Abstract: - The recent innovation in power electronic application in the electrical power system (EPS) has
given birth to an Improved Unified Power Quality Conditioner (IUPQC) that positively impacts the electrical
power system (EPS). The previously available mitigation approaches with the application IUPQC are
monotonous and are major designs for a particular power quality (PQ) issue which does not take care of the
degree of impart. This paper presents an effective control architecture of an IUPQC design for sensitive loads in
hybrid Photovoltaic Solar (PV) connected grid, concentrating on the voltage demand of loads that respond to
slight changes. The objective of this work is to design a flexible controller that can respond to the different
degrees of PQ challenges concerning voltage, variable load, and solar irradiation. It has combined the merits of
an IUPQC and grid-integrated PV source. Effective controllers for Voltage Source Inverter (VSI) connected in
series and Current Source Inverter (CSI) connected in shunt compensators of the UPQC are implemented to
increase device strength for different voltage and current distortions. The series compensator was controlled
using an enhanced Synchronous Reference Frame (SRF) technique based on adaptive notch filters. An
Adaptive Logarithmic Absolute Algorithm (ALAL) was deployed for the parallel section of the proposed
approach. The Mean Turning Filter (MTF) was used as a replacement for a low pass filter (LPF) for direct
current node voltage management, leaving high and low-frequency ripples unaffected. To maintain a constant
current on the grid side during grid disturbances, a feed-forward element has been introduced to the shunt CSI
controller. Under various network situations, such as under-voltage, over-voltage, voltage distortion,
harmonics, rapid load changes, and fluctuation in solar power, the control system performance is better as
confirmed by experimental validation. Finally, it is observed that the voltage profile of 0.984 p.u. due to
application control falling within the permissible limits. The proposed controllers are tested in the MATLAB
Simulink on a developed distribution system model and validated experimental prototype.
Keywords: - Solar Photovoltaic, Under-voltage, Voltage Sensitive Load (VSL), Over-voltage, Unbalance
voltage, improved unified power quality conditioner.
Received: June 28, 2022. Revised: January 9, 2023. Accepted: February 15, 2023. Published: March 17, 2023.
1 Introduction
The advancement in power electronics results in
various nonlinear loads at the load center, making
the distribution system increasingly prone to many
power quality issues, [1], [2]. A lot of power
conditioners have been proposed to achieve the
electricity value requirements in the distribution
network. Traditional UPQCs have proven their
ability to tackle a variety of PQ challenges among
all types and capacities of power quality
conditioners, [3], [4], [5]. Researchers have
proposed diverse power conditioners and UPQC in
response to various power system concerns. The
presence of diverse types of loads and voltage
fluctuation at the receiving end resulted in PQ
challenges, and there is a need for a mitigation
device in the distribution grid. Because current
harmonics cannot be reduced, the work, [6]
proposed a voltage amelioration approach for
critical loads to protect them from voltage
fluctuation. A repeatable controller with a
recursively least square technique was used in the
series compensator. The effective voltage restorer
used for loads with voltage sensitivity, [7], and [8]
suggested a controller centered on an improved
phase-locked loop (PLL).
Quite enough research has been carried out on
electric grid disruption prevention strategies to
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2023.18.4
Oluwafunso Oluwole Osaloni,
Ayodeji Stephen Akinyemi,
Abayomi Aduragba Adebiyi, Ayodeji Olalekan Salau
E-ISSN: 2224-350X
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Volume 18, 2023
An Effective Control Technique to Implement an IUPQC Design for
Sensitive Loads in a Hybrid Solar PV-Grid Connection
OLUWAFUNSO OLUWOLE OSALONI1, AYODEJI STEPHEN AKINYEMI2,
ABAYOMI ADURAGBA ADEBIYI2, AYODEJI OLALEKAN SALAU1,3
1Department Electrical Electronic and Computer Engineering, Afe Babalola University
Ado Ekiti, Ekiti-State, NIGERIA
2Department Electrical Power Engineering, Durban University of Technology, Durban, SOUTH AFRICA
3Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, INDIA
address (PQ) concerns such as distortion, imaginary
power improvement, dynamic routing, grid current
mitigation, flicker reduction, under voltage
reduction, and over-voltage advancement, [8], [9].
[6] proposed the application of a dynamic voltage
restorer (DVR) to safeguard vulnerable loads from
power supply variations. Although the loads
examined are voltage and current-vulnerable loads
that can exist in the grid and were not resolved, [4],
[6], [8], [9], [10]. The work done in, [13], [14]
suggested a specific UPQC architecture with a
series inverter at the receiving end to reduce voltage
signal alterations. For nonlinear and VSLs, [11],
[12], left shunt UPQC (LS-UPQC) is deployed in a
single-phase network for current and voltage
distortions. The LS-UPQC was used to eliminate
simultaneous voltage and current disturbances from
recent work in the literature. Due to numerous
groups of customers with different power quality
requirements at the point of use, they must choose
the level of power quality that best fits their budget.
