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Eduvest –
Journal of Universal Studies Volume 3 Number 5, May, 2023 p- ISSN 2775-3735-
e-ISSN 2775-3727 |
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FOUR-PHASE
INTERLEAVED BOOST CONVERTER FOR MAXIMUM POWER EXTRACTION IN PV SYSTEM |
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Beauty
Anggraheny Ikawanty1, Bambang Irawan2 Department Electrical Engineering, Politeknik
Negeri Malang, Indonesia1 Department Mechanical Engineering, Politeknik Negeri Malang, Indonesia2 |
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ABSTRACT |
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The use of renewable energy is increasing,
thus affecting the rapid use of DC-DC converter technology. The use of a
conventional boost converter has a weakness, namely high current ripple. This
input current ripple will enter the voltage source, so that the switching
noise will spread to other circuits. This problem can be overcome by using a
multiphase converter topology that can suppress current ripple. But the
conventional multiphase topology has large power losses, because the value of
the inductor used tends to be large. Ripple currents will also reduce the
efficiency of solar power plants. This study aims to design a four-phase
interleaved boost converter that is applied to PV (photovoltaic) with maximum
power extraction. The topology method of this circuit is to assemble a
conventional boost converter in parallel up to 4 levels, so that it can
suppress the input current ripple. This topology modification series also
uses the interleaved scaling method in order to reduce heat distribution on
each switch. The test method in this study uses a standard boost converter
circuit as a comparison, and observes its characteristics and performance
through simulation. The converter system is also operated as Maximum Power
Point Tracking (MPPT) using the PSO and P&O algorithm controls as a
comparison. Based on the simulation results, the MPPT tracking speed has the
same speed, which is 2 ms, but the speed to achieve
ripple stability in the standard circuit and four-phase interleaved boost
converter is 4.5 ms and 6.1 ms,
respectively. |
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KEYWORDS |
Four-phase interleaved boost converter; current ripple input; solar
power plant; MPPT; Particle Swarm Optimization |
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This work is licensed under a Creative
Commons Attribution-ShareAlike 4.0 International |
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INTRODUCTION
The output power generated from
renewable energy is generally difficult to control, a power electronic
converter capable of implementing high-speed and high-accuracy control is
required for renewable energy in power plants (Bayoumi, 2015). In
addition, the output voltage of the solar cell is limited, so a boost converter
circuit is needed to increase the voltage from the solar cell (Ikawanty et al., 2019). The main
factor of the solar cell itself is the existence of a power supply capable of
producing a continuous voltage. Currently the power supply works in switching
mode, because it has a much higher efficiency compared to a linear power supply
system. One of the main components of a switching mode power supply system is
the DC-DC converter (Lopa et al., 2016). In general,
DC-DC converters function to convert direct current (DC) electric power to
other forms of DC electric power that are controlled by current, or voltage, or
both (Midya et al., 1997). A boost
converter is a switching DC-DC converter that uses a solid-state switch to
perform its function. While the switching technique makes the boost converter
generally very efficient, it introduces noise. The noise is mainly caused by
the rapid switching on and off of the current through the switch, which results
in a pulsating interrupted current. This generated noise affects the input and
output terminals of the converter. On the input side, switching noise appears
as input current ripples, and if not suppressed properly, will travel back to
the DC bus and will propagate to other converters connected to the same bus (Ikawanty et al., 2022; Lentz, 2017). In PV
systems using Maximum Power Point Tracking (MPPT), input current ripple from
the boost converter will worsen MPPT performance and reduce PV system transfer
efficiency (Ikawanty et al., 2022; Schofield et al., 2012). Therefore,
minimizing the input current ripple from the boost converter in a PV system becomes
an important goal. But using a conventional boost converter result in limited
voltage gain and operating duty cycle close to 100% (Rosas-Caro et al., 2010). In
addition, a very large component value is needed, a large inductor value will
affect the magnitude of the input current ripple (Valdez-Resendiz et al., 2013).
Some
of the problems that arise in the use of conventional boost converters
resulting in large input current ripples are switching noise. The use of
switching mode in the boost converter further adds AC ripple to the input or
output signal (Ikawanty et al., 2022). Likewise,
a mistake in designing the boost converter will cause the switching noise to
spread to the circuit, and result in electromagnetic interference (EMI). EMI is
an electromagnetic radiation signal that damages the performance of electrical
systems (Geetha et al., 2009). The next
problem is the discontinuous current caused by the switching mode of the
converter. When the input current ripple enters the voltage source, the
switching noise will spread to other circuits, which use the same voltage
source. Current ripple will also worsen the maximum power point tracking (MPPT)
performance and reduce the transfer efficiency of photovoltaic systems (Schofield et al., 2012). So, by reducing
the current ripple in the converter will have a good impact on all systems.
