In this paper an intelligent method of maximum power point tracking (MPPT) using fuzzy logic control for stand-alone photovoltaic (PV) system has been presented. The PVsystem is composed of PV solar array, buck DC-DC converter, and MPPTcontroller. Fuzzy logic controller (FLC) is easy to implement, and does not need knowledge of the exact model of the system. Simulation results compared with those obtained by the conventional perturbation and observation (P&O) technique show the effectiveness of the fuzzy logic controller during steady-state and varying weather conditions.
The primary function of a charge controller in a stand- alonePVsystem is to maintain the battery at highest possible state of charge while protecting it from over- charge by the array and from over discharge by the loads. Wu et al. developed a new fast charging method that is applied to micro-grid photovoltaic systems to eliminate batteries undercharge or overcharge due to random changes of solar radiation . Some PV systems can be effec- tively designed without the use of charge control. In the present study, a charge control is required due to the fact that the load is unpredictable. Another reason for the charge control is that the battery storage is optimized resulting in undersized system, a charge control is need to prevent the severe discharge resulting in short life of the battery. The algorithm or control strategy of a battery charge controller determines the effectiveness of battery charging and PV array utilization, the ability of the sys- tem to meet the load demands and extend the lifetime of a battery. When the irradiation is high (typically during summer), energy generated by the PV array often ex- ceeds the electrical load demand. To prevent battery dam- age resulting from overcharge, a charge controller is used to protect the battery. A charge controller should prevent overcharge of a battery regardless of the system siz- ing/design and seasonal changes in the load profile, op- erating temperatures and solar irradiation. It has to be capable of carrying the short circuit current of the PV ar- ray. Thus, in this case, it can be chosen to handle 73.4 A and to maintain the DC bus voltage to about 36 V. 5.3. Design of the Inverter
Photovoltaic energy is a renewable energy with high potential, easy installation, simple maintenance, dependability and long life. Photovoltaic system output is non-linear and is affected by weather conditions, so maximum Power Point Tracker (MPPT) was implemented to draw out the maximum power from solar energy. In order to increase the efficiency of stand-alone photovoltaic (PV) system, it is most important an efficient Maximum Power Point Tracker (MPPT) is needed. This paper proposed a technique of tracking Maximum Power Point based on Incremental Conductance (INC) algorithm with Luo converter and three phase PWM Voltage Source Inverter (VSI) are implemented to measure the effectiveness of the Photovoltaic (PV) system and tracking mechanism.
ABSTRACT: The Renewable energy is important part of power generation system due to diminution of fossils fuel. Energy production from photovoltaic (PV) is widely accepted as it is clean, available in abundance, & free of cost. This project deals with modeling of Stand-alonePVsystem for operating the load. This model consists of photo-voltaic PV module, DC to DC Buck converter and Boost converter, MPPTController, Battery Storage, and Load. MPPTcontroller operates on adjusting the voltage power and tracks the maximum power at certain point. The one of the DC to DC converter used in this project is buck converter which produce an output voltage lower than the input source voltage which the voltage is used to charge the battery and the other converter is Boost converter is used to step-up the voltage and will give output voltage to operate the load.Here the battery is interlinked between buck and boost converter to operate as when system is under normal-load i.e., less than full-load where the power used to charge by 30-40 % of input power entering battery and if the load requirement is more the battery will compensate power. To track maximum power point (MPPT) Perturb & Observe (P & O) algorithm is used which periodically perturbs the array voltage and compare PV output power with that of previous perturbation cycle which controls duty cycle of DC-DC Buck converter and Boost converter will be operate by internal pulse generator. The main objective of this model is that by working as a stand- alonePV- system absence of connecting grid, we want to operate the normal household loads like lights, fans, street lights, traffic signals in remote area where transmission of power from grid is not feasible like toll-gates, forest check- posts, hill stations etc. The performance of the proposed model and achievement of desired compensation are confirmed by the results of the simulation using MATLAB/Simulink.
Abstract: In this paper, the Vector Based Swarm Optimization method is used for designing an optimal controller for the maximum power point tracker of a stand-alonePVSystem. The proposed algorithm is executed on vectors in a multi-dimension vector space. These vectors by appropriated orientation converge to a global optimum while the algorithm progresses. The Remarkable point of the VBSO algorithm is the fact that using completely random coefficients increases the algorithm performance. The generated energy by PV is delivered to a boost converter feeding a resistive load. The duty cycle of the converter’s switch is determined by a controller in order to minimize the dP/dV of the PV.
Stand-alone photovoltaic power systems are a low-maintenance, versatile solution to the electric power needs of any “off-grid” application. It is important to determine the correct system size, in term of both peak output and overall annual output, in order to ensure acceptable operation at minimum cost. If the system to large, it will more expensive than necessary without increasing performance levels unsubstantially and therefore the system will be less cost-effective than it could be. However, if too small a system is installed, the availability of the system will be low and the customer will be dissatisfied with the equipment. Again, the cost-effectiveness is reduced. Although the same principles are included in the sizing process, the approach differs somewhat for the stand-alone and grid connected .
