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This work presents a new maximum power point tracker system for photovoltaic applications. The developed system is an analog version of the “P&O-oriented” algorithm. It maintains its main advantages: simplicity, reliability and easy practical implementation, and avoids its main disadvantages: inaccurateness and relatively slow response. Additionally, the developed system can be implemented in a practical way at a low cost, which means an added value. The system also shows an excellent behavior for very fast variables in incident radiation levels.
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A reliable, fast and low cost maximum power point tracker
for photovoltaic applications
J.M. Enrique
, J.M. Andu
´jar, M.A. Boho
Departamento de Ingenierı
´a Electro
´nica, de Sistemas Informa
´ticos y Automa
´tica, Universidad de Huelva, Spain
Received 19 February 2009; received in revised form 22 July 2009; accepted 16 October 2009
Communicated by: Associate Editor Elias Stefanakos
This work presents a new maximum power point tracker system for photovoltaic applications. The developed system is an analog
version of the P&O-orientedalgorithm. It maintains its main advantages: simplicity, reliability and easy practical implementation,
and avoids its main disadvantages: inaccurateness and relatively slow response. Additionally, the developed system can be implemented
in a practical way at a low cost, which means an added value. The system also shows an excellent behavior for very fast variables in
incident radiation levels.
Ó2009 Published by Elsevier Ltd.
Keywords: Analog system; Efficiency; Low cost; Maximum power point tracker; Photovoltaic array; P&Oalgorithm
1. Introduction
In the specialized literature numerous proposals of MPP
tracking systems can be found. Most of them have similar
efficiency, which can also be considered acceptable for most
applications. As a result, the interest of the authors when
implementing this work has focused on achieving a certain
added value in the proposed system, which can be found in
the accurateness, speed and low cost. This allows its appli-
cation even to household installations, where investment
costs may be the most determining factor for decision mak-
ing. The developed system presents the advantage of its
high speed which also helps to improve the photovoltaic
system efficiency.
A photovoltaic (PV) array that functions under uniform
radiation and temperature conditions presents an I–V and
P–V characteristic as the one shown in Figs. 1(a) and (b),
respectively. As can be observed, there is a single point,
called MPP(Maximum Power Point), where the array
provides the maximum power possible for these environ-
mental conditions (radiation and temperature), and so
functions with the maximum performance. When a load
is connected directly to a PV array (direct coupling), the
operation point is defined by the intersection of its I–V
characteristics, as shown in Fig. 1(a).
In general, this operation point does not coincide with
the MPP. Thus, in direct coupling systems, the array must
be over-dimensioned to guarantee the power demand of the
load. Obviously, this implies a more expensive system. To
solve this problem, a DC/DC (Xiao et al., 2007) converter
with an algorithm for the automatic control of its duty
cycle dis inserted between the photovoltaic array and
the load (see Fig. 2), resulting in what is known as MPPT
(Maximum Power Point Tracker) system.
The MPPT must control the voltage or current (through
the dof the converter) of the PV array regardless of the
0038-092X/$ - see front matter Ó2009 Published by Elsevier Ltd.
Corresponding author. Address: Departamento de Ingenierı
´a Electro
nica, de Sistemas Informa
´ticos y Automa
´tica, Universidad de Huelva,
Huelva, Spain. Tel.: +34 959 217374/7656/7671; fax: +34 959 217348.
E-mail addresses: (J.M. Enrique), andu (J.M. Andu
´jar), (M.A. Bo-
Available online at
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Please cite this article in press as: Enrique, J.M. et al. A reliable, fast and low cost maximum power point tracker for photovoltaic applications. Sol.
Energy (2009), doi:10.1016/j.solener.2009.10.011
load, trying to place it in the MPP. The DC/DC converter
presents an input impedance (R
) which depends basically
on the load impedance (R
) and the duty cycle (d)(Enrique
et al., 2005a,b, 2007; Dura
´n et al., 2008, 2009). Therefore,
the MPPT must find the optimal dfor the operation point
of the PV array to coincide with the maximum power point
Although the solution to operating in the MPP may
seem immediate, it is not. This is because the location of
the MPP in the I–V curve of the PV array is not known
a priori. This point must be located, either by mathematical
calculations over a valid model, or by using some search
algorithm. This implies even more difficulty if we consider
the fact that the MPP presents non-linear dependencies
with temperature and radiation, as observed in Fig. 3.
Fig. 3(a) shows a set of I–V curves for different levels of
radiation and constant temperature. In Fig. 3(b), the same
set of curves is presented at a higher temperature. Observe
the change in the voltage and, especially, in the current of
the MPP.
Numerous MPPT algorithms have been proposed and
developed in the literature. Among them, the Perturbation
and Observation (P&O)algorithm is probably the most
Fig. 1. (a) IVcharacteristic of a PV array, MPP and system operation point. (b) PVcharacteristic of the PV array.
Fig. 2. Basic diagram of an MPPT system.
Fig. 3. (a) IVcharacteristic of a PV array at 40 °C and different radiation levels (200–400 to 600–800 and 1000 W/m
). (b) IVcharacteristic of a PV
array at 60 °C and different radiation levels (200–400 to 600–800 and 1000 W/m
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Energy (2009), doi:10.1016/j.solener.2009.10.011
extensively used in commercial MPPT systems. However,
there is no clear agreement on which algorithm is best.
