This document proposes methods to improve the dynamic response of a grid-connected hybrid power system comprising wind and photovoltaic generation. It implements an artificial neural network trained by genetic algorithm (ANN-GA) to maximize solar array output under varying irradiation and temperature conditions. It also uses a fuzzy logic controller for wind turbine pitch angle control in high wind speeds, compared to a conventional PI controller. Simulation results show the ANN-GA method achieves maximum power point tracking for the solar arrays more reliably than conventional perturb and observe or incremental conductance methods. The fuzzy logic controller also provides faster response and smoother power curves for the wind turbine, improving overall dynamic system performance.
Enhancement of On-grid PV System under Irradiance and Temperature Variations ...IJECEIAES
Solar Energy is one of the key solutions to future electrical power generation. Photovoltaic Plants (PV) are fast growing to satisfy electrical power demand. Different maximum power point tracking techniques (MPPT) are used to maximize PV systems generated power. In this paper, on grid PV system model in MATLAB SIMULINK is tested under sudden irradiance and cell temperature variations. Incremental Conductance MPPT is used to maximize generated power from the PV system with the help of new adaptive controller to withstand these heavy disturbances. The new adaptive controller is tuned for optimal operation using two different optimization techniques (Invasive weed and Harmony search).Optimization results for the two techniques are compared. .A robustness test is made to check system stability to withstand different random irradiance and cell temperature patterns without failure to track the maximum power point. Finally, a brief comparison is made with a previous literature and the new adaptive controller gives better results.
A Wind driven PV- FC Hybrid System and its Power Management Strategies in a GridIJERA Editor
This paper shows the work done on the method to operate a Wind driven grid connected hybrid system which is composed of a Photovoltaic (PV) array and a Proton exchange membrane fuel cell . A wind system provides with an opportunity to harness the abundantly available renewable resource. With the proton exchange membrane the hybrid system output power becomes controllable. Here the system uses two operation modes, the unit-power control (UPC) mode and the feeder-flow control (FFC) mode. This papers discusses the coordination of two control modes, the coordination of the PV array and the proton exchange membrane fuel cell in hybrid system and the way in which the reference parameters are determined.
Enhancement of On-grid PV System under Irradiance and Temperature Variations ...IJECEIAES
Solar Energy is one of the key solutions to future electrical power generation. Photovoltaic Plants (PV) are fast growing to satisfy electrical power demand. Different maximum power point tracking techniques (MPPT) are used to maximize PV systems generated power. In this paper, on grid PV system model in MATLAB SIMULINK is tested under sudden irradiance and cell temperature variations. Incremental Conductance MPPT is used to maximize generated power from the PV system with the help of new adaptive controller to withstand these heavy disturbances. The new adaptive controller is tuned for optimal operation using two different optimization techniques (Invasive weed and Harmony search).Optimization results for the two techniques are compared. .A robustness test is made to check system stability to withstand different random irradiance and cell temperature patterns without failure to track the maximum power point. Finally, a brief comparison is made with a previous literature and the new adaptive controller gives better results.
A Wind driven PV- FC Hybrid System and its Power Management Strategies in a GridIJERA Editor
This paper shows the work done on the method to operate a Wind driven grid connected hybrid system which is composed of a Photovoltaic (PV) array and a Proton exchange membrane fuel cell . A wind system provides with an opportunity to harness the abundantly available renewable resource. With the proton exchange membrane the hybrid system output power becomes controllable. Here the system uses two operation modes, the unit-power control (UPC) mode and the feeder-flow control (FFC) mode. This papers discusses the coordination of two control modes, the coordination of the PV array and the proton exchange membrane fuel cell in hybrid system and the way in which the reference parameters are determined.
Small Signal Stability Improvement and Congestion Management Using PSO Based ...IDES Editor
In this paper an attempt has been made to study the
application of Thyristor Controlled Series Capacitor (TCSC)
to mitigate small signal stability problem in addition to
congestion management of a heavily loaded line in a
multimachine power system. The Flexible AC Transmission
System (FACTS) devices such as TCSC can be used to control
the power flows in the network and can help in improvement
of small signal stability aspect. It can also provide relief to
congestion in the heavily loaded line. However, the
performance of any FACTS device highly depends upon its
parameters and placement at suitable locations in the power
network. In this paper, Particle Swarm Optimization (PSO)
method has been used for determining the optimal locations
and parameters of the TCSC controller in order to damp small
signal oscillations. Transmission Line Flow (TLF) Sensitivity
method has been used for curtailment of non-firm load to
limit power flow congestion. The results of simulation reveals
that TCSC controllers, placed optimally, not only mitigate
small signal oscillations but they can also alleviate line flow
congestion effectively.
Tracking of Maximum Power from Wind Using Fuzzy Logic Controller Based On PMSGIJMER
Wind energy has gained a growing worldwide interest due to the nonstop rise in fuel cost.
The main aim of the wind-energy system is to extract the maximum power present in the wind stream. In
order to extract the highest power, the maximum power point tracking (MPPT) algorithm is used. This
paper proposes the fuzzy logic MPPT controller to track the maximum power from the wind generation
system. The maximum power is achieved based on the rotor speed of the wind system which consists of
wind turbine and PMSG. The error and change in error is given as input to the fuzzy logic and its output
is connected to the boost converter. The voltage from the dc link is controlled by the Voltage Source
Inverter (VSI), and it is placed in grid side converter control. The proposed system is designed and
evaluated in MATLAB/SIMULINK. Simulation results show the good dynamic performance of the
proposed system
This paper focuses on the artificial bee colony (ABC) algorithm, which is a nonlinear optimization problem. is proposed to find the optimal power flow (OPF). To solve this problem, we will apply the ABC algorithm to a power system incorporating wind power. The proposed approach is applied on a standard IEEE-30 system with wind farms located on different buses and with different penetration levels to show the impact of wind farms on the system in order to obtain the optimal settings of control variables of the OPF problem. Based on technical results obtained, the ABC algorithm is shown to achieve a lower cost and losses than the other methods applied, while incorporating wind power into the system, high performance would be gained.
Design of Hybrid Solar Wind Energy System in a Microgrid with MPPT Techniques IJECEIAES
DC Microgrid is one feasible and effective solution to integrate renewable energy sources as well as to supply electricity. This paper proposes a DC microgrid with enhanced Maximum Power Point Tracking (MPPT) techniques for wind and solar energy systems. In this paper, the PV system power generation is enhanced by introducing a two-model MPPT technique that combines incremental conductance and constant voltage MPPT algorithms. Also, for the Wind Energy Conversion System (WECS) with pitch angle controlling technique, an Optimal Power Control MPPT technique is added. The Space Vector Pulse Width Modulation technique is introduced on grid side converter to improve the supply to the grid. The performance of proposed system is analyzed and the efficiency obtained with these methods is enhanced as compared with the previous methods.
This research presents tracking the maximum power of a photovoltaic to control a five-level inverter, a cascade type connecting a single-phase grid-connected system with a fuzzy logic control model. Maximum power tracking control In this research, the principle of controlling the maximum current amplitude of the photovoltaic multiplied by the sine signal per unit that used as a reference current compared to the grid current. Signal comparison with the PID controller allows the creation of five levels of PWM of cascade control of five-level inverter connects single-phase grids. The results of the simulation test using the program MATLAB/Simulink to compare with the generated prototype found that the fuzzy logic principle was used to control the maximum power tracking conditions of the P&O method, when the amount of radiation light intensity decreases suddenly, making it possible to track the maximum power of the photovoltaic. Also, when the inverter connected to the grid by controlling the power angle to compare results between the simulation and the prototype — found that the current flowing into the grid increases according to the power angle control. Resulting in a nearby waveform, sine wave and an out of phase angle to the grid voltage because the system is in the inverter mode, and the harmonic spectrum of the grid currently has total harmonic distortion (THD) is reduced as an indication of the proposed system can be developed and applications.
The significance of the solar energy is to intensify the effectiveness of the Solar Panel with the use of a primordial solar tracking system. Here we propounded a solar positioning system with the use of the global positioning system (GPS) , artificial neural network (ANN) and image processing (IP) . The azimuth angle of the sun is evaluated using GPS which provide latitude, date, longitude and time. The image processing used to find sun image through which centroid of sun is calculated and finally by comparing the centroid of sun with GPS quadrate to achieve optimum tracking point. Weather conditions and situation observed through AI decision making with the help of IP algorithms. The presented advance adaptation is analyzed and established via experimental effects which might be made available on the memory of the cloud carrier for systematization. The proposed system improve power gain by 59.21% and 10.32% compare to stable system (SS) and two-axis solar following system (TASF) respectively. The reduced tracking error of IoT based Two-axis solar following system (IoT-TASF) reduces their azimuth angle error by 0.20 degree.
