 Mvar (10 Mvar and 20 Mvar), the shunt capacitor itself led to a decrease
in the reactive power provided by a top generator for 9.3 Mvar.
Section III
Procedure
In the third part of the laboratory work, the same circuit was used to determine how increased perunit impedances affected power flow and losses. Table 2 shows all transmission lines' "per unit
impedance parameters" adjusted to various values. After that, this power network was simulated
with default and changed parameters to record power flow and power losses.
Figure 7. Power network with the increased per-unit impedances: iteration 2.
Figure 8. Power network with the increased per-unit impedances: iteration 4.
Table 2. losses on the transmission lines due to higher per-unit impedances.
Test
Pui
values
for 1-2
Pui
values
for 2-3,
1-5, 4-5
Transmissio
n line losses
for 1-2, 2-3
Transmission
line losses for
1-5
Transmission
line losses for
line 4-5
Total network
losses
R
X
R
X
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar
)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
1
0
10−5
0
10−5
0.000
0.000
0.000
0.000
0.000
0.0002
0.000
0.0003
2
0.1
0.01
0.01
0.1
0.000
0.000
0.0468
0.4681
0.1611
1.6112
0.2079
2.0795
3
0.2
0.02
0.02
0.2
0.000
0.000
0.0947
0.9471
0.3244
3.2441
0.4191
4.1914
4
0.3
0.03
0.03
0.3
0.000
0.000
0.1441
1.4413
0.4911
4.9111
0.6352
6.3525
5
0.4
0.04
0.04
0.4
0.000
0.000
0.1956
1.9557
0.6626
6.6258
0.8582
8.5817
Except for two lines connecting buses 1 and 2, and 2 and 3, transmission lines lose power.
Transmission line losses rise with per-unit impedance. Hence, per-unit impedance values affect
transmission line power losses: if they are 0, power losses are 0, but if they are nonzero but
elevated, power losses are likewise raised.
The top generator's actual and reactive power values changed during the simulation, however
the bottom generator's reactive power values remained constant:
1𝑠𝑡 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 20 MW, 16 Mvar for top generator; 40 MW, 5 Mvar for bottom generator;
2𝑛𝑑 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 20 MW, 19 Mvar for top generator; 40 MW, 3 Mvar for bottom generator;
3𝑟𝑑 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 20 MW, 20 Mvar for top generator; 40 MW, 5 Mvar for bottom generator;
4𝑡ℎ 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 21 MW, 21 Mvar for top generator; 40 MW, 6 Mvar for bottom generator;
5𝑡ℎ 𝑖𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛: 21 MW, 22 Mvar for top generator; 40 MW, 8 Mvar for bottom generator;
Section IV
Procedure
In order to assess the impact of increased active power provided by the bottom generator on the
power flow and on the performance of the other generator, the identical circuit utilized in the earlier
stages of the laboratory work was employed for the final portion of the study. Just the true power
levels produced by the bottom generator were raised by 5 MW in each cycle, and the "per unit
impedance parameters" of all transmission lines were once again set to 0. The power flow and
power losses were then recorded as the simulation of this power network was run with the default
parameters as well as with changed values.
Figure 9. Electricity network with bottom generator's higher actual power: iteration 4.
Figure 10. Power network with enhanced actual power from the generator at the bottom: iteration
5.
Test
Table 3. The increased real power supplied by the bottom generator and power flows.