Hohm and Ropp (2002) presented a study that basically
concludes with not very different performances for most
of the different algorithms and where the traditional P&O
is quite successful.
To establish the quality of a given MPPT system (and to
be able to compare it with other systems), it is necessary to
define the tracking efficiency (g), given by Eq. (1) (Hohm
and Ropp, 2002):
0PmaxðtÞdt ð1Þ
where, for radiation and temperature conditions in the gi-
ven time period, P
(t) is the instantaneous power supplied
by the MPPT system controlled PV array, and P
the actual MPP power.
2. Algorithms for MPP tracking
A very short revision of the most usual algorithms for
MPP tracking is presented below.
2.1. Perturbation and Observation (P&O)
The Perturbation and Observation (P&O) algorithm is
probably the most frequently used in practice, mainly due
to its easy implementation (Kim et al., 1996). Its operation
is briefly explained as follows: assume that the PV array
operates at a given point, which is outside the MPP. The
PV array operational voltage is perturbed by a small DV,
and then the change in the power (DP) is measured. If
DP> 0, the operation point has approached the MPP,
and therefore, the next perturbation must take place in
the same direction as the previous one (same algebraic
sign). If, on the contrary, DP< 0, the system has moved
away from the MPP and, consequently, the next perturba-
tion must be performed in the opposite direction (opposed
algebraic sign).
As stated before, the advantages of this algorithm are its
simplicity and easy implementation. However, it has limita-
tions that reduce its tracking efficiency. When the light
intensity decreases considerably, the PVcurve becomes
very flat. This makes it difficult for the MPPT to locate
the MPP, since the changes that take place in the power
are small as regards perturbations occurred in the voltage.
Another disadvantage of the P&Oalgorithm is that it
cannot determine when it has exactly reached the MPP.
Thus, it remains oscillating around it, changing the sign
of the perturbation for each DPmeasured. It has also been
observed that this algorithm can show misbehavior under
fast changes in the radiation levels (Kawamura et al.,
Several improvements in the P&Oalgorithm have
been proposed (Enslin et al., 1997; Andujar et al., 2005;
Xiao et al., 2007). One of them is the addition of a waiting
time if the system identifies a series of alternate signs in the
perturbation, meaning that it is very close to the MPP. This
allows reducing the oscillation around the MPP and
improves the algorithm efficiency under constant radiation
conditions. However, this algorithm causes the MPPT to
be very slow, making its misbehavior more noticeable in
partly cloudy days.
Other modifications to the P&Oalgorithm, as the
ones detailed below, directly affect the perturbation sign
according to whether certain conditions are given.
2.1.1. P&Ooriented algorithm
The P&Ooriented algorithm (Andujar et al., 2005)is
able to distinguish with certain accuracy whether the sys-
tem is operating to the right or left of the MPP and act con-
sequently, so increasing tracking efficiency. However, it is
observed that whenever there is a sudden variation in the
incident radiation (caused, for example, by the passing of
a cloud) and, therefore, in the power supplied by the pho-
tovoltaic generator, the system is unable to distinguish
instantaneously the appropriate direction of the change
in d(Hohm and Ropp, 2002). This algorithm is discussed
in detailed in Section 3.
2.1.2. P&Omodified algorithm
To correct the defect caused by sudden radiation varia-
tions in the previous algorithm, a slight variation has been
proposed (Andujar et al., 2005). As already known, varia-
tions in the light radiation have an effect mainly and
directly on the current supplied by the photovoltaic array
(Alonso, 1998). Thus, an increase in radiation will cause
a rise in the value of the MPP current (see Fig. 3). When
the algorithm detects a variation in radiation over a certain
threshold, its response is an immediate increase in d. In this
way, the DC/DC converter decreases its input impedance
, and so obliges the photovoltaic generator to move to
higher current points close to the MPP. An advantage of
this algorithm is that it does not require precise measure-
ments of radiation (this would remarkably increase the
price of its practical implementation), since it only needs
the sign of the radiation increase within an interval of mea-
sures. A simple photodiode can be useful for this purpose.
2.2. Constant voltage and current
The Constant Voltage (CV)algorithm (Hohm and
Ropp, 2002; Koizumi et al., 2006) is based on the fact that
in the IVcurves of a PV array the ratio between the max-
imum power point voltage and that of the open circuit is
roughly constant (something similar occurs with the ratio
between the current of the maximum power point and that
of the short circuit) (Noguchi et al., 2002; Mutoh et al.,
2006; Mutoh and Inoue, 2007), that is:
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Energy (2009), doi:10.1016/j.solener.2009.10.011
where V
is the maximum power point voltage and V
the open circuit voltage. The PV array is temporarily isolated
by the MPPT system to measure V
. Next, the MPPT cal-
culates the correct operation point using Eq. (2) and adjusts
the voltage of the PV array until it reaches the MPP. This
operation is repeated periodically to track the MPP.
Although this method is simple, choosing the optimal K
value, which, on the other hand, is not totally constant,
may be difficult. The literature indicates good values for
Kwithin the range 0.73–0.80 (Andersen and Alvsten,
1995; van der Merwe and van der Merwe, 1998; Abou El
Ela and Roger, 1984).
This method can be implemented in a relatively easy
way using analog software. However, its efficiency is lower
than that of other methods (Hohm and Ropp, 2002). The
main reasons are:
(I) Errors in the Kvalue.