The aim of this research is the speed tracking of the permanent magnet synchronous motor (PMSM) using an intelligent Neural-Network based adapative backstepping control. First, the model of PMSM in the Park synchronous frame is derived. Then, the PMSM speed regulation is investigated using the classical method utilizing the field oriented control theory. Thereafter, a robust nonlinear controller employing an adaptive backstepping strategy is investigated in order to achieve a good performance tracking objective under motor parameters changing and external load torque application. In the final step, a neural network estimator is integrated with the adaptive controller to estimate the motor parameters values and the load disturbance value for enhancing the effectiveness of the adaptive backstepping controller. The robsutness of the presented control algorithm is demonstrated using simulation tests. The obtained results clearly demonstrate that the presented NN-adaptive control algorithm can provide good trackingperformances for the speed trackingin the presence of motor parameter variation and load application.
Electric Vehicle as an Energy Storage for Grid Connected Solar Power SystemIAES-IJPEDS
In the past few years the growing demand for electricity and serious concern
for the environment have given rise to the growth of sustainable sources like
wind, solar, tidal, biomass etc. The technological advancement in power
electronics has led to the extensive usage of solar power. Solar power output
varies with the weather conditions and under shading conditions. With the
increasing concerns of the impacts of the high penetration of Photovoltaic
(PV) systems, a technical study about their effects on the power quality of
the utility grid is required. This paper investigates the functioning of a gridtied
PV system along with maximum power point tracking (MPPT)
algorithm. The effects of varying atmospheric conditions like solar irradiance
and temperature are also taken into account. It is proposed in this work that
an Electric Vehicle (EV) can be used as an energy storage to stabilize the
power supplied to the grid from the photovoltaic resources. A coordinated
control is necessary for the EV to obtain desired outcome. The modeling of
the PV and EV system is carried out in PSCAD and the proposed idea is
verified through simulation results utilizing real field data for solar irradiance
and temperature.
Simulink Model for Cost-effective Analysis of Hybrid SystemIJMER
Utilization of non conventional sources of energy to meet the present day energy requirement has become very much essential in the era of fossil fuel crises. The present paper discusses the importance of PV-Diesel hybrid system to meet electrical requirement in remote areas. A model of a photovoltaic array with diesel battery was designed by MATLAB simulink. In this paper, the cost-effective analysis which includes the fuel consumed, the energy obtained per gallon of fuel supplied, and the total cost of fuel. Simulations done for Diesel generator system, diesel-battery system and solar PV with diesel-battery system using a one-year time period. Based on simulation results energy payback period for PV array, the simple payback time for the PV module calculated. Simulation analysis includes the comparison of system cost, efficiency, and kWh per gallon with those predicted by Hybrid Optimization Model for Electric Renewables (HOMER).
Large-scale grid-tied photovoltaic (PV) station are increasing rapidly. However, this large penetration of PV system creates frequency fluctuation in the grid due to the intermittency of solar irradiance. Therefore, in this paper, a robust droop control mechanism of the battery energy storage system (BESS) is developed in order to damp the frequency fluctuation of the multi-machine grid system due to variable active power injected from the PV panel. The proposed droop control strategy incorporates frequency error signal and dead-band for effective minimization of frequency fluctuation. The BESS system is used to consume/inject an effective amount of active power based upon the frequency oscillation of the grid system. The simulation analysis is carried out using PSCAD/EMTDC software to prove the effectiveness of the proposed droop control-based BESS system. The simulation result implies that the proposed scheme can efficiently curtail the frequency oscillation.
Twitter is a free social networking microblogging service that allows registered members to broadcast, in real-time, short posts called tweets. Twitter members can broadcast tweets and follow other users’ tweets by using multiple devices, making this information system one of the fastest in the world. In this chapter, we leverage this characteristic to introduce a novel topic-detection method aimed at informing, in real-time, a specific user about the most emerging arguments expressed by the network around his/her domain interests. With this goal, we aim at formalizing the information spread over the network by studying the topology of the network and by modeling the implicit and explicit connections among the users. Then, we propose an innovative term aging model, based on a biological metaphor, to retrieve the freshest arguments of discussion, represented through a minimal set of terms, expressed by the community within the foci of interest of a specific user. We finally test the proposed model through various experiments and user studies.
Small Signal Stability Improvement and Congestion Management Using PSO Based ...IDES Editor
In this paper an attempt has been made to study the
application of Thyristor Controlled Series Capacitor (TCSC)
to mitigate small signal stability problem in addition to
congestion management of a heavily loaded line in a
multimachine power system. The Flexible AC Transmission
System (FACTS) devices such as TCSC can be used to control
the power flows in the network and can help in improvement
of small signal stability aspect. It can also provide relief to
congestion in the heavily loaded line. However, the
performance of any FACTS device highly depends upon its
parameters and placement at suitable locations in the power
network. In this paper, Particle Swarm Optimization (PSO)
method has been used for determining the optimal locations
and parameters of the TCSC controller in order to damp small
signal oscillations. Transmission Line Flow (TLF) Sensitivity
method has been used for curtailment of non-firm load to
limit power flow congestion. The results of simulation reveals
that TCSC controllers, placed optimally, not only mitigate
small signal oscillations but they can also alleviate line flow
congestion effectively.
Tracking of Maximum Power from Wind Using Fuzzy Logic Controller Based On PMSGIJMER
Wind energy has gained a growing worldwide interest due to the nonstop rise in fuel cost.
The main aim of the wind-energy system is to extract the maximum power present in the wind stream. In
order to extract the highest power, the maximum power point tracking (MPPT) algorithm is used. This
paper proposes the fuzzy logic MPPT controller to track the maximum power from the wind generation
system. The maximum power is achieved based on the rotor speed of the wind system which consists of
wind turbine and PMSG. The error and change in error is given as input to the fuzzy logic and its output
is connected to the boost converter. The voltage from the dc link is controlled by the Voltage Source
Inverter (VSI), and it is placed in grid side converter control. The proposed system is designed and
evaluated in MATLAB/SIMULINK. Simulation results show the good dynamic performance of the
proposed system
This paper focuses on the artificial bee colony (ABC) algorithm, which is a nonlinear optimization problem. is proposed to find the optimal power flow (OPF). To solve this problem, we will apply the ABC algorithm to a power system incorporating wind power. The proposed approach is applied on a standard IEEE-30 system with wind farms located on different buses and with different penetration levels to show the impact of wind farms on the system in order to obtain the optimal settings of control variables of the OPF problem. Based on technical results obtained, the ABC algorithm is shown to achieve a lower cost and losses than the other methods applied, while incorporating wind power into the system, high performance would be gained.
Design of Hybrid Solar Wind Energy System in a Microgrid with MPPT Techniques IJECEIAES
DC Microgrid is one feasible and effective solution to integrate renewable energy sources as well as to supply electricity. This paper proposes a DC microgrid with enhanced Maximum Power Point Tracking (MPPT) techniques for wind and solar energy systems. In this paper, the PV system power generation is enhanced by introducing a two-model MPPT technique that combines incremental conductance and constant voltage MPPT algorithms. Also, for the Wind Energy Conversion System (WECS) with pitch angle controlling technique, an Optimal Power Control MPPT technique is added. The Space Vector Pulse Width Modulation technique is introduced on grid side converter to improve the supply to the grid. The performance of proposed system is analyzed and the efficiency obtained with these methods is enhanced as compared with the previous methods.
This research presents tracking the maximum power of a photovoltaic to control a five-level inverter, a cascade type connecting a single-phase grid-connected system with a fuzzy logic control model. Maximum power tracking control In this research, the principle of controlling the maximum current amplitude of the photovoltaic multiplied by the sine signal per unit that used as a reference current compared to the grid current. Signal comparison with the PID controller allows the creation of five levels of PWM of cascade control of five-level inverter connects single-phase grids. The results of the simulation test using the program MATLAB/Simulink to compare with the generated prototype found that the fuzzy logic principle was used to control the maximum power tracking conditions of the P&O method, when the amount of radiation light intensity decreases suddenly, making it possible to track the maximum power of the photovoltaic. Also, when the inverter connected to the grid by controlling the power angle to compare results between the simulation and the prototype — found that the current flowing into the grid increases according to the power angle control. Resulting in a nearby waveform, sine wave and an out of phase angle to the grid voltage because the system is in the inverter mode, and the harmonic spectrum of the grid currently has total harmonic distortion (THD) is reduced as an indication of the proposed system can be developed and applications.
