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In-Depth Information
cations can be observed, depending
upon installation type. However, for the purpose of capacitor installation the
classi
In the literature, number of capacitor classi
cation can be given as
1. Fixed capacitors, and
2. Switched capacitors.
fixed capacitor has
the same kvar values at all the levels. Switched capacitors are connected as per the
requirement at the buses. But, the higher cost of the switched capacitors restricts
utilities to use them; this also simpli
In practice, both
fixed and switched capacitors are used. A
es the nature of the problem. Therefore, the
fixed capacitors are considered here.
Only the smallest standard size of capacitors and its multiples are allowed at the
buses, to have a more realistic optimal solution that can be implemented later with
no dif
culties. Capacitor banks are generally supplied in multiples of 150 kvar.
2.2 Bene
ts of Capacitor Placement
The shunt capacitors, connected at the feeder supplying load at lagging power
factor, offer several advantages, some of which are,
(a) Reduced Power System Losses. The reactive power compensation provided
by capacitor, substantially, reduces the network losses in between the sub-
station and point of capacitor installation. In order to maximize the bene
ts,
installation of the capacitor should be implemented as close to the customer
load as possible.
(b)
Improved Voltage Pro
le. Feeders in the distribution system, with high
utilization and reactive power demands, offer large voltage variation and poor
voltage pro
les. The desirable voltage regulation is within a narrow range, i.e.,
fluctuation
may lead to voltage deviation beyond their permissible limits. With the use of
the capacitors, the use of expensive voltage regulators can be minimized.
(c) Released Power System Capacity. The reactive current, supplied by the
capacitors connected, furnishes the magnetizing currents for the electromag-
netic devices such as, motors, transformers, etc. This reduction, in reactive
current, helps in reduction of overloading and permits the addition of addi-
tional load to the existing system. Thus, more customers can be connected to
the existing system.
±
5 % of the nominal value, with balanced loads. However, load
fl
In order to place the capacitor, the mathematical modeling of the capacitor
placement problem is performed. In modeling, its various components, namely,
load
flow analysis, modeling at fundamental and harmonic frequencies, load vari-
ations, different planning methods and constraints for the problem are discussed.
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