(II) The measure of V
) requires the momentary
interruption of the power supplied by the array.
2.3. Incremental conductance
The so called incremental conductancemethod
(Hohm and Ropp, 2002) derives directly from the power
equation, which will be given in the MPP by:
dV ð3Þ
If instantaneous conductance g
, and increasing conduc-
tance g
, are defined as:
dV ð4Þ
Then, expression (3) can be re-written in the form of:
The previous equation indicates that in the MPP the
instantaneous and incremental conductance must be equal.
If the operation point does not coincide with the MPP,
then a series of inequations directly derived from expres-
sion (5) (Hohm and Ropp, 2002; Koizumi et al., 2006)
allow us to know whether the operation voltage is higher
or lower than V
, and so to act consequently.
Once the MPP has been reached, every time a change
occurs in the radiation on the array the MPPT will tend
to increase or decrease the operation voltage to follow
the MPP.
The disadvantage of this method is that it needs a pre-
cise calculation of g
and g
, which makes the MPPT more
difficult and relatively slow.
2.4. Parasitic capacity
This algorithm is similar to the previous one, except that
in this algorithm the effect of the parasitic capacity of the
junction p–n is included. This effect can be modeled (Bramb-
illa et al., 1998) as a condenser connected between the termi-
nals of each cell. By connecting cells in parallel the parasitic
capacity observed by the MPP will increase. As a result, the
differences between the tracking efficiencies of the MPP
between Increasing Conductanceand Parasitic Capac-
ityalgorithms are more outstanding in high power arrays,
where there are numerous modules connected in parallel.
The practical implementation of this algorithm is com-
plex, especially for the difficulty entailed by the calculation
of increasing conductance g
. A detailed study of this algo-
rithm is shown in Brambilla et al. (1998).
2.5. Model-based algorithms
If a suitable model is available for a cell or photovoltaic
array and there are precise radiation and temperature mea-
sures available (which implies a significant increase in the
price of the system, although there have recently been devel-
oped sensors of temperature and radiation at a low cost
´nez and Andu
´jar, 2009; Martı
´nez et al., 2009), the
MPP voltage and current may be directly calculated by solv-
ing equation dP/dV = 0 (for example, using a numeric
method). Then, the MPPT would just have to adjust voltage
and current values to those calculated ones (Xiao et al., 2006).
Even so, the model-based MPPTs are not practical,
since the values for the cell parameters are not known with
accuracy and, in fact, can vary significantly between cells
from the same production series. Moreover, only the cost
of a precise light radiation sensor (pyranometer) can cause
this MPPT system to be non-viable in practice.
Having revised the most usual algorithms and methods
for MPP tracking, it seems that the P&O algorithm and,
more specifically, its orientedvariant, is the one with
the best ratio efficiency/easiness of practical implementa-
tion. This is mainly due to its proper operation, simplicity
and low cost (note that it needs no radiation and tempera-
ture sensors). Nonetheless, as already mentioned, it has the
disadvantage of its instantaneous confusion when facing
sudden variations in the incident radiation. This disadvan-
tage could be overcome with a system fast enough to make
its reaction speed higher than the speed of the incident radi-
ation change – which is the main reason in the MPP move-
ment. To achieve this without losing the advantages of the
P&O-oriented algorithm, the authors have developed a sys-
tem which is described below.
3. P&O oriented analog system
A completely analog system able to implement the algo-
rithm for MPP tracking, known as P&O-orientedalgo-
rithm, is presented in this section (Andujar et al., 2005).
3.1. Operation of the P&O-oriented algorithm
Consider Fig. 4, where the P–V characteristic of a pho-
tovoltaic array at a given temperature and radiation is
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Energy (2009), doi:10.1016/j.solener.2009.10.011
shown. Assume that, due to a modification in the duty
cycle (d) of the converter, the system evolves from V
(DV> 0 and DP> 0). As observed in Fig. 4, the MPP
voltage, V
, is higher than V
, and therefore, the output
voltage must keep increasing. Now assume that the pertur-
bation has moved the operation point from V
to V
this case, the voltage of the array must increase again to
approach V
. All possible combinations are shown in
Table 1.
The only variable to which the control system can access
is the duty cycle (d). Any increase in dimplies a decrease in
the input resistance R
of the DC–DC converter (and sub-
sequently, a decrease in the operation voltage of the photo-
voltaic generator) and vice versa (Enrique et al., 2005a,b,
2007; Dura
´n et al., 2008, 2009). The system starts from
an initial value (for example d= 0.5) that varies at constant
increase (Dd) according to expressions (6) and (7).
bi¼sign½ðDVÞðDPÞ ð6Þ
In each iteration i,DPand DVmeasures are obtained.
Next, the value of dis adjusted to approach it to the MPP.
Note that no temperature and solar radiation measures are
needed to do the tracking, which reduces the price of the
control system. The flow chart diagram of this algorithm
is shown in Fig. 5.
3.2. The developed system
The whole developed system is shown in Fig. 11.To
explain its operation, the system will be analyzed by blocks.
Fig. 6 shows the circuit that, from the voltage and current
measures at the PV array output, generates a reference sig-
nal, V
, which will then be used in another block to gen-
erate a PWM signal.
