This Report Presented in Partial Fulfilment of the Requirements for the Degree of Bachelor of Science in Electrical and Electronic Engineering

The use of newer power control mechanisms called Maximum Power Point Tracking (MPPT) algorithms has led to increased operating efficiency of solar modules and thus is effective in the field of using renewable energy sources[1], [ 2]. To fully utilize the power of the sun, we need to optimize the output from solar panels.

Motivation 3

When one changes D, we want the voltage and current to provide the most power at a given voltage level. To achieve this voltage level, a control algorithm is implemented to track and follow the highest input power from the solar array.

Solar Energy 4

Kinds of Solar Energy 5

Photovoltaic Solar Power 5

Recently, with the continuous decline in production costs (down 3% to 5% per year in recent years)[6], the use of PV technology has increased to include domestic and grid-connected power generation. Installations of PV systems are also increasing, largely due to comprehensive incentive programs that help reduce the cost of these systems and allow users to sell excess electricity back into the public grid.

Photovoltaic Modules 6

This typical construction is used because the PV module must "survive" outdoors for at least 20-25 years in various, sometimes extreme, weather conditions[4]. Such a long warranty is extremely long compared to most products and is due to the exceptional construction of the PV modules.

Solar Cell 7

Equivalent Circuit of a Solar Cell 11

Rs is the resistance offered by the contacts of the solar cell and the bulk semiconductor material. A PV panel is composed of many solar cells which are connected in series and parallel so that the output current and voltage from the PV panel is high enough for the requirements of the grid or equipment.

Open Circuit Voltage, Short Circuit Current and Maximum Power point 12

Taking into account the above-mentioned simplification, the output current-voltage characteristic of the photovoltaic panel is expressed by the following equation, where np and ns are the number of parallel and series solar cells. The solar cell generates the maximum power at the point of the current-voltage characteristic, where the product VI is the largest.

Solar Panel 13

This point is known as MPP and is unique as can be seen in the figure where the previous points are represented.

Solar Array 14

Kinds of Solar Panel 15

Monocrystalline Solar Cell 16

However, because solar cells are less demanding than microelectronics in terms of structural imperfections, monocrystalline solar cells (Sog-Si) are often used, while monocrystalline silicon is also being replaced by the cheaper polycrystalline or multicrystalline silicon. Monocrystalline solar cells can achieve an efficiency of 17%, while other types of cheaper cells, including thin-film and polycrystalline cells, can only achieve an efficiency of about 10%[10].

Poly Crystalline Solar Cell 16

Amorphous Solar Cell 17

Efficiency Comparison of Different of Solar Cells 17

Charge Controller 18

Analog to Digital Converter and Digital to Analog Converter 19

Pulse-Width Modulation (PWM) 20

DC-DC Converter 21

Storage Batteries 22

Glass Mat absorbent batteries are in my opinion the best available for solar power use. They are leak/spill resistant, do not outgas while charging and have superior performance.

Fig 1.17: Storage Batteries. Image from[15]

The Power Inverter 24

Square Wave Power Inverters 24
Modified Sine Wave Power Inverters 24
True Sine Wave Power Inverters 25
Grid Tie Power Inverters 25

A true sine wave power inverter produces the closest to a pure sine wave of any power inverter and in many cases produces cleaner power than the utility itself. I use a True Sine Wave power inverter myself and find that its automatic capabilities make it more like utility power[16].

LITERATURE SURVEY 27-30

Masters Thesis – Coba 27
Modeling and Simulation of Photovoltaic Module Using Matlab/Simulink 28
Advantage of Boost versus Buck Topology for Maximum Power Point Tracker in
Comparison of MPPT Algorithms for DC-DC Converter Based PV Systems 28
High Efficiency Switched Capacitor Buck-boost Converter for PV Application 29
A Novel MPPT Charge Regulator for a Photovoltaic Stand-alone Telecommunication
Improved Circuit Model of Photovoltaic Array 29
Comparative Study of Maximum Power Point Tracking Algorithms 30
Design and Implementation of Maximum Power Point Tracking Algorithm for a

Data sheet parameters were used as input in the equation describing the current output of the solar panel. Since the buck converter was used to step down the voltage of the solar array, the disadvantages of using buck with a solar array were analyzed. The most important aspect of the experiment is to get as much power out of the panels as possible.

