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Adaptive photovoltaic array reconfiguration based on real cloud patterns to mitigate effects of non-uniform spatial irradiance profiles
Abstract
This paper proposes a simple and dynamic reconfiguration algorithm for photovoltaic (PV) arrays in order to mitigate negative effects of non-uniform spatial irradiance profiles on PV power production. Spatially dispersed irradiance profiles incident on inclined PV module surfaces at each application site are generated based on real sky images. Models of PV modules are constructed in MATLAB/Simulink based on one-diode mathematical model of a PV cell. The proposed dynamic reconfiguration algorithm operates based on irradiance equalization principle aiming for creation of balanced-irradiance series-connected rows of PV modules. The proposed algorithm utilizes an irradiance threshold to obtain near-optimal configurations in terms of irradiance equalization and number of switching actions under any type of non-uniform spatial irradiance profile. The algorithm provides no limits on the number of PV modules within the array. The reconfiguration algorithm is examined with different irradiance profiles and significant improvements, almost equivalent to the ideal case corresponding to equal irradiance for all panels, are achieved for each shading pattern. The advantages of the algorithm are simplicity and providing significant improvements in array’s power generation alongside with reduced number of switching actions.
... Therefore, in order to get an optimal IEq arrangement, the authors in [27] have adopted an iterative and hierarchical sorting method. In addition, similar methods were discussed in [28] and [29], and recent methods like followed the regularized leader (FTRL) algorithm-based regression prediction model [30], and maximum-minimum tier equalization swapping (MMTES) algorithm [31], were proposed. These techniques apply the concept of shadow dispersion in the IEq concept for distributing the effects of shadow within the individual rows as equally as possible using specific rules. ...
... In this way, the currents in the different nodes and the voltage of the PV modules connected in parallel are equal, hence, there is no phenomenon of mismatch between PV modules. Each module is labeled with the index 'i, j' where 'i' indicates the row and 'j' denotes the column in which the module is linked [29]. ...
In photovoltaic (PV) systems, partial shading is a major issue that may cause power losses, hot spots, and PV modules damage. Thus, PV array dynamic reconfiguration approaches based on irradiance equalization (IEq) between rows have been proposed to alleviate the shading effect thereby improving PV power production. However, the existing IEq-based reconfiguration techniques focus only on the minimization of row current error, without taking into consideration the voltage effect, which in turn, may result in power losses. In this regard, an improved reconfiguration strategy is proposed in the present paper to maximize the power production of a TCT interconnected PV array operating under partial shading conditions. The proposed strategy aims to achieve a PV array reconfiguration that mitigates the droop voltage issue by considering irradiance levels in both rows and columns. An in-depth investigation of a typical PV module and TCT module is provided, demonstrating that there are cases where the partial shading does not affect the PV module current but the operating voltage. In addition, an analysis highlighting the limitations of the IEq technique regarding the droop voltage issue is presented. Furthermore, mathematical development is established for deriving the objective function of the proposed strategy. The efficiency of the proposed reconfiguration strategy is assessed through experimental tests carried out on a 20 MWp PV station in Ain El-Melh, Algeria. The obtained results reveal that the proposed method overcomes the weaknesses of the existing IEq strategy and ensures power production higher than the TCT and IEq configurations by 17.25% and 19.34%, respectively.
... Therefore, in order to get an optimal IEq arrangement, the authors in [27] have adopted an iterative and hierarchical sorting method. In addition, similar methods were discussed in [28] and [29], and recent methods like followed the regularized leader (FTRL) algorithm-based regression prediction model [30], and maximum-minimum tier equalization swapping (MMTES) algorithm [31], were proposed. These techniques apply the concept of shadow dispersion in the IEq concept for distributing the effects of shadow within the individual rows as equally as possible using specific rules. ...
... In this way, the currents in the different nodes and the voltage of the PV modules connected in parallel are equal, hence, there is no phenomenon of mismatch between PV modules. Each module is labeled with the index 'i, j' where 'i' indicates the row and 'j' denotes the column in which the module is linked [29]. ...
In photovoltaic (PV) systems, partial shading is a major issue that may cause power losses, hot spots, and PV modules damage. Thus, PV array dynamic reconfiguration approaches based on irradiance equalization (IEq) between rows have been proposed to alleviate the shading effect thereby improving PV power production. However, the existing IEq-based reconfiguration techniques focus only on the minimization of row current error, without taking into consideration the voltage effect, which in turn, may result in power losses. In this regard, an improved reconfiguration strategy is proposed in the present paper to maximize the power production of a TCT interconnected PV array operating under partial shading conditions (PSCs). The proposed strategy aims to achieve a PV array reconfiguration that mitigates the droop voltage issue by considering irradiance levels in both rows and columns. An in-depth investigation of a typical PV module and TCT module is provided, demonstrating that there are cases where the partial shading does not affect the PV module current but the operating voltage. In addition, an analysis highlighting the limitations of the IEq technique regarding the droop voltage issue is presented. Furthermore, mathematical development is established for deriving the objective function of the proposed strategy. The efficiency of the proposed reconfiguration strategy is assessed through experimental tests carried out on a 20 MWp PV station in Ain El-Melh, Algeria. The obtained results reveal that the proposed method overcomes the weaknesses of the existing IEq strategy and ensures power production higher than the TCT and IEq configurations by 17.25% and 19.34%, respectively.
... Akrami et al. [25] developed a methodology depending on power comparison to extract the maximum power from partially shaded array via rearranging the shaded panels. In [26], a dynamic reconfiguration of the PV array has been conducted via equalizing principle for irradiance striking the array surface. A bifurcation strategy using power electronic circuit and battery has been employed to perform the PV array reconfiguration in case of PS to minimize the generated losses and enhance the output power [27]. ...
... The tabulated results demonstrated the difference between the proposed AVOA and the others, moreover the result obtained in case V demonstrated the effectiveness of the proposed AVOA and clarified its reliability as an efficient tool for solving the problem of PV array reconfiguration process at PSC. In order to confirm the validity of the proposed AVOA, fill factor (FF), power enhancement (Pe) with respect to TCT configuration, and performance ratio (PR) are calculated based on the following formulas [26]: ...