From the voltage and current measures at the array out-
put (V, I), the variable power, P, is generated by using the
multiplier Mult. 1. Two differentiators followed by two
comparators generate the value of the functions sign(dV)
and sign(dP). These two signals are multiplied and com-
pared again to generate the analog equivalent of the bit
Fig. 4. PVcharacteristic of a photovoltaic array. The developed MPPT
algorithm is able to distinguish whether the system is operating to the right
or left of the MPP and act consequently.
Table 1
Possible cases and control law to enable the photovoltaic system follow the MPP.
Case System evolution Control law (V?V
=sign((DV)(DP)) V sign(DV)d
+1 +1 1"+1 ;
111"+1 ;
+1 1+1 ;1"
1+1+1 ;1"
Fig. 5. Flow chart of the MPPT P&O-oriented algorithm.
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. The iterations of expression (3) are formed by inte-
grating the subsequent b
. Finally, the output signal is lim-
ited in order to maintain it within the appropriate range,
generating V
. This signal can be used as control signal
of a PWM generating system (Enrique et al., 2005a,b).
To perform the practical implementation of the devel-
oped system, the chip AD633J has been selected as multi-
plier block. For the comparators, the cheap (approx.
0.5 $) and extensively used op-amp TL082 has been
selected. The integrator and differentiator blocks are shown
in Fig 7. Both structures are basic in analog electronics.
The op-amp TL082 has also been used for their
A lowpass RC filter has been inserted before each differ-
entiator block to remove part of the harmonic content of
the input signals. The output signal, V
, of the system in
Fig. 6 is used as reference voltage for a PWM generator
(see Fig. 8), so that its duty cycle can be adjusted.
The output PWM signal of the circuit in Fig. 8 allows
controlling the behavior of the DC/DC converter. This
converter (boost-type, in this case) is shown in Fig. 9 con-
nected to a 25 Xload.
To reduce the price of the sensors, the voltage input is
taken from the photovoltaic array using a high impedance
voltage divider with a voltage follower. The measurement
of the current variable is performed by measuring the volt-
age fall in a very low value resistance, located at one of the
PV array terminals. This measure must be amplified before
reaching the multiplier. For this purpose, a very low offset
voltage precision op-amp OP27 has been used (see Fig. 10).
Fig. 11 shows the diagram of the whole developed
MPPT system.
4. Simulations
The developed system has been verified using PSpice
The photovoltaic generator has been implemented using
ABM blocks (Analog Behavioral Modeling). The parame-
ters of the generator model correspond to the BP
Saturnomodule (ns = 60 and np = 1) (CIEMAT, 2000).
Fig. 12 presents the model and I–V and P–V curves of
the module used at 21 °C and 1000 W/m
.Table 2 shows
the MPP power and current (P
and I
for different levels of radiation and constant temperature.
To verify the correct operation of the system, fast vari-
ations in the incident radiation have been applied to it
(see Fig. 13). Observe that during start-up, an initial rise
of 688.7 W/m
in the incident radiation (P
= 55.2 W)
is reached by the system in approximately 10 ms. Once
the maximum power point has been reached, the system
maintains it even for variations higher than 5 10
/s, much higher than those present in nature. Addition-
ally, it can be observed that the system presents a high pre-
cision, since the actual trajectory of the MPP and the one
intended do not have practically noticeable differences.
Fig. 14 shows the current obtained with the tracker system.
Fig. 6. System generating the reference signal.
Fig. 7. Differentiator and integrator blocks used.
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With this sudden start-up, the tracking system is able to
obtain efficiencies superior to 97.2% in the first 100 ms.
Once the MPP has been reached (during the first millisec-
onds of the start-up) the system presents a tracking effi-
ciency ghigher than 99% (99.99%), even for variations in
the incident radiation as fast and extreme as those shown
in Fig. 13. This efficiency is superior to 81–85% of a classi-
cal P&Osystem (Perturb and Observed), superior to 88–
89% of an InCsystem (Incremental Conductance) and to
73–85% of a CVsystem (Constant Voltage)(Hohm and
Ropp, 2002). In Fig. 15, note how the system is able to
adjust automatically the duty cycle of the PWM signal.
Fig. 9. Boost converter used.
Fig. 8. System generating the PWM signal.
Fig. 10. Measure of variables Vand I.
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Fig. 11. Diagram of the whole developed system.
Fig. 12. Model and IVand PVcurves of the BP Saturnomodule.
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5. Conclusions
In this work, the design of a new maximum power point
(MPP) tracking system for photovoltaic systems has been
developed. The system is an analog version of the tracking
P&O-orientedalgorithm. From the results obtained by
simulation, it can be concluded that the developed system
presents an excellent precision and speed in the MPP track-
Table 2
and I
for different levels of radiation and constant temperature
corresponding to the BP Saturnogenerator.
Temperature (°C) Radiation (W/m
(W) I
21 688.7 55.2 1.86
21 1000 80.6 2.71
21 1721.8 136.2 4.76
Fig. 13. Top chart: applied variations in the incident radiation. Bottom chart: comparative between the actual trajectory of the MPP and that followedby
the developed system for variations in the incident radiation.
Fig. 14. Current supplied by the system for variations in the incident radiation.
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ing, even for very sudden variations in the levels of incident
radiation, so increasing the total energy performance of the
installation. The system is able to reach the MPP in the first
10 ms, getting high efficiency values practically from the
start-up. Once the system has reached the MPP, the effi-
ciency is superior to 99%, improving the ones obtained
by other methods (P&O,InC,CV). This quality,
along with its high simplicity and low price, makes the pro-
posed system highly suitable for use in any kind of photo-
voltaic installation.
