Download Comparison of PI and ANN Control Techniques for Nine

Comparison of PI and ANN Control Techniques for Nine Switches UPQC
to Improve Power Quality and Mitigation of Voltage Sag & Swell
SHAIK.MABUSUBANI
PG Student,
Dept of EEE,
Sri Mittapalli College of Engineering,
Guntur Dt, A.P, India.
Email Id: [email protected].
SURESH KORNEPATI
Associate Professor,
Head, Dept of EEE,
Sri Mittapalli College of Engineering,
Guntur Dt, A.P, India.
Email Id: [email protected].
Abstract- This paper presents a comprehensive
review on the UPQC to reinforce power quality.
Typically this can be often speculated to gift a
broad outline on the varied possible intelligent
controls used with UPQC. The most purpose of a
UPQC is to control on voltage flicker/unbalance,
reactive power and harmonics. In different words,
the UPQC has the potential of up power quality at
the purpose of installation on power industrial
power systems. The appliance of computing is
growing quick within the space of power
electronics and drives. From olden days to now
days we are using twelve switches used in back to
back configuration. But now we are using nine
switches instead of 12 switches. In 9 switch UPQC
converter given the most useful benefits compared
to 12 switches power converter. The nine switches
UPQC converter gets the best results by using of
two methods. They are one is PI controller
technique and other one is ANN controller
technique. By contrast PI and ANN, ANN is better
than PI for power quality enhancement and
voltage sag and voltage swell mitigations. The
factitious neural network (ANN) is taken into
account as a replacement tool to style
management electronic equipment for powerquality (PQ) devices. A whole simulation study is
administrated to analysis the performance of the
ANN controller and compares its performance
with the quality PI controller results. The nineswitch convertor has already been proved to
possess sure benefits, additionally to its part
saving topological feature. Despite these benefits,
the nine-switch convertor has thus far found
restricted applications because of its several
perceived performance tradeoffs like requiring
associate degree outsized dc-link capacitance,
restricted amplitude sharing, and unnatural part
shift between its 2 sets of output terminals. Rather
than acceptive these tradeoffs as limitations, a
nine-switch power conditioner is projected here
that nearly “converts” most of those topological
short comings into fascinating performance
benefits. Aiming more to cut back its switch losses,
Harmonics, Voltage Sag & Swell associate degree
acceptable discontinuous modulation theme is
projected and studied here thoroughly to doubly
make sure that top reduction of commutations is
achieved. With associate degree suitably designed
management theme with PI and ANN with
physical
phenomenon
controller
then
incorporated, the nine-switch convertor is shown
to favorably raise the general power quality in
Simulation, thus justifying its role as an influence
conditioner at a reduced value.
Index Terms-ANN, Active power filters, PI
controller, nine switch converter, Power quality,
UPQC.
I.INTRODUCTION
The use of electronic controllers within the electrical
power-supply system has become quite common.
These electronic controllers behave as nonlinear load
and cause serious distortion within the distribution
system and introduce unwanted harmonics within the
supply system, resulting in slashed potency of the
facility system network and instrumentality
connected within the network [1]. To satisfy the
wants of harmonic regulation, passive and active
power filters area unit being employed together with
the standard converters [2]. Presently, active power
filters (APFs) have become value-effective
attributable to cost reductions in power
semiconductor devices, their auxiliary components,
and integrated digital management circuits.
Additionally, the APF conjointly acts as a powerconditioning device that provides a cluster of
multiple functions, like harmonic filtering, damping,
isolation and termination, load equalization, reactivepower management for power-factor correction and
voltage regulation, voltage-flicker reduction, and/or
their mixtures. Resent analysis focuses on use of the
universal power quality conditioner (UPQC) to catch
up on power-quality issues [3], [4]. The performance
of UPQC principally depends upon however
accurately and quickly reference signals area unit
derived. Once economical extraction of the distorted
signal, an acceptable dc-link current regulator is used
to derive the particular reference signals. numerous
management approaches, like the PI, PID, fuzzylogic, sliding-mode, predictive, unified constant
frequency (UCF) controllers, etc., area unit in use
[5]–[7]. kind of like the PI standard controller, the
PID controller needs precise linear mathematical
models, that area unit tough to get, and fails to
perform satisfactorily beneath parameter variation
nonlinearity load disturbance, etc. fashionable
management theoretic controllers area unit state
feedback controllers, self-tuning controllers, and
model reference adjustive controllers, etc. These
controllers conjointly would like mathematical
models and area unit so sensitive to parameter
variations [8]. In recent years, a serious effort has
been afoot to develop new and unconventional
management techniques that may typically augment
or replace standard management techniques. Variety
of unconventional management techniques have
evolved, providing solutions to several tough
management issues in trade and producing sectors.
not like their standard counterparts, these
unconventional controllers (intelligent controllers)
will learn, remember, and create choices. Artificial
intelligence (AI) techniques, notably the NNs, area
unit having a major impact on power-electronics
applications. Neural-network-based managementlers
give quick dynamic response whereas maintaining
the soundness of the device system over a good in
operation vary and area unit thought of as a brand
new tool to style control circuits for PQ devices [9]–
[12]. Over the previous couple of years, major
analysis works are disbursed on feedback circuit style
for UPQCs with the target of getting reliable
management algorithms and quick response
procedures to get the switch management signals
[13]–[15]. During this paper, for raising the
performance of a UPQC, a multilayer feed forwardtype ANN-based managementler is meant for the
present control of the shunt active filter rather than
the standard PI controller. Associate rule for
coaching the ANN controller is developed and
trained offline. Numerous simulation results area unit
given and verified through an experiment, and
compare the performance of the ANN controller with
standard PI controller results. A DSP-based
microcontroller is employed for the period of time
simulation and implementation of the management
rule.