The significance of the solar energy is to intensify the effectiveness of the Solar Panel with the use of a primordial solar tracking system. Here we propounded a solar positioning system with the use of the global positioning system (GPS) , artificial neural network (ANN) and image processing (IP) . The azimuth angle of the sun is evaluated using GPS which provide latitude, date, longitude and time. The image processing used to find sun image through which centroid of sun is calculated and finally by comparing the centroid of sun with GPS quadrate to achieve optimum tracking point. Weather conditions and situation observed through AI decision making with the help of IP algorithms. The presented advance adaptation is analyzed and established via experimental effects which might be made available on the memory of the cloud carrier for systematization. The proposed system improve power gain by 59.21% and 10.32% compare to stable system (SS) and two-axis solar following system (TASF) respectively. The reduced tracking error of IoT based Two-axis solar following system (IoT-TASF) reduces their azimuth angle error by 0.20 degree.
The aim of this research is the speed tracking of the permanent magnet synchronous motor (PMSM) using an intelligent Neural-Network based adapative backstepping control. First, the model of PMSM in the Park synchronous frame is derived. Then, the PMSM speed regulation is investigated using the classical method utilizing the field oriented control theory. Thereafter, a robust nonlinear controller employing an adaptive backstepping strategy is investigated in order to achieve a good performance tracking objective under motor parameters changing and external load torque application. In the final step, a neural network estimator is integrated with the adaptive controller to estimate the motor parameters values and the load disturbance value for enhancing the effectiveness of the adaptive backstepping controller. The robsutness of the presented control algorithm is demonstrated using simulation tests. The obtained results clearly demonstrate that the presented NN-adaptive control algorithm can provide good trackingperformances for the speed trackingin the presence of motor parameter variation and load application.
Electric Vehicle as an Energy Storage for Grid Connected Solar Power SystemIAES-IJPEDS
In the past few years the growing demand for electricity and serious concern
for the environment have given rise to the growth of sustainable sources like
wind, solar, tidal, biomass etc. The technological advancement in power
electronics has led to the extensive usage of solar power. Solar power output
varies with the weather conditions and under shading conditions. With the
increasing concerns of the impacts of the high penetration of Photovoltaic
(PV) systems, a technical study about their effects on the power quality of
the utility grid is required. This paper investigates the functioning of a gridtied
PV system along with maximum power point tracking (MPPT)
algorithm. The effects of varying atmospheric conditions like solar irradiance
and temperature are also taken into account. It is proposed in this work that
an Electric Vehicle (EV) can be used as an energy storage to stabilize the
power supplied to the grid from the photovoltaic resources. A coordinated
control is necessary for the EV to obtain desired outcome. The modeling of
the PV and EV system is carried out in PSCAD and the proposed idea is
verified through simulation results utilizing real field data for solar irradiance
and temperature.
Simulink Model for Cost-effective Analysis of Hybrid SystemIJMER
Utilization of non conventional sources of energy to meet the present day energy requirement has become very much essential in the era of fossil fuel crises. The present paper discusses the importance of PV-Diesel hybrid system to meet electrical requirement in remote areas. A model of a photovoltaic array with diesel battery was designed by MATLAB simulink. In this paper, the cost-effective analysis which includes the fuel consumed, the energy obtained per gallon of fuel supplied, and the total cost of fuel. Simulations done for Diesel generator system, diesel-battery system and solar PV with diesel-battery system using a one-year time period. Based on simulation results energy payback period for PV array, the simple payback time for the PV module calculated. Simulation analysis includes the comparison of system cost, efficiency, and kWh per gallon with those predicted by Hybrid Optimization Model for Electric Renewables (HOMER).
Large-scale grid-tied photovoltaic (PV) station are increasing rapidly. However, this large penetration of PV system creates frequency fluctuation in the grid due to the intermittency of solar irradiance. Therefore, in this paper, a robust droop control mechanism of the battery energy storage system (BESS) is developed in order to damp the frequency fluctuation of the multi-machine grid system due to variable active power injected from the PV panel. The proposed droop control strategy incorporates frequency error signal and dead-band for effective minimization of frequency fluctuation. The BESS system is used to consume/inject an effective amount of active power based upon the frequency oscillation of the grid system. The simulation analysis is carried out using PSCAD/EMTDC software to prove the effectiveness of the proposed droop control-based BESS system. The simulation result implies that the proposed scheme can efficiently curtail the frequency oscillation.
Twitter is a free social networking microblogging service that allows registered members to broadcast, in real-time, short posts called tweets. Twitter members can broadcast tweets and follow other users’ tweets by using multiple devices, making this information system one of the fastest in the world. In this chapter, we leverage this characteristic to introduce a novel topic-detection method aimed at informing, in real-time, a specific user about the most emerging arguments expressed by the network around his/her domain interests. With this goal, we aim at formalizing the information spread over the network by studying the topology of the network and by modeling the implicit and explicit connections among the users. Then, we propose an innovative term aging model, based on a biological metaphor, to retrieve the freshest arguments of discussion, represented through a minimal set of terms, expressed by the community within the foci of interest of a specific user. We finally test the proposed model through various experiments and user studies.
Exposição 3 de 2015. Algumas obras já publicadas e outras ainda não publicadas, umas recentes, outras mais antigas mas alteradas recentemente. Obras em acrílico sobre tela. Arte, pintura, acrílico, quadros, painting, acrylic, artists.
16th Annual Meeting of the Inter-Agency Donor Group (IADG) on pro-poor livestock research and development. Hosted by GIZ in Berlin. Presentation given by Stuart Brown, GALVmed's Assistant Director of Business Development.
Solid State Drives - Seminar Report for Semester 6 Computer Engineering - VIT...ravipbhat
This report is intended as a guide to emerging solid state storage technology, in particular, to the introduction of solid state drives.
Adding a solid-state drive (SSD) to your computer is simply the best upgrade at your disposal, capable of speeding up your computer in ways you hadn't thought possible. But as with any new technology, there's plenty to learn.
The consumer is no longer limited to just accepting pre-configured systems and, even when purchasing a system, should have an avenue to understand what purpose the storage device within serves as well as how it does what it does.
A solid-state drive (SSD) is a data storage device for your computer.
In everyday use, it provides the same functionality as a traditional hard disk drive (HDD)—the standard for computer storage for many years.
A Reliable Tool Based on the Fuzzy Logic Control Method Applying to the DC/DC...phthanh04
Solar energy performs an important role in electric energy based on renewable energy generation systems when referring to
clear energy. Systems for harvesting renewable energy frequently use DC/DC converters, especially solar photovoltaic systems. The
DC/DC boost converter has been used for converting the output voltage from the solar PV system to the required voltage rating of the
utility grid under the disturbance in the photovoltaic temperature and irradiation level. Because of that, a new maximum power point
tracking based on the fuzzy logic controller (MPPT-FLC) algorithm applying the DC/DC boost converter is developed. The proposed
approach aims toward improving the PV system's performance and tracking effectiveness. This aim can be achieved by adjusting the
DC/DC boost converter's duty cycle to ensure that the PV system operates close to its MPP under varying environmental conditions. The
effectiveness of the proposed method is verified in the off-grid PV system under conditions of the change of irradiation and temperature,
and the comparison of between the proposed method, the incremental conductance (INC), perturb and observe (P&O), and modified P&O
methods is also made. The obtained simulation results show that the MPPT capability significantly improved and achieved the highest
MPPT efficiency of 99.999% and an average efficiency of 99.98% in total when applying the proposed method.
The purpose of this article is to extract the maximum power point at which the photovoltaic system can operate optimally. The system considered is simulated under different irradiations (between 200 W/m2 and 1000 W/m2), it mainly includes the established models of solar PV and MPPT module, a DC/DC boost converter and a DC/AC converter. The most common MPPT techniques that will be studied are: "Perturbation and Observation" (P&O) method, "Incremental Conductance" (INC) method, and "Fuzzy Logic" (FL) control. Simulation results obtained using MATLAB/Simulink are analyzed and compared to evaluate the performance of each of the three techniques.
