This document summarizes a study that simulated a grid-connected photovoltaic (PV) system incorporating an efficient maximum power point tracking (MPPT) algorithm. The study used PSIM software to model the PV module, boost converter with Perturb and Observe MPPT control, and inverter connecting the PV array to the grid. Simulation results showed the model achieved the MPPT function and improved the inverter output by reducing voltage ripple.
Development and Analysis of Fuzzy Control for MPPT Based Photovoltaic SystemIJERD Editor
In PV system control of Power electronics converters are very essential for the efficient utilization
of the solar System. This paper proposes modified Perturb & Observe Maximum power point tracking (MPPT)
with a fuzzy controller for DC-DC boost converter control in Photovoltaic system under shading and varying
atmospheric conditions. This paper proposes a different approach for MPPT of PV system so as to obtain
maximum power from PV system. In conventional methods, tracking power contains oscillation in the output
power. The Simulation and modeling of Photovoltaic system along with proposed algorithm are done using
MATLAB/SIMLINK software. Form Simulation results shows that P & O based fuzzy controller algorithm is
transient state is fast, less fluctuations and smooth in signal of generated power.
An Intelligent Technique By Using The Method of Constant Coefficient of Short...Ali Mahmood
Photovoltaic (PV) system is extensively increasing since it is clean,
pollution free, and inexhaustible and by consider available resource as a future
energy supply. The PV array output power is used to directly control the Pulse-width
modulation (PWM), dc/dc boost converter, thereby reducing the complexity of the
system. The resulting system has high efficiency with lower cost. This paper presents
an improved Constant Coefficient of Short Circuit Current (CCSCC) Maximum Power
Point Tracking (MPPT) technique under PWM control of photovoltaic (PV) power
generation systems to obtain the maximum output power. The solar panel is
modelled and analyzed in MATLAB/SIMULINK.
Maximum Power Point Tracking Method for Single Phase Grid Connected PV System...Ali Mahmood
Ordinary technique fail to ensure successful tracking of the maximum power point under partial shading conditions (PSC). This performs in significant reduction in the power generated as well as the reliability of the photovoltaic energy production system. For the effective utilization of solar panel under partial shading condition (PSC), maximum power point tracking method (MPPT) is required.
“MODELING AND ANALYSIS OF DC-DC CONVERTER FOR RENEWABLE ENERGY SYSTEM” Final...8381801685
This project portrays a comparative analysis of DC-DC Converters for Renewable Energy System. The electrolysis method which increases the hydrogen production and storage rate from wind-PV systems. It has been proved that DC-DC converter with transformer has the desirable features for electrolyser application. The converter operates in lagging PF mode for a very wide change in load and supply voltage variations, thus ensuring ZVS for all the primary switches. The peak current through the switches decreases with load current.This paper portrays a comparative analysis of DC-DC Converters for Renewable Energy System . The simulation and experimental results show that the power gain obtained by this method clearly increases the hydrogen production and storage rate from wind-PV systems. It has been proved that DC-DC converter with transformer has the desirable features for electrolyser application. Theoretical predictions of the selected configuration have been compared with the MATLAB simulation results. The simulation and experimental results indicate that the output of the inverter is nearly sinusoidal. The output of rectifier is pure DC due to the presence of LC filter at the output. It can be seen that the efficiency of DC-DC converter with transformer is 15% higher than the converter without transformer.
Development and Analysis of Fuzzy Control for MPPT Based Photovoltaic SystemIJERD Editor
In PV system control of Power electronics converters are very essential for the efficient utilization
of the solar System. This paper proposes modified Perturb & Observe Maximum power point tracking (MPPT)
with a fuzzy controller for DC-DC boost converter control in Photovoltaic system under shading and varying
atmospheric conditions. This paper proposes a different approach for MPPT of PV system so as to obtain
maximum power from PV system. In conventional methods, tracking power contains oscillation in the output
power. The Simulation and modeling of Photovoltaic system along with proposed algorithm are done using
MATLAB/SIMLINK software. Form Simulation results shows that P & O based fuzzy controller algorithm is
transient state is fast, less fluctuations and smooth in signal of generated power.
An Intelligent Technique By Using The Method of Constant Coefficient of Short...Ali Mahmood
Photovoltaic (PV) system is extensively increasing since it is clean,
pollution free, and inexhaustible and by consider available resource as a future
energy supply. The PV array output power is used to directly control the Pulse-width
modulation (PWM), dc/dc boost converter, thereby reducing the complexity of the
system. The resulting system has high efficiency with lower cost. This paper presents
an improved Constant Coefficient of Short Circuit Current (CCSCC) Maximum Power
Point Tracking (MPPT) technique under PWM control of photovoltaic (PV) power
generation systems to obtain the maximum output power. The solar panel is
modelled and analyzed in MATLAB/SIMULINK.
Maximum Power Point Tracking Method for Single Phase Grid Connected PV System...Ali Mahmood
Ordinary technique fail to ensure successful tracking of the maximum power point under partial shading conditions (PSC). This performs in significant reduction in the power generated as well as the reliability of the photovoltaic energy production system. For the effective utilization of solar panel under partial shading condition (PSC), maximum power point tracking method (MPPT) is required.
“MODELING AND ANALYSIS OF DC-DC CONVERTER FOR RENEWABLE ENERGY SYSTEM” Final...8381801685
This project portrays a comparative analysis of DC-DC Converters for Renewable Energy System. The electrolysis method which increases the hydrogen production and storage rate from wind-PV systems. It has been proved that DC-DC converter with transformer has the desirable features for electrolyser application. The converter operates in lagging PF mode for a very wide change in load and supply voltage variations, thus ensuring ZVS for all the primary switches. The peak current through the switches decreases with load current.This paper portrays a comparative analysis of DC-DC Converters for Renewable Energy System . The simulation and experimental results show that the power gain obtained by this method clearly increases the hydrogen production and storage rate from wind-PV systems. It has been proved that DC-DC converter with transformer has the desirable features for electrolyser application. Theoretical predictions of the selected configuration have been compared with the MATLAB simulation results. The simulation and experimental results indicate that the output of the inverter is nearly sinusoidal. The output of rectifier is pure DC due to the presence of LC filter at the output. It can be seen that the efficiency of DC-DC converter with transformer is 15% higher than the converter without transformer.
We introduce in this paper a new FPGA-based Maximum Power Tracker for photovoltaic systems. The developed approach targets to modify the perturb and observe in view of reaching rapid tracking and achieving excellent accuracy, while keeping the stability performance and the reduced complexity. To perform this improvement, an automatic and smart two steps switcher is integrated, in addition inputs FIR filters are incorporated. Therefore, a high sampling frequency is attained, and consequently the tracking speed is improved. MATLAB simulations and the Xilinx FPGA implementation results show that the improved approach reaches a performance very close to the recently published MPPT methods, with lesser complexity.