Since its initial introduction, static power convertor
development has full-grown quickly with several
convertor topologies currently pronto found within
the open literature. Incidental this development is that
the equally speedy identification of application areas,
wherever power converters will contribute absolutely
toward raising the general system quality [1], [2]. In
most cases, the known applications would need the
ability converters to be connected nonparallel [3] or
shunt [4], looking on the operational situations into
consideration. Additionally, they have to be
programmed with voltage, current, and/or power
regulation schemes in order that they\'ll swimmingly
make amends for harmonics, reactive power flow,
unbalance, and voltage variations. For even
additional tight regulation of provide quality, each a
shunt and a series convertor square measure more
with one amongst them tasked to perform voltage
regulation, whereas the opposite performs current
regulation. nearly always, these 2 converters square
measure connected in an exceedingly back to-back
configuration [5], victimization twelve switches in
total and sharing a typical dc-link capacitance, as
mirrored by the configuration drawn in Fig. 1(a).
Wherever obtainable, a small supply may be inserted
to the common dc link, if the intention is to supply
for distributed generation in an exceedingly small
grid [6], while not considerably impacting on the
long proved correct functioning of the succeeding
configuration.
Even though facing no major operative issues at the
present,
enhancements
through
topological
modification or replacement of the consecutive
configuration to scale back its losses, part count, and
quality would still be favored, if there\'s no or solely
slight expected trade-off in performance. A classical
different that may straight off be brought out for
thought is that the direct or indirect matrix device,
wherever eighteen switches area unit employed in
total. That represents six switches quite the
consecutive configuration, however has the
advantage of removing the intermediate electrical
condenser for compactness and period of time
extension. If the significant switch count remains of
concern, those indirect thin matrix converters planned
in [7], [8] is thought-about, wherever the minimum
switch count getable is 9, however at the expense of
supporting solely one-way power flow. Neither
storage electrical condenser nor dc micro source is
once more required, that therefore renders the
traditional and thin matrix converters as not the wellliked selection, if ride-through could be a demand.
Matrix converters also are not most popular, if
voltage buck and boost operations area unit each
required for a specified direction of power flow.
frequency operation on the 2 interfaced ac systems
that then makes it unsuitable for applications like
utility steam-powered adjustable speed drives and
series-shunt power conditioners.
Yet another reduced semiconductor topology is found
in [9], wherever the B4 device is introduced for dc–
ac or ac dc energy conversion. The B4 device uses
four switches to create 2 section legs with its third
section drawn from the centre of a split dc electrical
phenomenon link. For fastening 2 ac systems along, 2
B4 converters area unit required with their split dc
link shared [10]. The full variety of switches required
is therefore eight, that most likely is that the
minimum possible for interfacing 2 ac systems. The
ensuing ac–dc–ac device ought to then be a lot of
truly cited because the B8 device. The B8 device is,
however, known to suffer from massive dc-link
voltage variation, unless each systems area unit of
constant frequency and synchronized in order that no
basic current flows through the dc link. That actually
could be a constraint, additionally to the lower ac
voltage that may be made by every B4 device from
its given dc-link voltage.
More significantly, a far larger dc-link capacitance
and voltage ought to be maintained, so as to supply
similar ac voltage amplitudes as for the consecutive
convertor. Uncalled-for to mention, the larger dc-link
voltage would amplify the semiconductor switches
unnecessarily, and would possibly to some extent
overshadow the saving of 3 semiconductor switches
created potential by the nine-switch topology. The
attractiveness of the nine-switch convertor, if so any,
is thus not nonetheless absolutely brought out by
those existing applications mentioned in [13]–[15].
Though follow-up topological extensions will later be
found in [16], wherever a Z-source network and
different modulation schemes are introduced, they
didn’t absolutely address those crucial limitations
sweet-faced by the nine-switch convertor, and not its
ancient consecutive counterpart.
Overcoming some limitations of the B8 device is that
the 5 leg device introduced in [11], that conceptually
is viewed as adding a fifth section leg to the B8
device. The other section leg is shared by the 2
interfaced ac systems with currently no massive basic
voltage variation ascertained across its dc link. The
sole constraint here is that the imposition of common
Presenting a much better reduced semiconductor
different for top quality series–shunt compensation,
this paper proposes one stage integrated nine-switch
power conditioner, whose circuit association is
shown in Fig. 1(b). As its name roughly inferred, the
planned conditioner uses a nine-switch convertor
with 2 sets of output terminals, rather than the same
old twelve switch back-to back convertor. The nineswitch convertor was earlier planned in [12] and [13]
at regarding a similar time, and was counseled for
twin motor drives [14], rectifier–inverter systems,
and uninterruptible power provides [15]. Despite
functioning as supposed, these applications are
burdened by the restricted part shift and strict
amplitude sharing enforced between the 2 terminal
sets of the nine-switch convertor.