The article, [6] also presented the open UPQC
design, in which the shunt and series inverters
possessed individual dc-link capacitors. This novel
architecture can suit customers' needs by providing
quality power at distinct levels and varied prices to
manage open UPQC. Also, [16], [17], proposed a
controller with little arithmetical calculation
centered on an upgraded PLL.
The idea of open UPQC has been used by, [18],
and [19], for power control in intelligent low-
voltage grids. Open UPQC with multilevel
ameliorator architecture (O-UPQC-ML) was
presented in [20] to showcase the notion of reducing
the switching frequency of devices by multilayer
compensator and multiple power quality levels
supplied by O-UPQC. In [21], a novel O-UPQC
architecture for VSL with DVRs mounted at
specified load branches. Since renewable energy is
on the verge of grid absorption, power conditioners
are being used in distribution networks in a
transitional phase. As investigated and implemented
in [15], [16], the incorporation of solar photovoltaic
(PV) sources into the grid via distributed static
ameliorator (DSTATCOM) has gained favour in
maintaining current related PQ issues. Photovoltaic
solar interconnected with UPQC devices have
received a lot of consideration in the past few years.
To tackle concurrent grid challenges, the effective
use of PV-UPQC in these research investigations
results in a favorable level of PQ improvement,
[18], [19], [21]. However, the provision of various
electricity quality levels to end customers at varied
price levels has remained unaffected.
Furthermore, because the conventional device
enhances PQ for all end-users in the distribution
system, [19], the design fails to allow the customer
to select diverse PQ levels. There is a requirement
for a multifunctional device that can merge clean
power generation with power quality enhancement.
This is due to the request for clean energy and
sophisticated electronic loads demanding power
quality. The publications, [6], [20], offer a 3-phase
multipurpose solar energy conversion system that
accounts for load-side PQ concerns at a different
stage. However, this custom device enhances
voltage levels for all connected customers in the
electricity grid, these topologies fail to give freedom
for the customer to pick alternative power quality
levels.
This work offers a potential solution to the end-
user for all the PQ difficulties and varying PQ
levels, especially in the presence of loads with
voltage sensitivity, to create a distributed voltage
controller that allows for greater communication
among distributed generators and nearby controllers.
The connection of light loads, like computers and
information technology (IT) electronics end-user
consumers load, who are concerned about better
voltage quality, necessitates using a unique form of
the power conditioner. This work has proposed a
PV-fed IUPQC with PV fed parallel inverter of
UPQC at the connection point and VSI branch
connected with a load having voltage sensitivity
following in PCC 2 as shown in Figure 1. The PV-
IUPQC demands more effective controllers for its
ameliorators to protect the loads with voltage
sensitivity in case of any harmful grid condition at
the distribution level. As a result, more efficient and
effective controllers were developed and
implemented in this paper. The suggested system's
execution was evaluated in steady-state with
MATLAB and has proven possible to protect
critical loads from severe grid voltage disruptions.
Furthermore, current quality difficulties for different
load unbalancing scenarios in the distribution
system are avoided. The reaction of the system to
variations in solar irradiation has also been
investigated. The following is how the rest of the
article is structured: The suggested PV-IUPQC
topology's system setup was included in Section II.
Section III carried out a thorough expression of the
control algorithms. The simulations and results were
showcased in Section IV under different load
conditions. Finally, Section V brings this article to a
conclusion.
The characteristic of Figure 1 includes the IGBT
shunt and series inverter, the series and shunt
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DOI: 10.37394/232016.2023.18.4
Oluwafunso Oluwole Osaloni,
Ayodeji Stephen Akinyemi,
Abayomi Aduragba Adebiyi, Ayodeji Olalekan Salau
E-ISSN: 2224-350X
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transformer, the nonlinear load, inductors, and
resistors.
2 Network Framework
The approach proposed in [26], combines PV and
UPQC functionality to provide a unique solution for
VSLs. As illustrated in Figure 1, [26], the current
architecture has the DVR linked near the delicate
load and the shunt CSI closer to the primary side.
The shunt and series ameliorator in this system uses
a common DC-link. Furthermore, the series VSI and
the parallel CSI are coupled to the dc-link through
the PV.
