17-08-2012, 11:45 AM
APPLICATIONS OF SIMPLIFIED BI-DIRECTIONAL FEEDER MODELS FOR ACCELERATING THE VOLTAGE-DROP AND POWER-LOSS CALCULATIONS
APPLICATIONS OF SIMPLIFIED BI-DIRECTIONAL FEEDER MODELS FOR ACCELERATING.pdf (Size: 627.12 KB / Downloads: 229)
INTRODUCTION
The objective of distribution system operation is to
operate distribution systems efficiently, economically, and
reliably to satisfy load demands that vary with the time
and season. The system operation should consider the
effects of the load variation as well as the load distribution.
Recently, real-time distribution automation and control
@AC) is increasingly important to the power industry.
To meet the requirements of real-time operation, it is
required to simplify and accelerate the calculations of
voltagedrop and power-loss.
Fig. 1 illustrates the schematic diagram of a portion of
a typical distribution system. A distribution transformer
and its loads are integrated and represented as a dot in
this figure. Generally, there are two kinds of switches in a
modern power distribution system.
SZMULATION RESULTS
A physical feeder shown in Fig. 6 is used to
demonstrate the characteristic of the adopted feeder
models. The discrete loads, the transformer impedance
and resistance values, and the lengths of line sections are
indicated in the figure. The power infeed of the sample
feeder can be at Bus #1 or Bus #2.
Three Werent models are applied to the sample feeder.
The first model is the bidirectional voltagedrop model
(V-Drop Model in the figures); the second model is the bidirectional
line-loss model (Line-Loss); and the third
model is the bidirectional hybrid model (Hybrid) that
combines the voltagedrop and line-loss models. A
detailed model (called the Detailed Model in the figures)
is made in great detail and is used here as the standard for
comparison of study results. It is does not include any
compromises and simulates every tapped-off load point as
a bus.
The simulation results corroborate the correctness and
efficiency of each model and illustrate the voltage at the
end of the given feeder (End-Volt), the line loss, the
transformer core and copper losses, the system losses, and
the relative accuracy of each of the models (err YO),
expressed as a percentage of deviation from the detailed
model of these results.
CONCLUSION
The simulation results show that the total series voltage
drop, line loss, transformer core and copper losses, and
total system loss of the sample feeder for different power
infeeds are Werent. Hence, it is important to apply bidirectional
feeder models to accurately represent the
features of reversible power flow while performing the
system reconfguration or restoration fimction. The
hybrid model can simulate both the total series voltage
drop and total copper loss accurately, and is therefore
considered to be the most acceptable model. However, if
only total series voltage drop or copper loss is required,
the voltage-drop or line-loss model should be used to
simple the computing effort because almost the sazne
accuracy as that of the hybrid model can be obtained by
these simple models. Finally, the evaluations of feeder
voltage profiles and system losses using the simplified bidirectional
models are much more efficient than using the
detailed model. This is important, especially for the largescale
power distribution systems with thousands of
discrete loads along a feeder. The simulation results in
this paper corroborate the simplified bidirectional feeder
models is invaluable for distribution management system
OMS), especially for those with real-time control
hnctions.