1. ADAMA SCIENCE AND TECHNOLOGY
UNIVERSITY
Optimal Placement of D-STATCOM for Reduction of
Power Loss and Improvement of Voltage Profile using
Power Stability and Power Loss Indices in a Radial
Distribution System
Publisher: IEEE
Published in 2019
By Helen Tsegay
ID NO: PGR/21840/13
3. In the last few years, the distribution system has needed more
attention due to its significant role in power quality and planning.
Voltage sag, voltage instability and voltage fluctuation are common
issues in distribution system.
These lead to increase in losses, slow response time and
decrease in power flow.
Power loss reduction is a major issue that needs to be addressed
from the consumer point of view to improve the overall efficiency
of power delivery.
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INTRODUCTION
4. Shunt capacitors and series voltage regulator are used for
resolving these issues and maintaining the voltages within stability
limits.
But these have certain limitations like delayed response time,
inability of generation of continuous reactive power, presence of
oscillations in inductive circuits, etc.
To overcome these issues, FACTS devices are extensively being
used nowadays.
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Cont…
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Fig.1: Block diagram of DSTATCOM.
Distribution Static Compensator (D-STATCOM)
It is a shunt connected voltage source converter which has several
advantages such as:
Low harmonic production
Small in size
Low power losses and no resonance issues
6. Power Stability Index and Power Loss Index methods are used for
determining the optimal location of D-STATCOM.
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Fig. 2: Single line diagram of IEEE 12 bus distribution system.
7. POWER LOSS INDEX (PLI)
The bus which has the highest magnitude value of PLI is selected
as a candidate bus for this method.
After reading the line and bus data of the radial distribution
system, the load flow analysis is performed to calculate the
voltages and the losses.
Power Loss Indices are calculated as:
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[ ]
min
[ ]
max min
(1)
P i P
PLI i
P P
8. POWER STABILITY INDEX (PSI)
This index is developed after considering the line
parameters.
If a given line i-j has the largest PSI magnitude, then
the device is placed on bus j.
The value of PSI is calculated using the formula:
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4 ( )
[ ] =
2
( [ ]cos( ))
(2)
R Pl Pg
ij
PSI i
V i
9. RESULTS AND DISCUSSIONS
For base loading and double loading, the losses are acceptable and
the voltage profile is high, so considered triple loading condition.
a) Selection of Candidate Buses
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Fig. 3: Power Loss Indices on different buses.
10. Bus 9 has been chosen as the candidate bus with greatest PLI
value with magnitude 1.00.
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Fig.4: Power Stability Indices on different buses.
The highest value of PSI came in between buses 9 to 10, then we
consider bus 10 as the candidate bus with PSI magnitude of 0.1287.
11. Description Without D-
STATCOM
PLI
selection
PSI
selection
Candidate Bus ------ Bus 9 Bus 10
Active power loss 𝑃𝐿(MW) 0.203746 0.075934 0.077982
Reactive power loss 𝑄𝐿(MVAR) 0.079468 0.029449 0.030267
Minimum voltage (p.u) 0.8830 0.9478 0.9499
Reduction in 𝑃𝐿 (MW) 0 0.127812 0.125764
Reduction in 𝑄𝐿 (MVAR) 0 0.050019 0.049201
Table-I: Summary of results for PLI and PSI selection criteria
with and with D-STATCOM.
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12. CONCLUSION
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After increasing the load up to 300% of the base load, losses
were increase and decrease the voltage profile across the buses.
The PLI selection criteria proved itself better than the PSI
selection criteria in terms of reduction in power losses.
The PSI selection criteria proved itself better than the PLI
selection criteria for improvement of voltage profile.