Fig. 1: Topology of PV-IUPQC Architecture,
[26]
2.1 Control Design Architecture
The regulated architecture of PV-UPQC's structure
for the function of compensators is critical for
improving PQ and meeting the demands of end
consumers and the distribution network. To
sufficiently switch pulses, the control algorithm's
overall structure incorporates two primary
algorithms: a flexible notch filter centered on
synchronous reference frame theory (FNF-SRF) for
the VSI and an adjustable logarithmic (AL) for the
CSI. The PV source is made linked to the grid via
UPQC because the highest power point tracking
(HPPT) approach of perturbation and observation (P
& O) has been used to harvest full PV power
harvested from the PV array.
2.2 VSI Controller
This work has developed a flexible method for the
PV-IUPQC controller to increase the execution of
the series VSI of the UPQC. Flexible notch filter
technology is suggested for the network
interconnection of the Synchronous Reference
Frame (SRF) controller for series VSI. The flexible
notch filter (FNF) was first developed in [22], [23],
for accurate grid integration by giving correct core
signals even in highly inaccurate grids and
removing PLLs from the system's controller. Lately,
in [24], FNF was applied to control UPQC because
of its flexible disposition to network instabilities.
Thus, an FNF-SRF controller has been considered to
enhance the controller implementation to produce
turning signals for the series VSI of PV-IUPQC.
Evaluation of grid voltage in PV interconnection
procedures is critical with phase angle;
consequently, FNF built synchronization technique
is examined in this article as given in Figure 2. The
current approach, which runs without a typical PLL,
provides an exact and speedy performance in
distorted and imbalanced grid circumstances. The
flexible notch filter is applied for harmonization,
which delivers an appropriate harmonization signal
regardless of the disruption in the network. The FNF
can be described, [25] with the set of the equation
as:
(1)
(2)
(3)
where is the estimated frequency, and are
adjustable, accurate positive parameters that define
the Estimation Accuracy (EA) and the Convergence
Speed (CS) of the FNF. The FNF block's input state
vector is (), which comprises the essential and
distortion elements. The EA and CS are provided by
the FNF differential equations of FNF, which have
two variable parameters () and (). For a single
sinusoid input signal
, this ANF has a distinctive
periodic and distinctive orbit located at (4):
(4)
Figure 2 shows a simple mathematical description
of FNF and the controller for a series VSI. The
synchronization unit based on FNF can offer details
on phase, frequency, phase angle, and harmonic
component. The phase angle value in Cos/Sin is
extracted using FNF in the current SRF controller.
The work in [25], [26] provides a more extensive
description of the FNF-based synchronization unit.
The advanced adaptive control techniques required
in RDS are the central focus of this paper to protect
VSLs from voltage variations. The FNF scheme is
used in conjunction with the SRF theory to improve
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E-ISSN: 2224-350X
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controller efficiency. Even in grid voltage
disruptions, the FNF synchronization scheme gives
reliable information to the SRF controller. In
addition, to increase the elimination of low-
frequency ripples, a moving average filter was used
in conjunction with a dc-link controller of a series
APF.
Fig. 2: Series ameliorator for FNF-SRF controller
The PV-IUPQC system has been implemented in
this article to suit the voltage quality requirement of
a particular end-user. The series ameliorator
possesses a self-supporting DC-link and the capacity
to inject quadrature voltage. The quadrature voltage
compensation is accountable for load imaginary
power correction. This function minimizes total
reliance on parallel CSI designed for imaginary
power compensation. The FNF-based SRF
procedure has been used to alleviate voltage
disturbances triggered by the series VSI. As
illustrated in Figure 3, the standard coupling (PCC)
voltage point is identified and then transformed to a
d-q-0 frame by applying the park transformation and
information from the FNF unit. Low pass filters
removed harmonic and oscillating elements from the
d-axes and q-axes elements of source voltages. Input
voltages' d-axes and q-axes features can be
showcased as (5) and (6):
(5)
(6)
where are the input voltages for dc
and ac components under d-axes, while
are the input voltages for dc and ac
components under q-axes. The self-supported
capacitor's dc bus voltage should be adjusted at a
constant level to obtain appropriate series
compensator performance. The measured DC-Link
Voltage (DCLV) is conveyed via a moving average
filter (MAF) rather than a fundamental LPF to lower
extreme and low-frequency ripples. For the dc
voltage control device to extract the dc element, the
MAF has been utilized to measure the dc voltage
without sacrificing effective implementation. MAF
application is deployed for the DCLV management
mechanism, [21], [25] for a wind turbine with low
power, and, [22] for a power transformation circuit
of the fuel cell. On the other hand, this article
introduces MAF usage for the PV-IUPQC dc-link
mechanism. The MAF transfer function is written as
(7):
(7)
The MAF's window length can be represented as
. The filtered output of the MAF device was
matched to the reference DCLV, and the inaccuracy
found was sent to the dc bus PI regulator. The
voltage loss is calculated by employing the output of
the PI regulator on the direct current bus. The
following formula in (8) and (9) can be utilized to
represent the voltage drop acquired for the sample
instant point:
Fig. 3: Flexible for absolute algorithm-based
controller for shunt ameliorator
(8)
(9)
where the
series real filter controller's
reference dc voltage, is the DCLV
inaccuracy, is the PI controller's output,
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is the relative increase, and is the integral
increase. As a result, the load voltage (LV)
reference d-axis elements can be written as (10):
(10)
The terminal LV amplitude is calculated using (11):
(11)
where are the voltages per phase at
the load terminal, the error produced between the
load and reference voltage is sent into the controller
after comparison. The imaginary element of the LV
is quantified at the receiving end of the PI
regulation (13). The inaccuracy is regulated by
employing the PI voltage controller to offer a
reference number to produce the source q-axis
element of LV.