Analysis of power quality improvement in grid connected wind driven induction...eSAT Journals
Abstract As a promising renewable alternative, the wind power is one of the significant sources of generation. Reactive power compensation and harmonic reduction in a low voltage distribution networks for integration of wind power to the grid are the main issues addressed in this paper. This paper proposes a control scheme based on instaneous Pq theory for compensating the reactive power requirement of a three phase grid connected wind driven induction generator as well as the harmonics produced by the non linear load connected to the PCC using STATCOM. The proposed control scheme is simulated using MATLAB/SIMULINK. The Simulation results are presented in this paper. Keywords- wind power, distribution network, induction generator, STATCOM, reactive power.
Real Time Implementation of Variable Step Size Based P&O MPPT for PV Systems ...IJPEDS-IAES
Nowadays Solar energy is an important energy source due to the energy crisis and environment pollution. Maximum power point tracking (MPPT) algorithm improves the utilization efficiency of a photovoltaic systems. In this paper an improved P&O MPPT algorithm is developed and simulated using MATLAB / SIMULINK to control the DC/DC buck converter. The obtained simulink model is also verified using dspace tool. Both the simulated and experimental results are validated by also comparing them with conventional MPPT methods. The performance measures show the increase in the efficiency of PV system by the proposed model.
The International Journal of Engineering and Science (IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
A new bidirectional multilevel inverter topology with a high number of voltage levels with a very reduced number of power components is proposed in this paper. Only TEN power switches and four asymmetric DC voltage sources are used to generate 25 voltage levels in this new topology. The proposed multilevel converter is more suitable for e-mobility and photovoltaic applications where the overall energy source can be composed of a few units/associations of several basic source modules. Several benefits are provided by this new topology: Highly sinusoidal current and voltage waveforms, low Total Harmonic Distortion, very low switching losses, and minimum cost and size of the device. For optimum control of this 25-level voltage inverter, a special Modified Hybrid Modulation technique is performed. The proposed 25-level inverter is compared to various topologies published recently in terms of cost, the number of active power switches, clamped diodes, flying capacitors, DC floating capacitors, and the number of DC voltage sources. This comparison clearly shows that the proposed topology is cost-effective, compact, and very efficient. The effectiveness and the good performance of the proposed multilevel power converter (with and without PWM control) are verified and checked by computational simulations.
An improved luo converter for high power applicationseSAT Journals
Abstract
Power conversion is one of the major requirements in various industries and in daily life. Among various types of power
conversion, DC-DC conversion has greater importance. DC-DC conversion can be reliably performed using luo converter. It
employs voltage lift technique so that output voltage is increased stage by stage, in arithmetic progression. Luo converter can be
incorporated with the Z network or impedance network so as to ensure simple start up and smooth power conversion. An
impedance network consist of two identical inductors and two identical capacitors connected in ‘X’ shape. Besides power
conversion it also offers filtering operation. The luo converter in this scheme is of switched capacitor type. It helps to provide
regulated output voltage from an unregulated source of power supply. The major benefits of this proposed scheme is that it
combines the advantages of the switched capacitor, voltage lift technique and the impedance network. Hence the proposed scheme
has various advantages such as high power density, larger range of output DC voltage, lower or no inrush current, lower
harmonic injection, simple circuit, high voltage transfer gain, can process upto several tens of watts of power. The simulation
analysis and the hardware implementation shows that the output voltage obtained is higher than the expected theoretical value.
i.e, it is the highly boosted voltage output.
Keywords: Z-network, boost voltage, voltage lift technique
Grid-Connection Control and Simulation of PMSG Wind Power System Based on Mul...ijsrd.com
This dissertation proposes a wind energy conversion system is composed of a wind turbine PMSG, a rectifier, and an inverter. The wind turbine PMSG transforms the mechanical power from the wind into the electrical power, while the rectifier converts the AC power into DC power and controls the speed of the PMSG. The controllable inverter helps in converting the DC power to variable frequency and magnitude AC power. With the voltage oriented control, the inverter also possesses the ability to control the active and reactive powers injected into the grid. Multilevel inerter is used to step up the voltage and to reduce the THD. Here nine level and eleven level inverter are used and the voltage increases and THD reduces from 12.87 % to 7.46 %. Active and reactive power is controlled dc stabilization and the reactive power is near to unity Here PI controller is used to control the inverter output rms voltage and LC filter is used to remove the harmonics available in the system.
Power System Stability Enhancement Using FLC and MPC for STATCOMIJERA Editor
In modern power system, Static Compensator (STATCOM) is used to alleviate the transient stability problem
and damping power system oscillations. In this paper different STATCOM control scheme using fuzzy logic
controller (FLC) and model predictive controller (MPC) for the Single Machine Infinite Bus (SMIB) system in
improving transient stability is simulated using MATLAB/ Simulink in power systems block set. PI, FLC and
MPC signals are used to control and exchange the required reactive power among the STATCOM and the power
grid. A load disturbance is simulated and the behavior of the system for voltage fluctuations has been studied.
Simulation results using Proportional-Integral (PI) controller, Fuzzy Logic Controller (FLC) and Model
Predictive Controller (MPC) have been compared. The effectiveness of the different controllers in damping
oscillations and improving power system stability has been discussed.
Improving efficiency of Photovoltaic System with Neural Network Based MPPT Co...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Maximum PowerPoint Tracking of PV System Based on a SEPIC Converter Using Fuz...IJERA Editor
This paper presents the MPPT (Maximum power point tracking) operation of PV (Photovoltaic) system based
on a SEPIC (Single Ended Primary Inverter Converter) converter using fuzzy logic controller. MPPT method
such as Incremental conductance base on FLC (Fuzzy Logic Controller) is used to extract maximum output
power of the PV system. PV energy is the most essential energy resources since it is pollution free, clean and
endless. The FLC proposed scheme is interface with the MPPT to generate the PWM (Pulse Width Modulation)
for the SEPIC controller for maximum power point tracking operation.FLChas used Mamdani’s method for
convergent and divergent of membership function. FLC is used for more efficient performance under the
variation in different atmosphere. The fuzzy logic controller with SEPIC for MPPT scheme extract the
maximum power point tracking without any change in the voltage at the inverter at different load condition. The
behavior of the converter and controller tested in simulation at different operating conditions. Proposed scheme
is used for accurately tracking maximum point and also send the smooth, error free signal to the inverter.
Design of a Grid-Connected Photovoltaic Inverter with Maximum Power Point Tra...IAES-IJPEDS
There is no easy way to convert Photovoltaic (PV) energy with high
efficiency due to dynamic changes in solar irradiance and temperature. This
paper illustrates a control strategy to design and implementation of
Maximum Power Point Tracking (MPPT) in a photovoltaic system using
Perturb and Observe (P&O) algorithm. The PSIM simulation results confirm
proper functioning of the proposed MPPT sub-circuit to achieve a constant
48V DC output from fluctuating voltage of solar panel by varying duty cycle
of the MOSFET in the 24V-48V boost converter. The filtered output
waveform of the SPWM driven H-bridge inverter via the L-C low pass filter
is found to be a pure sine-wave of 48V peak which is then stepped-up 312V
peak (220V rms) by using a step up transformer. The frequency of output
voltage is found to be 50Hz with a total harmonic distortion (THD) of 0.001
which is much lower than the IEEE 519 standard.