Investigating more by taking a more in-depth read at
those existing applications delineate earlier, a general
note discovered is that they normally use the nineswitch convertor to exchange 2 shunt converters
connected consecutive. Such replacement can limit
the total functionalities of the nine-switch convertor,
as explained in Section II. Within the same section,
an alternate conception is mentioned, wherever the
nine-switch convertor is chosen to exchange a shunt
associate degreed a series convertor found in an
integrated power conditioner, rather than 2 shunt
converters. Underlying operational principles are
mentioned comprehensively to demonstrate however
such “series–shunt” replacement will induce the total
blessings of the nine-switch convertor, whereas
nonetheless avoiding those limitations sweet-faced by
existing applications. Details explaining sleek
transitions between traditional and sag operational
modes are provided to clarify that the lot of restricted
nine-switch convertor won\'t underperform the lot of
freelance back-to back convertor even for sag
mitigation.
During voltage sags, the second set of management
schemes conjointly has the flexibility to endlessly
keep the load voltages inside tolerable vary. This sag
mitigation ability, along with different abstract
findings mentioned during this paper however not
within the open literature, has already been verified
in experiment with favorable results discovered.
modification of electrical hundreds nature. These
hundreds area unit at the same time the key causers
and also the major victims of power quality issues
[8]. because of their non-linearity, of these hundreds
cause disturbances within the voltage undulation.
along side technology advance, the organization of
the worldwide economy has evolved towards
globalisation and also the profit margins of the many
activities tend to decrease [11]. The magnified
sensitivity of the overwhelming majority of processes
(industrial, services and even residential) to PQ
issues turns the provision of electrical power with
quality an important issue for fight in each activity
sector. the foremost crucial area unitas are the
continual method trade and also the info technology
services [15]. once a disturbance happens, immense
money losses could happen, with the ensuing loss of
productivity and fight. though several efforts are
taken by utilities, some shoppers need tier of PQ
beyond the extent provided by fashionable electrical
networks [12]. this means that some measures should
be taken so as to attain higher levels of Power
Quality.
III.UNIFIED POWER QUALITY
CONDITIONER
Fig. 1. (a) back-to-back and (b) nine-switch power
conditioners.
II.POWER QUALITY
Power Quality (PQ) connected problems area unit of
most concern today. The widespread use of
equipment, like info technology instrumentality,
power physical science like adjustable speed drives
(ASD), programmable logic controllers (PLC),
energy-efficient lighting, diode to a whole
The Unified Power Quality Conditioner may be a
custom power device that\'s used within the
distribution system to mitigate the disturbances that
have an effect on the performance of sensitive and/or
essential load [19]. it\'s a kind of hybrid APF and is
that the solely versatile device which might mitigate
many power quality issues connected with voltage
and current at the same time thus is multi functioning
devices that compensate numerous voltage
disturbances of the ability offer, to correct voltage
fluctuations and to stop harmonic load current from
getting into the ability system. The system
configuration of a single-phase UPQC is shown in
Fig. 2. Unified Power Quality Conditioner (UPQC)
consists of 2 IGBT primarily based Voltage supply
converters (VSC), one shunt and one series cascaded
by a typical DC bus. The shunt convertor is
connected in parallel to the load. It provides power
unit support to the load and provides harmonic
currents. Whenever {the offer the availability the
provision} voltage undergoes sag then series
convertor injects appropriate voltage with supply [2].
Therefore UPQC improves the ability quality by
preventing load current harmonics and by correcting
the input power issue. the most elements of a UPQC
square measure series and shunt power converters,
DC capacitors, low-pass and high-pass passive filters,
and series and shunt transformers the most purpose of
a UPQC is to catch up on offer voltage power quality
problems, such as, sags, swells, unbalance, flicker,
harmonics, and for load current power quality issues,
such as, harmonics, unbalance, reactive current, and
neutral current. The key elements of this technique
square measure as follows.
1) 2 inverters —one connected across the load that
acts as a shunt APF and different connected
nonparallel with the road as that of series APF.
2) Shunt coupling inductance Lsh is employed to
interface the shunt electrical converter to the
network. It conjointly helps in smoothing this wave.
Generally associate isolation electrical device is
employed to electrically isolate the electrical
converter from the network.
3) a typical dc link that may be fashioned by
employing a condenser or associate inductance. In
Fig. 2, the dc link is accomplished employing a
condenser that interconnects the 2 inverters and
conjointly maintains a continuing independent dc bus
voltage across it.
4) Associate LC filter that is a passive low-pass filter
(LPF) and helps to eliminate high-frequency switch
ripples on generated electrical converter output
voltage.
5) Series injection electrical device that\'s
accustomed connect the series electrical converter
within the network. an acceptable flip magnitude
relation is commonly thought-about to scale back the
voltage and current rating of series electrical
converter.
In principle, UPQC is associate integration of shunt
and series APFs with a typical independent dc bus.
