Approximation of Optimized Fuzzy Logic Controller for Shunt Active Power Filter - Complex System Modelling and Control Through Intelligent Soft Computations - page 561

on three main areas, i.e., PQ problem of current harmonics and its mitigation,
selection of optimized FLC for shunt APF and complexity reduction of optimized
FLC using an approximation technique. The proposed approximation is based on
minimizing the sum of square errors, between the outputs of large rule FLC and
simplest 4-rule FLC. This approximation of large rules optimized FLC results in
reduced computational and functional complexity and less memory requirement
without compromising the control performances of FLC in terms of dynamic
response and harmonic compensation capabilities. Proposed approximation tech-
nique considerably improves the harmonic compensation performance of shunt
APF, due to effective approximation and smoother transition of output in the entire
UOD.

1 Introduction

Electrical power is one of the most dominant factors in our society. Reliability and
quality are the two most important facets of any power delivery system. Power
generation, transmission, distribution and usage are undergoing signi cant changes

that affect the electrical quality. The recent deregulation of electric power industry
has also contributed to the need for high quality of power. The load side is also
experiencing some signi cant changes such as increased use of power electronics

based converters and devices. These devices are main contributors and simulta-
neously most sensitive to PQ problems.
Technological advancement has lead to the spread of electronic equipments in
residential, commercial and industrial sectors owing to their numerous advantages.
Due to the inherent non-linear characteristics of these devices, their increased
application cause serious side effects on the distribution system, resulting in various
PQ problems (Akagi et al. 1984 ; Arrillaga et al. 1985 ; Subjak and McQuilkin
1990 ). Conventionally, the passive

filters were used to provide solution to these
problems, but their various demerits such as bulky size, detuning with ageing effect,
resonance issues, etc., have encouraged the research community to explore more
effective alternatives. Consequently, shunt active power filter (APF) has emerged as

a potential alternative to conventional passive filters for providing effective current

harmonic mitigation and reactive power compensation (Akagi et al. 1984 ; Singh
et al. 1999 , 2007 ; Jain et al. 2002 ).
The conventionally used control techniques for shunt APF are not always suf-

ficient to deal with the more demanding requirements of the system to deliver with
high precision and improved ef cial intelligence

(AI) based techniques has open up a new horizon for the control engineers to
investigate the control methodologies derived from human behaviour and experi-
ence based fuzzy computation, mathematical models based on human nervous
system analogy and nature inspired optimization algorithms (Dixon et al. 1999 ; Jain
et al. 2005 ; Singh et al. 2011a ).

ciency. The advancement of arti