The photovoltaic (PV) system operation faces great challenges as its performance depends on the weather conditions like irradiance and temperature. One of the phenomena that has negative effect on the PV array is operation under partial shade condition (PSC) as it causes hot spots, increases the power loss, and reduces the generated power. Therefore, this work proposes recent methodology incorporated metaheuristic approach named African vultures optimization algorithm (AVOA) that is applied for the first time to reconfigure the PV array operated at PSC for maximizing the generated power. The merit of AVOA is its high ability to escape from the local optima. Five shade patterns of short wide (SW), long wide (LW), short narrow (SN), long narrow (LN), and lower triangle are analyzed. Moreover, comparison to total cross tied (TCT), SudoKu, harris hawks optimizer (HHO), Aquila optimizer (AO), and antlion optimizer (ALO) is conducted. Furthermore, comparative analysis in terms of fill factor (FF), power enhancement (Pe) with respect to TCT arrangement, power loss, and performance ratio (PR) is conducted. The proposed AVOA outperformed the others in terms of the power enhancement and performance ratio. The best Pe obtained via the proposed AVOA is 39.91% in the fifth shade pattern while the best PR is 82.9125% in the third pattern. Additionally, Wilcoxon sign rank, Friedman, ANOVA table, and multiple comparison tests are performed. The results demonstrated that, AVOA results are significantly different from HHO over the five studied cases. The reported p-values based on Friedman and ANOVA illustrated the existence of significant differences among algorithms. The best p-values for Friedman and ANOVA are 9.4725e−08 and 7.3013e−13 in the fourth and fifth patterns respectively. The results confirmed the preference of the proposed AVOA in achieving the best reconfiguration of the PV array at PSC. Chaotic mapping is recommended to adaptively set the proposed AVOA parameters.
... A new irradiance equalization based Dynamic PVA (DPVA) wassuggested in Ref. [15]. The developed algorithm searches the optimal configuration in the way to mitigate on real-time the nonuniform spatial irradiance profiles effect. ...
... Hence, the evaluation of all possible configurations guarantees the best configuration. However, an important computation time is needed as in the case of Irradiance Equalization (IE) approaches where the IE index is calculated for each configuration [13,15]. ...
In this paper, an experimental analysis and validation of a simple reconfigurable photovoltaic (PV) array is carried out. An assessment of a new reconfiguration method based on fuzzy logic (FL) under partial shading conditions is introduced. Furthermore, a recursive least squares based irradiance estimator is proposed aiming to reduce the investment cost of the dynamic PV array. An experimental comparison with other estimators showed the high precision of the proposed estimator. The estimation error has decreased by an average of 10% compared to the first estimator (based on the PV current and voltage measurement) and by 4.28%compared to the second estimator(based on the PV current measurement).On the other hand, the results validated the FL Controller ability to switch to the appropriate configuration under prevailing shading conditions. The method was tested for a simple configuration but it could be generalized for small-scale configurations as residential house (average power output equal to 5kWh). To evaluate the performance of the FL method an extended simulation of DPVA of 16 PV modules is also realized. The mismatch loss is mitigated by nearly 50% compared to fixed Total-Cross-Tied and 8% compared to basic Irradiance Equalization techniques.
... The irradiation equalization reconfiguration (IER) method is based on equalizing the radiant intensities of PV panels in the rows of the array [20][21][22][23]. In this method, shaded panels are connected to the line containing unshaded panels to reduce current mismatch between the panels. ...
Photovoltaic systems are among the most popular renewable energy sources due to their ease of installation and low operating costs. However, they are characterized by low efficiency, non-linear electrical properties, and sensitivity to radiant intensity on the panels. To address these limitations, researchers have focused on improving the efficiency of these systems. The most effective method for enhancing the maximum power point of a PV array is reconfiguration, which involves rearranging the connection structures of the panels. This study presents a method for determining the reconfiguration of panels based on their radiant intensity using a genetic algorithm (GA). The method matches the rows of the PV array to achieve similar radiant intensities, thereby increasing power efficiency. An algorithm was developed to enable the adaptive panels to connect to any row of the fixed section in a PV array divided into dual-adaptive and fixed sections, controlling this connection structure. This GA-based algorithm utilizes short-circuit currents obtained from specific points of the PV array to identify the most suitable connection structure within the solution space and generates control signals for reconfiguration. Simulation results with various array structures and shading scenarios demonstrate that the proposed method increases array efficiency and achieves results within a practically applicable cycle time.
... The static reconfiguration does not require complex algorithms, sensors, switching matrix and auxiliary circuits. Sudoku [15], improved sudoku [16], magic square [17], zigzag puzzle [18], rough set theory-based reconfiguration [19], ken-ken [20], latin-square (LS) puzzle [21], odd even (OE) [22], are examples of static reconfiguration. ...
... In [37], the issue of irradiance equalization control is discussed, where the mean irradiance of the PV array does not equal the sum of the irradiance of each row. To mitigate the impact of nonuniform spatial irradiance profiles on real-time PV power generation, a dynamic reconfiguration approach was presented [38]. A flexible switching matrix-based elastic photovoltaic structure (EPVS) was proposed [39]. ...
... Methods include connecting shaded panels to unshaded rows, utilizing switching matrices, and employing algorithms to maximize power output. These approaches aim to reconstruct the IE, ensuring efficient PV array reconfiguration under varying shading conditions [37][38][39][40][41]. ...
In the rapid progress towards sustainable energy systems Photovoltaic (PV) systems are notably susceptible to power losses and gaining hotspots due to partial shading, a pervasive issue that significantly diminishes power output. This article presents a systematic review of more than seventy up-to-date relevant articles that are involved in PV array reconfiguration, and their strategic response to combat the detrimental effects of partial shading. These studies were meticulously chosen for their relevance to current PV array practices, their methodological robustness, and the reliability of their empirical or simulated results. The provided analysis is a multi-dimensional assessment of these methods, considering factors such as array size, complexity, execution speed, merits, demerits, acquired parameters, and alongside, validation methods employed. A significant finding from this review is the emerging preference for reconfiguration techniques that blend static and dynamic elements, particularly those employing meta-heuristic algorithms, over purely dynamic approaches. The article presents a comprehensive reference for and a lucid primer in the domain of PV array reconfigurations.
... The authors of [34] proposed an iterative hierarchical sorting algorithm based on the irradiance equalization method to achieve near-optimal configuration in a small number of iterations. In [35], the author used a modeling technique that can generate spatially dispersed irradiance profiles incident on the surface of photovoltaic modules at the application site. The goal of the algorithm is to provide near-optimal array reconfiguration in terms of irradiance equalization and the number of switching actions. ...