The shunt electrical converter in UPQC is
managementled in current management mode such it
delivers a current that is adequate to the set price of
the reference current as ruled by the UPQC control
algorithmic program [20]. To boot, the shunt
electrical converter plays a vital role in achieving
needed performance from a UPQC system by
maintaining the dc bus voltage at a group reference
price. so as to cancel the harmonics generated by a
nonlinear load, the shunt electrical converter ought to
inject a current. Similarly, the series electrical
converter of UPQC is managementled in voltage
control mode such it generates a voltage and injects
nonparallel with line to realize a curved, free from
distortion and at the required magnitude voltage at
the load terminal. Within the case of a voltage sag
condition, actual supply voltage can represent the
distinction between the reference load voltage and
reduced offer voltage, i.e., the injected voltage by the
series electrical converter to take care of voltage at
the load terminal at reference price. Altogether the
reference papers on UPQC, the shunt electrical
converter is operated as controlled current supply and
also the series electrical converter as controlled
voltage supply except during which the operation of
series and shunt inverters is interchanged.
A unified power quality conditioner (UPQC) may be
a device .The UPQC, sort of a UPFC, employs 2
voltage supply inverters (VSIs) that area unit
connected to a standard dc energy storage condenser.
One among these 2 VSIs is connected serial with the
AC line whereas the opposite is connected in shunt
with an equivalent line. A UPFC is used in an
exceedingly power gear mechanism to perform shunt
and series compensation at an equivalent time.
Equally a UPQC may perform each the tasks in an
exceedingly power distribution system. However, at
now similarities within the operational principles of
those 2 devices finish. Since an influence cable
typically operates in an exceedingly balanced,
distortion (harmonic) free surroundings, a UPFC
should solely give balanced shunt or series
compensation. An influence distribution system, on
the other hand, could contain unbalance, distortion
and even dc elements. Thus a UPQC should operate
below these surroundings whereas providing shunt or
series compensation.
The UPQC may be a comparatively new device and
not a lot of work has been reported thereon however.
It has been viewed as an integration of series and
shunt active filters. It has been shown that it may be
accustomed attenuate current harmonics by inserting
a series voltage proportional to the road current.
Instead, the inserted series voltage is supplemental to
the voltage at the purpose of common coupling
specified the device will give a buffer to eliminate
any voltage dip or flicker. It is additionally potential
to control it as a mixture of those 2 modes. In either
case, the shunt device is employed for providing a
path for the important power to flow to assist the
operation of the series connected VSI. Additionally
enclosed during this structure may be a shunt passive
filter to that all the comparatively low frequency
harmonics area unit directed.
Fig. 2: UPQC general block diagram
IV.OVERALL CONTROL CIRCUIT
CONFIGURATION OF NINE SWITCH UPQC
be then adore pure curving signal with unity (p.u.)
amplitude. The extraction of unit vector templates is
U a  sin( wt )
U b  sin( wt  120)
(1)
U c  sin( wt  120)
Multiplying the height amplitude of basic input
voltage with unit vector templates of equation (1)
offers the reference load voltage signals,
V *abc Vm .U abc
(2 )
The error generated is then taken to a physical
phenomenon controller to get the desired gate signals
for series APF. The unit vector template are often
applied for shunt Fig.3 Extraction of Unit Vector
Templates and three-Φ Reference Voltages shown
within the Fig.3.The unit vector templates square
measure generated APF to compensate the harmonic
current generated by non-linear load. The shunt APF
is employed to catch up on current harmonics
likewise on maintains the dc link voltage at constant
level [13-14]. to realize the higher than mentioned
task.
REFERENCE GENERATION (PHASE
LOCKED LOOP)
Reference currents and voltages square measure
generated victimization part secured Loop (PLL).
The management strategy is predicated on the
extraction of Unit Vector Templates from the
distorted input provide. These templates are going to
be then adore pure curving signal with unity (p.u.)
amplitude. The 3-ph distorted input supply voltage at
PCC contains basic element and distorted element. to
induce unit input voltage vectors Uabc, the input
voltage is perceived and increased by gain adequate
to 1/Vm, wherever Vm is adequate to peak amplitude
of basic input voltage. These unit input voltage
vectors square measure taken to part secured loop
(PLL). With correct part delay, the unit vector
templates square measure generated.
The management strategy is predicated on the
extraction of Unit Vector Templates from the
distorted input provide. These templates are going to
Fig.3. Extraction of 3-Φ Reference Voltages Unit
Vector Templates
The dc link voltage is perceived and compared with
the reference dc link voltage. A PI controller then
processes the error. The signal from PI controller is
increased with unit vector templates of equation (1)
giving reference supply current signals. The supply
current should be adequate to this reference signal. so
as to follow this reference current signal, the 3-phase
supply currents square measure perceived and
compared with reference current signals. The error
generated is then processed by a physical
phenomenon current controller with appropriate
band, generating gating signals for shunt APF. The 9
Switch UPQC uses 2 consecutive connected 3 part
VSI‟s sharing a standard dc bus. The physical
phenomenon controller is employed here to manage
the switch of the each VSI’s.
In order to own distortion less load voltage, the load
voltage should be adequate to these reference signals.