Abstract:Electricity is the world's fastest-growing form of end-use energy consumption. Net electricity generation worldwide will rise by 2.3 percent per year on average till 2035. Renewables are the fastest growing source of new electricity generation. Indian Solar PV Market enjoys its Place in the solar applications following the Infusion of tracking requirements. This paper focuses on the comparative study of maximum power point tracking (MPPT) techniques. It has been analysed with different MPPT methods following the same goal of maximizing the PV system output power by tracking the maximum power on every operating condition. In this paper maximum power point tracking techniques are reviewed on basis of simplicity, convergence speed, digital or analogical implementation, sensors required, cost, range of effectiveness, and in other aspects.
Stochastic control for optimal power flow in islanded microgridIJECEIAES
The problem of optimal power flow (OPF) in an islanded mircrogrid (MG) for hybrid power system is described. Clearly, it deals with a formulation of an analytical control model for OPF. The MG consists of wind turbine generator, photovoltaic generator, and diesel engine generator (DEG), and is in stochastic environment such as load change, wind power fluctuation, and sun irradiation power disturbance. In fact, the DEG fails and is repaired at random times so that the MG can significantly influence the power flow, and the power flow control faces the main difficulty that how to maintain the balance of power flow? The solution is that a DEG needs to be scheduled. The objective of the control problem is to find the DEG output power by minimizing the total cost of energy. Adopting the Rishel’s famework and using the Bellman principle, the optimality conditions obtained satisfy the Hamilton-Jacobi-Bellman equation. Finally, numerical examples and sensitivity analyses are included to illustrate the importance and effectiveness of the proposed model.
In photovoltaic (PV) systems, maximum power point tracking (MPPT) techniques are used to track the maximum power from the PV array under the change in irradiance and temperature conditions. The perturb and observe (P&O) is one of the most widely used MPPT techniques in recent times due to its simple implementation and improved performance. However, the P&O has limitations such as oscillation around the MPP during which time the P&O algorithm will become confused due to rapidly changing atmospheric conditions. To overcome the above limitation, this paper uses the fuzzy logic controller (FLC) to track the maximum power from the PV system under different irradiance, integrates it with a DC-DC boost converter as a tracker. The result of the FLC performance is compared with the traditional P&O method and shows the MPPT algorithm based on FLC ensures continuous tracking of the maximum power within a short period compared with the traditional P&O method. Besides that, the proposed method (FLC) has a faster dynamic response and low oscillations at the operating point around the MPP under steady-state conditions and dynamic change in irradiance.
Abstract:Electricity is the world's fastest-growing form of end-use energy consumption. Net electricity generation worldwide will rise by 2.3 percent per year on average till 2035. Renewables are the fastest growing source of new electricity generation. Indian Solar PV Market enjoys its Place in the solar applications following the Infusion of tracking requirements. This paper focuses on the comparative study of maximum power point tracking (MPPT) techniques. It has been analysed with different MPPT methods following the same goal of maximizing the PV system output power by tracking the maximum power on every operating condition. In this paper maximum power point tracking techniques are reviewed on basis of simplicity, convergence speed, digital or analogical implementation, sensors required, cost, range of effectiveness, and in other aspects.
Keywords: MPPT, Tracking techniques, Convergence speed, Digital or analogical implementation.
SIMULATION AND ANALYSIS OF DIFFERENT MPPT ALGORITHMS FOR PV SYSTEMIAEME Publication
Photovoltaic (PV) system isa renewable form of energy, using direct sunlight and converting it into electrical power PV cells which are coupled as an array to generate usable electrical energy constitute the most critical parts of this system. Electronic converters are required to transform the output of system current &voltage into an appropriate form if consider the situation of system load & its requirements. The electronic converter more typically employed is a DC-DC converter with a solar cell low voltage generating high voltage. This paper looks at the DC/DC converters & PV system with references to both cases: the first case is, The design of the system as a loop system closed in the first case because the system's scenario is dependent on an different types of algorithm separately for MPPT, that captures the sunlight higher amount to produce the highest optimized electrical power. Although the system was created with MPPT in mind, the simulation was carried out with different a controller such as P&O, PSO, Inc and fuzzy logic. The simulation& execution results for such instances are shown to demonstrate the ability of o/p voltage to return to steady-state if the input voltage impact changed. There is also evidence of a brief settling time & overshoot in the output voltage return and comparative result shown that PSO and fuzzy algorithm found accepted results means best result compassion with the existing algorithm. This optimization was carried out with the assistance of MATLAB 2018(a)
A photovoltaic system using supercapacitor energy storage for power equilibri...IJECEIAES
In a photovoltaic system, a stable voltage and of tolerable power equilibrium is needed. Hence, a dedicated analog charge controller for a storage system which controls energy flow to impose power equilibrium, and therefore, voltage stability on the load is required. We demonstrate here our successful design considerations employing supercapacitors as main energy storage as well as a buffer in a standalone photovoltaic system, incorporating a dedicated supercapacitor charge controller for the first time. Firstly, we demonstrated a photovoltaic system employing supercapacitors as main energy storage as well as a buffer in a standalone photovoltaic system. Secondly, we design a constant voltage maximum power point tracker (MPPT) for peak power extraction from the photovoltaic generator. Thirdly, we incorporated a supercapacitor charge controller for power equilibrium and voltage stability through a dedicated analog charge controller in our design, the first of its kind. Fourthly, we analyzed the use of supercapacitor storage to mitigate disequilibrium between power supply and demands, which, in turn, causes overvoltage or under voltage across the load. Lastly, we then went ahead to demonstrate the control of the energy flow in the system so as to maintain rated voltage across a variant demand load.
Various Methods are used to Improve the Capacity and Performance of Solar and...ijtsrd
Photovoltaic PV and wind turbine as a renewable form of energy play an important role in the generation of electricity in the sector. So, its marketed to consumers. The output forces of these systems are highly non linear and are dependent on the systems I P and V P characteristics, as well as on the conditions of irradiation. As a consequence, a number of research projects have been carried out to increase performance and produce maximum capacity from PV and wind turbines. This paper provides a brief literature study of the Maximal Power Point Tracker MPPT for these systems. For this purpose, the PV circuit layout with its mathematical model is introduced. The new papers on the various methodologies of design are then reviewed. Gaurav Chilhate | Manish Kethoriya "Various Methods are used to Improve the Capacity and Performance of Solar and Wind Power Systems - A Review" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-5 , August 2022, URL: https://www.ijtsrd.com/papers/ijtsrd50459.pdf Paper URL: https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/50459/various-methods-are-used-to-improve-the-capacity-and-performance-of-solar-and-wind-power-systems--a-review/gaurav-chilhate
Overall fuzzy logic control strategy of direct driven PMSG wind turbine conne...IJECEIAES
The fuzzy logic strategies reported in the literature about the control of direct drive permanent magnet synchronous generator (PMSG) connected to grid are limited in terms of inclusiveness and efficiency. So an overall control based on fuzzy logic and anti-windup compensation is proposed in this paper. Aiming at the inadequate of hill climb search (HCS) MPPT with fixed step size, the fuzzy logic is introduced in the stage of "generating rotor speed reference" to overcome the oscillations and slowness in traditional method. PI controllers are replaced by anti-windup fuzzy logic controllers in the "machine side control" stage and in "grid side control" stage to pertinently regulate the reference parameters. Then comparison tests with classical methods are implemented under varying climatic conditions. The results obtained demonstrate that the developed control is superior to other methods in response time (less than 4.528E-04 s), precision (an overshoot about 0.41%) and quality of produced energy (efficiency is 91%). The study verifying the feasibility and effectiveness of this algorithm in PMSG wind turbine connected to grid.
Modeling and Simulation of Wind Energy Conversion System Interconnected with ...idescitation
The global electrical energy consumption is steadily rising and consequently there
is a demand to increase the power generation capacity. A significant percentage of the
required capacity increase can be based on renewable energy sources.The integration of
Distributed Generations into grid has a great importance in improving system reliability.