In order to address the issue of power loss resulting from partial shadow and enhance the efficiency of photovoltaic power generation, the photovoltaic array reconfiguration technology is being increasingly utilized in photovoltaic power generation systems. This paper proposes a reconfiguration method based on improved hybrid particle swarm optimization (HPSO) for the photovoltaic array of TCT (total-cross-tied) structure. The motivation behind this method is to get the best reconfiguration scheme in a simple and efficient manner. The ultimate goal is to enhance the output power of the array, save energy, and improve its overall efficiency. The improved HPSO introduces the concept of hybridization in genetic algorithms and adopts a nonlinear decreasing weight method to balance the local search and global search ability of the algorithm and prevent it from falling into the local optimal solution. The objective function used is the variation coefficient of the row current without the weight factor. This approach saves time and balances the row current of the array by altering the electrical connection of the component. In the 4 × 3 array, the improved HPSO is compared with the Zig-Zag method. In the 9 × 9 array, the improved HPSO is compared with the CS (competence square) method and the improved SuDoKu method. The simulation results show that the power enhancement percentage of the improved HPSO is between 6.39% and 28.26%, and the power curve tends to single peak characteristics. The improved HPSO has a smaller mismatch loss and a higher fill factor in the five shadow modes, which can effectively improve the output power, and it is convenient to track the maximum power point later.
... The reconfiguration techniques also need regular maintenance. For identifying the PV cell defects, there are many approaches were proposed as in [95][96][97]. These methods use electrical parameters, computational algorithms, Soft computing methods, image processing tools, and so on for obtaining the fault details in the PV system. ...
Solar photovoltaic (PV) systems are susceptible to power loss caused by environmental factors such as partial shading and temperature changes. To address this issue, PV modules are connected in array configurations. However, these configurations can lead to mismatch losses between the PV rows, which reduce power output. While there are many solutions to mitigate these losses, the performance of each solution can vary depending on the environmental conditions and the array configuration logic. This research paper evaluates the performance of fifteen existing static PV array configuration techniques under various shading patterns. We analyze the mathematical formulation and logic used behind each configuration, as well as the shade dispersion rate, power generation, power losses, advantages, and disadvantages. Our analysis includes a MATLAB/Simulink® model of a 5×5 array for each configuration under different shading patterns. The performance of consistent and best configurations is also evaluated in a real-time environment. The results categorize each configuration as consistent, best, average, or poor. This paper provides a detailed analysis of the different PV array configurations and their performance, which can help in selecting the optimal configuration for specific environmental conditions.
... Terefore, it is necessary to establish the output characteristics model of the PV array in the case of moving cloud shading. By describing the moving cloud shadow itself and its motion factors, the target shadow of the object to be studied can be modelled [33]. Shadows blocking the PV array can be seen as projections on the horizontal plane of the PV array; hence, the movement of shadows can be regarded as the movement of particles. ...
Photovoltaic (PV) reconfiguration is an effective solution for reducing the hot spot effect caused by partial shadows on PV arrays. This paper proposed an efficient atom search optimization- (ASO-) based PV reconfiguration method. The analysis and comparison with the other four reconfiguration methods were performed by three evaluation criteria, which are mismatch loss, fill factor, and standard deviation, respectively. The conclusion can be drawn that the efficiency, rapidity, and reliability of ASO are superior to those of other methods. Besides, a moving cloud shadow mode of 9 × 9-scaled PV array is designed in this paper, which can be widely recommended to thoroughly study a PV reconfiguration approach.
... In dynamic reconfiguration techniques, physical locations SPV array remain unchanged and shade dispersion is achieved by changing electrical connections of the SPV array. Electrical array reconfiguration (EAR) [45], Irradiation equalization (IE) [46] reconfiguration and Adaptive array reconfiguration (AAR) [47] are dynamic reconfiguration methods reported in the literature based on switching between the connections of a solar PV array to mitigate mismatch losses. In recent studies, optimization algorithms have been attracted researchers and found a feasible alternative for reconfiguration of a solar PV array. ...
Extraction of maximum power from large scale solar photovoltaic power systems is the most challenging and demanding research in the current scenario. Solar photovoltaic panels are highly susceptible to a phenomenon known as partial shading. Partial shading increases mismatch losses and reduces the output of the solar photovoltaic system The output reduction in the partially shaded array is proportional to the shaded area, shaded panel's placement within the array, panel connections, shade geometry, etc. There are several approaches for reducing Partial shading effects in the literature. The most efficient approach to mitigating the mismatch losses due to Partial shading in large-scale solar photovoltaic systems is the reconfiguration technique, which distributes shaded panels more evenly and increases the maximum power output. The current work utilizes a set of reconfiguration rules for selecting the location of shaded panels within an array that allows for multiple reconfiguration options. The results show that the proposed reconfiguration has obtained an improved Performance enhancement ratio of 25% in one shading pattern i.e. short wide shading, Performance enhancement ratio of 6.4% in short narrow and centre shading and Performance enhancement ratio of 5.9% in long narrow shading. The proposed reconfiguration was found to be the most suitable, simple, and cost-effective solution for large size of solar photovoltaic system under all shading conditions.
... In Reference [11], a similar approach is presented for TCT only. Reference [12] is a good technique viz. simplicity and scalability; however, it requires irradiance sensors; the threshold of which offsets the switching operation. ...
An optical isolator circuit is developed to detect and dynamically relocate the photovoltaic (PV) module under partial shading. The suggested system control structure operates in two modes. Mode 1 governs the system at global maxima (GM) by tracing the power-voltage (PV) curve. Mode 2 detects and separates all the bypassed modules from a PV string/array by means of a decentralized control and stores its power in the battery. Simulations are performed on different shading patterns to verify the efficacy of the suggested system. The results showcase that the averaged harnessed power using the proposed circuit is 25.26% more than the total cross-tied (TCT) and series-parallel (SP) array configurations. The proposed circuit does not require complex gate driver circuits and large switch counts. The circuit is scalable and can be implemented on an “N × N” array.
... If the activated threshold of SDI is set too low, the power will be enhanced at the expense of high switching times. As the threshold of the SDI profoundly depends on the characteristic of the shading [27], herein, the activated threshold of the SDI on the PV array is determined by using the trial-and-error method during the simulation process. ...
The operation of the photovoltaic (PV) system under partial shading conditions (PSC) is complicated since the output characteristic of the PV system is profoundly affected by the heterogeneous irradiance of PSC. This paper proposes a dynamic reconfiguration framework to tackle PSC in the PV array. Continuous operation of the dynamic PV array reconfiguration under cloud-induced partial shading is considered by developing an emulator of the moving cloud. In addition, the Particle Swarm Optimization and Rao algorithms are improved to obtain the optimal PV array configuration under PSC. The operation of switching is enhanced by simultaneously considering the total switching times and the operation of highly active switches. The simulation results on the 9×9 PV array demonstrate the effectiveness of the proposed framework in terms of reducing the number of local maximum power points on the power-voltage characteristic, enhancing power output, and relieving stress on the switching operation of the PV array under different PSC.