The present work is a contribution of the DPI2007
62336/project, funded by The Spanish Ministry of
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... An MPPT system basically consists of a DC/DC converter located between the photovoltaic generator and the load functioning as an impedance adapter. This converter is governed by an algorithm that determines the duty cycle ( ) for the system to operate efficiently [1][2][3]. ...
... Traditionally, the positioning criterion of these systems is to maximize the power delivered by the generator [1][2][3][4][5][6][7][8][9][10], however, this work aims to show the validity of the criterion of maximizing the power delivered to the output of the DC/DC converter, this is in the system load, what could be called useful power. ...
... Among the most common methods of tracking the MPP, the well-known P&O (Perturb & Observed) [3,4] is the most used due mainly to its simplicity and robust-ness. This paper analyzes the behavior of a photovoltaic system governed by a traditional P&O, but instead of maximizing the output power of the PVG, the MPPT tries to maximize the power delivered in the load, that is, in the DC/DC output (useful power). ...
Conference Paper
The methods of tracking the maximum power point used in photovoltaic systems try to set de duty cycle value for the DC/DC converter that connects the generator with the load, so as to maximize the power dilivered by this generator. This approach ignores the fact that the performance of the converter also depends on the service cycle with which it operates, so that the value of this variable that maximizes the power delivery of the generator does delivery to the load. In this paper a comparative study is made, based on the well-known algorithm "Perturb and Observed, P&O" of the performance obtained by measuring the output power of the generator, as it is traditionally done, and at the output of the converter, considering the characteristics of it, that is, its dependence on dutty cycle. Using a boost converter for the connection between the photovoltaic generator and the load, ther performances obtained for different atmospheric conditions (radiation and temperature) and different load profiles are shown. The results obtained are analyzed to quantify the loss of performance derived from the classic approach and the convenience or not of developing system that determine the optimun duty cycle that maximizes the useful power, that is, to the output of the DC/DC converter.
... La intersección entre la característica de carga y la característica I-V del arreglo fotovoltaico define el punto de funcionamiento del sistema fotovoltaico (figura 5). Usualmente, cuando la carga y el arreglo están directamente acoplados, el punto de operación obtenido no corresponde a la tensión y corriente que producen la potencia máxima (MPP) que el arreglo fotovoltaico puede transferir a la carga (Enrique, Andújar, & Bohórquez, 2010). Por lo tanto, es necesario un algoritmo de control para mantener estable el punto de operación en el MPP. de control para manipular la impedancia de entrada de un convertidor DC-DC. ...
... La impedancia de entrada de los convertidores DC-DC es una cantidad variable que depende básicamente de la relación de trabajo (δ) y la carga que está conectada al convertidor (Enrique et al., 2010). Esto significa que, al controlar la relación de trabajo del convertidor, la resistencia característica del arreglo fotovoltaico podría coincidir con la impedancia de entrada del convertidor, de modo que el punto de funcionamiento de máxima potencia MPP del arreglo fotovoltaico podría rastrearse incluso con temperatura y condiciones de radiación solar variables. ...
Full-text available
Este artículo describe algunos fundamentos sobre los sistemas fotovoltaicos (Photovoltaics – PV) y también estudia muchos aspectos relacionados con el control de la eficiencia de los arreglos fotovoltaicos acoplados directamente a una carga de corriente continua (DC). Los arreglos fotovoltaicos tienen algunas características intrínsecas que pueden afectar su potencia de salida durante diferentes condiciones de funcionamiento. Por lo tanto, la potencia de salida de los arreglos fotovoltaicos generalmente se mantiene relativamente constante mediante el uso de algoritmos de control. El algoritmo de perturbación y observación – Perturb and Observe (P&O) – es uno de estos algoritmos de control y es estudiado con detalle en el presente artículo. Se analizan las fallas del algoritmo P&O para mantener estable la eficiencia del arreglo con condiciones ambientales variables rápidas. En ese sentido, se plantea la posibilidad de investigar algunos algoritmos P&O modificados que se pueden encontrar en la literatura para mejorar los resultados del algoritmo P&O con respecto a su efectividad para controlar la eficiencia del arreglo y su facilidad de implementación en un sistema fotovoltaico.
... Unfortunately, photovoltaic (PV) modules conversion energy is characterized by low efficiency. Nevertheless, techniques of extracting maximum power of these sources need extensive research and developments in maximum power point tracking (MPPT) to improve reliability, lower manufacturing and usage, recycling costs and increasing energy efficiency [3][4]. PV energy is extracted directly from solar irradiation by means of PV panels, composed of solar cells array connected in series or parallel, having ability to transform photons into electrical energy, used in direct current for charging batteries, conditioned into grid AC electricity or hybrid forms, operating in power wide range, depending on climatic changes (solar irradiance, ambient temperature) and electrical load. ...
... Among MPPT conventional techniques based on feedback control power unit, P&O and InCond are simplest and most used maximization algorithms in commercial products [3][4][5][6][7]. These control techniques impose fixed perturbation step size determined by accuracy and tracking speed around MPP. Indeed, perturbation is necessary to know PVG output power variations to readjust duty ratio D of dc-dc converters by making sure that operating point oscillates continuously as close as possible to MPP. ...