The measured load voltages square measure
compared with reference load voltage signals. The
error generated is then taken to a physical
phenomenon controller to get the desired gate signals
for series APF. The unit vector templates are often
applied for shunt APF to compensate the harmonic
current generated by non-linear load. The shunt APF
is employed to catch up on current harmonics
likewise on maintains the dc link voltage at constant
level. to realize the higher than mentioned task the dc
link voltage is perceived and compared with the
reference dc link voltage. A PI controller then
processes the error. The signal from PI controller is
increased with unit vector templates of equation (1)
giving reference supply current signals. The supply
current should be adequate to this reference signal. so
as to follow this reference current signal, the 3-ph
supply currents square measure perceived and
compared with reference current signals. The error
generated is then processed by a physical
phenomenon current controller with appropriate
band, generating gating signals for shunt APF.
V. CONTROL STRATEGY OF NINE
SWITCH UPQC
Static Shunt Compensator using PI
Nine Switch UPQC consists of series compensator
and shunt compensator. The shunt compensator is
managementled by a PWM current control formula,
whereas the series convertor is managementled by a
PWM voltage control formula. in step with the
adopted management theme, these 2 components of 9
Switch UPQC have totally different functions as
follows:
Static Shunt Compensator
Shunt electrical converter control: during this study,
shunt electrical converter undertakes 2 main duties.
initial is compensating each current harmonics
generated by nonlinear load and reactive power,
second is injecting active power generated by PV
system. The shunt electrical converter dominant
system ought to be designed during a manner that
it\'d give the power of enterprise 2 higher than duties.
Shunt electrical converter management calculates the
compensation current for current harmonics and
reactive power once PV is out of the grid. the facility
loss caused by electrical converter operation ought to
be thought-about during this calculation. Also, shunt
electrical converter management undertakes the duty
of (stabilizing) DC link voltage throughout series
electrical converter operation to compensate voltage
distortions. DC link electrical condenser voltage
dominant loop is employed here by applying PI
controller. Fig.4 shows the circuit diagram of shunt
electrical converter dominant.
Fig .4.Control block diagram of shunt inverter using
PI.
Shunt electrical converter management in
interconnected mode: Mode one of shows UPQC
shunt voltage supply electrical converter dominant
diagram applying synchronous coordinate system
theory technique wherever sensitive load currents
area unit Ia, Ib and Ic
Measured load currents applying synchronous
coordinate system conversion technique (dq0), area
unit transferred to dq0 frame victimization curved
functions. Sinusoidal functions are obtained by PLL
using grid voltage. Currents during this synchronous
reference area unit rotten to 2 DC and AC (50 Hz)
quantities (using ~ sign higher than the parameter).
dq 0
Ildq 0  Tabc
I abc
dq 0
Tabc

cos 

2
  sin 
3
 1

 2
( 1)
2 
2  


cos   
cos   


3 
3 


2 
2  


sin    
 sin    

3
3 




1
1

2
2

Ild  Ild  Ild , Ilq  Ilq  Ilq
(2)
(3)
where, Id is active and IQ is reactive a part of power.
AC and DC components is extracted by an occasional
pass filter.In this case:
Il  I s  I c
(4)
In Eq. 4, Is is that the supply current, Il is that the
load current and Ic is that the compensating
currentinjected by shunt electrical converter. If
compensation reference currents area unit thoughtabout as follow:
I *fd  Ild , I *fq  Ilq
(5)
In this case, the system`s currents are:
I sd  Ild , I sq  I lq
(6)
In the Eq. 6, simply the load current harmonics area
unit remunerated. If power issue is taken into account
too, the reference currents would be as follow:
I *fd  Ild , I *fq  Ilq
(7)
then system currents are:
I sd  Ilq , I sq  0
average worth of DC bus. alternative distortions like
unbalanced and unexpected load current variations
will cause oscillation in DC bus voltage. so as to
trace the error exists between the measured and
desired worth of electrical condenser voltage, a PI
controller is applied. This dominant signal is applied
to current system in shunt voltage supply during a
manner that it management DC electrical condenser
voltage by getting needed active power (Id) from the
grid. The output a part of PI controller (Δidc), is
additional to the letter of the alphabet a part of
reference current, where, the reference current would
modification as follow:
I cd*  Ild  idc , I cq*  Ilq
(9)
As it is shown in Fig. 4, the reference currents can
transfer to fundamentals frame by reverse changing
the synchronous coordinate system, as Eq. 1.
Resulted reference currents are compared with shunt
electrical converter output currents (Ifa, Ifb, Ifc)
during a PWM current controller (hysteresist type)
and needed dominant pulses area unit generated.
Applying these signals to shunt electrical converter
power switches gate, needed compensation current is
generated by electrical converter.
In addition to earlier duties, shunt electrical converter
management ought to inject active power of PV
system to the grid once PV is working. Active power
is injected to grid by electrical condenser voltage
dominant loop. In alternative words, once voltage
will increase and reaches to {the worth|the worth}
that is quite the reference voltage value, shunt
electrical converter injects active power to grid and
once it decreases to worth that is a smaller amount
than the reference voltage value; shunt electrical
converter receives active power from the grid.
Static Shunt Compensator using ANN
(8)
So, no harmonic and reactive power are provided by
the supply. Switching losses and therefore the power
that the series electrical converter receives from
electrical condenser, will scale back the voltage
In Figure.5 the fast current of the nonlinear load is
expanded into three terms. the primary term is that
the load functions sent from PLL (Phase latched
Loop) in accordance with equation.(3)
I Ldq 0 Tabc dq 0iLabc
(10)
By this remodel, the basic positive sequence parts
area unit remodeled into dc Quantities in d and letter
of the alphabet axes, which may simply be extracted
by low-pass, filter (LPF).
