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To explore the suitability of optimized membership function for a conventional
large rule FLC based on various performances indices in terms of dynamic
response and harmonic compensation capability of shunt APF.
Complexity reduction of the optimized FLC by an approximated FLC, without
compromising the control performance.
Performance analysis of approximated optimized FLC under randomly varying
load conditions.
The rest of this chapter is organized as following: Basic compensation principle
and control scheme of shunt APF is discussed in Sect.
2
. Section
3
deals with the
introduction to FLC, need of approximation of large rule FLC and technique used
for approximation. Simulation results of 49-rule FLC with different membership
functions (MFs) are presented in Sect.
4
, where, optimized MF is selected, based on
the performance comparison. Also, numerical results, their analysis, and discus-
sions obtained using FLC with proposed approximation technique; and optimized
MF, are presented. Finally, the major contributions and conclusions of the work are
summarized in Sect.
5
.
2 Compensation Principle and Control Scheme of Shunt
Active Power Filter (APF)
The basic topology of shunt APF, providing harmonic and reactive power com-
pensation is shown in Fig.
1
. The compensation is based on the principle of
injecting equal and opposite distorted current in the supply line (Akagi et al.
1984
).
The shunt APF acts as a current source producing harmonic compensating
current component. The harmonic current components in the source currents are
cancelled, making source currents sinusoidal and in phase with the supply voltage,
thereby providing harmonic and reactive power compensation.
Bose (
1994
) and Ibrahim and Morcos (
2002
) have explored the possibilities of
applications of arti
cial intelligence (AI), expert system, fuzzy logic and neural
network in power electronics, motion control and PQ related areas. This work
provides a new space of opportunities for control engineers.
The inherent nature of FLC is explored in this chapter to develop a
flexible
control strategy. The schematic diagram of control scheme of shunt APF using FLC
is shown in Fig.
2
. The entire control task comprises of two loops, i.e., outer voltage
control loop and inner current control loop, as shown in Figs.
3
and
4
, respectively.
In voltage control loop, the DC link voltage of shunt APF is compared with a set
reference value. The error (e) and change in error (ce) between actual and reference
values of DC link capacitor voltages are used as the input variables to the FLC.
fl
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