The power generation with renewable energy sources is essential in now-a-days to control
the atmospheric pollution and global warming. To get fast tracking for maximum power, it
is preferable to use incremental conductance method. MPPT control for variable speed
wind turbine is driven by Induction Generator. The wind turbine generator is operated
such that the rotor speed varies according to wind speed to adjust the duty cycle of power
inverter and maximizes wind energy conversion system efficiency. The system includes the
wind turbine, induction generator, three phase rectifier, DC link voltage controller, three
phase inverter. In this paper, modeling and simulation of wind energy conversion system
(WECS) with incremental conductance maximum power point tracking (MPPT) is
presented. This WECS is connected to electric utility to measure the performance. In this
paper, the objective such as optimal location and sizing of DG units are studied to check the
system performance in reducing the power losses, increase in voltage profile and reliability.
For analyzing the performance of WECS, a case study is carried out on IEEE 15 bus radial
distribution system. The case studies shows that there is gradual improvement in voltage
profile, reduction in power losses and variation in reliability indices and results were
simulated in the MATLAB/SIMULINK. The results shown in this paper can contribute well
to electrical utilities with radial distribution systems.
Performance Comparison of PID and Fuzzy Controllers in Distributed MPPTIJPEDS-IAES
With an increase of Green Technology applications, Photovoltaic have
emerged as the most appropriate solution for electricity generation purposes.
However, due to variable temperature and irradiance, under the partial or
shaded conditions Maximum Power Point Tracking is needed to determine
highest efficiency of the system. The paper describes dynamic modeling and
control of variable temperature and irradiance on solar panel in SIMULINKMATLAB
environment. The implementation of Buck Converter is used for
power switching and impedance matching on connecting the panel to the
load. The effectiveness of the model, with enhanced efficiency through
voltage stabilization, is performed using Proportional-Integral-Derivative and
Fuzzy-Logic-Controllers. A comparative study is made for PID and FLC on
the basis of outputs to deal with online set point variations. FLC gives closer
results to Standard Test Conditions when compared with PID. The Fuzzy
system developed, using tested membership functions serve as a platform for
sustainable standalone and grid-based applications using distributed MPPT.
1. ARCHIVES OF ELECTRICAL ENGINEERING VOL. 64(2), pp. 291-314 (2015)
DOI 10.1515/aee-2015-0024
Dynamic response improvement of hybrid system
by implementing ANN-GA for fast variation
of photovoltaic irradiation and FLC for wind turbine
MAZIAR IZADBAKHSH, ALIREZA REZVANI, MAJID GANDOMKAR
Department of Electrical Engineering, Saveh Branch
Islamic Azad University, Saveh, Iran
e-mail: m.izadbakhsh@iau-saveh.ac.ir
(Received: 30.09.2014, revised: 05.02.2015)
Abstract: In this paper, dynamic response improvement of the grid connected hybrid
system comprising of the wind power generation system (WPGS) and the photovoltaic
(PV) are investigated under some critical circumstances. In order to maximize the output
of solar arrays, a maximum power point tracking (MPPT) technique is presented. In this
paper, an intelligent control technique using the artificial neural network (ANN) and the
genetic algorithm (GA) are proposed to control the MPPT for a PV system under varying
irradiation and temperature conditions. The ANN-GA control method is compared with
the perturb and observe (P&O), the incremental conductance (IC) and the fuzzy logic
methods. In other words, the data is optimized by GA and then, these optimum values are
used in ANN. The results are indicated the ANN-GA is better and more reliable method
in comparison with the conventional algorithms. The allocation of a pitch angle strategy
based on the fuzzy logic controller (FLC) and comparison with conventional PI control-
ler in high rated wind speed areas are carried out. Moreover, the pitch angle based on
FLC with the wind speed and active power as the inputs can have faster response that
lead to smoother power curves, improving the dynamic performance of the wind turbine
and prevent the mechanical fatigues of the generator.
Key words: hybrid system, photovoltaic, FLC, permanent magnet synchronous generator
(PMSG), ANN-GA
1. Introduction
Compared with the fossil fuels and thermal power, the renewable energy is inexhaustible
and has non-pollution characteristics. Wind and PV as the types of renewable energy have re-
ceived considerable attentions for producing electricity because of natural, inexhaustible re-
sources and cost competitiveness in comparison with other types of energy. However, the
hybrid energy systems are used for overcoming intermittency, uncertainty and low availability
of each renewable energy source which makes the system more reliable. Hence, there have
been different works concentrating on the Wind/PV hybrid system [1, 2].
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2. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.292
There are many methods to integrate different alternative energy sources to form a hybrid
system. The methods can be generally classified into two categories: DC coupling and AC
coupling. The AC couple is utilized in this paper. The AC hybrid system characteristics are
consisting of: 1) High reliability, if one of the energy sources is out of service, it can be
isolated from the system easily, 2) Ready for the grid connection, 3) Standardizing interfacing
and modular structures, 4) Easy multi-voltage and multi-terminal matching, 5) Well estab-
lished scale economy.
The hybrid system is connected to the grid by using a P-Q controller of the grid side conver-
ter to exchange active and reactive power and observe system efficiency in different conditions.
PVs have high fabrication cost and low energy conversion efficiency. Therefore, using
MPPT method has been recommended. In other words, the output power of a PV module
varies as a function of the voltage and also, the maximum power point (MPP) is change by
variation of temperature and sun irradiance [3].
In recent years, many different methods have been applied in order to reach MPP. The
most prevalent technics are P&O algorithm [4, 5], IC algorithm [6, 7], fuzzy logic [8, 9] and
ANN method [10-12]. According to the above mentioned researches, the benefits of the P&O
and IC algorithms are: 1) low cost implementation, and 2) simple algorithm. Another draw-
backs of these methods are vast fluctuations of the output power around the MPP even under
a steady state which resulting in the loss of available energy [13, 14].
Using fuzzy logic can solve the two mentioned problems dramatically. In fact, with FLC,
proper switching can reduce oscillations of output power around the MPP and losses. Further-
more, in this method, convergence speed is higher than the two other methods mentioned.
A drawback of fuzzy logic, compared to the ANN, refers to oscillations of output power
around the MPP [15, 16].
Nowadays, artificial intelligence (AI) techniques have numerous applications in determin-
ing the size of the PV systems, MPPT control and optimal structure of the PV systems. In
most cases, multilayer perceptron (MLP) neural networks or radial basis function network
(RBFN) have been employed for modeling PV module and MPPT controller in PV systems.
ANN based controllers have been used to estimate voltages and currents corresponding to the
MPP of PV module for irradiances and variable temperatures. A review on AI techniques
applications in renewable energy production systems have been presented in these literatures.
Neural networks are the best approximation for non-linear systems and some problems such as
oscillations of output power around the MPP and time to reach the MPP are reduced [17-19].
In [10, 20-23], GA is used for data optimization and then, the optimum values are utilized for
training neural networks and the results show that, the GA technic has less fluctuations in
comparison with the conventional methods. However, one of the major drawbacks in men-
tioned papers that they are not practically connected to the grid in order to ensure the analysis
of hybrid system performance, which is not considered.
In terms of WPGS is proposed as one of the outstanding renewable energy sources.
Amongst the synchronous and asynchronous generators, PMSG is more favorable due to self-
excitation, lower weight, smaller size, less maintenance cost and the elimination of gearbox
have high efficiency and high power factor comparing to WRSG, SCIG, DFIG and so on [24].
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3. Vol. 64 (2015) Dynamic response improvement of hybrid system 293
In comparing PIDs and the fuzzy logic technics, fuzzy logic has more stability, faster and
smoother response, smaller overshoot and does not need a fast processor; also it's more
powerful than other non-linear controllers [25-27]. In [28-30], pitch angle based on FLC is
presented. In [30] active power and in [28, 29] both reactive power and rotational rotor speed
are used as input signals. As in mentioned items, wind speed's is ignored, the controller have
not fast response and may cause mechanical damages to synchronous generator. Further,
another problem with these studies is that they are not practically connected to the grid to
analyze the system performance [29-31].
In [32], presented a power management strategy which, studied power fluctuations in
a hybrid PV/wind turbine/FC power system. In [33] a simple and economic control with DC-
DC converter is used for MPPT and hence maximum power extraction from the wind turbine
and photovoltaic arrays. The simulation of Wind/PV hybrid system is investigated in [34]. In
[35, 36], the wind-solar hybrid power system in stand-alone mode are presented.