Enhanced MPPT Technique For DC-DC Luo Converter Using Model Predictive Contro...IJERD Editor
The present study explored an enhanced maximum power point tracking technique which ensures fast tracking in PV systems. This system represents a Model Predictive Control (MPC) MPPT technique. Extracting the maximum power from PV systems has been widely investigated. The main benefaction of this article is an improvement of the Perturb and Observe (P&O) method through a fixed step predictive control under measured fast solar radiation. The preferred predictive control to achieve Maximum Power Point (MPP) speeds up the control loop since it predicts error before the switching signal is applied to the DC-DC Luo converter. Comparing the improved technique to the conventional P&O method indicates significant improvement in PV system performance. The proposed MPC-MPPT technique for a Luo converter is implemented using the MAT LAB SIMULINK
We introduce in this paper a new FPGA-based Maximum Power Tracker for photovoltaic systems. The developed approach targets to modify the perturb and observe in view of reaching rapid tracking and achieving excellent accuracy, while keeping the stability performance and the reduced complexity. To perform this improvement, an automatic and smart two steps switcher is integrated, in addition inputs FIR filters are incorporated. Therefore, a high sampling frequency is attained, and consequently the tracking speed is improved. MATLAB simulations and the Xilinx FPGA implementation results show that the improved approach reaches a performance very close to the recently published MPPT methods, with lesser complexity.
Analysis of power quality improvement in grid connected wind driven induction...eSAT Journals
Abstract As a promising renewable alternative, the wind power is one of the significant sources of generation. Reactive power compensation and harmonic reduction in a low voltage distribution networks for integration of wind power to the grid are the main issues addressed in this paper. This paper proposes a control scheme based on instaneous Pq theory for compensating the reactive power requirement of a three phase grid connected wind driven induction generator as well as the harmonics produced by the non linear load connected to the PCC using STATCOM. The proposed control scheme is simulated using MATLAB/SIMULINK. The Simulation results are presented in this paper. Keywords- wind power, distribution network, induction generator, STATCOM, reactive power.
Real Time Implementation of Variable Step Size Based P&O MPPT for PV Systems ...IJPEDS-IAES
Nowadays Solar energy is an important energy source due to the energy crisis and environment pollution. Maximum power point tracking (MPPT) algorithm improves the utilization efficiency of a photovoltaic systems. In this paper an improved P&O MPPT algorithm is developed and simulated using MATLAB / SIMULINK to control the DC/DC buck converter. The obtained simulink model is also verified using dspace tool. Both the simulated and experimental results are validated by also comparing them with conventional MPPT methods. The performance measures show the increase in the efficiency of PV system by the proposed model.
The International Journal of Engineering and Science (IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
A new bidirectional multilevel inverter topology with a high number of voltage levels with a very reduced number of power components is proposed in this paper. Only TEN power switches and four asymmetric DC voltage sources are used to generate 25 voltage levels in this new topology. The proposed multilevel converter is more suitable for e-mobility and photovoltaic applications where the overall energy source can be composed of a few units/associations of several basic source modules. Several benefits are provided by this new topology: Highly sinusoidal current and voltage waveforms, low Total Harmonic Distortion, very low switching losses, and minimum cost and size of the device. For optimum control of this 25-level voltage inverter, a special Modified Hybrid Modulation technique is performed. The proposed 25-level inverter is compared to various topologies published recently in terms of cost, the number of active power switches, clamped diodes, flying capacitors, DC floating capacitors, and the number of DC voltage sources. This comparison clearly shows that the proposed topology is cost-effective, compact, and very efficient. The effectiveness and the good performance of the proposed multilevel power converter (with and without PWM control) are verified and checked by computational simulations.
An improved luo converter for high power applicationseSAT Journals
Abstract
Power conversion is one of the major requirements in various industries and in daily life. Among various types of power
conversion, DC-DC conversion has greater importance. DC-DC conversion can be reliably performed using luo converter. It
employs voltage lift technique so that output voltage is increased stage by stage, in arithmetic progression. Luo converter can be
incorporated with the Z network or impedance network so as to ensure simple start up and smooth power conversion. An
impedance network consist of two identical inductors and two identical capacitors connected in ‘X’ shape. Besides power
conversion it also offers filtering operation. The luo converter in this scheme is of switched capacitor type. It helps to provide
regulated output voltage from an unregulated source of power supply. The major benefits of this proposed scheme is that it
combines the advantages of the switched capacitor, voltage lift technique and the impedance network. Hence the proposed scheme
has various advantages such as high power density, larger range of output DC voltage, lower or no inrush current, lower
harmonic injection, simple circuit, high voltage transfer gain, can process upto several tens of watts of power. The simulation
analysis and the hardware implementation shows that the output voltage obtained is higher than the expected theoretical value.
i.e, it is the highly boosted voltage output.
Keywords: Z-network, boost voltage, voltage lift technique
Grid-Connection Control and Simulation of PMSG Wind Power System Based on Mul...ijsrd.com
This dissertation proposes a wind energy conversion system is composed of a wind turbine PMSG, a rectifier, and an inverter. The wind turbine PMSG transforms the mechanical power from the wind into the electrical power, while the rectifier converts the AC power into DC power and controls the speed of the PMSG. The controllable inverter helps in converting the DC power to variable frequency and magnitude AC power. With the voltage oriented control, the inverter also possesses the ability to control the active and reactive powers injected into the grid. Multilevel inerter is used to step up the voltage and to reduce the THD. Here nine level and eleven level inverter are used and the voltage increases and THD reduces from 12.87 % to 7.46 %. Active and reactive power is controlled dc stabilization and the reactive power is near to unity Here PI controller is used to control the inverter output rms voltage and LC filter is used to remove the harmonics available in the system.
Power System Stability Enhancement Using FLC and MPC for STATCOMIJERA Editor
In modern power system, Static Compensator (STATCOM) is used to alleviate the transient stability problem
and damping power system oscillations. In this paper different STATCOM control scheme using fuzzy logic
controller (FLC) and model predictive controller (MPC) for the Single Machine Infinite Bus (SMIB) system in
improving transient stability is simulated using MATLAB/ Simulink in power systems block set. PI, FLC and
MPC signals are used to control and exchange the required reactive power among the STATCOM and the power
grid. A load disturbance is simulated and the behavior of the system for voltage fluctuations has been studied.
