I

I. INTRODUCTION1
The vast use of semiconductor devices are the main causes
of power distortion. Since from 1970’s inventions of
thyristors has been changed the way of current control 12.
These devices control the current with atomic level and they
are called atomic switching power devices. By virtue of this
property, these devices give very fast control response. Very
fast ON and OFF response makes the line current distorted
and eventually distorted voltage. These distortion increases
the harmonics 3 and reduced the power quality. It has been
known that 5th and 7th order harmonics are more significant in
power system 3. Fourier Transformation Theory is very
useful for analysis of harmonics3 4. One phenomena that
is “harmonic propagation” 1 which is a result of series
and/or parallel harmonic resonance between line inductors
and shunt capacitors in power system. So ‘harmonics
damping’ has done with series active filter and other
phenomena ‘harmonic elimination’ 1 has been carried out
with shunt active power filter.
Now a day devices like TV, computers, mobile charger,
LED bulb, regulator of fan, arc furnace, Adjustable speed
drive (ASD), Power electronic converter etc. are used at
homes and private companies. In early days effect of these
devices on power quality not properly known. But maloperation
of protecting devices such as relays and circuit
breakers open the new search area of power quality.
1978-1-5386-1138-8/18/$31.00 ©2018 IEEE
So these kind of switching devices generate nonlinear
current 3 and is called non-linear load. Before SAPF,
passive filters were used. But because of more disadvantages
23, usage of active power filter becomes popular. Since
After remarkable work done by Hirofumi Akagi, the new way
of control with SAPF have been opened up. He suggested the
methods by which the flow of current can be controlled in
such a way that source current will become near to pure
sinusoidal 1.
There after lots of other methods have been proposed by
authors 125679. These techniques are for reducing
harmonics, voltage regulation, correction of power factor etc.
New techniques have been developed by engineers using
Neural networks and fuzzy logic10. In this paper we
considering three different techniques. And there is wide
classification of SAPF based on different topology, based on
supply type and based on connection 2.
In section (II) Basic Operation is given that shows how
SAPF generates the compensating current and how to design
parameters for SAPF with mathematical equations. Here
10%,20%,30% unbalance given from supply side.10%
unbalance means 10% of peak value. For phase A no change.
For phase B 10% increased. And for phase C 10% decreased.
Same for 20% and 30%. And same is true for phase angle
unbalance Which is given in table2.
In section (III), Constant Instantaneous Power (CIP)
technique, Sinusoidal Current Control (SCC) technique,
Fryze current control technique discussed with mathematical
equations and circuit diagrams. Then in section (IV)
simulation results are represented with wave forms, tabular
data, and Total Harmonic Distortion (%THD). In this paper
performance of SAPF under unbalancing conditions have
been evaluated considering possible occurrence of unbalance
during the unsymmetrical fault condition.