(12)
(13)
The LV, the imaginary element of the voltage at the
load terminal combined with the dc filtering element
of voltage quadrature in (14):
(14)
The source d-axis, and q-axis element
of LVs (LVs) are the input to the Inverse Park's
transformation (IPT) to evaluate the Reference LVs
(RLVs) correspond to as , and
. To calculate the reference LVs and the IPT
uses the reference and element of LVs. The RLVs
contrast to the detected LVs to create inaccuracies
sent to the pulse with a modulator (PWM) voltage
regulator to produce an electrical signal for the VSI.
2.3 Inverter Active Power Filter Controller
The PV-O-shunt UPQC's compensator controller
calculates the source currents for generating a pulse
signal for the parallel real power filter. Estimating
the Reference Current (RC) gets challenging when
there are grid voltage disturbances. As a result, the
shunt compensator requires an adaptive controller
for typical operations. In [20], multiple adaptive
Filtering Algorithms (FAs) are suggested, with the
ALAL filtering algorithm demonstrating its
permanence in the existence of several network
disruptions. Furthermore, due to its compelling
character, the fundamental logarithmic purifying
technique has previously been employed for a PV-
DSTATCOM method in severe weak grid
situations, [21]. The ALAL filtering technique can
extract fundamental current even during significant
grid voltage disruptions. The control algorithm for
the Insulated Gate Bipolar Transistor (IGBT) of the
parallel real power filter has several subsections,
including unit template computation and MAF-
based DCLV controller, for appraisal feed-forward
term, fundamental real weight element resolution,
production of switching signal generation, and the
current Reference Signal (RS). Figure 3 depicts the
detailed controller, and the phase voltages are in
charge of determining the terminal source voltage's
amplitude given in (15):
(15)
The phase unit models are determined by the ratio
of calculated terminal sending end voltage
amplitude to per phase voltage in each case
(16)
(17)
(18)
Grid disruptions are expected in grid-connected PV
systems owing to demand dissimilarity and voltage
oscillations at the grid. As a result, even in voltage
changes, the feed-forward term must uphold the
suitable current at the right level to adjust the power
equilibrium. As shown here, the feed-forward pulse
of PV, is calculated using the amplitude of
terminal voltage and the power collected from the
PV panel as shown in (19):
(19)
The feed-forward term ensures that the current at the
grid is regulated in the event of voltage variations.
Any atmospheric variations reflected in the PV
energy source are supplied into the real current
element via the feed-forward term. The perceived
DCLV is compared to the reference DCLV after
passing through an average turning filter to
minimize undesired ripples. After passing through a
moving average filter, the sensed DCLV is
compared to the reference DCLV to minimize
undesired ripples. The (P & O) HPPT algorithm
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produces the reference DCLV by detecting the PV
voltage and PV current. The dc bus PI controller
receives the error created by the comparison. The
quantified error for the sample sudden error
produced by the DCLV is expressed in equations
(20) and (21):
(20)
(21)
where , and are the comparative and
integral benefits for the PI regulator of the DCLV
regulator, with the real loss element of the RC
quantified at the PI regulator's production. The
output of RC signals is answerable for amelioration
in the current system. This necessitates the
determination of a helpful reference in altered signal
settings that appears to be problematic. Controller
adaptation to network voltage perturbations can
manage this delicate condition by including an
adaptive element in the RC signal assessment
process. The outstanding function of the LA filters
is assessed, [27], [28]. [29] demonstrated the
efficacy of a total logarithmic controller for
DSTATCOM. As a result, the writers used this
notion in this article for the PV-IUPQC. The
proposed logarithmic fundamental algorithm, as
described by (22), is used to compute the natural
weight element of total Load Current (LC) for phase
A:
(22)
where the value of performance error is chosen so
that it does not exceed the bound as shown in (27).