Fig.6. Control block diagram of series inverter using
PI.
Fig.5. Control of the shunt Converter of the Nine
Switch UPQC using ANN.
All harmonic parts area unit remodeled into ac
quantities with a harmonic shift
I Lq i Lq i Lq
Since
iL is ic
(11)
(12)
This means there\'s no harmonics and reactive parts
within the system currents. The change loss will
cause the dc link electrical condenser voltage to
decrease. alternative disturbances, like unbalances
and unexpected variations of masses can even cause
this voltage to fluctuate. so as to avoid this, in Figure
four. a PI controller is employed. The input of the PI
controller is that the error between the particular
electrical condenser voltage and therefore the desired
worth, its output then additional to the reference
current part within the d-axis to create a replacement.
Series inverter control using PI:
The duty of series electrical converter is
compensating voltage distortions that ar caused by
fault in distribution grid. Series electrical converter
management calculates the voltage reference values,
that ar injected to grid by series electrical converter.
In order to regulate series electrical converter of
UPQC, load curving voltage dominant strategy is
projected. during this condition, UPQC series
electrical converter would be controlled during a
approach that it compensates the total distortions and
helps the voltage of load voltage keep (balanced
curving 3-phase). so as to succeed in this aim,
synchronous frame of reference theory is applied
(11).
In this methodology the specified worth of load
section voltage is replaced in d and q-axises rather
than high pass and low pass filters. Load voltage
ought to be utterly a curving perform and has
constant frequency and amplitude. Desired voltage of
load is as combining weight. 14:
*
ldq 0
V
*
labc
V
T
dq 0
abc
*
labc
.V
Vm 
  0 
 0 
 Vm cos t    


 Vm cos t    120  
Vm cos t    120  
(13)
(14)
where, Vm is desired peak worth of load voltage and
(θ) is voltage point that is calculated by section
latched loop (PLL). By subtracting the specified
worth of d-axis section voltage
from Vsd, all
distortions in d-axis ar obtained. Also, the specified
worth of load section voltage in q-axis is zero. In
alternative words, Vsq represents total q-axis
distortions. So, series compensation reference voltage
is resulted by combining weight. 16:
*
*
V fdq
0  Vldq 0  Vsdq 0
(15)
These voltages ar compared with associate angular
wave form in PWM controller and needed dominant
pulses (g1,..., g6) ar generated to be applied to series
voltage supply electrical converter switches.
This corrected methodology is programmable with an
occasional price. the opposite advantage is that the
dominant system`s calculation time is shortened and
then dominant system`s response is quicker. Fig.6
shows the diagram of series compensator`s dominant
circuit applying synchronous frame of reference
methodology. so as to enhance series electrical
converter operation, SPWM methodology is
employed wherever, the resulted worth of subtracting
from Vfabc is increased to a continuing constant and
also the obtained worth is superimposed to .
Applying this methodology distinctively improves
operation of series electrical converter.
VI.ARTIFICIAL NEURAL NETWORK
The ANN controller used is a feed forward one,
comprising three neuron layers, the input layer, the
hidden layer and the output layer shown in the Fig 8.
The input layer offers connection points to transmit
the input signal to the hidden layer. The latter begins
the learning process and the output layer continues
the learning process and provides outputs. The
hidden layer neurons have a tan-seg-moid transfer
function, and the output layer neurons have a linear
transfer function.
The control objective of the NN is to provide the
wanted proper gating patterns of the PWM inverter,
leading to adequate tracking of the APF reference
phase currents and constant DC voltage. Neurons in
the hidden layer is specified as the minimum number
that produces the permitted training criterion. The
training criterion is taken as the mean square error of
the NN outputs with a value of 0.0001. Sufficient
input-output training examples are obtained by using
the triangular carrier modulation technique.
Series inverter control using ANN:
The system aspect voltage might contain negativezero-sequence still as harmonics parts which require
to be eliminated by the series compensator [15-16].
The management of the series compensator is shown
in Figure.7. The system voltages ar detected then
reworked into synchronous dq-0 frame of reference
exploitation equation (6).
Fig.7 Control block diagram of the series converter of
the UPQC using ANN.
Fig.8 The basic architecture of the feed forward
neural network with accompanying equations that
describe the transfer functions between layers.
An ANN is basically a cluster of fittingly
interconnected non-linear components of terribly
easy kind that possess the flexibility of learning and
adaptation. These networks square measure
characterized by their topology, the means during
which they convey with their atmosphere, the style
during which they\'re trained and their ability to
method data [18]. Their easy use, inherent
reliableness and fault tolerance has created ANNs a
viable medium for management. An alternate to
fuzzy controllers in several cases, neural
managementlers share the requirement to switch
laborious controllers with intelligent controllers so as
to extend control quality. A feed forward neural
network works as compensation signal generator.
This network is meant with 3 layers. The input layer
with 7 neurons, the hidden layer with 21 and
therefore the output layer with 3 neurons. Activation
functions chosen square measure tan sigmoid and
pure linear within the hidden and output layers
severally.