Simulation results using Proportional-Integral (PI) controller, Fuzzy Logic Controller (FLC) and Model
Predictive Controller (MPC) have been compared. The effectiveness of the different controllers in damping
oscillations and improving power system stability has been discussed.
Improving efficiency of Photovoltaic System with Neural Network Based MPPT Co...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Maximum PowerPoint Tracking of PV System Based on a SEPIC Converter Using Fuz...IJERA Editor
This paper presents the MPPT (Maximum power point tracking) operation of PV (Photovoltaic) system based
on a SEPIC (Single Ended Primary Inverter Converter) converter using fuzzy logic controller. MPPT method
such as Incremental conductance base on FLC (Fuzzy Logic Controller) is used to extract maximum output
power of the PV system. PV energy is the most essential energy resources since it is pollution free, clean and
endless. The FLC proposed scheme is interface with the MPPT to generate the PWM (Pulse Width Modulation)
for the SEPIC controller for maximum power point tracking operation.FLChas used Mamdani’s method for
convergent and divergent of membership function. FLC is used for more efficient performance under the
variation in different atmosphere. The fuzzy logic controller with SEPIC for MPPT scheme extract the
maximum power point tracking without any change in the voltage at the inverter at different load condition. The
behavior of the converter and controller tested in simulation at different operating conditions. Proposed scheme
is used for accurately tracking maximum point and also send the smooth, error free signal to the inverter.
Design of a Grid-Connected Photovoltaic Inverter with Maximum Power Point Tra...IAES-IJPEDS
There is no easy way to convert Photovoltaic (PV) energy with high
efficiency due to dynamic changes in solar irradiance and temperature. This
paper illustrates a control strategy to design and implementation of
Maximum Power Point Tracking (MPPT) in a photovoltaic system using
Perturb and Observe (P&O) algorithm. The PSIM simulation results confirm
proper functioning of the proposed MPPT sub-circuit to achieve a constant
48V DC output from fluctuating voltage of solar panel by varying duty cycle
of the MOSFET in the 24V-48V boost converter. The filtered output
waveform of the SPWM driven H-bridge inverter via the L-C low pass filter
is found to be a pure sine-wave of 48V peak which is then stepped-up 312V
peak (220V rms) by using a step up transformer. The frequency of output
voltage is found to be 50Hz with a total harmonic distortion (THD) of 0.001
which is much lower than the IEEE 519 standard.
Enhanced MPPT Technique For DC-DC Luo Converter Using Model Predictive Contro...IJERD Editor
The present study explored an enhanced maximum power point tracking technique which ensures fast tracking in PV systems. This system represents a Model Predictive Control (MPC) MPPT technique. Extracting the maximum power from PV systems has been widely investigated. The main benefaction of this article is an improvement of the Perturb and Observe (P&O) method through a fixed step predictive control under measured fast solar radiation. The preferred predictive control to achieve Maximum Power Point (MPP) speeds up the control loop since it predicts error before the switching signal is applied to the DC-DC Luo converter. Comparing the improved technique to the conventional P&O method indicates significant improvement in PV system performance. The proposed MPC-MPPT technique for a Luo converter is implemented using the MAT LAB SIMULINK
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Acoustic Analysis of Commercially Available Timber Species in NigeriaIJERA Editor
Several acoustic techniques have been used to determine elastic and damping properties of trees, logs and beams in different parts of the world but such acoustic data on timber are not available in standard form in Nigeria. Ten species of locally occurring Nigerian timber (five hardwood species and five softwoods species) were sampled and subjected to acoustic analysis using a „Portable Ultrasonic Non destructive Digital Indicating Tester (PUNDIT), with a view to assessing the stiffness and strength characteristics of the timber species by obtaining the velocity of ultrasonic longitudinal stress waves through the timber piece and hence calculating the dynamic Modulus of Elasticity (MoE) of each species. Results obtained showed that the velocity of acoustic waves through a timber piece and hence the dynamic modulus of elasticity (MoE) of the piece is directly proportional to the strength of the wood. Of all the timber species tested, the species with the highest MoE value (8.48GPa) was Mansonia (mansonia altissima) while that with the lowest MoE value (1.64GPa) was Alstonia (alstonia booeneicongensis). This study thus provides for the first time, valuable data on the strength characteristics of ten commercially available species of Nigerian timber represented in terms of their dynamic MoE values.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
3D printing device for numerical control machine and wood depositionIJERA Editor
The paper presents the development of a new sustainable approach in additive manufacturing adapted on a Numerical Control (NC) machining. Wood has several advantages that are transferable to various derivatives allowing the introduction of sustainable material into the product lifecycle. The application involves the integration of wood pulp into rapid prototyping solutions. Wood is the main material studied for its ecological aspect. The primary goal was to create reconstituted wood objects through a rapid manufacturing. Additive manufacturing technology is most commonly used for modeling, prototyping, tooling through an exclusive machine or 3D printer. An overall review and an analysis of technologies show that the additive manufacturing presents some little independent solutions [9] [12]. The problem studied especially the additive manufacturing limits to produce an ecological product with materials from biomass. The study developed a 3d printing head as solution for shaping wood pulp or powder materials. Some technological problematic require enslavement to the NC controller, the programming building of model, and the realization of wood pulp. This work also presents a wood pulping process characterized by adding wood flour and starch. A machine implementation and some application examples used for its development are presented.
Modeling the transport of charge carriers in the active devices diode submicr...IJERA Editor
A Monte Carlo simulation program was developed to simulate the movement of electrons in a submicron GaInP diode three dimensional (3D) with 0.1 microns-long active layer. The algorithm couples a standard Monte Carlo particle simulator for the Boltzmann equation with a 3D Poisson solver. Thus a series of hits for a specific MC submicron diode (GaInP), with an active layer (n = 2x1015cm-3) of length 0.1μm surrounded by two regions doped with n = 5x1017cm-3, are presented. The lattice temperature is 300K and the anode voltage Va is 1V. The analysis also showed that the average drift velocity to the electrons in the channel is about 5x106 cm/sec
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Reactive Power Compensation in Distribution Network with Slide Mode MPPT Cont...IJRST Journal
The Grid connected PV system requires a proper voltage control controller.
In this paper an efficient voltage control by using slide mode controller with
Maximum Power Point Tracking (MPPT) is presented. The voltage
command is determined by the PV panel. Here the sliding mode controller is
designed so as to balance the power flow from PV panel to the grid and load
such that the PV power is utilized effectively. The design and simulation
using MATLAB is presented in this work.
Modeling and Simulation of Fuzzy Logic based Maximum Power Point Tracking (MP...IJECEIAES
This paper presents modeling and simulation of maximum power point tracking (MPPT) used in solar PV power systems. The Fuzzy logic algorithm is used to minimize the error between the actual power and the estimated maximum power. The simulation model was developed and tested to investigate the effectiveness of the proposed MPPT controller. MATLAB Simulink was employed for simulation studies. The proposed system was simulated and tested successfully on a photovoltaic solar panel model. The Fuzzy logic algorithm succesfully tracking the MPPs and performs precise control under rapidly changing atmospheric conditions. Simulation results indicate the feasibility and improved functionality of the system.