The appropriate value of should be considered
when extracting the amplitude of the fundamental
component of LC. For the supposed system, the
current approach performs better at = 0.018. The
error produced by the adaptive integrant of the
method under consideration is denoted by .
Therefore, each phase can appraise the error as
shown in (23) to (27):
(23)
(24)
(25)
(26)
(27)
The real power element of the dc bus of PV-IUPQC
and the average size element of the real power of
LC (), as well as the feed-forward component,
can be used to calculate the total weight of the
essential fundamental element of the RC as shown
in (28):
(28)
where the following equation has been applied to
calculate the average size of the real power element
of LC as given by (29):
(29)
The RC for each phase is now calculated as follows
in (30):
(30)
The established RC is equated to the actual detected
current. The difference is sent to the hysteresis
current controller, which produces switching signals
for the PV-IUPQC parallel active filter's insulated
gate bipolar transistor.
3 Simulation Results and Discussions
This phase lays the groundwork for intensive
simulation experiments to determine the viability of
the proposed PV-IUPQC device. The network was
created in MATLAB SIMULINK 2021. Its
functions were evaluated in various simulation
scenarios, including system efficiency under
different potential quality problems, dynamic
performance under unusual operating voltage,
efficient functioning under unbalanced load
conditions, and effective performance under solar
irradiation variations. Table 1 lists the system
parameters that were used in the simulation. The
simulation results confirmed the system's efficacy
and performance under various dynamic
circumstances. The implementation of the
developed effective SRF voltage controller is
authenticated using a simulation test system and
settings from Table 1.
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Table 1. Simulation Parameters
The opening test shows the planned controller's
capacity to track RSs. At t = 0:24s, the d-element of
the RS voltage drops to 0:2679 pu, and at t = 0:77 s,
the q-element of the RS voltage jumps to 0.217 pu
from 0:2524 pu. Figure 4 represents the
investigational and simulation results of the
standalone microgrid network as a result of these
step transitions in load RSs. The effects reveal that
the suggested controller has good tracking
performance when regulating LVs.
Fig. 4: Effective feedback of test network owing to a
purely resistive load change (a) dq-elements of the
LV, (b) control inputs, and (c) 3phase LVs
Furthermore, Figure 4 shows that the modelling
results match the experimental data. However,
owing to the pulse harmonics of the PWM-based
Voltage Source Converter (VSC), some ripples in
the LVs were noticed in the investigational
outcomes. According to IEEE guidelines, [30], [31],
the quantity of ripple is acceptable.
The suggested voltage controller manages the d and
q elements between 0.79 p.u and 0.59 p.u at LVs,
correspondingly, in the second test. As shown in
Table 1, the load inductance/capacitance are also set
to their nominal standards. At roughly t = 200ms,
the LRs in the 3-phases are scaled down similarly
from five lamps to zero. The effective reaction of
the test network as a result of the resistive load
variation is shown in Figure 5. The d and q elements
of the LVs were regulated to 0.929 p.u and 0.368
p.u, correspondingly, in the third test. The load
inductances in the three phases are suddenly stepped
increased from 5mH to 25mH while the Load
Resistance (LRs) and Load Capacitance (LCs) are
secured at their nominal values.
Fig. 5: Effective feedback of the simulation test
network owing to an inductive load change: (a) dq-
elements of the LV (b) dq voltage control inputs
signal (c) instant LVs
Then, at t = 0.5 s, they rapidly drop to 5 mH. A
variation in LC is considered in the last test. The
system's second inductance load modification
effective feedback signal is presented in Figure 5
(c), as shown between 0.5 s and 0.55 s. The three-
phase LCs are abruptly altered from 850 F to 1700 F
at roughly t = 1:1 s. In contrast, the LRs and load
inductances are set based on the values listed in
Table 1. Figure 5 shows the adequate reaction of the
test network due to purely capacitive load.
3.1 Effective Implementation during Unusual
Voltage Conditions
The controller efficiency has also been evaluated
based on the system's performance during voltage
imbalance at PCC 2. The imbalance voltages at
PCC2 are shown in Figure 6 (a), obtained using a
tracking set digital storage oscilloscope on
Simulink. As displayed in Figures 6 (b) and (c),
amelioration of the imbalance situation of the LV
using UVTG and SRF controllers is insufficient.