... The "maximum power point tracking" (MPPT) technique for the PV system under partially shaded conditions (PSCs) has been studied extensively. In order to mitigate the negative effects of PSCs on PV power generation, one solution is to change the hardware circuit of the PV array, such as incorporating the switch matrix to reorganize the PV system configuration [79]. ...
Solar photovoltaic (PV) systems have drawn significant attention over the last decade. One of the most critical obstacles that must be overcome is distributed energy generation. This paper presents a comprehensive quantitative bibliometric study to identify the new trends and call attention to the evolution within the research landscape concerning the integration of solar PV in power networks. The research is based on 7146 documents that were authored between 2000–2021 and downloaded from the Web of Science database. Using an in-house bibliometric tool, Bibliometrix R-package, and the open-source tool VOSviewer we obtained bibliometric indicators, mapped the network analysis, and performed a multivariate statistical analysis. The works that were based on solar photovoltaics into power networks presented rapid growth, especially in India. The co-occurrence analysis showed that the five main clusters, classified according to dimensions and significance, are (i) power quality issues that are caused by the solar photovoltaic penetration in power networks; (ii) algorithms for energy storage, demand response, and energy management in the smart grid; (iii) optimization, techno-economic analysis, sensitivity analysis, and energy cost analysis for an optimal hybrid power system; (iv) renewable energy integration, self-consumption, energy efficiency, and sustainable development; and (v) modeling, simulation, and control of battery energy storage systems. The results revealed that researchers pay close attention to “renewable energy”, “microgrid”, “energy storage”, “optimization”, and “smart grid”, as the top five keywords in the past four years. The results also suggested that (i) power quality; (ii) voltage and frequency fluctuation problems; (iii) optimal design and energy management; and (iv) technical-economic analysis, are the most recent investigative foci that might be appraised as having the most budding research prospects.
... Adaptive-bank based [28] Bubble-sort model-based control algorithm -Identifies the best panel for proper distribution of the shadows -Requires continuous switching -Complex and time-consuming switches -Requires separate sensors implementation. [29] Fuzzy logic -Determines the optimal connection structure -Accurate and fast, Suitable for systems of different sizes -Determining radiation based on the amount of short-circuit currents is a difficult and expensive task [30] Scanning algorithm -Increases efficiency significantly -Selects the best configuration -Runs on panels with different levels and features -Getting the short circuit current of all the rows is a difficult task -Can't be applied for large dimensions of PV arrays [33,34] Elastic photovoltaic structure -Select the best configuration -It requires many switches (complex) -Unable to provide TCT [35] Shading degree model-based reconfiguration algorithm -Reduces computing time -Reduces mismatch -Reduces hot spots -Frequent short circuit errors [36,37] Artificial Neural Network -Has great effectiveness -Strength and accuracy -Has many connections [38,39] Image processing -Reduces the effects of partial shadows -Reduces energy loss for installations in small systems -Ability to improve output power in case of partial shadows and module failure in commercial systems -Obtaining voltage and current gives more complexity -Requires long time (Proposed image processing algorithm takes one frame every two minutes) Irradiance equalization based [14] Munkres Assignment Algorithm -Reduces the effects of mismatch -Minimizes aging of switches in the switching matrix -Minimizes the number of switching operations -Can't render for large dimensions -There are more replacements [40] Random search algorithm -Fast -It provides different results for input data due to randomness -The complexity of control algorithms -It requires a large number of switching devices [33] Best-Worst storing -Fast and provides the optimal solution in some cases -Needs a lot of switching devices -Contains sophisticated control algorithms -In most cases, do not have the desired result [41] Greedy algorithm -Optimal configuration in low computing time -Optimal configuration without the need for heavy programming -It can be used for large dimensions -Need a lot of switching actions -Contains sophisticated control algorithms [42] Reconfiguration algorithm -Simplicity -Providing important improvements in array's power production alongside a reduced number of switching action -Expensive -Numerous wiring -Complex to control throughout the PV array and improves the power reduction by reducing the mismatch loss. Reducing the effects of PSC on the power generation of TCT PV arrays has been done in [49] using a new reconfiguration method called Odd-Even configuration. ...
Non-uniform irradiance due to partial shading conditions (PSCs) reduces the power delivered by the photovoltaic (PV) cell. The output power reduction in the PV arrays directly depends on the shading pattern and type of array configuration which is selected. So far, many dynamic and static reconfiguration methods have been used for maximum power point tracking under PSCs in the PV arrays. However, most conventional methods suffer from some major problems such as the need for additional equipment and sensors, complex wiring, the use of expensive sensors, production of complex switching matrices, high costs, and inability to reconfigure PV arrays with very small, large, and non-square sizes. Accordingly, this paper, after reviewing the dynamic and static PV array reconfiguration methods, presents a novel static-based technique called 8-Queen's for reconfiguring the PV modules corresponding to the Total-Cross-Tied (TCT) inter-connection PV array. The 8-Queen's technique has a great ability to apply on high dimensions and rectangular shapes PV arrays and is based on the movement of 8 queens on the chessboard so that none of the queens can attack the others. The effectiveness of the suggested method is expressed by implementing it on 7 cases of the TCT PV array in different sizes and various PSCs. In a comparative scenario, the performance and effectiveness of the proposed 8-Queen's technique are evaluated compared to other conventional methods. Indicators of global maximum power point (GMPP), fill factor, power efficiency, and mismatch losses evaluate the results of the employed methods. The evaluation of results represents the effectiveness of the 8-Queen's technique compared to other used methods. In addition, the performance evaluation of the proposed technique in real-world PV arrays is performed by modeling a sample PV array taking into account measurement errors. The results in this step also show that the proposed technique can also provide acceptable performance for solving problems related to maximum power point tracking under PSCs in PV systems.
... [34] I pv , V pv SP, TCT Sudoku [35] I pv , V pv , S SP, TCT, BL, HC, SP-TCT, BL-HC Dominance square [12] I pv , V pv , S SP, TCT, BL, HC Skyscraper puzzle [36] S, shadow pattern TCT Irradiance equalization [23] I pv , V pv SP, TCT Power comparison technique [20] I pv , V pv TCT GA [37] I pv , V pv , S TCT Standard deviation and GA [13] I pv , V pv TCT (PSO) Particle Swarm Optimization [38] I pv , V pv TCT DPA (Democratic Political Algorithm) ...
Reconfiguration of PV arrays is one of the most suitable options to face issues affecting the power produced by panels, such as partial shading. This paper presents a reconfiguration procedure based on a genetic algorithm. The execution times obtained with the proposed approach validate its good performance compared with a traditional brute force algorithm. Finally, different shading patterns are considered in the simulations
... However, the "redundant" links within the TCT array structure may incur a cost penalty. Several researchers [15][16][17] showed that some power drop might also occur when using TCT configuration under certain shading conditions. Other promising techniques for mitigating partial shading issues are using reconfiguration strategies [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. ...