Drive Applications of Fuzzy Logic Controlled Interleaved Boost Converter for ...EECJOURNAL
The improvement in the efficiency, a reduced ripple and reduction in the passive elements is proposed in this project through the interleaved boost converter. The interleaved boost converter operates multiple phase approach, is used for the power factor control applications. The proposed converter is used to extract the power output from the solar panel with reduced ripple losses and greater efficiency thereby obtaining the maximum power from the solar panel. The control of the current with energy saving method is obtained with the efficiency of 95%. The converter operation is controlled by the fuzzy logic controller to operate the switches with the finest and reduced power loss constrains. The proposed method is mathematically modeled and the results are analysed. A similar prototype model is designed and the results are compared with the theoretical values.
Modeling and simulation of three phases cascaded H-bridge grid-tied PV inverterjournalBEEI
In this paper a control scheme for three phase seven level cascaded H-bridge inverter for grid tied PV system is presented. As power generation from PV depends on varing environmental conditions, for extractraction of maximum power from PV array, fuzzy MPPT controller is incorporated with each PV array. It gives fast and accurate response. To maintain the grid current
sinusoidal under varying conditions, a digital PI controller scheme is adopted. A MATLAB/Simulink model is developed for this purpose and results are presented. At last THD analysis is carried out in order to validate the performance of the overall system. As discussed, with this control strategy the balanced grid current is obtained keeping THD values with in the specified range of IEEE-519 standard.
A Simple Control Strategy for Boost Converter Based Wind and Solar Hybrid Ene...IJRES Journal
This paper deals about the improvement of output from hybrid (Wind and PV) system through the maximum power point technique (MPPT). Though various power tracking techniques are available, Constant Voltage method is simple and effective way to track the maximum power. In this method output voltage is compared with the maximum voltage and based on the comparison gate signal is generated to the boost converter switch. Two boost converters are used individually for PV and Wind system. The whole system is modeled by using the Matlab/Simulink Model.
Modeling and Simulation of Solar Photovoltaic Systemijtsrd
Solar energy is a vital untapped resource in a tropical country like ours. The main hindrance for the penetration and reach of solar PV systems is their low efficiency and high capital cost. The efficiency of solar PV is very low. In order to increase the efficiency, Maximum Power Point Tracking (MPPT) techniques are to be undertaken to match the source and load property. These techniques are employed in PV systems to make full utilization of PV array output power. Recently, many MPPT algorithms of PV system have been proposed which depends on solar irradiation and temperature, but perturb and observe (P&O) and Incremental conductance algorithms are basic and most widely used. This project firstly introduces a Mat lab Simulink of photovoltaic array. To achieve the maximum power point tracking the Incremental Conductance method and perturb and observed (P&O) method are used. These two algorithms are employed with PV model along with converter in Mat lab Simulink. Three different converter boost, buck boost and cuk converter are design according to requirement and used. Few comparisons such as voltage, current and power output for each different combination have been recorded. Irfan Khan | Ameen Uddin Ahmad"Modeling and Simulation of Solar Photovoltaic System" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-6 , October 2017, URL: http://www.ijtsrd.com/papers/ijtsrd5743.pdf http://www.ijtsrd.com/engineering/electrical-engineering/5743/modeling-and-simulation-of-solar--photovoltaic-system/irfan-khan
Z - Source Multi Level Inverter Based PV Generation SystemIJERA Editor
In this paper a novel technique of Z-Source multilevel Inverter based PV Generation system is implemented and simulated using MATLAB-Simulink simulation software. The Photovoltaic cells are healthier option for converting solar energy into electricity. Due to high capital cost and low efficiency PV cells have not yet been a fully smart choice for electricity users. To enhance the performance of the system, Z-Source multi level inverter can be used in place of conventional Voltage Source Inverter (VSI) in Solar Power Generation System. The PV cell model is developed using circuit mathematical equations. The Z-Source multilevel inverter is modeled to realize boosted DC to AC conversion (inversion) with low THD. Outcome shows that the energy conversion efficiency of ZSMLI is a lot improved as compared to conventional voltage Source Inverter (VSI). By doing FFT analysis we can know the total THD.
Simulation of various DC-DC converters for photovoltaic systemIJECEIAES
This work explains the comparison of various dc-dc converters for photovoltaic systems. In recent day insufficient energy and continues increasing in fuel cost, exploration on renewable energy system becomes more essential. For high and medium power applications, high input source from renewable systems like photovoltaic and wind energy system turn into difficult one, which leads to increase of cost for installation process. So the generated voltage from PV system is boosted with help various boost converter depends on the applications. Here the various converters are like boost converter, buck converter, buck-boost converter, cuk converter, sepic converter and zeta converter are analysed for photovoltaic system, which are verified using matlab / simulink.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
High Proficiency Grid ConnectedPhotovoltaic Power Generation SystemIJRES Journal
Solar energy hasbecomepopular nowadays and desire for clean energy. Since the solar radiation on no occasion remains constant,it keeps on insecure throughout the day. The need of the hour is to distribute a constant voltage to the grid irrespective of the deviation in temperatures and solar insolation. The inverter is designed from a boost converter along with a line frequency. The voltage from the boost converter is fedto the grid through inverter. In this proposed method high efficiency can be achievedby using only one switch functioning at high frequency at a time. The converter uses IGBT and ultra-fast reverse recovery diode. The simulation and experiment results are verified using MATLAB/Simulink software.
High Proficiency Grid ConnectedPhotovoltaic Power Generation System
A0411030109
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Modelling and Simulation of a Grid-Connected PV System based on Efficient Maximum Power Point Tracking Algorithm
F. Q. Al-Enezi, M. Rotaru, J. K. Sykulski Electronics and Computer Science, Faculty of Physical Sciences and Engineering, University of Southampton, UK
Abstract— The results presented in this paper have been acquired through simulation of a grid-connected photovoltaic system (GCPV) to a specific section of Alsabyia generation station part of Kuwait national grid with efficient maximum power point tracking (MPPT) algorithm incorporated into a DC-DC boost converter. The simulations were performed using Power Simulation Software (PSIM). The analytical model of a photovoltaic (PV) module has been combined with a ‗perturb and observe‘ (P&O) method so that MPP is achieved with the external temperature and solar radiation (SR) also considered. A DC-AC inverter is used to track the output voltage of the converter and interface the PV array with the grid. The results show that the model not only achieves the MPP function but also improves the output of the inverter by reducing the ripples in the sine waveforms.