The
next obstacle to the solar power system is weather changes and the cloud cover
factor for solar panels. In addition, solar cell energy is a non-linear source,
highly dependent on load and weather conditions such as solar cell temperature
and variations in solar irradiance (Faizal & Setyaji, 2016; Salah & Ouali, 2011). Under
these conditions, the efficiency becomes low. In addition, in the case of a
solar cell array under partial shade conditions, hotspot problems will occur
which can damage the solar cells. Partial shading causes a change in the peak
of the P-V characteristic curve, in other words, more than 80% of solar energy
is not converted into useful electrical energy but is lost in the environment (Ngan & Tan, 2011). There are
various ways to overcome power optimization in solar power systems, including
non-physical and physical-electrical engineering mechanisms. Non-physical
engineering is carried out through the Maximum Power Point Tracking (MPPT)
mechanism, or a method based on Artificial Intelligent Control (AIC). MPPT is
used to extract the maximum available power from the PV array to maximize the
utilization efficiency of the solar cell array (Ji et al., 2010).
Therefore,
this research will correct some of the deficiencies with the MPPT method using
a four-phase interleaved boost converter with Particle Swarm Optimization
(PSO), with this combination it is hoped that it can improve tracking speed.
The second is a modification of the four-phase interleaved boost converter, so
you will get low input current ripple. Moreover, the study aims to design a
four-phase interleaved boost converter that is applied to PV (photovoltaic)
with maximum power extraction.
RESEARCH METHOD
The method
used in this study to reduce current
ripple is to modify the
boost converter, with
parallel method or in other words is multiphase. Multiphase
converters offer various benefits over phase converters conventional single.
The use of two phases effectively
doubles the operation converter frequency.
The two-phase implementation
provides the benefit of higher
frequency switching without
many of the
drawbacks and disadvantages of switching associated with increase the
switching frequency of a single-phase converter.
The use
of multiple phases improves the input and
output characteristics of converter. The input
current ripple shows lower amplitude
and harmonics. Because the
total input ripple represents the combination of the four
inductor inputs charging and discharging is
out of phase,
ripple cancellation occurs. This effect
produces a peak ripple to the
input peak the current is
equal to quarter of
the inductor per phase. Operation multiphase also
increases the quality of the
output voltage. Output voltage ripple frequency effectively multiplied,
reducing filter requirements.
Ripple reduction significantly reduces
the stress applied to the
capacitor, which it generally has shortest life
of all components.
While most of the components
generally operating in tens
or hundreds of thousands of
hours, electrolytic capacitors show a period life under ten thousand hours
when operated at full load.
The circuit in Figure 1 is
the result of a four-phase interleaved boost converter.
Figure 1. Four-phase Interleaved Boost Converter
Solar cells
will not automatically work at their
maximum working point, but must
be controlled. Maximum Power Point Tracking (MPPT) is a method used to
find the maximum working point of solar cells and maintain
the solar cells working at that
point. By getting the optimal voltage and current values
so that the maximum output
power is obtained from the
solar cell. This maximum output power will result
in high efficiency and reduce power
loss in the system.
There are several
MPPT techniques to get the maximum
power point. P&O has advantages over other algorithms, namely easy and fast
computation. The P&O algorithm
can be illustrated
in Figure 2 as a flow chart explaining the P&O algorithm. The operation of the
MPPT P&O algorithm depends
on the dP/dV perturbation term. When dP/dV
is positive, the algorithm will
automatically increase the voltage magnitude
to the maximum
dP/dV point.
Conversely, when dP/dV is
negative, the algorithm will automatically reduce the amount of
voltage to a maximum dP/dV.
This condition will continue until the maximum point
is reached.
Figure 2. Flowchart of P&O algorithm
The PSO algorithm can be
illustrated in Figure 3, begins by determining the particle swarm size of N. After that, degenerate the initial solution
value population, for each particle
with a value of x. The objective function of each
particle is calculated: f(x). In this step, the iteration value
is set equal to 1. And the
value 0 is assigned to the
velocity value of each particle
in this iteration (1st iteration). In the next iteration, the parameters for each particle
j are calculated, namely Pbest and Gbest.
