22-09-2014, 12:14 PM
Simulation on Maximum Power Point
Tracking of the Photovoltaic Module using
LabVIEW[/color]
Simulation on Maximum.pdf (Size: 895.05 KB / Downloads: 121)
Abstract:
Model of a solar cell and solar module is built in the LabVIEW software. Solar cell model is in single diode model
and it is solved by familiar Newton Raphson method. IV characteristics and PV characteristics are simulated in LabVIEW
and it verified at different temperature and irradiance conditions. Maximum power point tracking is incorporated in the
simulation of PV module and the Maximum power point, voltage and current at this maximum power point were simulated
at standard conditions and verified the result. The simulation system used for the analysis of solar photovoltaic module at
different temperature value, solar irradiation value, series resistance Rs and shunt resistance Rsh . Behavior of the solar
module in different diode ideality factor also analyzed. This model can be used for analysis of PV characteristics and for
simulation with Maximum Power Point Tracking Algorithm(MPPT) algorithms.
INTRODUCTION
Energy is required for the large number of thing from home to cars to electronics. The traditional energy used for these purpose are
coal natural gas, nuclear energy ,oil etc. Due to the crisis of traditional energy sources we need to find out the other source of
energy. Solar energy is a good option and the electricity produced is clean and silent. They are long lasting and having little
maintenance due to the absence of any moving part. The major disadvantages is their limited efficiency levels ;compared to other
renewable energy sources. The output of solar cell is greatly depend on the weather conditions and fluctuating in nature. So we
need to capture the maximum power from the solar panel. DC-DC converter based maximum power point tracking [2]is used for
this purpose .For the study of this kind we need the model of a solar cell or module to check the performance of MPPT going to
implement. Not only the MPPT system but also the device going to connect to the PV system need the model of a solar cell and the
panel and it is important in designing the storage batteries stand alone PV system, grid connected system etc. LabVIEW
(Laboratory Virtual Instrumentation Engineering Workbench ) is a good simulation as well as automation software , therefore the
PV cell and module model in LabVIEW is very important. This paper is organized as follow: Section I gives the introduction of
PV technology and the importance of mathematical simulation model in LabVIEW. Section II is helpful to understand the model of
solar cell and related equations in developing the simulation on LabVIEW. In section III model of solar module is designed with
the help of solar cell mathematical model and the section IV give Newton Raphson method for solving the nonlinear current
voltage equation. Section VI show the simulated result of solar module and at last section VII concludes the paper and followed by
the references.
I
MODEL OF A SOLAR CELL
Photovoltaic cell consist of PN junction that when exposed to light releases electrons. The solar cell can be modeled as a current
source parallel with a forward biased diode. The diode current Id is varies with the junction voltage Vd and the cell reverse
saturation current Io. Most popular method of modeling solar cell is the single diode model that is shown in Fig.1[5]-[9] . In
practical , solar cell is not ideal diode so there is some losses .In real cells, the effect is degraded by the presence of series resistance
Rs and parallel resistance Rsh . Series resistance Rs is very small, which arises from the ohmic contact between metal and
semiconductor internal resistance. But Shunt resistance Rsh is very large and represents the surface quality along the periphery.
Leakage of current through the periphery represents Ish. Both the diode current Id and shunt current Ish given by the photocurrent
Iph. In ideal case Rs is 0 and Rsh is ∞. The resultant current relationships are in the following equation, as dictated by Kirchhoff’s
CONCLUSIONS
In this work, it is found that the current voltage relationship is non linear and there is a maximum power at a particular current and
voltage .This maximum power is varying with respect to the atmospheric condition such as irradiation value of solar light
,atmospheric temperature and wind speed etc. In this analysis the of effect irradiation and atmospheric temperature on current -
voltage characteristics and power- voltage characteristics are studied . When the irradiation level reduced the photo generated
current reduced significantly. The open circuit voltage (Voc) is reduces also reduced but the effect is negligible. In decreasing
atmospheric temperature value, at solar irradiation of 1000 w/m2 ,open circuit voltage is only decreased and the photo generated
current remain constant . In effect the power is decreases with increase in temperature. When analyzing the effect of series
resistance, we can see that the Isc and Voc remain constant but the maximum power point is varying. The series resistance
influences the slope of the IV characteristics at the constant voltage region. At the same time parallel resistance Rsh influences the
slope of the curve at the constant current region. The fill factor is affected by the change in parallel and series resistance. Ideality
factor have a role in finding the maximum power point of solar cell at given condition. Ideality factor (A) having value between 1
and 2 and we can see that power peak of a PV Curve is affected by the ideality factor of the solar cell. This model can be used for
analysis of PV characteristics and for simulation with MPPT algorithms.