Index Terms— Solar radiation (SR), Grid-connected photovoltaic (GCPV), Maximum power point tracking (MPPT) I. INTRODUCTION When larger PV installations are designed, there is a need to understand their performance when integrated with the power system (a specific section of Alsabyia generation station part of Kuwait national grid). Therefore, simulations of large PV installations integrated within the electrical grid are necessary. Numerically the problem that needs to be solved is a combination of non-linear equations describing the PV generators, including the switching inverters, operational DC-DC converter and the PV generation with linear equations describing the rest of the power system. Many studies have discussed and proposed solutions to the numerical problems posed by GCPV power simulations [1, 2]. From a purely mathematical point of view, at each step of the simulation, the set composed of non-linear equations representing PV generators and linear equations describing the rest of the power system must be solved, using an iterative numerical algorithm [2]. Some power system simulation tools adopt this approach, such as PSIM and MATLAB/Simulink. This approach is accurate, but with the drawback of a heavy computational burden when simulating large distribution networks including PV systems [3]. Moreover, the non-linear equations introduce a dependency of the current injected by a PV generator on the terminal voltage, which in turn is related to the operating conditions of the whole power system. Such a dependency can cause numerical instability of the simulation [4]. II. GCPV SYSTEM SIMULATION SETUP
The system considered in this study consists of a PV module, a DC-DC boost converter and a DC-AC inverter. The system described here uses a simplified PV cell model however, the model includes the effects of changing the SR. The maximum power of the PV module is tracked with the help of an MPPT algorithm that is incorporated into the DC-DC converter. The inverter used to regulate the output voltage of the converter is connected to the rest of Alsabyia grid through an LC filter which ensures clean current injection. Figure 1 shows a general topology of a PV generation system. The PV depicted below is a standard integrated PV system connected to a DC-DC converter and then to a pulse-width modulated (PWM) DC-AC inverter. Since the output voltage of the PV module has a very broad voltage range, in general a DC-DC converter is used to ensure constant high output DC voltage with MPPT to track the maximum power of the PV system. In order to use the DC output power for residence applications, it is required to convert the DC output power to AC power using a PWM inverter.
Figure 1: Schematic diagram of a complete PV generation system
RESEARCH ARTICLE OPEN ACCESS
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The simulation process is quite sophisticated. It uses a current-voltage (I-V) curve characterization of the PV module accounting for the instantaneous cell temperature. We chose to evaluate a specific area in a square meter off-grid PV array in Kuwait not far away from Alsabyia grid. Specifications (input variables for the simulation process) carried in the database and transferred to the PV simulation are:
Total SR over Kuwait area.
Actual capacity of the PV array.
Length and width of the PV module.
Open-circuit voltage.
Short-circuit current.
Voltage temperature coefficient.
Current temperature coefficient.
Number of modules in series.
Number of modules in parallel.
Panel configuration.
Characteristics of the selected PV module: efficiency, cell temperature, sizing factor and temperature coefficients.
Characteristics of the selected inverter: AC power, voltage, PV voltage range at maximum power, maximum efficiency and maximum input current.
The system characteristics are system voltage, current, panel capacity, mismatch, and the inverter power and inverter efficiency at rated power. In the algorithm presented here, which simulates the GCPV system, the controller is assumed to achieve cell operation at the MPP. In the following sections of the paper each of the important parts of the model will be introduced and explained. First the PV cell model is introduced. The model is simple, accurate, and takes SR into consideration. Then the MPPT control algorithm is discussed. The P&O method is then used in conjunction with the MPPT algorithm. The results obtained from a PSIM simulation are also presented. Section III explains the reasons for using a boost converter for this application as a DC-DC converter, and it discusses the operating principles. Finally, the last part of the system, the DC-AC inverter, is discussed before the whole PV system is presented. The system simulation results are presented and discussed. III. SYSTEM COMPONENTS
Simulation of the system is not an end in itself; it is to permit insight into the operation of the system in such a way that weaknesses can be identified. The proposed model of the entire components and control system are all simulated in PSIM Software. The simulation results under PSIM show the control performance and dynamic behavior of the GCPV system.
1) PV Module
The single-diode equivalent circuit is the most commonly adopted model of PV cells, accounting for the photon-generated current and the physics of the p- n junction of a PV cell. The simulation structure of the PV model in PSIM has been shown in Figure 2.
Figure 2: Simulation structure of PV model A PSIM program was used to validate the developed solar module model. The parameters used to define the PV cell are shown in Table 1. Table 1: Parameters of the PV Cell in PSIM Model Parameter Variable Value
Current at Maximum Power
Im
4.95 A
Voltage at Maximum Power
Vm
35.2 V
Open Circuit Voltage
Voc
44.2 V
Short Circuit Current
Isc
5.2 A
Temperature Coefficient of Short Circuit Current
a
0.015 A/°K
Temperature Coefficient of Open Circuit Voltage
b
0.7V/°K
Internal Series Resistance
Rs
0.217 Ω
Reference Solar Radiation
SRref
1000 W/m2
Reference Temperature
Tref
25°C
The PV-side DC voltages, currents and power are illustrated in Figures 3 to 5. As expected, the results obtained with this simulation show that the PV module voltage, current and power settle to 52 V, 5.7 A and 293 W, respectively, after a brief transient due to the switching. These results gave us confidence in the PV module model. The output is a voltage that
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drives an assumed resistive load, RL. Note that the
solar panel current can be varied by changing the load
resistance and both voltage and current at the output
of the solar panel can be tracked and measured. It is
encouraging that there is very good agreement
between expected (53 V, 5.8 A) and simulated signals
(EPV, IPV).
Figure 3: PV-side voltage waveform per module
Figure 4: PV-side current waveform of per module
The simulation results for the I-V and P-V curves
are shown in Figures 6 and 7. Figure 6 shows the I-V
characteristic curve of one PV string, while Figure 7
shows the P-V characteristic curve. The model curves
show three significant details: the short-circuit
current, the open-circuit voltage, and the maximum
power point. It can be noticed that the PV string
behaves like a current source when the output voltage
is less than a threshold value as the current changes
very little with the change in output voltage whereas
above the threshold voltage it behaves more like a
voltage source whit a sharp drop in current as the
voltage is increased.
Figure 5: PV-side power waveform per module
The span of the I-V curve of one PV string ranges
from the short circuit current (ISC = 275 A) at zero
volts, to zero current at the open circuit voltage (Voc =
3650 V). At the ‗knee‘ of a normal I-V curve there is
a point where the PV cell generates the maximum
power, called the maximum power point, MPP, (Imp =
250 A, Vmp = 3000 V). In an operating PV system, one
of the jobs of the inverter is to constantly adjust the
load, seeking out the particular point on the I-V curve
at which the array as a whole yields the greatest DC
power. At voltages well below Vmp, the flow of solar-generated
electrical charge to the external load is
relatively independent of output voltage. Near the
knee of the curve, this behavior starts to change. As
the voltage increases further, an increasing percentage
of the charges recombine within the solar cells rather
than flowing out through the load. At Voc, all of the
charges recombine internally. The maximum power
point (MPP = Pmax(string) = 750 kW), located at the
knee of the curve, is the (I, V) point at which the
product of current and voltage reaches its maximum
value.