Pbest is the value of
the optimum objective function encountered by a particle j.
Figure 3. PSO MPPT Algorithm Flow Chart
RESULT AND
DISCUSSION
The
simulation of maximum power extraction in the four-phase interleaved boost
converter uses 2 algorithms, namely the P&O and PSO algorithms. The next
step is to combine four-phase interleaved boost converters with PV arrays and
MPPT. This simulation aims to select the appropriate algorithm for the four-phase
boost converter modification circuit. The simulation results were carried out
with different irradiation values between 600 to 1000 W/m2 at a constant
temperature of 25°C. Changes in the irradiation step at 700 W/m2 occurred at t
= 0.4 s, 600 W/m2 at t = 0.5 s, 900 W/m2 at t = 0.6 s, 1000 W/m2 at t = 0.7 s,
800 W/m2 at t = 0.8 s, and 700 W/m2 at t = 0.9 s.
Figure 4 shows
a graph of the voltage, current
and power of the PV array
in a four-phase interleaved boost converter with the P&O algorithm. In the figure, it can
be seen that
the PV current is unstable at
0.4 s when the irradiation changes from 0 to 700 W/m2, which affects the
graph of PV power.
Figure
4. Voltage,
current and power of PV array in four-phase interleaved boost converter
with
P&O algorithm
Figure 5 is a graph
of voltage, current and load
power in a four-phase interleaved
boost converter with the P&O algorithm. In the picture, it can
be seen that
the current and power voltages at the load
have high ripple.
Figure
5. Voltage, current and load power in four-phase
interleaved boost converter
with
P&O algorithm
In Figure
6 is a graph of
the simulation results of voltage,
current and PV array power in a four-phase interleaved
boost converter with the PSO algorithm.
At the beginning of the change
in irradiation at t = 0.4 s
the three graphs show stability
even though the irradiation varies. So that
the effect on voltage, current
and power on the load
still shows stability as shown in Figure 7.
Figure
6. Voltage, current and PV array power in four-phase
interleaved boost converter
with
PSO algorithm
Figure
7. Voltage, current and load power in four-phase interleaved
boost konverter with PSO algorithm
Figure 8 shows
a graph of the results of
the comparison of the P&O and PSO algorithms. Based on the
figure, PSO has a higher output power value
than P&O. PSO has better
accuracy and fast tracking for
MPP compared to P&O. So the PSO algorithm
is suitable for four-phase boost converter
circuits.
Figure
8. Power in four-phase interleaved
boost converter
with
P&O and
PSO algorithm
The next
simulation is to compare the
standard circuit and the four-phase interleaved
boost converter with the P&O and PSO algorithms. Figure 9
shows the power tracking speed for standard
and modified circuits. From the graph it
can be seen
that the value of the
speed to reach the maximum
power is the same, which
is equal to 2 ms, but
for the standard
and modified circuits, they still contain ripples
of up to
6.1 ms and 4.5 ms, respectively.
Figure
9. Maximum
power tracking speed for standard
circuits and four-phase interleaved boost converters
In Figure
10 is the result
of power simulation in the standard circuit and four-phase interleaved boost converter with the PSO algorithm.
From the two graphs there
is no significant
difference, both have a good tracking
response. Similar to Figure 11, which
is the result
of a power simulation on a standard circuit and a four-phase interleaved boost converter with the P&O algorithm, it also
has the same tracking response. But when compared
between the PSO and P&O algorithms from the two
images, the P&O algorithm has a larger ripple of 3.33% while the PSO algorithm
has a 0.001% ripple and the tracking response
on P&O is less stable at
t = 0.4 s and irradiation
600 W/m2 to t = 0.53 s and irradiation 900 W/m2.
Figure 10. Power on standard circuits and four-phase interleaved
boost converters with the PSO algorithm
Figure
11. Power on standard circuits
and four-phase interleaved boost converters with P&O algorithms
CONCLUSION
A
four-phase interleaved
boost converter with PSO and P&O MPPT algorithms for the PV array has been presented.
The simulation results for the two MPPT algorithms are at PSO almost zero
steady-state oscillation, capability to track MPP under unsettled irradiation
conditions. Whereas the P&O has a large steady-state oscillation, poor to
track MPP under unsettled irradiation conditions. The simulation results for
the tracking speed between the conventional circuit and the four-phase boost
converter are the same, namely 2 ms, they still contain ripples of up to
6.1 ms and 4.5 ms, respectively.
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