A Real-time Modeling of Photovoltaic Array

This paper mainly aims at the modeling problem of the photovoltaic (PV) array with a 30 kW PV grid-connected generation system. An iterative method for the time-varying parameters is proposed to model a plant of PV array. The relationship of PV cell and PV array is obtained and the solution for PV array model is unique. The PV grid-connected generation system is used to demonstrate the effectiveness of the proposed method by comparing the calculated values with the actual output of the system.

Wind-sand movement characteristics and erosion mechanism of a solar photovoltaic array in the middle of the Hobq Desert,Northwestern China

The operation and power generation of utility-scale solar energy infrastructure in desert areas are affected by changes in surface erosion processes resulting from the construction of solar photovoltaic(PV)power stations.However,few studies have addressed the interactions between solar PV arrays and aeolian erosion processes.In this study,wind flow field characteristics and the vertical distribution of sediments were investigated in the near-surface transport layer at three different locations with respect to the solar PV arrays in a 200 WM-p PV power station in the central Hobq Desert,northwestern China.The results indicate that the sediment transport varied around the panels,with the greatest transport occurring between the panels,followed by behind and in front of the panels.The sediment fluxes of all of the observation sites obey an exponential function.The secondary flow field zones formed around the PV panels:the conflux accelerating zone between the panels,the resistance decelerating zone of the under panels,and the transition zone of the rapid velocity increase in front of and behind the panels.This resulted in a greater shear force in front of the panels under the downward flow diversion effect of PV panels,and the wind erosion depressions were finally formed here.The results of this study provide information for planning better technical schemes for wind-sand hazards at solar PV power stations,which would ensure operational stability and safety in desert areas.

Impact of utility-scale solar photovoltaic array on the aeolian sediment transport in Hobq Desert, China

Deserts are ideal places to develop ground-mounted large-scale solar photovoltaic (PV) powerstation. Unfortunately, solar energy production, operation, and maintenance are affected bygeomorphological changes caused by surface erosion that may occur after the construction of the solar PVpower station. In order to avoid damage to a solar PV power station in sandy areas, it is necessary toinvestigate the characteristics of wind-sand movement under the interference of solar PV array. The studywas undertaken by measuring sediment transport of different wind directions above shifting dunes andthree observation sites around the PV panels in the Hobq Desert, China. The results showed that the twoparameterexponential function provides better fit for the measured flux density profiles to the near-surfaceof solar PV array. However, the saltation height of sand particles changes with the intersection anglebetween the solar PV array and wind direction exceed 45°. The sediment transport rate above shifting duneswas always the greatest, while that around the test PV panels varied accordingly to the wind direction.Moreover, the aeolian sediment transport on the solar PV array was significantly affected by wind direction.The value of sand inhibition rate ranged from 35.46% to 88.51% at different wind directions. When theintersection angle exceeds 45°, the mean value of sediment transport rate above the solar PV array reducesto 82.58% compared with the shifting dunes. The results of our study expand our understanding of theformation and evolution of aeolian geomorphology at the solar PV footprint. This will facilitate the designand control engineering plans for solar PV array in sandy areas that operate according to the wind regime.

A Continuous Health Monitoring System for Photovoltaic Array Using Arduino Microcontroller

In this paper new technique is developed to monitor the health status of the PV panels in the array. For finding the health status short circuit current is measured continuously over a fixed time period. This technique can classify the health status into four categories such as Healthy, Low Fault, Medium Fault and High Fault. By this classification faulty operation can be rectified and power generation may be improved. In case of high faults, PV panels can be protected. The cost requirement for the implementation is very low. The proposed technique is implemented in MATLAB Simulation and hardware. The array considered in this paper is 2 × 2 Series Parallel.

Maximizing aged photovoltaic array power:a computer modelling study

Photovoltaic(PV)modules age with time for various reasons such as corroded joints and terminals and glass coating defects,and their ageing degrades the PV array power.With the help of the PV array numerical model,this paper explores the effects of PV module ageing on the PV array power,and the power gains and costs of rearranging and recabling aged PV modules in a PV array.The numerical PV array model is first revised to account for module ageing,rearrangement and recabling,with the relevant equations presented herein.The updated numerical model is then used to obtain the array powers for seven different PV arrays.The power results are then analysed in view of the attributes of the seven PV array examples.A guiding method to recommend recabling after rearranging aged modules is then proposed,leading to further significant power gains,while eliminating intra-row mismatches.When certain conditions are met,it was shown that recabling PV modules after rearranging them may lead to further significant power gains,reaching 57%and 98%in two considered PV array examples.Higher gains are possible in other arrays.A cost-benefit analysis weighing annual power gains versus estimated recabling costs is also given for the seven considered PV array examples to guide recabling decisions based on technical and economic merits.In the considered examples,recabling costs can be recovered in<4 years.Compared with the powers of the aged arrays,power gains due to our proposed rearranging and recabling the PV arrays ranged between 73%and 131%in the considered examples—well over the gains reported in the literature.Moreover,the cost of our static module rearrangement and recabling method outshines the costs of dynamic reconfiguration methods recently published in the literature.