Without a continuous connection to utilize the panel's output, all the energy that would have been collected while the switch was in the breaker is collected. This right half plane zero causes the boost converter response to fluctuate in the opposite direction first before correcting itself.

SYSTEM OVERVIEW 32-45

Modeling of Components under Test 34

Solar Array 34
Buck-boost Converter 36
Load 38
IGBT 39
Pulse Width Modulation Generation 39
DC-AC Converter 40
Low-pass Filter 41
MPPT Algorithms 42

The output voltage is of the same polarity as the input, and can be lower or higher than the input. When the active time of the switch 𝑡𝑜𝑛 increases, it increases the DC voltage at the output. The basic principle of the buck-boost converter is quite simple as seen in figure 3.5.

When the switch is in the On state, the input voltage source is directly connected to the inductor (L). The diode is in reverse biased mode. By analyzing the output voltage, we can evaluate the efficiency of the boost converter.

Figure 3.3: The Current versus Voltage and Power versus Voltage plots from the Panel modeled

Maximum Power Point Tracking 47

An MPPT tracks the maximum power point, which will be different from the STC (Standard Test Conditions) rating in almost all situations. In very cold conditions, a 120 watt panel is actually capable of delivering over 130 watts because the power increases as the temperature of the panel drops - but if you don't have some way to track that power point, you'll lose it. . On the other hand in very hot conditions, the power drops - you will lose power when the temperature rises.

Fig 4.1: Solar Photovoltaic system with maximum power point tracker. Image from[14]

Effect of Variation of Solar Irradiation 50

Effect of Variation of Temperature 51

Comparison of the tracking power for different MPPT system 52

Sensing Circuits 53

Voltage Sensor 53
Current Sensor 54

To allow the MPPT controller to measure the current supplied by the solar panel, a single resistor (Rsense) is placed in series between the solar panel and the DC-DC converter. The voltage across Rsense is input into an AD8215 current sensor manufactured by Analog Devices, whose output voltage is then input into an ADC driver circuit (op-amp in a voltage follower configuration that feeds into a low-pass filter) before being delivered to the ADCINA1 channel of the MPPT controller.

Duty Cycle 54

Duty cycles can be used to describe the percentage time of an active signal in an electrical device, such as the power switch in a switching power supply or the firing of action potentials by a living system such as a neuron.

Methods for MPPT 55

Perturb and Observe Method 55
Incremental Conductance Method 55
Parasitic Capacitance Method 56
Constant Voltage Method 56
Constant Current Method 56

This method, which is not so widely used because of the losses during operation, depends on the relationship between the open circuit voltage and the maximum power point voltage. The open circuit voltage is therefore obtained experimentally and the operating voltage is adjusted to 76% of this value. Similar to the constant voltage method, this method depends on the relationship between the open circuit current and the maximum power point current.

The short-circuit current is therefore obtained experimentally and the operating current is adjusted to 95% of this value. Choice must be made as to which algorithm will be used taking into account the need of the algorithm and the operating conditions.

MPPT ALGORITHMS TEST AND DATA ANALYSIS 58-80

Run Result 59

Duty Cycle versus Power 61

Matlab Code for Incremental Conductance Algorithm 61

Run Result 63
Duty Cycle versus Power 65

Comparison 65

P&O versus Inc 65

Verification of the Conditions of the Algorithms 67

Perturb and Observe Algorithm 67
Incremental Conductance Algorithm 68

The quotient of the difference in current and voltage is 0.199 and is not equal to, but greater than the negative value of the quotient of current and voltage. The quotient of the difference in current and voltage is 0.0628 and is not equal to, but greater than the negative value of the quotient of current and voltage. The quotient of the difference in current and voltage is -.0007 and is not equal to, but less than the negative value of the quotient of current and voltage.