Partial Shading Conditions (PSCs) significantly impact the output power performance of a Photovoltaic (PV) solar array. Such an issue can be addressed by partly or wholly cross-tying the modules in the array rows and reconfiguring the positions of these modules within it. This paper proposes a novel Magic Square-Enhanced Configuration (MS-EC) algorithm to overcome the partial shading issues. Hence, the proposed algorithm disperses the shading effects more evenly over the entire array surface, reducing the conductions losses due to the bypass diode operation. When using the MS-EC scheme, PV modules are physically re-wired and moved into other locations in the array structure without altering their electrical connections. The key advantage of the MS-EC reconfiguration over the existing techniques is that it requires fewer iterations, easing the Maximum Power Point Tracking of the array. The performance of the proposed algorithm is assessed using several indicators, such as maximum power generation, number of iterations required, complexity and mismatched power losses. MATLAB-SIMULINK software environment is used to simulate the MS-EC scheme. Hence, the former method compares favourably with the existing techniques and a traditional Tied-Cross-Ties (TCT) configuration, giving average power improvements of 16 – 43% under most of the realistic weather conditions.
... Several reports [7,8] concludes that partial shading is the major cause of reduced energy yield. Often, the shading results in disproportionate loss in the energy yield; for example, the work in Ref. [9] suggests that partial shading of 9% results in approximately 50% power loss. Moreover, the shading leads to the formation of hot spots in the shaded module. ...
To simultaneously cover multiple wireless services and protocols, the antenna in communication devices should operate over a wide and ultra-wide frequency band. The use of wide/ultra-wideband antennas not only lessens the number of antennas necessary to cover multiple frequency bands but also decreases the system complexity, size, and costs. To operate over the ultra-wide frequency band, in this paper a CPW-fed small antenna is reported for portable communication devices. The anticipated antenna comprises a bow-tie-shaped patch and two ground planes. One inverted L-shaped and one extended U-shaped ground plane are asymmetrically placed with the main radiator which helps the antenna prototype to realize a functional band of 3.05 – 11.25 GHz (VSWR ≤ 2). In the functional band, the studied antenna accomplished a maximum peak gain of 4.98 dBi and maximum efficiency of 94.4%. Moreover, it exhibits symmetric omnidirectional radiation patterns and good time-domain behavior. The lucrative characteristics such as simple design, very small size (24.5 × 20 mm²), ultra-wide operating band, good gain and efficiency, stable radiation characteristics, and good time-domain characteristics make it a potential candidate to be used in portable communication devices.
... Several reports [7,8] concludes that partial shading is the major cause of reduced energy yield. Often, the shading results in disproportionate loss in the energy yield; for example, the work in Ref. [9] suggests that partial shading of 9% results in approximately 50% power loss. Moreover, the shading leads to the formation of hot spots in the shaded module. ...
This paper reviews and evaluates the hardware solutions to mitigate the effect of partial shading for grid-connected photovoltaic (PV) system. It encompasses both the module-level as well as the array-level approaches. The former enhances the energy yield by maximizing the power extraction capability of each individual module. Here, three methods, namely the micro inverter, the power optimizer and the energy recovery circuit are covered. On the other hand, the array-level mitigation—which includes the dynamic and static array reconfigurations optimize the arrangement of the modules to minimize the effect of partial shading on the energy yield. Besides updating the important aspects of the technologies, this paper delves into the economic viability of the solutions, as well as the challenges and future trend. In addition, it benchmarks the performance of the module-level solutions with the system with string inverter using Simulink. It is discovered that if the plant is highly shaded, the net energy gain of the micro-inverter and power optimizer is significant. On the other hand, if the shading is non-existent, employing these devices can be counterproductive (in terms of yield).
... Most previous researchers, such as [19,36], implemented the REA method inthe TCT scheme as an alternative solution in dealing with theshading effects. The TCT topology undeniably provides superior and more energetic performances by generating the most power production under various shading patterns and mismatching conditions, compared to other interconnections. ...
This paper focuses on improvising conventional static PV systems' performance and efficiency by introducing a new solution that involves reconfiguring electrical wiring using switches under different shading profiles. This paper used a meta-heuristic algorithm, Firefly Algorithm (FA), as an optimization algorithm to control the switching patterns under non-homogenous shading profiles and also track the highest global peak of power coefficient produced by the numerous switching patterns. This paper aims to solve the current problems faced by the static, such as unequal dispersion of shading exposed towards solar panels, multiple peaks, and hot spot phenomenon that can contribute to a greater power loss and efficiency reduction. The experimental setup focuses on software development and the system or model developed in the MATLAB Simulink platform. The thorough and comprehensive analysis was done by comparing the proposed method's overall performance and power generation with the static novel Series-Parallel (SP) topology and Total-Cross-Tied (TCT) scheme. SP configuration is widely used in the PV industry. In contrast, the TCT configuration has superior performance, and energy yield generation compares to other static PV configurations such as Bridge-Linked (BL) and Honey Comb (HC) configurations. The results presented in this paper provided valuable information about the proposed method's features in enhancing PV arrays' overall performance and efficiency.
... To implement, the shading pattern on PV modules is captured by using a camera and then directed to the shadow detection algorithm called the Canny edge algorithm, which is responsible for identifying the desired configuration by means of a switching matrix. Another dynamic reconfiguration method applicable for TCT connection has been introduced in [17], wherein to identify the shading locations, sky images happening in real time across the PV array are captured. Also, the desired interconnections of the PV array are chosen with the help of the switching matrix controller developed on the basis of IE. ...
Under partial shading conditions, photovoltaic (PV) arrays are subjected to different irradiance levels caused by nonuniform shading. As a result, a mismatch between the modules, a reduction in the power generated, and the hotspot phenomenon will be observed. One method to reduce mismatch losses is to reconfigure the total-cross-tied (TCT) array in dynamic and static forms, where improved performance can be achieved through more efficient shading distribution thanks to increased dimensions. However, the increase in dimensions leads to the complexity of wiring and installation in static reconfiguration and the large number of switches and sensors required in dynamic reconfiguration. To rectify these problems, a two-step method is proposed in this paper. In the first step, the modules inside the PV array are divided into subarrays with wiring in static reconfiguration, rather than being wired as large-scale PV arrays. In the second step, an algorithm is developed for dynamic reconfiguration. The introduced algorithm searches for all possible connections and finally identifies the most optimal solution. As an advantage, this algorithm employs only the short-circuit current values of the subarray rows, which reduces the number of switches and sensors required in comparison to dynamic reconfiguration. Under 8 different partial shading patterns, simulations are conducted and results confirm that the proposed method outperforms the TCT array and statically modified TCT array in terms of power and mismatch losses. Among these, the highest power improvement is obtained with regard to the TCT array and statically modified TCT array under the fourth and eighth shading patterns, respectively.