In this paper, a multi loop proportional-integral (PI) controller is presented. The multi loop PI is used to control the operation of the dc/dc converters due to its robustness and good performance with any type of unknown arbitrary load. This system has a number of advantages. First, the flexibility for various types of operating modes, with and without energy storage, is strongly guaranteed without the control configuration change. Second, the system can be applied even with a single 24 V commercial battery without any extra connection.
stands that, the relationship between voltage and current is nonlinear. In order to reduce distortions created by these type of loads, the Active Power Filter (APF) is nowadays one of the most powerful solutions. It is therefore used in a distribution power system to avoid serious inherent problems such as transformer overheating, machine vibration, motor failures, higher line losses, etc. The switching actions of power converters result to distortion on the input currents, which contain a fundamental and some higher order harmonics. Injection of compensation currents in the electrical power supply by means of an APF, allows reactive power compensation as well as sinusoidal current shape recovery, to meet Total Harmonics Distortion (THD) limits set by IEEE Standard 519-1992. This standard has now been revised as IEEE Standard 519-2014 . Nevertheless, the THD limit of 5% for current is still valid in the latest IEEE standard.
largest variations in the output power of PV systems. Squall lines can cause the output power of a PVsystem to fall to zero, and thus, they lead to the worst-case scenario for the operation of the system. However, squall lines are predictable, and thus, the periods of time during which the PVsystem will be out of service can be predicted. On the other hand, cumulus clouds result in lower loss of the PV power, but they cause the output of the PVsystem to fluctuate more frequently as the irradiance fluctuates due to the passage of such clouds. The time period of fluctuations can range from few minutes to hours depending on the wind speed, the type and size of passing clouds, and the area covered by and topology of the PVsystem.
Over the past decades alone, the Government has been continuously subsidizing the population’s fossil fuels need. The fuel subsidy in 2005 alone was about RM25 billion, where RM9 billion were for power generation and RM16 billion were for the transport sector. Therefore, new and effective ways to reduce the overwhelming dependence on natural gas, as well as the energy subsidy, have to be found. One natural resource that Malaysia has in abundance and which is totally free is the sunlight (MGCC, 2007).
To harvest maximum power from a PV module, MPPT based on modified P&O algorithm is implemented in this paper. The hardware consists of a high efficiency DC/DC buck converter and a microcontroller based MPPTcontroller, and is tested for battery charging. A conventional charge controller and the designed charge controller are compared when charging a 12 V battery from a 200 W solar PV module. It shows that the modi- fied P&O algorithm provides an efficient and reliable maximum power tracking performance under rapid change in irradiance and temperature conditions. The experimental results show that the proposed system is more efficient than the conventional design.
This paper demonstrates the DC isolated loop network which is fed by PV systems for supplying unbalanced AC loads. We made the main concept of the power management strategy, and then, on the power flow and voltage control. In this paper PSCAD/EMTDC software has been used for the modeling and the simulation of the system component and proposed control strategies for power electronic interfaces, in order to investigate the DC network voltage behaviors, power quality problems and high reliability. The results show that the proposed strategies provide the suitable load sharing between DC/DC converters in order to achieve optimized plant management, while the DC network voltage remains with acceptable level. The paper shows that a DC network with PVsystem is very realistic and more reliable. The results also show that the proposed system can supply the unbalanced AC load with balanced voltages. It is shown that the unbalancing would not be occurred in the DC network by the unbalanced AC load. Finally, we believe that isolated DC network with distributed generation from renewable sources could be one of the most promising alternatives for the supplying the standalone loads, where villages are often far away from the utility grid.
The density of power radiated from the sun (referred to as the ‘‘solar energy constant’’) at the outer atmosphere is 1.373Kw/m2. Part of this energy is absorbed and scattered by the earth’s atmosphere. The final incident sunlight on earth’s surface has a peak density of 1Kw/m2 at noon in the tropics. The technology of photovoltaic (PV) is essentially concerned with the conversion of this energy into usable electrical form. The basic element of a PVsystem is the solar cells which are made up by different materials. Solar PV cell converts photon energy of sun light into electrical power which is in DC electrical energy form. Solar cells rely on a quantum-mechanical process known as the ‘‘Photovoltaic effect’’ to produce electricity. Photovoltaic cells are made of several types of semiconductors using different manufacturing processes. A typical solar cell consists of a p-n junction formed in a semiconductor material similar to a diode.
battery is greatly increased because of its limited service time (Saucer et al., 1997). The expected battery lifetime is reduced if there is low PV energy availability for prolonged periods or improper charging control, both resulting in low battery state of charge (SOC) for long time periods. The overall system cost can be reduced by the use of proper battery charging/ discharging control techniques, which achieve high battery SOC, and consequently longer lifetime. In order to regulate the converter due to non linearity conventional controller like PI controller with Perturb and Observe algorithm is proposed and simulated. The tracking algorithm integrated with a solar PVsystem has been simulated with buck DC-DC converter for the application of battery charging in stand-alonePVsystem. The proposed PV charger system with buck DC-DC converter is shown in Fig.1.