Figure 6: I-V characteristic of one PV string
0 0.0002 0.0004 0.0006 0.0008 0.001
Time (s)
30
35
40
45
50
55
60
65
VP1
0 0.0002 0.0004 0.0006 0.0008 0.001
Time (s)
3.5
4
4.5
5
5.5
6
6.5
7
I1
0 0.0002 0.0004 0.0006 0.0008 0.001
Time (s)
0
100
200
300
400
500
Power
0 500 1000 1500 2000 2500 3000 3500 4000
0
50
100
150
200
250
300
Current [A]
Voltage [V]
Threshold voltage
Isc
Voc
Imp
Vmp
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Figure 7: P-V characteristic of one PV string
2) Maximum Power Point Tracking (MPPT)
Control Algorithm
An MPPT is used to extract the maximum power
from the PV cell and transfer it to the load [5]. Since
the output power of a PV cell is related to many
parameters, such as SR, temperature and load, the
output characteristic is nonlinear with respect to the
output voltage. It is necessary for the PV system to
work at the maximum power point under changing
external environment to achieve best performance.
Furthermore, this point depends on the SR and
temperature of the panels and both conditions change
during the day and are different depending on the
season of the year. Moreover, SR can change rapidly
due to changing atmospheric conditions such as
clouds. It is very important to track the MPP
accurately under all possible conditions so that the
maximum available power is always obtained.
Improving the tracking of the MPP with the
developed control algorithms (see Figures 9 and 10)
is easier, not expensive and can be done even in
plants which are already in use by updating their
control algorithms, which would lead to an immediate
increase in PV power generation and consequently a
reduction in its price [6]. On the other hand, trying to
improve the efficiency of the PV panel and the
inverter, although important, is not simple and could
be very costly as it depends on many variables and
manufacturing technologies available.
MPPT algorithms are necessary in PV
applications because the MPP of a PV panel varies
with the SR, so the use of MPPT algorithms is
required in order to obtain the maximum power from
a PV array. In this study, we chose the Perturb and
Observe (P&O) method for its simplicity, relative
accuracy and rapid response [7-8]. The P&O method
involves a perturbation in the operating voltage of the
DC link between the PV array and the power
converter. This method is easy to implement, because
the sign of the last perturbation and the sign of the
last increment in the power are used to decide what
the next perturbation should be. If there is an
increment in the power, the perturbation should be
kept in the same direction and if the power decreases,
then the next perturbation should be in the opposite
direction. Using these observations, the algorithm is
implemented. The process is repeated until the MPP
is reached. Then the operating point oscillates around
the MPP. Figure 8 shows the flowchart of the P&O
method. By comparing the PV cell output power of
each control cycle before and after the perturbation,
the new perturbation direction can be determined. If
the output power is increasing, the previous voltage
perturbation direction will be followed in the new
cycle. Otherwise, the voltage perturbation direction
will change. By this algorithm, the operating point of
PV cell can get closer to the maximum power point
and finally reach a steady state.
One of the objectives of this study is to develop a
model to test the dynamic performance of the MPPT
algorithm shown in Figure 8 independently of the
converter used. A detailed model of a PV system,
with the switching model of the power converter, is
computationally very demanding while the time that
can be simulated in a normal computer is only a few
seconds. However, the simulation time required for
testing the system with the SR profiles can be up to
several minutes, which can be difficult or impossible
to achieve on conventional PC, if a complete model
of the PV system would be used. The main limitation
for such simulation is the limited amount of memory
available on a conventional PC. For example, to
increase the reference voltage and go back to compute
the new output power the program has to check again
all the power values with different average daily and
monthly SR and this process takes several minutes.
Figure 8: Flowchart of P&O method
0 500 1000 1500 2000 2500 3000 3500 4000
0
1
2
3
4
5
6
7
8
x 10
5
Power [W]
Voltage [V]
MPP
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The model proposed here was developed in PSIM and consists of a PV array model, a DC-link capacitor and a controlled current source, which replaces the power converter. The MPPT control block generates the reference voltage using the algorithm under test (see Figure 9a). The reference voltage generated by the MPPT control block is converted to a current reference using the control scheme shown in Figure 9b. In this scheme, the error between the reference and the actual DC voltage (the output voltage of the PV array) is fed in a proportional gain, whose value depends on the DC link capacitance and the sampling period. The output of this gain is subtracted from the current of the PV module and the result is the reference current for the controlled current source. As the model is more complex, the simulation time can be much longer, the time needed to simulate 130 seconds is only a few minutes, and the simulation time can be over 1000 seconds. However, if the model includes a detailed switching power converter model, for example a three phase inverter, the simulation time can be only a few seconds and the time needed for MPPT efficiency tests is much longer. The simulation model for the P&O MPPT algorithm is shown in Figure 10. The new perturbation is decided based on previous and current output power as follows: if ΔP×ΔV > 0, the operating voltage should increase; while if ΔP×ΔV < 0, the operating voltage should decrease. The operating voltage change is accomplished by adjusting the step size ΔD of the duty cycle D for the DC-DC converter. (The DC-DC converter will be introduced in the next section). This model has two parameters, the step size ΔD and the time between iterations. The smaller the P&O step size, the more accurate the result however, this will result in a longer simulation time.
Figure 9: Control circuit used for simulation The parameters of the system studied in this paper are summarized in Table 2.
Table 2: System Parameters
Solar panel characteristics at STC
Open-circuit voltage
900 V
Voltage at MPP
700.2 V
Short-circuit current
20 A
Current at MPP
17.6 A DC-Link Capacitor
Capacitance
700 μF
ESR
1 mΩ Sampling frequency
MPPT algorithm
25 Hz
V and I measurements
20 kHz
The characteristics of the solar array were chosen in order to fulfill the requirements of the inverter. The input voltage of the inverter (VMPP) has to be greater than the peak line-to-line voltage of the output ( 6 × 230 V ≈ 563 V). The current was selected so that the power level is over 100 MW. The sample frequency of the MPPT algorithm should not be very high because the changes in the weather conditions are relatively slow compared to the dynamics of systems typically studied in control theory, whereas the sampling frequency of the voltage and current measurements was chosen according to the sampling time of a modern DSP.
Figure 10: Simulation model for P&O MPPT algorithm
3) DC-DC Converter with PV Module Simulation
The output voltage of a PV system is very low and fluctuates, as the SR and temperature change daily and seasonally. Therefore, a DC-DC converter is used to get constant high output DC voltage. Furthermore, a DC-DC converter serves the purpose of transferring maximum power from the solar PV cell to the load. The converter acts as an interface between the load and the PV cell. By changing the duty cycle D, the load impedance is varied and
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matched at the point of the peak power with the source, so as to transfer the maximum power [10]. There are four basic configurations and topologies of DC-DC converters as buck, boost, buck-boost and cuk. The boost type converter is considered the most advantageous to implement together with the MPPT algorithm for the following reasons:
a) The output voltage is always higher than the input PV cell voltage, which is useful as the PV cell needs to be connected to the grid eventually.
b) The topology of the boost converter is simple, easy to implement, low cost and has high efficiency.
c) The control of the boost converter is also relatively easy hence fluctuations can be minimized and also there is increase tracing accuracy.