Bottom
generator
Top
generator
Overall
network losses
Transmission
line losses for
1-2, 2-3
Transmission
line losses for 15
Transmission
line losses for
line 4-5
MW Mvar
MW
Mvar
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
𝑃𝑙𝑜𝑠𝑠
(MW)
𝑄𝑙𝑜𝑠𝑠
(Mvar)
1
40
5
20
16
0.000
0.0003
0.000
0.000
0.000
0.000
0.000
0.0002
2
45
5
15
16
0.000
0.0004
0.000
0.000
0.000
0.0001
0.000
0.0002
3
50
5
10
16
0.000
0.0005
0.000
0.000
0.000
0.0001
0.000
0.0003
4
55
5
5
16
0.000
0.0005
0.000
0.000
0.000
0.0001
0.000
0.0003
5
60
5
0
16
0.000
0.0006
0.000
0.000
0.000
0.0002
0.000
0.0004
As seen in Table 3, increasing the actual power provided by the bottom generator had an impact
on the active power of the other generator. With each repetition, the real power of the later
generator decreased by 5 MW while the real power of the former generator increased. The reactive
powers of both generators remained unaltered. The other generator's power supply was 0 MW at
the fifth repetition, even though the bottom generator's true power output was 60 MW. The value
of the active power provided by the second generator begins to exhibit negative numbers, such as
-5 MW, -10 MW, and so on, when actual power produced by the bottom generator is increased
further and exceeds 60 MW. As a result, the top generator serves as a load and consumes energy
from the system since it is no longer providing the genuine power. There is a restriction on the
iteration process as a result: only a certain number of iterations may be carried out. In this instance,
the answer is 5, since the generator begins to function as a load at iteration 6. Since the per-unit
impedance values of all transmission lines were set to 0, the power losses on them are
approximately 0. Yet, it can be shown that the reactive power losses on transmission lines also
grow as the actual power produced by the bottom generator increases.
This laboratory study examines how the increased load consumption, per-unit impedance
values, and active power produced by one generator affect the network's power flow, transmission
line losses, and the active power produced by a different generator. To examine this impact, many
simulations were run while the necessary parameters were changed. In Section I, the circuit was
formed using components with default characteristics. The transmission lines' power losses were
roughly zero since the per-unit impedance values were set to zero. This situation therefore
demonstrated the need of lowering the per-unit impedance characteristics of resistance and
reactance in order to decrease power losses in transmission lines.
Figure. 11: The active and reactive losses in the network
The load parameters for both loads were raised by 10 MW in Section II. Once again, the
transmission line losses were close to zero, yet the top generator's true power output was rising.
This figure was raised by 20 MW at each phase in order to adapt to the load consumption. In this
instance, the shunt capacitor had an impact on the reactive power generated by the identical top
generator: it reduced it.
The transmission lines' per-unit impedance characteristics were raised differently in Section
III. Increased power losses were noted during these scenarios because changes in those parameters
have an impact on the power losses in transmission lines. Moreover, only the reactive power
provided by the other generator was changing, but both the reactive and active powers produced
by the top generator were gradually growing.
For each test in Section VI, the bottom generator's active power output was raised by 5 MW.
The outcomes demonstrated that this modification had an impact on the active power provided by
the other one, which reduced by 5 MW throughout each test. Moreover, only a certain number of
repetitions may be performed to use both generators; otherwise, the top generator begins to
function as a load. That indicates that in order for this generator to continue to run, power must be
provided by the bus, which is not ideal.
References
[1]
Laboratory manual
[2]
Abdelhay A. Sallam; Om P. Malik, "Power Factor Improvement," in Electric Distribution
Systems , IEEE, 2019, pp.361-378, doi: 10.1002/9781119509332.ch13.
[3]
Y. Yao, A. Cosic and C. Sadarangani, "Power Factor Improvement and Dynamic
Performance of an Induction Machine with a Novel Concept of a Converter-Fed Rotor," in
IEEE Transactions on Energy Conversion, vol. 31, no. 2, pp. 769-775, June 2016, doi:
10.1109/TEC.2015.2505082.
[4]
R. Kushwaha and B. Singh, "Power Factor Improvement in Modified Bridgeless
Landsman Converter Fed EV Battery Charger," in IEEE Transactions on Vehicular
Technology, vol. 68, no. 4, pp. 3325-3336, April 2019, doi: 10.1109/TVT.2019.2897118.