Abstract— The system consists of PVsystem, wind energy conversion system (WECS) and battery and intelligent MPPTcontroller. The PV/wind hybrid system can give fluctuating output that makes the system unstable, a battery is connected to the system to reduce the fluctuations in output voltage. To get the stable response for the system intelligent MPPTcontroller is used. The intelligent MPPTcontroller uses artificial neural network to extract maximum power point. PV and wind energy conversion system consists of MPPT algorithms. An Artificial Neural Network (ANN) based MPPT is proposed to get the maximum power from the system. The DC-DC boost converter is connected to the DC link. The output signal from MPPTcontroller is used as duty cycle of the DC-DC boost converter. The PV and wind block with intelligent MPPTcontroller are modeled separately in MATLAB/Simulink before connecting them together to build a hybrid system. The performance analysis is done under different wind speeds, solar irradiance and temperature in MATLAB/Simulink.
strongly depends on load condition as reported for a single phase induction motor . However, this PF could be improved using a booster capacitor, which provides PF more than 0.97 throughout the process. Insignificance changes in motor supply voltage were observed and maintained about 227 V at a supply frequency of 50 Hz. Inverter average efficiency was calculated as 75 % and it was quite reasonable and because of low DC voltage system. Other total losses were calculated as 25 %, which includes all switching losses and inverter standby losses. Kapila Bandara et al. reported as, an off-grid PVsystem with battery energy storage, which employs a cascaded DC-AC inverter without a transformer and provided lower switching losses . The standby losses were specified by the manufacturer as 32 %, which used for this study.
Therefore, the motivation of this thesis is to obtain the maximum power point (MPP) of photovoltaic (PV) system by using Fuzzy Logic Controller (FLC). Hence, this thesis focused on the well-known Perturb and Observe (P&O) algorithm and compared to a design fuzzy logic controller (FLC). A simulation work dealing with MPPTcontroller, a DC/DC Boost converter feeding a load is achieved. The result will show the validity of the proposed Fuzzy Logic MPPT in the PVsystem.
In present time electrical energy plays role as an important factor for development of human colonization and economic growth of country. Due to increase in industrialization and population, there is more demand for electrical energy. Heavy consumption of electricity challenges the power generated by using non-renewal energy sources. A photovoltaic panel can be used for power generation since the solar energy is a non- conventional energy resource and has quite promising results. The initial installation cost of non-conventional generation system is very high (counting the maintenance cost also). PV modules have cells arranged inside in series and parallel as per the user‘s requirements. By taking each PV module in series and parallel arrangement we can meet our load demand. An ideal PV cell is modeled as current source with anti-parallel diode. This diode is the cause of non-linear characteristic of I Vs V of a PV module. Among all others, solar energy is the mostly used renewable resource owing to its availability and it supports green being an environmental friendly resource.The PV array efficiency is comparatively very less and also the solar irradiation is not constant whole day .A PV panel happens to have a unique point called as the maximum power point, which is observed to give/extract maximum power for given climatic conditions such as irradiation and temperature.The MPPT depends not only on the climatic conditions but also on the PV panel manufacturing characteristics.A soft computing control technique is required for tracking the maximum power point at which PVsystem operates.
Hybrid system based on photovoltaic is considered an effective option to electrify remote and isolated areas far from grid. This is true for areas that receive high averages of solar radiation annually. Using diesel generator as a standby source will make utilization of hybrid systems more attractive. An economic feasibility study and a complete design of a hybrid system consisting of photovoltaic (PV) panels, a diesel generator as a backup power source and a battery system supplying a small community in Palestine were presented in this paper. Other scenarios were also studied and analyzed in this paper to ascertain which of them the most appropriate considering cost and pollutant emissions are. A simulation program using iterative approach is developed to optimize the sizes of PVsystem and battery bank. Specifications of the hybrid system components are then determined according to the optimized values. Solar radiation data is firstly analyzed and the tilted angle of the PV panels is also optimized. Costs of different components, hourly solar radiation and ambient temperatures and other design considerations are inputs of the simulation program. It is found that electrifying rural small community using this hybrid system is very beneficial and competitive with other types of conventional sources as it decreases both operating costs and pollutant emissions.
Fig. 1 is the circuit diagram of the SEPIC dc–dc converter together with the MPPT and the fuzzycontroller with battery. The design of the fuzzycontroller was done using Mamdani’s method for the converter. The maximum power point can be achieved in case of a grid-connected system, a full-load condition, or using battery charging in case of a standalone system. However, if the load need is lower than PV capacity, the PV voltage will move right in the PV curve, achieving the opportune power. This case happens even if the batteries of the standalone system are full and the load is lower than PV power. In grid-connected systems, the load is always there due to the huge number of clients. Therefore, the maximum power point can always be achieved subject to the load need.