Conference Paper
Full-text available
This paper considers comparison of dynamic performance of incremental conductance technique, fuzzy logic and neuro-fuzzy controllers to track maximum power point of photovoltaic systems. To deliver maximum power, buck-boost maximum power point tracking converter is inserted between photovoltaic generator and load for power adaptation. It is shown that neuro-fuzzy control is superior to fuzzy control and classical incremental conductance method in terms of convergence speed, tracking accuracy and stability under different operating conditions. Experimental results confirm the superiority of the neuro-fuzzy MPPT over the conventional methods.
... The developed P&OM algorithm is based on the classical P&O, widely used in photovoltaic systems [35,36]. In this case, the obtaining of the maximum power point (MPP) is based exclusively on the experimental behaviour of the PEMFC polarization curve. ...
Full-text available
APU system for refrigerated light trucks based on hydrogen technology. • Integral solution based on BoP, power, control and acquisition electronics, control loops. • Step-by-step design of acquisition, control, and power electronics. • Validation of experimental performance on refrigerated light truck. • Proven performance of the proposed solution in terms of autonomy, cost reduction and CO 2 emissions. A R T I C L E I N F O Keywords: Refrigerated light trucks and vans Air-cooled PEM fuel cell Hydrogen-powered refrigeration system Refrigerated food transport sector Energy management system A B S T R A C T Urban population and the trend towards online commerce leads to an increase in delivery solution in cities. The growth of the transport sector is very harmful to the environment, being responsible for approximately 40% of greenhouse gas emissions in the European Union. The problem is aggravated when transporting perishable foodstuffs, as the vehicle propulsion engine (VPE) must power not only the vehicle but also the refrigeration unit. This means that the VPE must be running continuously, both on the road and stationary (during delivery), as the cold chain must be preserved. The result is costly (high fuel consumption) and harmful to the environment. At present, refrigerated transport does not support full-electric solutions, due to the high energy consumption required, which motivates the work presented in this article. It presents a turnkey solution of a hydrogen-powered refrigeration system (HPRS) to be integrated into standard light trucks and vans for short-distance food transport and delivery. The proposed solution combines an air-cooled polymer electrolyte membrane fuel cell (PEMFC), a lithium-ion battery and low-weight pressurised hydrogen cylinders to minimise cost and increase autonomy and energy density. In addition, for its implementation and integration, all the acquisition, power and control electronics necessary for its correct management have been developed. Similarly, an energy management system (EMS) has been developed to ensure continuity and safety in the operation of the electrical system during the working day, while maximizing both the available output power and lifetime of the PEMFC. Experimental results on a real refrigerated light truck provide more than 4 h of autonomy in intensive intercity driving profiles, which can be increased, if necessary, by simply increasing the pressure of the stored hydrogen from the current 200 bar to whatever is required. The correct operation of the entire HPRS has been experimentally validated in terms of functionality, autonomy and safety; with fuel savings of more than 10% and more than 3650 kg of CO 2 / year avoided.
... Therefore, a MPPT algorithm performance and comparison parameter, often called tracking efficiency, is needed in order to quantify the performance of a specific MPPT control algorithm under different operating conditions and to be able compare it with other MPPT algorithms. In simulated PV systems, the tracking efficiency can be estimated as follows [25][26][27]: ...
Operating with maximum power point tracking (MPPT) strategy is the key functions of the solar energy management system in solar PV deployment. Therefore, in this paper, the strengths and weaknesses of the MPPT based on an incremental conductance (IC) algorithm are analyzed. Furthermore, assessments in terms of performance of two MPPT-IC techniques are presented. More specifically, a two-stage optimized MPPT-IC algorithm in this study is developed and implemented for isolated solar PV system with the conventional single-stage MPPT-IC algorithm. Both MPPT-IC methods are analyzed and compared based on their tracking efficiencies, steady state error and transient speed responses. For the case of the two-mode MPPT-IC algorithm, significant modification is carried-out by combining the conventional IC and modified constant voltage methods. As a result, a better performance under both sunny and cloudy weather scenarios respectively is achieved with higher tracking efficiencies than the conventional IC algorithm. The two stage-algorithm not only rapidly tracks the maximum power point (MPP) under dynamic weather conditions, but also significantly reduces the fluctuations in power around the MPP when subjected to fast and slow speed’s change of irradiations.
... The microgrid is based on a 360 VDC battery supported DC bus, see Fig. 1. As the renewable energy source, a 10 kWp photovoltaic (PV) field is available and connected to the DC bus through a DC/DC converter [43] that implements maximum power point tracker algorithm, specifically a modified perturbation and observation (P&OM) algorithm [44]. The required PV power has been calculated by simulations based on the daily PV generation profiles of the site, as well as the expected demand, obtained from the Institute for Energy Diversification and Saving of Spain (typical consumption of a single-family house plus additional power for the production of renewable hydrogen and an electric car recharging point). ...