However, all of the aforementioned papers have some drawbacks such as: 1) They are not
considered FLC for controlling the output power of wind turbine and ANN-GA for MPPT in
PV system to analyze and improve the dynamic performance of hybrid system, 2) In some
mentioned papers, the hybrid system performance are investigated in stand-alone or not
practically connected to the grid, 3) The DGs dynamic model is not included, which could
have a great effect on the dynamic performances of hybrid system, 4) Some of them are not
considered the detailed model in different circumstances (variation of irradiance, temperature,
wind speed and load), 5) Most of them are not used the AC coupling, which is already
mentioned the advantage of AC coupling comparing to DC coupling in this paper.
In this paper, the dynamic performance improvement of wind/PV hybrid system is pro-
posed. The application of ANN-GA controller to capture the MPPT of PV panels mounted in
the hybrid system. Temperature and irradiance as inputs data are given to GA and the optimal
voltages (Vmpp) corresponding to the MPP are obtained; then, these optimum values are used in
neural network training. As well as, the FLC is used to control the output power of the grid
connected wind turbine in high speeds with comparing to PI controller.
2. Photovoltaic cell model
Figure 1 shows the equivalent circuit of one PV cell [5]. Characteristic of one solar array is
explained by following Equations.
Fig. 1. Equivalent circuit of one PV array
,IIII RPdPV ++= (1)
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4. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.294
.1exp0
p
S
th
S
pv
R
IRV
nV
IRV
III
+
−⎥
⎦
⎤
⎢
⎣
⎡
−⎟
⎠
⎞
⎜
⎝
⎛ +
−= (2)
Where, I is the output current, V is the output voltage, Ipv is the generated current under
a given insolation, Id is diode current, IRP is the shunt leakage current, I0 is the diode reverse
saturation current, n is the ideality factor for a p-n junction, Rs is the series loss resistance, and
RP is the shunt loss resistance. Vth is known as the thermal voltage. Red sun 90 W is taken as
the reference module for simulation and the name-plate details are given in Table 1. The array
is the combination of 6 cells in series and 6 cells in parallel of the 90 W module; hence an
array generates 3.2 kW.
Table 1. Red Sun 90 W
IMP (current at maximum power) 4.94 A
VMP (voltage at maximum power) 18.65 V
PMAX (maximum power) 90 W
VOC (open circuit voltage) 22.32 V
ISC (short circuit current) 5.24 A
NP (total number of parallel cells) 1
NS (total number of series cells) 36
3. Maximum Power tracking – neural network and GA technic
3.1. The Steps of Implementing GA and ANN
In order to pursue the optimum point for maximum power in any environmental condi-
tions, ANN and GA technic are implemented. Besides, GA is used for optimum values and
then, optimum values are used for training ANN [10, 22]. The procedure employed for imple-
menting GA is as follows [23, 37]: 1) Defining the objective function and recognizing the
design parameters, 2) Defining the initial production population, 3) Evaluating the population
using the objective function, 4) Conducting convergence test stop, if convergence is provided.
The objective function of GA is used for its optimization (using Matlab software) by the
following: finding the optimum X = (X1, X2, X3,..., Xn) to put the F(X) in the maximum value,
where the number of design variables are considered as 1. X is the design variable equal to
array current and also, F(X) is the array output power which should be maximized [22, 23]. To
determine the objective function, the power should be arranged based on the current of array
(IX). The GA parameters are given in Table 2.
,*)( XXx IVF = (3)
.0 SCX II << (4)
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5. Vol. 64 (2015) Dynamic response improvement of hybrid system 295
Table 2. The GA parameters
Number of design variable 1
Population size 25
Crossover constant 75%
Mutation rate 15%
Maximum Generations 30
The current constraint should be considered too. By maximizing this function, the optimum
values for Vmpp and MPP will result in any particular temperature and irradiance intensity.
3.2. MPPT Improvement by Combination of Proposed ANN with GA
Neural networks are most appropriate for the approximation (modeling) of nonlinear
systems. Non-linear systems can be approximated by multi-layer neural networks and these
multi-layer networks have better result in comparison with the other algorithm [16, 18]. In this
paper, feed forward neural network for MPPT process control is used. The important section
of this technic is that, the required data for training process must be obtained for each PV mo-
dule and each specific location [11]. Based on the PV characteristic which depend on PV mo-
del and climate change, neural network should be trained periodically. Neural network inputs
can be selected as PV array parameters like Voc, Isc and climate data, temperature or both of
them. The output is usually one reference signal like duty cycle or DC link voltage or Vmpp.
The proposed neural network has three layers which the temperature and solar irradiance
as input variables and output variable of the neural network is Vmpp corresponding to MPP as
shown in Figure 2. Also, a simple block diagram of the PV system with the proposed MPPT is
shown in the Figure 3.
Fig. 2. Feed forward neural network for MPPT
Fig. 3. Proposed MPPT scheme
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6. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.296
The output characteristic of arrays has changed during time and environmental conditions.
Therefore, needing for periodic training of the neural network in order to increase precision is
essential. According to Figure 4 for training of the neural network a set of 390 data is used
(temperatures between –5°C to 55°C and irradiance between 0.05 to 1 kilo-watt per square
meters (kW/m2
)) and also, a set of 390 Vmpp corresponding to MPP is achieved by GA that is
shown in Figure 5. Our aim is to show the effectiveness of the proposed method in comparing
to conventional methods by using Matlab software. However, in the real conditions it should
consider all level of the temperature.
Fig. 4. Inputs data of irradiance and temperature
Fig. 5. The output of Vmpp-MPP optimized by GA
In order to implementation of the ANN for MPPT, first it should be determined the number
of layers, number of neurons in each layer, transmission function in each layer and type of
training network. The proposed ANN in this paper has three layers which first and second
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7. Vol. 64 (2015) Dynamic response improvement of hybrid system 297
layers have respectively 17 and 9 neurons and third layer has 1 neuron. The transfer functions
for first and second layers are Tansig and for third layer is Purelin. The training function is
Trainlm. The acceptable sum of squares for network is supposed to be 10-9
. Which training
this neural network in 900 iterations, will converge to a desired target. After training, the output
a)
b)
c)
d)
Fig. 6. Shown the output of the neural network by fallowing: a) The output of the neural network with
the amount of target data; b) The output of the neural network Vmpp with the amount of target data; c)
Percentage of the total error of the Vmpp training data; d) Train output versus target
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8. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.298
a)
b)
c)
d)
Fig. 7. Shown the output of the neural network test by following: (a) The output of the neural network
test with the amount of target data; (b) The output of the neural network test Vmpp with the amount of
target data; (c) Percentage of the total error of the Vmpp test data; (d) Test output versus target
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9. Vol. 64 (2015) Dynamic response improvement of hybrid system 299
of training network should be close to optimized output from GA. Figure 6 show the output of
the neural network with the amount of target. A set of 80 data is used for the ANN test. Figure
7 illustrate the output of the neural network test with the amount of target which showing
a negligible training error percentage of about 0.2%.
4. WPGS configuration
The diagram of a WPGS based on the PMSG is illustrated in Figure 8. Turbine output is
rectified by using the uncontrolled rectifier. Then DC link voltage is adjusted by PI controller
until it reached a constant value and then, this constant voltage is inverted to AC voltage using
sinusoidal pulse width module (PWM) inverter. Inverter adjusted the DC link voltage and
injected active power by d-axis and injected reactive power by q-axis using P-Q control
method. Furthermore, turbine output is regulated by pitch angle based on FLC in extra high
wind speeds.
Fig. 8. The block diagram of WPGS
4.1. Wind turbine modeling
The amount of electricity a turbine is able to produce depends on the speed of the rotor and
the speed of the wind that propels the rotor [31, 38]. Aerodynamic wind power is calculated in
following equations.
( ) ,,5.0 3
wp VACP βλρ= (5)
,
w
m
V
RW
−λ (6)
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10. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.300
( ) ,54.0
116
5176.0,
21
i
eC
i
p
λ
β
λ
βλ
−
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
−−= (7)
.
1
035.0
08.0
1
1
3
−
⎥
⎦
⎤
⎢
⎣
⎡
+
−
+
=
ββλ
λi (8)
Where P, ρ, A, Vw, Wm and R are power, air density, rotor swept area of the wind turbine,
wind speed in m/sec, rotor speed in rad/s and radius of turbine respectively. Also, Cp is the
aerodynamic efficiency of rotor [39]. Furthermore, CP is depends on tip speed ratio (TSR) and
blade pitch angle. Figure 9 illustrates the typical variation of CP respect to the TSR for various
values of the pitch angle (β).