The stable condition of the LVs was attained after
applying the recommended effective controller to
the series VSI, as shown in Figure 6 (b) at t equal to
Selected Parameters
Values
Voltage @ grid side
220 V
System Standard frequency
50 Hz
Source Inductance
0.5 mH
DC bus capacitor
3.5 mF
Series VSI inductance
0.5 mH
Shunt CSI inductance
3.5 mH
Non-linear load
100 4mH
Phase load
50 100 85/55mH
Switching frequency
10 kHz
PV power @ MPPT
600 watts
Voltage (Vmp) @ MPPT
220 V
Current (Imp) @ MPPT
2.7 Amp
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Volume 18, 2023
0.7 s for both d and q components. The findings
indicate that the suggested series compensator
controller has superior performance. It is critical to
manage the LV under abnormal voltage situations at
PCC2 to safeguard the loads that are voltage
sensitive.
Fig. 6: Effective feedback of the results test network
owing to a capacitive load variation: (a) dq-elements
of the LV (b) dq voltage control inputs (c) instant
LV
The Simulink implementation of the purported
enhanced SRF theory centered on FNF for the
studied network has been provided for different
voltage disruptions such as under-voltage, over-
voltage, and unbalanced voltage. As illustrated, the
voltage signals at PCC2, which have an under-
voltage from nominal 110 V to 60 V, have been
measured. Figure 7 (b) shows the system's ability to
adjust LVs in a sag condition. Figure 7 (c) also
indicates interior added voltage signals, structured
DCLV, and continuous PV current. In the final test,
the effect of LC variation is investigated. In this
regard, the LCs in the 3 phases were being rapidly
shifted from the nominal value of 850 F to 1700 F at
approximately t = 1.1s, while the LR and load
inductances are set using the values provided in
Table 1. Figure 7 depicts the test system's
appropriate approach. The outcome of the result, in
this case, is shown in Figure 7 (e) that voltage
disruptions experienced in (a) to (b) are cleared out
at the activation of FNF control architecture.
Fig. 7: The tracking reference pre-determine point:
(a) d-element of LV at load centre (b) q-element of
LV at load centre (c) d-element PV unit control
signal (d) q-element PV unit control signal (e)
instant PCC 2 LVs
The nominal network voltage is amplified to 149.9
V from 110 V, as indicated in Figure 8 (a), during a
voltage rise situation, the quantified voltage at the
connection point 2. As revealed in Figure 8 (b) and
Figure 8 (c), the examined network proficiently
controlled the DCLV and the load center. During
voltage swells, grid current decreases to sustain real
power balance, as indicated in Figure 8 (d). In the
same figure, the point of connection 2 shows the
network's decline in voltage harmonics. The
suggested adaptive series VSI, as displayed in
Figure 8 (e), regulates and maintains sinusoidal
LVs. As presented in Figures 8 (b) and 8 (c), The
system under consideration proficiently controlled
the load and DCLV. During a voltage sag, grid
current decreases to maintain active power balance,
as depicted in Figure 8 (d). Figure 8 also shows the
elimination of voltage harmonics at PCC 2. LVs are
tightly controlled and maintained sinusoidal by the
recommended influential series ameliorator, as
depicted in Figure 8 (b).
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2023.18.4
Oluwafunso Oluwole Osaloni,
Ayodeji Stephen Akinyemi,
Abayomi Aduragba Adebiyi, Ayodeji Olalekan Salau
E-ISSN: 2224-350X
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Volume 18, 2023
Fig. 8: The tracking reference pre-determine point:
(a) d-element at PCC1 for LV (b) q-element at
PCC1 for LV (c) d-element of PV unit control
signal (d) q-element of PV unit control signal (e)
instant LVs
3.2 Effective Execution under Load
Unbalancing Condition
Appearance unbalance load occurs at PCC2 when
one load is removed abruptly, as seen in Figure 9
(a). The load power requirement is reduced with the
separation of a single-phase load. As a consequence,
an upsurge in system current is seen in Figure 9 (a),
indicating that the real power stability is being
maintained. In the current realistic scenario, this
graph illustrates the regulator's capacity to maintain
the source current sinusoidal. Figure 9 (b) depicts
the effectiveness under nonlinear load addition at a
single phase. The significant raise in load power
required by the end user causes a reduction in grid
current measured at the connection point 2.
Regardless of whether the load is isolated and added
easily, the matching phase-A' current remains
sinusoidal. The output power of the PV then
fluctuates as a result of a shift in its local load.
Because PV units contribute to lowering overall
power requirements, the Synchronous Reference
Frame (SRF) controller assigns the following new
setpoints for each Photovoltaic module at t = 1.49s:
= 1.01, = 1, and
Figure 9 (e) displayed the
response of each PV unit due to the setpoint
changes.