The speedy detection of the disturbance signal with
high accuracy, quick process of the reference signal,
and high dynamic response of the controller square
measure the prime needs for desired compensation
just in case of UPQC. the traditional controller fails
to perform satisfactorily below parameter variations
nonlinearity load disturbance, etc. now shows that
NN-based controllers offer quick dynamic response
whereas maintaining stability of the device system
over wide operational vary. Shows The Fig.9 ANN is
created of interconnecting artificial neurons. It is
basically a cluster of befittingly interconnected
nonlinear components of terribly straightforward kind
that possess the power to find out and adapt. It
resembles the brain in 2 aspects: 1) the data is
nonheritable by the network through the educational
method and 2) interneuron association strengths
square measure wont to store the data. These
networks square measure characterized by their
topology, the means during which they convey with
their atmosphere, the style during which they are
trained, and their ability to method info. ANN has
gained plenty of interest over the previous few years
as a robust technique to solve several world issues.
Compared to standard programming, they own the
aptitude of finding issues that don't have recursive
answer and square measure thus found appropriate to
tackle issues that folks square measure sensible to
unravel like pattern recognition. ANNs square
measure getting used to solve AI issues while not
essentially making a model of a true dynamic system.
For up the performance of a UPQC, a multilayer feed
forward- kind ANN-based controller is intended. This
network is intended with 3 layers, the input layer
with two, the hidden layer with twenty one, and also
the output layer with one somatic cell, severally.
Fig.9 The basic architecture of ANN
This network is meant with 3 layers, the input layer
with a pair of, the hidden layer with twenty one, and
therefore the output layer with one vegetative cell,
severally. The big information of the dc-link current
for n and (n-1) intervals from the traditional
methodology area unit collected and area unit hold on
within the Mat lab space. These information area unit
used for coaching the NN. The activation functions
chosen area unit tan colon for hidden and input layers
and pure linear within the output layer, severally.
This multilayer feedforward-type NN works as a
compensation signal generator. The topology of the
ANN is as shown in Fig. 10.
Fig.10 Block diagram of the ANN-based
compensator for offline training.
The compensator output depends on the evolution
and its input. The NN is trained for output basic
reference currents. The signals so obtained area unit
compared during a physical phenomenon band
current controller to produce change signals.
VII. SIMULATION CIRCUITS
Fig. 11 Block diagram of without UPQC
Fig .12 Block diagram of Nine Switch UPQC
Fig.13 Block diagram of Nine Switch UPQC with PI controller
Fig.14 Block diagram of Nine Switch UPQC with ANN controller
Fig.15 Neural network sub circuit
Fig.16 Neural network layer 1
Fig.18. without UPQC at Load Voltage, input
Voltage, and Injected Voltage
Fig.17 Neural network layer 2
VIII.SIMULATION RESULTS
The harmonic content of input and output of the
Bridge convertor ar shown in Fig.18. (three phase
voltages) and Figure nine. (three phase currents).
because of non-linear masses, like massive thyristor
power converters, rectifiers, voltage and current
unsteady because of arc in arc furnaces, sag and swell
because of the shift of the loads etc. one in every of
the numerous solutions is that the use of a combined
system of shunt and active series filters like 9 Switch
Unified power quality conditioner (UPQC) .
Fig.19.PI without UPQC at Load Current, input
Current, and Injected Current
This device combines a shunt active filter beside a
series active filter in an exceedingly consecutive
configuration, to at the same time compensate the
provision voltage and also the load current or to
mitigate any kind of voltage and current fluctuations
and power issue correction in an exceedingly power
distribution network. The management methods used
here are supported PI & ANN controller of the 9
Switch UPQC well. The management methods are
sculptured victimization MATLAB/SIMULINK. The
simulation results are listed compared of various
management methods are shown in figures.
To verify the operational performance of the
projected 9 Switch UPQC, a 3-Φ electrical system, a
PLL extraction circuit with physical phenomenon
controlled 9 Switch UPQC is simulated victimization
MATLAB software system. Figure 22. Shows the
unit vector templates generated by victimization
projected management technique.