Fig. 9. CP vs. λ (TSR) for various pitch angles β
4.2. PMSG modeling
A synchronous generator with reference to Park’s transformation is illustrated which d-
axis is rotating along magnetic field direction. PMSG voltage equations are given by [38]:
[ ],
1
qsqdssds
d
ds
iLiRV
Ldt
di
ω+−−= (9)
[ ].
1
mdsdqssqs
q
qs
iLiRV
Ldt
di
ωφω +−−−= (10)
Where Vds, Vqs are q and d axis machine voltages, Ids, Iqs are q and d axis machine currents,
Rs: Stator Resistance, W: electrical angular frequency, Ld: d-axis inductance, Lq: q-axis
inductance, Nm: amplitude of the flux linkage caused by permanent magnet. If rotor is
cylindrical (Ld ≈ Lq = Ls), the electromagnetic torque (EM) equation written as following:
,
2
3
qsme ipT φ= (11)
where p is the number of pole pairs of the PMSG.
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11. Vol. 64 (2015) Dynamic response improvement of hybrid system 301
4.3. Pitch angle based on FLC
FLC is made of three parts which is demonstrated in Figure 10. First part is fuzzification
which is the process of changing a real scalar value into a fuzzy set. Second part is fuzzy in-
ference system that combines IF-THEN statements based on fuzzy principle and finally, it has
defuzzification which is the process that changes a fuzzy set into a real value in output [29].
Fig. 10. The structure of fuzzy logic system
The presented FLC consists of two input signals and one output signal. The first input
signal is based on the deviation between active power and the rated value in P.U, which is
mentioned as error signal. Thus, its positive value indicates turbine’s normal operation and its
negative value shows the extra power generation during the above rated wind speed. In this
case, controller should modify pitch angle degree by increasing the nominal value. The pitch
angle degree is regulated on zero in a normal condition. The whole wind energy can be
converted to mechanical energy and when the pitch angle starts to increase from the zero
value, the wind attach angle to the blades will be increased, thereby leading to aerodynamic
power reduction and consequently, drawing down the output power. Besides, the second
signal is taken from anemometer Nacelle [39].
Controller’s response is so faster when wind speed is used as an input signal compared to
the time when inputs are rotor rotational speed or active power in large turbines with a high
moment of inertia [28-30]. However, mechanical erosion in large and high speed turbines is
diminished by adjusting this FLC. Designing a pitch angle based on FLC for wind turbine
power adjustment in high wind speeds is being proposed in this paper. Three Trapezoidal
membership functions are considered in this paper. Furthermore, Min-Max method is used as
a defuzzification reference mechanism for centroid. Given membership functions are shown in
Figure 11.
Moreover, the rules implemented to obtain the required pitch angle (β) are shown in
Table 3. The linguistic variables are represented by VG (very great), SG (small great), OP
(optimum), SL (small low), and VL (very low) for error signal and VL (very low), SL (small
low), OP (optimum), SH (small high) and VH (very high) for wind speed signal and NL (nega-
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12. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.302
a)
b)
c)
Fig. 11. The membership function of fuzzy logic: (a) Membership functions of active power (error
signal); (b) Membership functions of wind speed; (c) Membership functions of output (β)
tive large), NS (negative small), Z (zero), PS (positive small) and PL (positive large) for out-
put signal, respectively. The three dimensional curve in FLC is shown in Figure 12.
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13. Vol. 64 (2015) Dynamic response improvement of hybrid system 303
Table 3. Fuzzy rules
Pitch command Active power (error)
VG SG OP SL VL
VL PL PS Z Z Z
SL PL PS Z Z Z
OP PL PS Z Z Z
SH PL PS PS PS PS
Wind speed
VH PL PL PL PL PL
Fig. 12. The three dimensional curve in FLC
5. P-Q control strategy
The inverter by PWM technic produces high frequency harmonics, that need to utilize
filter to eliminate them and the voltage source inverter (VSI) can play role as an ideal sinu-
soidal voltage source.
Since wind power is fluctuates due to wind velocity, output voltage and frequency change
continuously. A bridge rectifier provides AC to DC and then, DC link voltage using PI
controller to obtain constant value, then DC voltage will be inverted to get desired AC voltage.
( ),
2
3
qqgdgd IVIVP += (12)
( ),
2
3
qdgdgq IVIVQ += (13)
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14. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.304
If synchronous frame is synchronized with the grid voltage, voltage vector is V = Vgd + j0
which, active and reactive power may be as following:
,
2
3
dgd IVP = (14)
,
2
3
dgq IVQ = (15)
Synchronous reference is calculate quantities of d-axis, q-axis and zero sequence in two
axis rotational reference vector for three phase sinusoidal signal illustrated in Figure 13. The
equations are given by (16), (17).
,,
00
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
=
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
=
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
c
b
a
q
d
c
b
a
q
d
i
i
i
C
i
i
i
V
V
V
C
V
V
V
(16)
⎥
⎥
⎥
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎢
⎢
⎢
⎣
⎡
+−−−−
+−
=
2
1
2
1
2
1
)
3
2
sin()
3
2
sin(sin
)
3
2
cos()
3
2
cos(cos
3
2
0
π
θ
π
θθ
π
θ
π
θθ
dqC (17)
Fig. 13. The synchronous reference machine
Inverter control model is depicted in Figure 14. The goal of controlling the grid side is
keeping the DC link voltage in a constant value regardless of production power magnitude.
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15. Vol. 64 (2015) Dynamic response improvement of hybrid system 305
Inverter control strategy is consisting of two control loops. Internal control loop is control the
grid current and external control loop is control the voltage .Internal control loop which is
responsible for power quality such as low total harmonic distortion (THD) and improvement
of power quality and external control loop is responsible for balancing the power. In grid-
connected mode hybrid system must supply local loads to decrease power from the main grid.
One of the main aspects of P-Q control loop is operating in grid connected and stand-alone
mode. The advantages of this operation mode are higher power reliability and higher power
quality [40]. Active and reactive components of the injected current are id and iq, respectively.
For the independent control of both id and iq, the decoupling terms are used. To synchronize
the converter with grid, a three phase lock loop (PLL) is used. PLL reduces the difference be-
tween grid phase angle and the inverter phase angle to zero using PI controller, thereby syn-
chronizing the line side inverter with the grid [41].
Fig. 14. Control scheme for inverter
6. Simulation results
In this section, simulation results under different terms of operation in hybrid system are
presented. The block diagram of hybrid system is shown in Figure 15a). Our target is to show
the effectiveness of the proposed methods (ANN-GA and FLC) with conventional methods in
PV and WPGS and enhanced the dynamic performance of hybrid system to meet the load
demand in different conditions (Load, wind speed, irradiance and temperature variations) by
using AI techniques. The important priority of this hybrid system is supplying the 100 kW AC
load (electrical load) requirement in critical circumstances. Structure of the P/Q controller is
depicted in Figure 15b). The grid voltage and frequency are 220 V and 60 Hz respectively.
The PV and wind systems connected to the grid by applying P-Q controller are shown in
Figures 16 and 17, respectively. Detailed model descriptions are given in Appendix A.
6.1. Case 1: Variation of irradiance and temperature
The main objective of this case is investigated comparative study of four widely-adopted
MPPT algorithms under variations of irradiance and temperature in PV system. The hybrid
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16. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.306
system is connected to the main grid that includes 3.2 kW photovoltaic system, 97 kW wind
turbine system and the amount of load is 100 kW. There is no power exchange between hybrid
system and grid in normal condition.
Fig. 15a. Block diagram of proposed wind/PV hybrid system
Fig. 15b. Structure of the P-Q controller
The following simulation is presented for different insolation levels at fixed temperature of
25°C as shown in Figure 18a). The output voltage and the current of PV are depicted in
Figures 18b) and 18c), respectively. When irradiance is increased at t = 4 s and t = 8 s, it lead
to increase in the output current of PV as shown in Figure 18c). The evaluation of the pro-
posed controller is compared and analyzed with the conventional techniques of fuzzy logic,
P&O and IC. The proposed MPPT algorithm can track accurately the MPP when the irra-
diance changes continuously; also, it produces extra power rather than aforementioned me-
thods as indicated in Figure 18d). Therefore, the injected power from the main grid to hybrid
system is decreased as demonstrated in Figure 18e).