Maximum power point tracking of a photovoltaic energy system using neural fuzzy techniques

In order to improve the output efficiency of a photovoltaic （PV） energy system, the real-time maximum power point （MPP） of the PV array should be tracked closely. The non-linear and time-variant characteristics of the photovoltaic array and the non-linear and non-minimum phase characteristics of a boost converter make it difficult to track the MPP as in traditional control strategies. A neural fuzzy controller （NFC） in conjunction with the reasoning capability of fuzzy logical systems and the learning capability of neural networks is proposed to track the MPP in this paper. A gradient estimator based on a radial basis function neural network is developed to provide the reference information to the NFC. With a derived learning algorithm, the parameters of the NFC are updated adaptively. Experimental results show that, compared with the fuzzy logic control algorithm, the proposed control algorithm provides much better tracking performance.

Design and Development of a Computer-controlled PV Array Simulator

In this paper,a computer-controlled photovoltaic(PV)array simulator consisted of a synchronous buck DC converter and its associate control software is proposed and developed to simulate the current-voltage(I-V)output characteristics of a real-time PV array with actual loads connected.The main advantage of this simulator is its ability in simulating different types and sizes of arrays under various illumination and temperature conditions.It can replace the actual PV array and perform all the simulations indoor instead of outside field testing.The mathematical model implemented in this system requires minimum manufacturer's data.This system is a very cost effective and reliable laboratory tool to investigate the output characteristics of PV array under various weather conditions,and is helpful for developing new maximum power point tracking(MPPT)algorithms.

Composite Semiconductor Quantum Dots CdSe/CdS Co-sensitized TiO_2 Nanorod Array Solar Cells

CdSe/CdS semiconductor quantum dots co-sensitized TiO2 nanorod array was fabricated on the transparent conductive fluorine-doped tin oxide （FTO） substrate using the hydrothermal and successive ionic layer adsorption and reaction （SILAR） process. The structural and morphological properties of the samples were characterized by X-ray diffraction （XRD）, field-emission scanning electron microscopy （FESEM）, and transmission electron microscopy （TEM）. The results indicate that CdSe/CdS QDs are uniformly coated on the surface of the TiO2 nanorods. The shift of light absorption edge was monitored by taking UV-visible absorption spectra. Compared with the absorption spectra of the TiO2 nanorod array, deposition of CdSe/CdS QDs shifts the absorption edge to the higher wavelength. The enhanced light absorption in the visible-light region of CdSe/CdS/TiO2 nanorod array indicates that CdSe/CdS layers can act as co-sensitizers in quantum dots sensitized solar cells （QDSSCs）. By optimizing the CdSe layer deposition cycles, a photocurrent of 5.78 mA/cm2, an open circuit photovoltage of 0.469 V and a conversion efficiency of 1.34 % were obtained under an illumination of 100 mw/cm2.

Impact of Photovoltaics

Photovoltaics(PV)can convert sunlight into electricity by making use of the photovoltaic effect.Solar panels consist of photovoltaic cells made of semiconductor materials(such as silicon)to utilise the photovoltaic effect and convert sunlight into direct current(DC)electricity.Nowadays,PV has become the cheapest electrical power source with low price bids and low panel prices.The competitiveness makes it a potential path to mitigate the global warming.In this paper,we investigate the relationship of PC array output with irradiance and temperature,the performance of PV array over 24 hours period,and the simulation of PV micro grid by MATLAB simulation.

A maximum power point tracker for photovoltaic energy systems based on fuzzy neural networks

To extract the maximum power from a photovoltaic （PV） energy system, the real-time maximum power point （MPP） of the PV array must be tracked closely. The non-linear and time-variant characteristics of the PV array and the non-linear and non-minimum phase characteristics of a boost converter make it difficult to track the MPP for traditional control strategies. We propose a fuzzy neural network controller （FNNC）, which combines the reasoning capability of fuzzy logical systems and the learning capability of neural networks, to track the MPP. With a derived learning algorithm, the parameters of the FNNC are updated adaptively. A gradient estimator based on a radial basis function neural network is developed to provide the reference information to the FNNC. Simulation results show that the proposed control algorithm provides much better tracking performance compared with the filzzy logic control algorithm.

Maximum power point tracking (MPPT) control of a photovoltaic system based on dual carrier chaotic search

The output power of the photovoltaic （PV） array changes with the change in external environment and load. Therefore, maximum power point tracking （MPPT） technology is needed to maximize the efficiency of the PV device. At present, existing methods have realized MPPT to some extent. However, the tracking precision and speed remain to be improved. In the current paper, the chaos search theory is first applied on the MPPT technology of the PV system. The chaos search algorithm based on dual carrier increases the adequacy of chaos search and overcomes the blindness of the traditional chaos search, thereby improving the search efficiency. Comparative tests show that the proposed method can quickly and accurately track the step response, and can obtain better optimization results. The simulation and experimentalresults show the effectiveness and good performance of the proposed method.