Hybrid energy storage systems (HESS) are considered for use in renewable residential DC microgrids. This architecture is shown as a technically feasible solution to deal with the stochasticity of renewable energy sources, however, the complexity of its design and management increases inexorably. To address this problem, this paper proposes a fuzzy logic-based energy management system (EMS) for use in grid-connected residential DC microgrids with HESS. It is a hydrogen-based HESS, composed of batteries and multi-stack fuel cell system. The proposed EMS is based on a multivariable and multistage fuzzy logic controller, specially designed to cope with a multi-objective problem whose solution increases the microgrid performance in terms of efficiency, operating costs, and lifespan of the HESS. The proposed EMS considers the power balance in the microgrid and its prediction, the performance and degradation of its subsystems, as well as the main electricity grid costs. This article assesses the performance of the developed EMS with respect to three reference EMSs present in the literature: the widely used dual-band hysteresis and two based on multi-objective model predictive control. Simulation results show an increase in the performance of the microgrid from a technical and economic point of view.
... An efficiency of more than 98% was recorded. The authors of [16] utilize a wide range current multiplier, that follows the maximum power point (MPP) in the solar system. The slope detection circuit detects the sign of the slope dP/dV at the operating point. ...
Full-text available
The tracking of the maximum power point (MPP) of a photovoltaic (PV) solar panel is an important part of a PV generation chain. In order to track maximum power from the solar arrays, it is necessary to control the output impedance of the PV panel, so that the circuit can be operated at its Maximum Power Point (MPP), despite the unavoidable changes in the climate conditions such as temperature and Irradiance. A new MPPT analog technique to track the Maximum Power Point (MPP) of PV arrays is proposed. This new technique uses simple and classical functions of electronic circuits. An Off-Grid PV system was considered to apply and validate the proposed new technique. The entire circuit was implemented in circuit-oriented simulator Proteus-ISIS. We present the results associated with the design, the realization, and the experimentation of a PV system equipped with a new analog MPPT command. The obtained results have shown good efficiency of analog technique (more than 98.5%). The second part of the paper consists of the description of the design and the realization of the novel analog MPPT integrated chip. The integrated circuit (IC) was designed and realized using HV CMOS technology 0.35-mm.
This paper aims to maintain power quality for a two-stage solar photovoltaic (SPV) gird integrated system in case of dynamic disturbances such as unbalanced nonlinear load and variable solar irradiance. The proposed robust adaptive inverse hyperbolic sine function (RA-IHSF)-based control primarily extracts the fundamental load current weight component and is employed to control the voltage source converter (VSC) by altering the switching patterns of pulses. The maximum power can be retrieved from the SPV generation system by implementing a maximum power point tracking control based on incremental conductance method along with DC-to-DC boost converter. The VSC feeds active power to load and grid together with reactive power compensation. The proposed control technique also provides load balancing and mitigates harmonic content of grid current along with power factor correction. The response of the system to the implementation of proposed RA-IHSF illustrates that it is more expedient as compared to conventional adaptive filter-based algorithms showing improved dynamic response with less computational burden.
Conference Paper
This paper presents a model predictive control (MPC) for a three-level neutral-point clamped (NPC) inverter operating as a shunt active power filter (SAPF) with a photovoltaic (PV) system. In this proposal, the PV system is used to associate three-level NPC inverter for converting the dc voltage to three phase ac voltages by employing MPC. At the same time, The SAPF injects compensation current at the point of common coupling to cancel the current harmonics. In addition, this work introduces a fuzzy logic maximum power point tracking (MPPT) to the DC-DC boost converter for extracting maximum power from the photovoltaic array. The performance of the conventional perturbation and observation (P&O) and fuzzy logic MPPT algorithm is compared. The effectiveness of the proposed strategy has been verified in MATLAB/Simulink simulation platform. From the simulation results, it is found that the developed system provides excellent performance to achieve reference currents tracking, balance in the DC-link capacitor voltage, as consequence a reduction in the harmonics significantly.
Renewable energy sources are the best solution to reduce dependence on conventional and nonrenewable sources that also cause environmental pollution. With the increase in the prices of conventional fuels globally, the increase of gas emissions resulting from its use, and the impact on the environment and the global climate; various renewable energy sources have emerged as an alternative to traditional sources of energy. Ssolar energy is one of the most important renewable energy sources used globally; The technology used is relatively simple and uncomplicated, compared to the technology used in other renewable energy sources. Solar energy is the ideal alternative to conventional energy in the Gaza Strip in Palestine, due to the relatively high solar radiation in the region, which makes its application more practical and economical compared to other parts of the world. Palestine has higher rates of total solar absorption, ranging from 4-8 kWh / m2 per day, which is high compared to other countries. This paper offers a solution to the Gaza Strip, which has suffered from a severe power shortage due to the Israeli blockade, by using solar PV as a backup system and a good alternative to diesel generators. Photovoltaic cells convert the sunlight into DC electric power. Where the major problem of the PV is that with the changing of atmospheric conditions, the voltage is changing, and so the maximum power is changing. We know that PV systems are still very expensive; therefore, the Artificial Neural Network controller is designed for the converter to secure the maximum power to the system to increase the efficiency of it. ANN controller is designed to bring out the maximum power from the solar panel. This paper uses a controller that utilizes MPPT technique to increase the efficiency of converting solar energy into electrical energy by modifying the duty cycle of Puls Width Modulation (PWM) for the boost converter to obtain the MPP energy from solar cells at all times. A solar panel applied and their components are individually modeled in the MATLAB / SIMULINK program to simulate a real PV system behavior, then an MPPT technique, including DC/DC boost converter was designed. Then an ANN controller is designed and then trained to get the maximum power 65 point from the solar panel at different atmospheric conditions. Also, this controller is compared with the direct connected method without an MPPT controller. The system performance is measured by changing solar radiation and temperature of the PV module. The findings indicate that MPPT ANN has a fast response to the variability and is more efficient, which means more power transfer to the system. The outcome shows that the photovoltaic module directly associated without MPPT technique has less efficiency because of the mismatch between the photovoltaic module and the load.