The quotient of the current difference and the voltage difference is equal to zero and is equal to the negative value of the current and voltage quotient. So, according to the algorithm, the duty cycle measured one step earlier will not change and will be the same as the current step.

Correlation 71

Correlation between Input Power & Duty Cycle (P & O algorithm) 71
Correlation between Input Power & Duty Cycle (InC algorithm) 74
Correlation between Duty Cycles obtained from P&O and InC algorithms 77

Interpretation: The correlation between duty cycle and power of the perturbation-observation algorithm is 0.31. This indicates a low association between the variables. Interpretation: The correlation between the duty cycle and the power of the incremental conductance algorithm is -0.31. This indicates a low association between the variable. Explanation: The correlation between the duty cycle of the perturb and observe algorithm and the duty cycle of the incremental conductance algorithm is -0.9999. This indicates a very high correlation between the variable.

Table 5.5: Correlation between Input Power & Duty Cycle (InC algorithm)

Simulink Model 82

Simulink Model using P&O Algorithm 82
Simulink Model using Inc Conductance Algorithm 83

Effect of Irradiance and Temperature on PV Voltage, Current and Power 84

By optimizing the buck boost converter independent of the MPPT and solar array, the converter efficiency was greater than 96% during steady-state operation. The MPPT was discussed after the buck-boost converter and greatly improved MPP tracking. Finally, the InC algorithm was tested; however, tuning the parameters for this algorithm was the most difficult.

This can only be calculated due to the complexity of the calculations of the InC algorithm and the speed of operation. Depending on the amount of light and the configuration of the solar panels, a boost converter may be best suited for this application[4].

Fig 6.4: Effect of Irradiance and Temperature on PV Voltage

Waveforms for P&O Algorithm 87

PV Voltage and Current 87
PV Power 88
Input and Output Voltage of Buck-boost Converter 88
Duty Cycle 89
AC Voltage Output 89

Waveforms for Inc Conductance Algorithm 90

PV Voltage and Current 90
PV Power 90
Input and Output Voltage of Buck-boost Converter 91
Duty Cycle 91
AC Voltage Output 92

Comparison 92

Comparison of the tracking power,voltage,current with different MPPT system
Comparison of the tracking power,voltage,current without MPPT system for
Comparison of the tracking power,voltage,current between NO MPPT and
Comparison of the tracking power,voltage,current between NO MPPT and
Comparison of the elapsed time for different MPPT system 95

Conclusion 97

This innovation was necessary in order to quickly converge to the MPP, but still have good granularity when approaching the PPK. This extension was not too difficult to implement and generally provided very fast tracking and convergence to the MPP. It can be seen that with a multi-stage MPPT, the overall system speed will remain fast and track the MPP well.

Due to the optimization problems of the InC algorithm, the results of these runs do not exactly give the optimal performance of the algorithm. Given more time to properly optimize DD, the algorithm should track the MPP faster and with greater certainty than the P&O algorithm.

Future Work 98

UAV Flight Endurance 98
Second Stage Constant Voltage Output 99
Test MPPT on Real Hardware 99

Azab, “Improved Photovoltaic Array Circuit Model,” International Journal of Electrical and Power Systems Engineering, vol. Haritha, “Comparison of mppt algorithms for pv systems based on dc converters”, International Journal of Advanced Research. Mohammed, “Photovoltaic module modeling and simulation using matlab/simulink,” International Journal of Chemical and Environmental Engineering, vol.

Haritha, "Comparison of mppt algorithms for dc-dc converter based pv systems," International Journal of Advanced Research in Electrical, Electronics, and Instrumentation Engineering, vol. Thangavel, “Design and implementation of maximum power point tracking algorithm for a stand-alone pv system,” International journal of scientific and engineering research, vol.

Waveforms of Input (Bottom) and Output Voltage (Top) of Buck-Boost Converter

Waveform of Duty Cycle versus Time 89