... Therefore, in [25], an iterative and hierarchical sorting method was proposed for achieving a nearly optimal irradiance equalization configuration. Similar approaches were presented in [26], [27]. These techniques use the idea of shade dispersion in the irradiance equalization principle to distribute the shading effects in each row as evenly as possible according to certain rules. ...
In actual operation, photovoltaic arrays inevitably encounter shadow problems, resulting in a power output decline and multiple peaks in the output characteristics. The effect of partial shade can be satisfactorily reduced by photovoltaic array reconfiguration. Almost all current reconfiguration techniques are based on the irradiance equalization principle. However, by analyzing the output characteristics of photovoltaic array, it is found that the irradiance equalization principle improves the output power by increasing only the minimum row current without considering the effect of the voltage, so the reconfiguration techniques based on this principle cannot obtain the global optimal configuration under some partial shading conditions. In order to maximize the output power of photovoltaic array under any partial shaded condition, this paper proposes a reconfiguration strategy based on direct power evaluation. In this approach, the reconfiguration problem is formulated as a 0–1 multi-knapsack problem, and a novel mathematical model is established to directly evaluate the maximum output power of photovoltaic array. Then, the optimal reconfiguration scheme is determined by solving the mathematical model. Finally, the effectiveness of the proposed reconfiguration strategy is proved in theory and simulations.
... Irradiance Equalization aims to obtain balanced average irradiance values in a SP topology. [11] This results in connecting modules of irradiance values which are similar to the irradiance value of other modules which were earlier having similar or different value depending upon the effect of partial shading. This is done by relocating shaded PV modules with different irradiance value within the array so that the maximum power is achieved by the application of a switching matrix. ...
The output of the photovoltaic array is directly related to the external environment and solar irradiation. Photovoltaic arrays are affected by partial shading which deviates the VI and PV curve from ideal state. This phenomenon influences the operating efficiency of Photovoltaic arrays, as generated power is reduced and hotspots are formed. One possible way to get rid of such negative phenomenon is to reconfigure the Photo voltaic arrays and another method is to operate Photo voltaic panels in peak voltage, which includes global maximum power (GMP) but it has few drawbacks like high complexity, time-consuming. This paper proposes a new methodology of reconfiguring series-parallel (SP) photovoltaic array, which is implemented on MATLAB Simulink. The scheme extracts maximum power by electrically connecting all the shaded or underperforming photovoltaic panels in a common series connection, such that the restricted flow of electricity due to shaded panels is only restricted through one part of the series-parallel photovoltaic array. This method is unlike some interconnection method as it utilizes a reconfigurable part to normalize the fixed part, it is completely adaptable. The obtained results from simulation prove the reliability and overall efficiency under partially shaded array configuration.
... Dynamic reconfiguration is a control strategy that automatically rearranges the PV array by obtaining the switching signals from the switching matrix. The main types of popular dynamic methods include electrical array reconfiguration (Sahu and Nayak 2016), irradiance equivalence, and artificial intelligence methods such as rough set theory (Velasco-Quesada et al. 2009), Munkres optimization (Sanseverino et al. 2015), and reconfiguration using capturing sky images (Jazayeri, Jazayeri, and Uysal 2017). Major challenges in the course of execution of dynamic reconfiguration methods are the requirement of an extensive monitoring system and identification of an optimal configuration by optimization techniques. ...
Partial shading on photovoltaic (PV) systems causes a reduction in generated power and multiple peaks on their electrical characteristics. These adverse effects depend on the types of interconnection between modules and the intensity of insolation. This paper proposes a new configuration of PV modules, known as Diagonally dispersed Total Cross Tied (D-TCT), to achieve an enhanced performance under partial shading conditions. The unequal distribution of the shaded modules in various rows of TCT configuration produces greater power loss and more number of peaks in the electrical characteristics. The basic idea of this method is to disperse shaded modules to various rows such that an approximate-balanced distribution of shaded modules is possible for almost all practical shading patterns resulting in the enhanced performance.
... This method increases the processing speed to select the optimal reconfiguration of a PV array. A new dynamic reconfiguration for TCT connection was proposed in [82] that is based on capturing sky images that occur in real-time over the PV array to identify the shading positions. In this method, the switching matrix controller is developed based on IE to select the optimal interconnections of the PV array. ...
Environmental conditions have a strong influence on the behavior and quality of the generated photovoltaic (PV) power. The partial sharing condition is a natural phenomenon that reduces the lifetime of the PV array and the effectiveness of the entire system. Dispersing the shadow equally over PV panels is the solution to avoid the negative impact of the partial shading condition. Accordingly, PV array reconfiguration has become an attractive topic of study for researchers. In this paper, the authors provide a comprehensive review of all the schemes proposed for the PV reconfiguration system. In addition, a comparative study among all the published approaches and the challenges facing each approach are presented. Future research topics that highlight new methods to produce higher power from an available PV system are discussed.
Laser-based wireless power transfer (LWPT) technology has attracted more and more attention in the field of long-range wireless power transfer (WPT). In practical applications, the light intensity distribution of the laser beam at the receiving end has a crucial impact on the efficiency of the power transfer system. In this article, the optimization of photovoltaic (PV) array configuration is explored in an atmospheric turbulent environment under the irradiation of Gaussian (GS) and flat-top (FT) laser beams. By comparing the photoelectric conversion efficiency of 3×3 PV arrays under the irradiation of GS beams and three different orders of FT beams, we conducted a comprehensive investigation on the impact of GS beam and FT beams as light sources on the performance output of PV arrays. We develop a model of atmospheric turbulence and analyze its effects on laser power transmission. Further numerical simulation was performed to evaluate the photoelectric conversion efficiency of the two laser beams when irradiated by the PV array after experiencing atmospheric turbulence. The results indicate that the FT beam exhibits superior characteristics compared to the GS beam in most cases. FT beams with orders 2, 5, and 10 exhibit an over 8% increase in power compared to a GS beam upon direct irradiation. After passing through weak turbulence for a distance of 2 km, the power enhancement exceeds 9% for all three FT beams. These findings highlight the potential advantages of FT beams in LWPT and offer new insights into the design and optimization of long-range WPT systems.