Full-text available
The basic operation of a solar cell, module or photovoltaic generator under different irradiation and temperature conditions is characterized by its I-V characteristic curve. Only the experimental measurement of the I-V curve allows us to know with precision the electrical parameters of a photovoltaic cell, module or array. This measure provides very relevant information for the design, installation and maintenance of photovoltaic systems. Currently, the I-V characteristic curve is obtained by connecting a variable charge to the panel terminals in order to achieve that the current of the terminals ranges from zero to the short circuit current. In this paper we propose a new experimental way to measure this characteristic curve by using Buck-Boost-Derived DC-DC converters. It has been proved that the optimal topologies for this purpose are the SEPIC (Single-Ended Primary Inductance Converter) and Cuk converters. The theoretical analysis performed has been validated by means of simulation and experimentally. Additionally, a comparison between three known conventional methods and the proposed one is provided.
Conference Paper
Full-text available
The achievement of I-V and P-V curves of photovoltaic modules gives the possibility of obtaining their characteristic parameters: the short-circuit current (I<sub>sc</sub>), the open-circuit voltage (V<sub>oc</sub>), the maximum power point (MPP) and the fill factor (FF). These values are significant for the design of a photovoltaic system. These curves depend on the global irradiance (G), the temperature (T) and the spectral distribution of the solar irradiation. In this paper, a new methodology to determine the afore mentioned curves by using DC-DC converters is proposed. This methodology allows carrying out the complete sweep of the voltage and the current (including V<sub>oc</sub> and I<sub>sc</sub>). Regarding the traditional methods, this new one provides the following advantages: a) minimum power loss with regard to the systems that operate in lineal zone (active zone); this implies several advantages in size and cost; and b) this new method allows an automatic adaptation of the interpolation interval.
The implementation of a novel control loop in a chopper that is used to extract maximum power from a photovoltaic array has yielded exceptional energy transfer efficiency in a low power (60 W) array, in virtue of its low power consumption. Loop performance is dependent on a reference signal produced by a special circuit. Correct feedback response is noted for load variations, as well as a modification of solar array conditions. Since the control process is applied only to the input terminal, rather than the output terminal, it may be deduced that the load I-V characteristics will not affect the performance of the loop as the system is tested for very low values of load (up to the optimal load for the array).
The operating point of a photovoltaic generator that is connected to a load is determined by the intersection point of its characteristic curves. In general, this point is not the same as the generator’s maximum power point. This difference means losses in the system performance. DC/DC converters together with maximum power point tracking systems (MPPT) are used to avoid these losses. Different algorithms have been proposed for maximum power point tracking. Nevertheless, the choice of the configuration of the right converter has not been studied so widely, although this choice, as demonstrated in this work, has an important influence in the optimum performance of the photovoltaic system. In this article, we conduct a study of the three basic topologies of DC/DC converters with resistive load connected to photovoltaic modules. This article demonstrates that there is a limitation in the system’s performance according to the type of converter used. Two fundamental conclusions are derived from this study: (1) the buck–boost DC/DC converter topology is the only one which allows the follow-up of the PV module maximum power point regardless of temperature, irradiance and connected load and (2) the connection of a buck–boost DC/DC converter in a photovoltaic facility to the panel output could be a good practice to improve performance.
This paper describes a methodology and the developed system for measuring, capturing, and displaying I–V and P–V characteristic curves of photovoltaic (PV) modules or arrays based on single-ended primary inductance converters (SEPIC) in parallel connection, operating in interleaved mode. The proposed methodology and the developed system allow the real time capture and displaying of the I–V and P–V curves of a PV panel or array, and show several advantages with regard to classical methods: simple structure, scalability, fast response, versatility, direct display, and low cost. The measuring of the characteristic curves of PV modules includes high speed of response and high fidelity, with low ripple. An experimental prototype based on four SEPIC converters in parallel connection has been implemented to validate the proposed methodology. This new methodology and experimental system has been registered in the Spanish Patent and Trademark Office with the number P200930198. Copyright © 2009 John Wiley & Sons, Ltd.
Maximum power point trackers (MPPTs) play an important role in photovoltaic (PV) power systems because they maximize the power output from a PV system for a given set of conditions, and therefore maximize the array efficiency. Thus, an MPPT can minimize the overall system cost. MPPTs find and maintain operation at the maximum power point, using an MPPT algorithm. Many such algorithms have been proposed. However, one particular algorithm, the perturb-and-observe (P&O) method, claimed by many in the literature to be inferior to others, continues to be by far the most widely used method in commercial PV MPPTs. Part of the reason for this is that the published comparisons between methods do not include an experimental comparison between multiple algorithms with all algorithms optimized and a standardized MPPT hardware. This paper provides such a comparison. MPPT algorithm performance is quantified through the MPPT efficiency. In this work, results are obtained for three optimized algorithms, using a microprocessor-controlled MPPT operating from a PV array and also a PV array simulator. It is found that the P&O method, when properly optimized, can have MPPT efficiencies well in excess of 97%, and is highly competitive against other MPPT algorithms. Copyright © 2002 John Wiley & Sons, Ltd.