Research on the maximum power point tracking method of photovoltaic based on Newton interpolation-assisted particle swarm algorithm

Solar energy has attracted a lot of attention because it is clean and has no pollution.However,due to the partially shaded condition,the photovoltaic array cannot work uniformly at the maximum power point,resulting in a large power loss.To improve this problem,the research of the maximum power point tracking(MPPT)algorithm is discussed by scholars.In this paper,an improved particle swarm optimization(PSO)algorithm is proposed to achieve the goal of MPPT,which uses Newton interpolation-assisted conventional PSO.After tracking to the maximum power point,the Newton interpolation method is used to calculate the maximum power point,reduce the number of iterations of the conventional PSO algorithm and reduce the steady-state oscillation.The simulation is carried out in MATLAB^(■)/Simulink^(■)and compared with conventional PSO.The results show that the improved PSO has better tracking ac-curacy and speed than the conventional algorithm,and the initial tracking speed is increased by>30%.

A Simple Primary Key Algorithm Based Shade Dispersion Method for Maximizing PV Power Generation under Partial Shading Conditions

The output power generation of a photovoltaic(PV)array reduces under partial shading,resulting in multiple local maxima in the PV characteristics and inaccurate tracking of the global maximum power point(GMPP).Various interconnection schemes are available to reduce power losses under partial shading.In this study,a primary key algorithm is proposed for distributing shading across an array.This method is suitable for any n×n PV array configuration and involves fewer calculations and variables,leading to reduced computational complexity.The power generations of a 9×9 PV array under four different shading conditions were compared with the configurations of:total cross-tied(TCT)and Su Du Ku,physical relocation and fixed column position of modules with fixed electrical connection(PRFCPM-FEC),and magic square(MS)and improved-odd-even-prime(IOEP).The advantage of the proposed method is that once the primary key elements are obtained,the remaining array elements are numbered in a simpler manner.The results obtained using the proposed arrangement show that the power is enhanced with reference to the TCT and is comparable to the Su Do Ku,PRFCPM-FEC,MS,and IOEP reconfigurations.

Reconfiguration of PV Arrays(T-C-T,B-L,H-C)Considering Wiring Resistance

Partial shadings on the photovoltaic(PV)array causes reduction in maximum power generation.Reconfiguration of PV arrays plays an important role in increasing the maximum power generation from PV array configurations under partial shadings.In general,partial shadings on the PV arrays are concentrated on a group of modules.Therefore,the distribution of shading over the array increases the maximum power generation.This paper uses a modified Sudoku pattern to increase the maximum power generation from the PV array configurations.The PV array configurations are analyzed by considering column wiring resistance and cross ties resistance.The modified Sudoku pattern is applied to Total-Cross-Tied(T-C-T),Bridge-Link(B-L)and Honey-Comb(H-C)configurations and their performances are analyzed under various shading patterns,such as short narrow,short wide,long narrow,long wide,middle and diagonal.The specifications,such as Global Maximum Power(GMP),Mismatch losses,Fill Factor,Efficiency are considered to see the efficacy of various PV array configurations and their reconfigurations.From the results,it can be concluded that reconfigured T-C-T PV array generates the highest GMP compared to other configurations under considered shading patterns.

Research on Maximum Power Point Tracking in Redundant Load Mode for Photovoltaic System

In order to ensure that the photovoltaic(PV) array always works at the global maximum point of power to increase the system's overall efficiency, this paper leads the study on maximum power point tracking(MPPT) in redundant load mode. A new control system is designed by combining the redundant electronic load module, embedded controller, supportive capacitor and boost circuit. The system adjusts duty ratio of boost circuit dynamically based on the maximum power point parameter provided by redundant load unit in order to realize MPPT. An experiment shows that no matter whether system is under an even illumination or partly perturbed by shadow, this method can find the exact maximum power point.

An improved MPPT control strategy based on incremental conductance algorithm

PV power production is highly dependent on environmental and weather conditions,such as solar irradiance and ambient temperature.Because of the single control condition and any change in the external environment,the first step response of the converter duty cycle of the traditional MPPT incremental conductance algorithm is not accurate,resulting in misjudgment.To improve the efficiency and economy of PV systems,an improved incremental conductance algorithm of MPPT control strategy is proposed.From the traditional incremental conductance algorithm,this algorithm is simple in structure and can discriminate the instantaneous increment of current,voltage and power when the external environment changes,and so can improve tracking efficiency.MATLAB simulations are carried out under rapidly changing solar radiation level,and the results of the improved and conventional incremental conductance algorithm are compared.The results show that the proposed algorithm can effectively identify the misjudgment and avoid its occurrence.It not only optimizes the system,but also improves the efficiency,response speed and tracking efficiency of the PV system,thus ensuring the stable operation of the power grid.