Fig.20.PI controller with SAG condition at Load
Voltage, input Voltage, and Injected Voltage
Fig.21.PI controller with SAG condition at Load
Current, input Current, and Injected Current
Fig.24.PI controller with SWELL condition at Load
Current, input Current, and Injected Current
Fig.22.Dc voltage, without compensation and Neutral
compensation current
Fig.25.PI controller with SAG & SWELL condition
at Load Voltage, input Voltage, and Injected Voltage
Fig.23.PI controller with SWELL condition at Load
Voltage, input Voltage, and Injected Voltage
Fig.26.PI controller with SAG & SWELL condition
at Load Current, input Current, and Injected Current
Fig.27.ANN controller with SAG condition at Load
Voltage, input Voltage, and Injected Voltage
Fig.30.ANN controller with SWELL condition at
Load Current, input Current, and Injected Current
Fig.28.ANN controller with SAG condition at Load
Current, input Current, and Injected Current
Fig.31.ANN controller with SAG & SWELL
condition at Load Voltage, input Voltage, and
Injected Voltage
Fig.29.ANN controller with SWELL condition at
Load Voltage, input Voltage, and Injected Voltage
Fig.32.ANN controller with SAG & SWELL
condition at Load Current, input Current, and
Injected Current
Without UPQC Utility side voltage THD is 4.15% at
3rd harmonic order
Fig.33. without UPQC Utility side voltage at 3rd
harmonic
Without UPQC utility side Current THD is 12.11% at
3rd harmonic order
Fig.34. without UPQC utility side current at 3
harmonic
rd
Without UPQC utility side voltage THD is 4.15% at
5th harmonic order
Fig.35. without UPQC Utility side voltage at 5th
harmonic
Without UPQC Utility side Current THD is 12.15%
at 5th harmonic order
Fig.36. without UPQC Utility side current at 5th
harmonic
Without UPQC Utility side voltage THD is 4.15% at
7th & 9th harmonic orders
Fig.37. without UPQC Utility side voltage at 7th & 9th
harmonics
Without UPQC Utility side Current THD is 12.17%
at 7th & 9th harmonic orders
Fig.38. without UPQC Utility side current at 7th & 9th
harmonics
Utility side voltage THD with pi 3.99% at 3rd
harmonic order
Utility side current THD with pi 2.33% at 5th
harmonic order
Fig.39. Utility side voltage THD with PI at 3rd
harmonic
Fig.42. Utility side current THD with PI at 5th
harmonic
Utility side current THD with PI 2.29% at 3rd
harmonic order
Utility side voltage THD with PI 3.88% at 7th & 9th
harmonic orders
Fig.40. Utility side current THD with PI at 3rd
harmonic
Fig.43. Utility side voltage THD with PI at 7th & 9th
harmonics
Utility side voltage THD with PI 4.09% at 5th
harmonic order
Utility side current THD with PI 2.26% at 7th & 9th
harmonic orders
Fig.41. Utility side voltage THD with PI at 5th
harmonic
Fig.44. Utility side current THD with PI at 7th & 9th
harmonics
Utility side voltage THD with ANN 1.36% at 3rd
harmonic order
Utility side current THD with ANN 1.31% at 5th
harmonic order
Fig.45. Utility side voltage THD with ANN at 3rd
harmonic
Fig.48. Utility side current THD with ANN at 5th
harmonic
Utility side current THD with ANN 1.48% at 3rd
harmonic order
Utility side voltage THD with ANN 1.37% at 7th &
9th harmonic orders
Fig.46. Utility side current THD with ANN at 3rd
harmonic
Fig.49. Utility side voltage THD with ANN at 7th &
9th harmonics
Utility side voltage THD with ANN 1.35% at 5th
harmonic order
Utility side current THD with ANN 1.39% at 7th &
9th harmonic orders
Fig.47. Utility side voltage THD with ANN at 5th
harmonic
Fig.50. Utility side current THD with ANN at 7th &
9th harmonics
IX. RESULT TABLE
Order of
harmonics
WITHOUT
UPQC
utility side
voltage
WITHOUT
UPQC utility
side current
UPQC with PI
controller
utility side
voltage
UPQC with
PI controller
utility side
current
UPQC with
ANN
controller
utility side
voltage
UPQC with
ANN
controller
Utility side
current
3rd
4.15
12.11
3.99
2.29
1.36
1.48
5th
4.15
12.15
4.09
2.33
1.35
1.31
7th &9th
4.15
12.17
3.88
2.26
1.37
1.39
X. CONCLUSION
The UPQC performance mainly depends upon how
accurately and quickly reference signals are derived.
Then conventional compensator was replaced with PI
controller and ANN. The simulation results have
shown that the UPQC perform better with ANN and
PI controller proposed scheme eliminates both
voltage as well as current harmonics effectively. The
ANN controller also performs in a similarly with
slightly better voltage compensation It is also
observed that the response time for derivation of
compensation signals reduces significantly with
improved accuracy. the response of ANN controller
is faster and the THD is minimum for the both the
voltage and current which is evident from the plots
and comparison Table.1. Proposed model for the
Nine Switch UPQC is to compensate input voltage
harmonics and current harmonics caused by nonlinear load. The work can be extended to compensate
the supply voltage and load current imperfections
such as sags, swells, interruptions, voltage imbalance,
flicker, and current unbalance. Proposed Nine Switch
UPQC can be implemented using simple analog
hardware, because it is having PLL and Hysteresis
blocks.
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Mr. SHAIK. MABUSUBANI is a student of Sri
Mittapalli
College
of
Engineering, Guntur, AP.
Currently he is pursuing
M.Tech
in
Power
Electronics and Electrical
Drives
(12U91D5408)
from
S.M.C.E.
He
completed B.Tech (E.E.E.)
in Chalapati Institute of
Technology. His area of
interests include Power
Quality by Custom Power Devices, controllers like
controllers, Artificial intelligence controlling
techniques, power Electronics & Drives, Neuro
controller Neuro-fuzzy controllers, renewable energy
resources, Fuzzy controllers.
Mr. SURESH. KORNEPATI presently working as
Associate Professor &
Head, Deportment of
EEE in Sri Mittapalli
College of Engineering,
Guntur, A.P. His area of
interests
include
renewable
energy
resources, Power Quality
by
custom
Power
Devices, Power System Operation, Control &
Stability, Intelligent controlling techniques and
Power Electronics & Drives.