Fig. 9: Tracking reference set-point at: (a) d-element
at PCC2 for LV (b) q-element at PCC 2 for LV (c)
d-element of PV unit control signal (d) q-element of
PV unit control signal (e) instant PCC2 LVs.
3.3 Execution during Stochastic in Solar
Irradiations
The PV-IUPQC device's performance under
practical settings of solar irradiation variability is
examined in this section. The system's performance
was evaluated under two different types of solar
irradiation. The drop in solar irradiation from 1000
to 600 W/m2 is seen in Figure 10 (a). In Figure 10
(a), the reduction in grid current at PCC1 with
decreasing irradiation is visible. In Figure 10 (b), a
boost in solar intensity from 600 to 1000 W/m2 has
also been observed. As shown in Figure 10 (b), a
rise in grid currents is associated with an increase in
irradiation.
Fig. 10: Reference pre-determines tracking for
stochastic in solar PV: (a) d-element at PCC1 for
LV (b) q-element at PCC1 for LV (c) d-element of
PV unit control signal (d) q-element of PV unit
control signal (e) instant LVs
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2023.18.4
Oluwafunso Oluwole Osaloni,
Ayodeji Stephen Akinyemi,
Abayomi Aduragba Adebiyi, Ayodeji Olalekan Salau
E-ISSN: 2224-350X
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Volume 18, 2023
4 Prototype Development and
Execution
As illustrated in Figure 4, the PV-O-UPQC system
hardware prototype was created using a Solar PV
Array simulator, multiple voltage source
ameliorators, a VSL, and a programmable AC
source. Hall effect transducers (sensors LV35-P,
current sensors LA66-P) are used to detect analog
signals, which are sent into a DSP processor for
UPQC system control. The DSP processor has been
used to implement the developed control algorithms.
The PV-UPQC performance was assessed using a
power analyzer and a digital storage oscilloscope.
To study and authenticate the efficacy, and
performance of the created system under a variety of
active situations, extensive tests were done using
chosen parameters as shown in Table 1.
Fig. 11: Experimental outcome due to unbalance
voltage condition: (a) dq-element of voltage at PCC
2, (b) regulated LV with SRF regulator, (c) LV
regulated with UVTG controller, (d) regulated
voltage with the intended regulator.
4.1 Experimental Implementation during
Unusual Voltage Conditions
The controller efficiency has also been evaluated
based on the system's performance under voltage
unbalance at PCC2. The unbalanced voltages at
PCC2 are shown in Figure 11 (a), which were
obtained using a RIGOL-1153Z digital storage
oscilloscope. As depicted in Figures 11 (b) and (c),
amelioration of the unbalanced state of the LV
applying SRF controller is insufficient. The LVs
were compensated after installing the proposed
efficient regulator to the control circuit, as depicted
in Figure 11. (d). The collected findings indicate
that the suggested series ameliorator controller has
improved performance. To protect VSLs at PCC 2,
during abnormal voltage conditions, it is critical to
adjust the LV. For different voltage disruptions such
as undervoltage, overvoltage, and unbalanced
voltage, the active functioning of the recommended
improved SRF theory based on FNF for the
researched system is presented. The voltage signals
at the connection point 2 exhibit a voltage sag
ranging from nominal 110 to 60 V, as shown in
Figure 12 (a). Figure 12 (a) depicts the system's
capability to modify LVs in low-voltage situations.
Figure 12 shows that the currents at the connection
point 2 have enhanced to retain power balance
throughout an undervoltage scenario. (d). Internal
signals such as infused voltage monitored DCLV
and current flowing in solar PV are also shown in
Figure 12 (c).
Fig. 12: Experimental under voltage situation: (a)
voltage magnitude at PCC 2, (b) regulated LV, (c)
VSC series injected voltage, DCLV, (d) PCC 2
current, PV current.
The measured voltage at PCC2 in an over-voltage
situation, in which the nominal grid voltage is raised
to 150 V from 110, is displayed in Figure 13 (a). As
shown in Figure 13 (b) and Figure 13 (c), the
investigated system effectively controlled the
DCLV and LV. The grid current drops during a
voltage swell to maintain the balance of active
power, as shown in Figure 13 (d).
In Figure 14, the reduction of voltage harmonics at
PCC2 is also seen. The suggested effective series
ameliorator, as illustrated in Figure 14 (b) regulates
and maintains sinusoidal LVs.
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2023.18.4
Oluwafunso Oluwole Osaloni,
Ayodeji Stephen Akinyemi,
Abayomi Aduragba Adebiyi, Ayodeji Olalekan Salau
E-ISSN: 2224-350X
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Volume 18, 2023
Fig. 13: Experimental over-voltage situation: (a)
voltage magnitude at PCC 2, (b) LV regulated, (c)
VSC series delivered voltage, DCLV, (d) PCC 2
current, PV array current.