This paper presents a performance investigation of three different types of photovoltaic (PV)arrangements under various shading situations. The PV arrangements are categorized as series parallel (SP), total cross-tied (TCT), and physical relocation arrangement (PRA). Furthermore, these PV arrangements are classified based on three different types of bypass diode associations: without bypass diode, over-lapped bypass diode (OLBD), and non-over-lapped bypass diode (NOLBD). The paper analyzes the electrical behavior, specifically the I-V (current-voltage) and PV (power-voltage) profiles, of different types of PV arrangements, including SP-WBD, TCT-WBD, PRA-WBD, SP-OLBD, TCT-OLBD, PRA-OLBD, SP-NOLBD, TCT NOLBD, and PRA-NOLBD. Additionally, the performance investigation of the presented PV arrangements is conducted in terms of the maximum probability of short circuit current (SCC), electrical behavior, dissipated power, power enhancement, and reduction of SCC. The results indicate that the NOLBD-based PRA arrangement outperforms others. During cases 5(e) and 5(f), the NOLBD-based TCT arrangement performs better than others. Furthermore, the SP type of PV arrangement generates the least
amount of power compared to TCT and PRA types. In comparison among SP-WBD, TCT-WBD, PRA-WBD, SP-OLBD, TCT-OLBD, PRA OLBD, SP-NOLBD, and TCT-NOLBD, the PRA-NOLBD type of PV arrangement obtains more power.
Solar photovoltaic (PV) systems are emerging progressively due to their wide compatibility range, ease of installation, and environmental friendliness. The module mismatch (MM) losses and module open circuit (MOC) fault can cause the power mismatch between different PV modules. This significantly affects the energy output from the PV module. Also, the intermittent nature of solar PV power makes the solar PV systems unreliable; to compensate for this, conventional PV systems utilize a battery storage system (BSS) with separate bidirectional converter. These bidirectional converters require two‐stage power conversion and massive battery bank connected at the DC link. This leads to the further reduction in overall efficiency. To address these issues, this paper proposed a multi‐input PV battery system (MIPBS) that uses nonisolated buck and boost converter combinations. It requires single‐stage power conversion to extract maximum power from each PV module along with BSS charging and discharging. Its modular design allows it to function across a wide range of voltage, power, and BSS choices. The proposed system is capable of mitigating the MM loss and sustaining the MOC fault. This paper discusses the operation, steady‐state analysis, and dynamic analysis of the proposed MIPBS. The performance of the proposed MIPBS is validated using a state‐of‐the‐art experimental setup with two PV modules, each having a rating of 60.53 W. A multi‐input photovoltaic (PV) battery system (MIPBS) requires single‐stage power conversion to extract maximum power from each PV module along with battery charging and discharging. The proposed system can mitigate the module mismatch loss such as partial shading and withstands the module open circuit fault.
Under partial shading conditions, photovoltaic (PV) systems exhibit multiple peaks in their power-voltage (
) characteristics. It is essential to extract maximum energy from the PV system. The global maximum power point tracking (GMPPT) algorithms presented in the literature, track the global peak using different methods. It is imperative to have minimal convergence time for GMPPT process. This paper proposes a novel algorithm to track the global peak using voltage and current perturbation. The new GMPPT algorithm operates in a current perturbation or voltage perturbation mode, based on the value of a control variable. In either mode, the proposed technique generates reference current or reference voltage, for navigating the operating point to GMPP location. The proposed algorithm is compared with two GMPPT algorithms, namely, modified maximum power trapezium (M-MPT) and high-performance GMPPT algorithms. The simulation studies are performed in MATLAB and is validated using a laboratory prototype, with dSPACE 1202 MicroLabBox controller for implementing GMPPT methods. Simulation and experimental results show that the new technique exhibits superior performance in terms of tracking time. Also, the energy efficiency is improved by 40% while using the proposed GMPPT algorithm for the irradiance profiles considered in this paper compared to the other two techniques.
The output power generated by a photovoltaic cell decreases remarkably because of irregular irradiance pattern. Thus, the overall system performance is degraded. The decrease in the power output is not dependent on the shaded area but is rather dependent on the array configuration and the shading pattern. To eliminate partial shadings, many strategies have been documented in the state‐of‐the‐art literatures. These strategies may not improve the maximum output power to the required level but definitely to a certain extent. Thus, to minimize these losses, a promising reconfiguration approach is needed, i.e. reconfiguring the photovoltaic modules inside the photovoltaic array to improve the maximum power output. These techniques are broadly divided into two categories viz., static and dynamic reconfiguration methods. The advanced photovoltaic array reconfiguration solutions to improve global power output under mismatch and partial shading scenarios is presented in this paper. According to the results of the review paper studied in this research, dynamic approaches are costlier as compared to static reconfiguration strategies, but they are more effective to reduce the partial shading impact in comparison to the static techniques. This article is protected by copyright. All rights reserved.
There is a significant effect of partial shade on the generation of power from solar plants. Hence, this paper proposes a new simple reconfiguration technique called Sequential Arrangement Technique (SAT) to disperse the shade on Photo-Voltaic (PV) modules. This method facilitates the numbering of the PV modules, based on the shading pattern during the PV array installation. Furthermore, the PV modules irradiation is distributed column-wise by providing wiring similar to Total Cross Tied (TCT) connection to get minimum row current and enhanced maximum power of 12.31% compared to conventional TCT. The performance of SAT is validated through the analysis, MATLAB simulations, and experimentation under various shading patterns. Furthermore, the analysis has been extended with the energy savings and income generation on various reconfiguration methods under various partial shade conditions. The more energy savings and income generation compared to the existing reconfiguration methods show its adaptability in real-time implementation. The outcomes of the proposed research work are as follows: (i) less wiring line losses along with the less renumbered PV modules of around 39.5%, (ii) developing a simple non-puzzle-based reconfiguration technique to reduce the complexity in implementation, and (iii) improved efficiency with enhanced power generation. To show the effectiveness and usefulness of the SAT reconfiguration, a comparative assessment with the conventional puzzle-based methods is developed with various performance indices.
Partial shading is a serious obstacle to effective utilization of photovoltaic (PV) systems since it result in significant output power reduction. PV array reconfiguration strategy is one of the most efficient used solutions to overcome negative effect caused by the partial shading in PV systems. This paper presents a comprehensive review of the major existing PV array reconfigurations approaches which are used to overcome the problem of partial shading.
The different approaches are evaluated and compared according to their techniques, advantages and drawbacks.
This work represents an interesting reference for researchers working in the field and a simple guide that serves as help for beginners on PV array reconfiguration.