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17. Vol. 64 (2015) Dynamic response improvement of hybrid system 307
Fig. 16. PV system in grid-connected mode by applying P-Q controller
Fig. 17. WPGS in grid-connected mode by applying P-Q controller
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18. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.308
Fig. 18. Simulated results for PV (Variation of Irradiance) in case 1: a) Irradiance; b) Inverter output
voltage; c) Inverter output current; d) PV power; e) Grid power
Table 4 shows the comparison of real power value and presented methods in the different
irradiation conditions. In order to realize a precise analysis of the ANN-GA technique, dif-
ferent temperature levels at fixed insolation of 1000 W/m2
as shown in Figure 19a) is con-
sidered. The grid voltage is indicated in Figure 19b). The ANN-GA method shows smother
power, less oscillating and better stable operating point than P&O, IC and fuzzy logic. It has
more accuracy for operating at MPP and also, it generates exceeding power rather than men-
tioned techniques as depicted in Figure 19c). Consequently, the grid power injection to hybrid
system is declined as illustrated in Figure 19d). Table 5 shows the comparison of real power
value and presented methods in the different temperature conditions.
Table 4. Output power values of solar array (watt) in various irradiation conditions
PV powerIrradiance
variations Real value ANN+GA Fuzzy logic IC P&O
0s to 4s 1020 1007 1000 891 886
4s to 8s 2430 2421 2413 2252 2220
8s to 12s 3200 3191 3181 2985 2970
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19. Vol. 64 (2015) Dynamic response improvement of hybrid system 309
Fig. 19. Simulated results for PV (Variation of Temperature) in case 1: a) Temperature;
b) Grid voltage; c) PV power; d) Grid power
Table 5. Output power values of solar array (watt) in various temperature conditions
PV powerTemperature
variations Real value ANN+GA Fuzzy logic IC P&O
0s to 3.5s 1435 1427 1416 1387 1381
3.5s to 7.5s 3200 3191 3179 2981 2974
7.5s to 12s 2352 2341 2303 2298 2295
6.2. Case 2: variation of wind speed and load
In this case, the evaluation of FLC with comparing to conventional PI controller in pitch
angle of wind system is carried out. The variations of wind speed and load to analyze of
hybrid system performance are implemented. There is no power exchange between hybrid
system and grid in normal condition. During 0 < t < 1 s, the load power is 100 kW and at
t = 1 s, it has 50% step increase in load that is constant until t = 2 s. Then, at t = 3 s, it has step
decrease 35% in load power, that is constant until t = 3.5 s.
Wind speed during 0 < t < 4.5 s, is 12 m/s which at t = 4.5 s, it is reduced to 9.5 m/s. Then,
during 1< t < 1.5 s, wind speed is 10 m/s and after that, at t = 6.5 s, it is extremely increased to
18 m/s. By designing FLC, when wind speed is more than nominal speed (12 m/s), turbine
output power is increased by extremely increasing wind speed; however, with PI controller,
the power is constant at a high level power and in the presence of FLC, it is more reduced to
the nominal power and made it more smoother, thereby leading to improvement of dynamic
performance and the prevention of mechanical fatigue to PMSG.
Figure 20a) shows the variation of wind speed. The reactive power produced by the wind
turbine is regulated at zero such that the power factor maintained unity as shown in Figure
20b). One of the most important aspects of using DG sources and connecting them to grid is
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20. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.310
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21. Vol. 64 (2015) Dynamic response improvement of hybrid system 311
Fig. 20. Simulated results for WPGS in case 2: a) Wind speed; b) Reactive power; c) THD (%); d)
Variation of pitch angle by FLC; e) Inverter output voltage; f) DC link voltage; g) Inverter output current
with absence of FLC; h) Inverter output current with presence of FLC; i) Turbine output power with
absence of FLC; j) Turbine output power with presence of FLC; k) Active powers with absence of FLC;
l) Active powers with presence of FLC; m) Grid current with absence of FLC; n) Grid current with
presence of FLC
keeping the THD at the minimum of its value. According to IEEE Std.1547.2003, it should be
around 5%. In THD curve, it is around 4% to 6%. THD is shown Figure 20c). Figure 20d)
displays the variation of pitch angle in the presence of FLC. As can be seen, in normal
situations, the pitch angle is set as zero. Inverter output voltage is invariant, which is shown in
Figure 20e). DC link voltage remains at a constant value (1150 V), thereby proving the
effectiveness of the established FLC as illustrated in Figure 20f). At wind speeds above the
rated wind, the extracted wind power has to be limited by increasing the pitch angle (β).
Figures 20g) and 20h) show the turbine output power in the absence and presence of FLC
according to wind speed. It is obvious that FLC make a smoother power curve. Table 6 shows
the comparison of real power value and proposed methods in the different wind speed
conditions, which it shows in high wind speeds, the output power of WPGS by using FLC
method is more declined and more prevent the mechanical fatigues to PMSG. Figures 20i) and
20j) show inverter output current in the absence and presence of FLC, respectively. It shows
the effectiveness of FLC by increasing pitch angle degree. The exceeding power of wind
turbine is limited and also, the inverter output current is reduced in comparison with PI
controller. Pitch angle based on FLC is more limited the exceeding output power of turbine.
Therefore, by the reduction of injected output power of wind turbine, the injection of extra
total active power of hybrid system to grid is more declined which is illustrated in Figures
20k) and 20l). In Figures 20k) and 20l), the effectiveness of FLC is evaluated. Figures 20m)
and 20n) show the grid current in the absence and presence of FLC, respectively.
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22. M. Izadbakhsh, A. Rezvani, M. Gandomkar Arch. Elect. Eng.312
Table 6: Output power values of WPGS (kW) in various Wind speeds
Wind powerWind speed
variations
Real value PI FLC
0 s to 4.5 s 97.1 97.1 97.1
4.5 s to 6.5 s 77.5 77.5 77.5
6.5 s to 12 s 124.860 118.600 99.290
7. Conclusion
In this paper, the dynamic response of the grid connected Wind/PV hybrid system under
load circumstances and the variations of wind speed, irradiance and temperature were pro-
posed. The control strategy modeling of a DC/AC grid connected converter was presented.
Inverter adjusted the DC link voltage and active power was fed by d-axis and reactive power
was fed by q-axis (using P-Q control mode).
The simulation results indicated that using the ANN-GA controller could dramatically
reduce the disadvantages of previous approaches. In fact, ANN-GA controller could decrease
oscillations of output power around the MPP and increase convergence speed to achieve the
MPP in comparison with conventional methods in the grid-connected mode. Also, the pro-
posed FLC in the pitch angle, by adding wind speed as an input signal, could have faster and
smoother response. The advantage of FLC was that it kept the turbine output in an admissible
value and could prevent more mechanical fatigue and also, the dynamic performance of wind
turbine could be improved. In other words, by increasing the pitch angle via FLC, the exce-
eding power of the wind turbine was limited, reaching the nominal value and reducing the
inverter output current. Therefore, by the reduction of injected the output power of the wind
turbine, the injection of extra total active power of the hybrid system to the grid was de-
creased. It was clear that, the Wind/PV hybrid system by applying FLC in pitch angle with the
cooperation of grid could easily meet the load demand.
Appendix A: Description of the Detailed Model
PV parameters: output power = 3.2 kW, Carrier frequency in VMPPT PWM generator: 4.3
kHz and in grid-Sid controller: 5 kHz, boost converter parameters: L = 3.5 mH, C = 630 µF, PI
coefficients in grid-side controller: KpVdc = 3.5, KiVdc = 7.3, KpId = 8.4, KiId = 343, KpIq = 8.4,
KiIq = 343.
PMSG parameters: output power = 97 kW, Stator resistance per phase = 2.8 Ω, inertia
= 0.8e-3
kg-m2
, torque constant 12N-M/A, Pole pairs = 8, Nominal speed = 12 m/s, Ld = La =
7.3 mH.
Grid parameters: X/R = 7, and other parameters, DC link capacitor = 5600 µF, DC link
voltage = 1150 V. PI coefficients in grid-side controller: KpVdc = 9, KiVdc = 473, KpId = 0.94,
KiId = 8, KpIq = 0.94, KiIq = 8.
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