The function of a boost converter is to regulate the output voltage from the PV array at different operating conditions. Figure 11 shows the topology of a DC-DC boost converter, as a combination of power semiconductor switch operating at a switching frequency, a diode and an LC filter. For this converter, power flow is controlled by means of the on/off duty cycle of the switching transistor. When the switch is ‗On‘ for ton seconds, current flows through the inductor in clockwise, and energy Vi I1 ton is stored in the inductor. When the switch is ‗Off‘ for toff seconds, current will be reduced for increasing impedance. The only path of the inductor current is through diode D to the capacitor C and resistive load R. The polarity of the inductor will change. The energy accumulated in the inductor during the On- state will be released, (Vc-Vi) I1 toff. Hence, Vi I1 ton = (Vc-Vi) I1 toff (1) Therefore, Vc = 푡표푓푓 푡표푛+ 푡표푓푓 푉푖 = 푇 푡표푓푓 푉푖 = 11+ 퐷 푉푖 (2) where D is the duty cycle, which is the fraction of the commutation period T during which the switch is On. Since 푇 푡표푓푓 ≥ 1, the output voltage is always higher than the source voltage.
Figure 11: Topology of DC-DC boost converter The circuit model of the DC-side of the proposed GCPV system is shown in Figure 13. It is composed of the developed circuit PV module model with a DC- DC boost converter model. A PWM boost converter of parameters shown in Table 3 is used for MPPT. The simulation model for the DC-DC converter is shown in Figure 12. Table 3: Parameters of the DC-DC Converter PSIM Parameter Value
Inductor L
0.01 H
Capacitor C
2 × 10-3 F
Capacitor C1
2 × 10-3 F
Resistor R
500 Ω
Figure 12: Simulation model for DC-DC converter
When temperature and SR are fixed, T = 25°C and SR = 1000 W/m2, it can be seen from Figure 14 that the system reaches the maximum power point at a time t = 0.2 s. The time t = 0 to t = 0.05 s is a period for the system to initiate its state, at time t = 0.05 s the
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PV cell has output voltage, but its current is zero therefore the output power is zero too. From time t = 0.05 s to t = 0.2 s, the simulated voltage output with the MPPT control based on P&O method overshoots and undershoots. However, after t = 0.2 s, the voltage value oscillates around 36 V in a very regular manner. This is due to the P&O method used here.
Figure 13: PV module with step up DC-DC converter circuit model
Figure 14: Simulation results for MPPT when temperature and SR keep unchanged, T = 25°C,SR = 1000 W/m2 As shown in Figure 15, the boost (step-up) converter has raised the output voltage of one PV string from 2.2 kV up to 15 kV. This voltage level can be now interfaced with a suitable DC-AC inverter. The output voltage is free from ripple and it is in the real time domain. The DC output current is shown in Figure 16, ignoring the switching transient, its amplitude is 241.3 A.
Figure 15: DC-DC boost converter output voltage of one PV string
Figure 16: DC-DC boost converter output current of one PV string In addition, the result of the DC output power of one PV panel is illustrated in Figure 17. The output power of one panel is approximately 0.710 MW and it is 94.7% of its calculated value (0.75 MW) which is very satisfactory.
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Figure 17: DC output power of one PV panel
4) DC-AC Inverter Simulation Model
The DC voltage that a PV array produces has to
be converted into an AC voltage so that it can be fed
into Alsabyia grid. In this study a three-phase PWM
inverter with a low-pass filter was employed to
perform this task. The inverter is connecting the
output DC bus voltage of the converter to the PV
system providing the necessary conversion and
regulation from the DC bus to the AC load. The
output voltage is required to be sinusoidal and in
phase with the grid voltage. The LC filter, which
comprises an inductor and a capacitor driven by
a voltage source, can generate good output voltage
regulations at a particular frequency (50 Hz). Figure
18 shows the simulation model of the whole GCPV
system. The inverter is controlled using a current-mode
control. The reference current i* is sent to
compare with the DC-AC output current. The
compared result is sent to a discrete PI controller to
generate signals for a PWM generator. The PWM
signal can be used to control switches of the inverter.
The frequency of the PWM waveform is set to 5 kHz,
which can reduce the switching noise, simplify the
system design and improve the dynamic performance
[9]. Some important parameters related to the
simulation process for the whole GCPV system have
been shown in Table 4.
Table 4: Parameters of the full GCPV System
Simulation Model
The AC
voltage source
(grid voltage)
PI controller
LC
filter
Peak amplitude
155.5 V
Instantaneous
time
T = 5 × 10-7
L1 = 10
mH
Phase = 0
Proportional
gain Kp = 6
C = 2
μF
Frequency =
50 Hz
Integral gain
Ki = 256
A Power Simulation Software (PSIM) has been
implemented to simulate the proposed overall PV
system.
Figure 18: Simulation model of whole GCPV system
The simulation result shown in Figure 19 is
obtained when the temperature and SR are kept
constant at T = 25°C,SR = 1000 W/m2. After 0.05 s,
the output current of the inverter is almost sinusoidal
and in phase with the grid voltage. The total harmonic
distortion (THD) % of the inverter‘s current is
4.122%, which satisfies UL1747 standard
requirements for THD [10].
Figure 19: Simulation result when temperature and
SR keep unchanged, T = 25°C ,SR = 1000 W/m2
IV. CONCLUSIONS
In this study a full GCPV model connected to a
section of Alsabyia generation station part of Kuwait
national grid has been developed, simulated and
analysed. The PV modules are modelled using an
analytical description of PV cells. The maximum
0 0.1 0.2 0.3 0.4 0.5
Time (s)
0
1e+006
2e+006
3e+006
4e+006
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Power
9. F. Q. Al-Enezi et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 11( Version3), November 2014, pp.01-09
www.ijera.com 9 | P a g e
power of the PV module is tracked with an adjusted P&O MPPT algorithm based on boost DC-DC converter. A DC-AC inverter is employed to connect the PV module to Alsabyia grid and regulate the output voltage of the converter. The effects of unchanged temperature and SR have been simulated and analysed. The whole GCPV systems was built and simulated within the PSIM package and allows easy access to all its variables and system inputs. This model provides a very good tool to design size and analyse GCPV systems in a very reasonable time and with relative high accuracy. The overall simulation model is able to maintain constant voltage and good output voltage regulations especially with an LC filter. REFERENCES
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