Fig. 14: Harmonics voltage condition: (a) the PCC 2
voltage with harmonics, (b) regulated LV.
4.2 Experimental Execution under Load
Unbalancing Condition
Presence load unbalancing occurs at PCC 1 when a
single-phase load is removed abruptly, as seen in
Figure 15 (a). The disengagement of a single-phase
load reduces the load's power requirement. To
preserve the real power balance, an increase in grid
current is seen, in Figure 15 (a). The controller's
efficiency in maintaining the sinusoidal source
currently under the current dynamic state is shown
in this diagram.
Similarly, as illustrated in Figure 15 (b), single-
phase performance under nonlinear load addition
has been investigated. The increase in load power
demand caused a load increase at the consumer end
resulting in a drop in current at the grid recorded at
PCC 1. The matching phase a' current remains
sinusoidal even when the load is removed and added
suddenly.
Fig. 15: Load unbalancing situation: (a) unexpected
load disconnection, (b) instant load connection.
4.3 Experimental Execution Stochastic
Variation in Solar Irradiations
This section looks at the PV-UPQC system's
performance under solar irradiation fluctuations.
The system's performance was measured under two
different solar irradiation scenarios. Figure 16 (a)
shows the decrease in solar irradiation from 1000 to
600 W/m2. Figure 16 (a) shows that the drop in grid
current at PCC1 with decreasing irradiation is
visible. In Figure 16 (a), a surge in solar irradiation
from 600 to 1000 W/m has also been observed. In
this case, as shown in Figure 16 (b), the grid
currents increase is associated with an increase in
irradiation.
Fig. 16: Solar irradiations variation situation: (a)
decline in current, and irradiation, (b) Rise in
current, and irradiation.
5 Discussion
Overall, the effectiveness of the architectural control
design was justified through the obtained simulation
and experimental results. In all conditions the
control is subjected to it proves very robust and
flexible. Under the PV-UPQC system's performance
under solar irradiation fluctuations, the decrease in
solar irradiation from 1000 to 600 W/m2 shows that
the drop in grid current at PCC1 with decreasing
irradiation is visible. Also, a surge in solar
irradiation from 600 to 1000 W/m has been
observed, In this case, grid currents increase is
associated with an increase in irradiation.
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2023.18.4
Oluwafunso Oluwole Osaloni,
Ayodeji Stephen Akinyemi,
Abayomi Aduragba Adebiyi, Ayodeji Olalekan Salau
E-ISSN: 2224-350X
36
Volume 18, 2023
6 Conclusion
The evolution and execution of the PV-IUPQC were
presented in this work. The main focal point was the
improvement of the PQ in the presence of several
voltage disturbance issues. The regulated
architecture gives the consumer the option of
selecting the power quality (PQ) level that
corresponds to their requirements. The generated
adequate RS in severe voltage disruptions, a
synchronous reference frame (SRF) regulator based
on a flexible notch filter (FNF) was used. This
allows the consumer to operate at different PQ
levels within the network. The suggested
Logarithmic Absolute (LA) algorithm determines
the effective decisive component of the basic LC.
The use of ATF as a low pass filter (LPF) substitute
for dc bus voltage decreases the chance of high and
low-frequency ripple. The proposed algorithm has
substantiated the authenticity of the simulation
outcomes. Likewise, the effectiveness of the
architectural control design was justified through the
obtained simulation results. Finally, the results
obtained from the experiment indicate that the new
approach delivers a reasonable, effective
performance in the toughness of PV-IUPQC at load
parameters variations and voltage tracking from PV
according to IEEE standard 45. An optimal
implementation of the control architecture can be
developed in subsequent research to accommodate
the stochastic nature of the PV source to produce
better results.
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Abayomi Aduragba Adebiyi, Ayodeji Olalekan Salau
E-ISSN: 2224-350X
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WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2023.18.4
Oluwafunso Oluwole Osaloni,
Ayodeji Stephen Akinyemi,
Abayomi Aduragba Adebiyi, Ayodeji Olalekan Salau
E-ISSN: 2224-350X
38
Volume 18, 2023
Contribution of Individual Authors to the
Creation of a Scientific Article (Ghostwriting
Policy)
The authors equally contributed in the present
research, at all stages from the formulation of the
problem to the final findings and solution.
Sources of Funding for Research Presented in a
Scientific Article or Scientific Article Itself
No funding was received for conducting this study.
Conflict of Interest
The authors have no conflicts of interest to declare
that are relevant to the content of this article.
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