Occurrence of partial shading and its high impact on the performance of photovoltaic (PV) system have received considerable attention during the last few years. It has forced the researchers to explore more novel PV array configurations to sustain under partial shading conditions (PSCs). To diminish the effects of PSCs, this paper presents an overview of the state-of-the-art developments of various PV array configuration models for PV systems. Different modeling approaches are analyzed while emphasizing their benefits and inadequacies. Different models available in the recent state-of-the-art literatures are studied and categorized according to vital configurations and features. Mainly, various PV array configurations such as advanced, futuristic configurations are also compared with the existing configurations. In this paper, recent research developments (that deserve further examination) are acknowledged and deliberated for the future researchers working in this domain.
Unequal solar irradiance of the Photovoltaic (PV) modules diminishes the PV array's maximum power output; this effect is due to Partial Shading Conditions (PSCs). There are a few technical options to fix this issue. One of these is the dynamic reconfiguration technique, which means that the electrical connections between the PV modules in the array are dynamically modified to spread shading effects and increase the power output. This paper proposed a novel adaptive reconfiguration method for 3×3 Total-Cross-Tied (TCT) PV array to enhance the maximum power under partial shading conditions. In this work, the PV module's electrical connections are altered dynamically with the proposed logic algorithm's help to maintain the identical row currents in the array. This technique is implemented on 3×3 size of an array using MATLAB and validated experimentally using OPAL-RT software. Further, the proposed technique performance is compared with the existing PV array connections such as Series-Parallel (SP), Total-Cross-Tied (TCT), Bridge-Link (BL), Honey-Comb (HC), and Shade Dispersion Positioning (SDP). Additionally, for different reconfiguration methods, revenue generation from energy savings is estimated. Based on the observations from the results, it is understood that the proposed technique enhanced the maximum power of the TCT array at a higher level as compared to the other PV array connections under PSCs.
Partial shading condition drastically reduces the maximum power output of photovoltaic array. Partial shading occurs due to several factors, such as flying birds, trees, and passing clouds. Many ways can be mitigated partial shading problems in photovoltaic (PV) array. One among the way is reconfiguration techniques, namely reconfigure the location of PV modules in PV array based on irradiance levels in order to distribute shading effects and increasing maximum power. This paper proposed an optimal SuDoKu reconfiguration pattern for total-cross-tied (TCT) PV array to improve maximum power under partial shading conditions. In this approach, the physical location of PV modules in TCT array are rearranged based on optimal SuDoKu style without altering the electrical connections, so that the shading effects can distribute over the array. Further, the performance of proposed pattern investigated with existing SuDoKu pattern under different shading conditions by comparing the global maximum power point, mismatch losses, fill-factor, and efficiency using MATLAB-Simulink. Based on the results of this paper, it concluded that the proposed optimal SuDoKu reconfiguration arrangement is reducing the wiring arrangement and increasing the shading distribution over the array as compared to SuDoKu arrangement.
In this paper, a strategy for the dynamic reconfiguration of photovoltaic (PV) strings and inverters is proposed to improve the PV system efficiency and reduce the harmonic emissions of the PV system under low irradiance conditions. In the proposed PV group control system, parallel-bridge switches are controlled to form multi-PV groups that can run jointly with multi-inverters. The benefit and harmonic current of the group control system are used to define the performance index. The dynamic reconfiguration strategy is used to control the connection mode of the PV system to optimize the index. The fluctuation of the PV string output power on the time scale is considered, the PV power variation range is predicted based on the least squares regression algorithm, the connection modes of the PV system are evaluated to prevent inverter overload, and the optimal connection mode is decided when the system frequently switches based on the voting theory method. An experimental system platform comprising three PV array simulators and three inverters is designed, and several scenarios of PV system operation are constructed to verify the feasibility and effectiveness of the proposed strategy. Experimental results show that compared with the conventional PV operation mode, the proposed strategy can improve PV generation performance under low solar irradiation. Based on the benefits of the control strategy, the scheme cost and recovery time are evaluated, and investors can quickly recover costs.
Intra-hour solar generation and ramp forecasting with sky imagers benefits from fast, frequent and accurate cloud base height (CBH) calculation. Using two sky imagers, CBH is determined using a two dimensional (2D) method for single homogeneous cloud layers and an enhanced three dimensional (3D) method to provide CBH of the cloud field with high resolution. The 2D method is based on georeferenced projection and statistical correlation of two sky images from the pair of sky cameras. The 3D method utilizes the epipolar technique to determine CBH for each cloud pixel. The 2D method was validated against ceilometer CBH measurements on four days. Several technical considerations for the set up of the sky cameras for CBH calculation, as well as strength and weaknesses of the proposed methods are discussed.
A method for intra-hour, sub-kilometer cloud forecasting and irradiance nowcasting using a ground-based sky imager at the University of California, San Diego is presented. Sky images taken every 30 s were processed to determine sky cover using a clear sky library and sunshine parameter. From a two-dimensional cloud map generated from coordinate-transformed sky cover, cloud shadows at the surface were estimated. Limited validation on four partly cloudy days showed that (binary) cloud conditions were correctly nowcast 70% of the time for a network of six pyranometer ground stations spread out over an area of 2 km2. Cloud motion vectors were generated by cross-correlating two consecutive sky images. Cloud locations up to 5 min ahead were forecasted by advection of the two-dimensional cloud map. Cloud forecast error increased with increasing forecast horizon due to high cloud cover variability over the coastal site.Highlights► Intra-hour solar irradiance forecasts with a ground-based total sky imager. ► A combined clear sky library and sunshine parameter method for cloud decision algorithm. ► Cloud shadow mapping and cloud motion determination for ground-based sky imagery.
This paper applies a dynamical electrical array reconfiguration (EAR) strategy on the photovoltaic (PV) generator of a grid-connected PV system based on a plant-oriented configuration, in order to improve its energy production when the operating conditions of the solar panels are different. The EAR strategy is carried out by inserting a controllable switching matrix between the PV generator and the central inverter, which allows the electrical reconnection of the available PV modules. As a result, the PV system exhibits a self-capacity for real-time adaptation to the PV generator external operating conditions and improves the energy extraction of the system. Experimental results are provided to validate the proposed approach.
A procedure of simulation and modelling solar cells and PV modules, working partially shadowed in Pspice environment, is presented. Simulation results have been contrasted with real measured data from a commercial PV module of 209 Wp from Siliken. Some cases of study are presented as application examples of this simulation methodology, showing its potential on the design of bypass diodes configuration to include in a PV module and also on the study of PV generators working in partial shading conditions.
The electrical characteristics of array interconnection schemes are investigated, using simulation models to find a configuration that is comparatively less susceptible to shadow problems and power degradation resulting from the aging of solar cells. Three configurations have been selected for comparison: simple series-parallel (SP) array, which has zero interconnection redundancy; total-cross-tied (TCT) array, which is obtained from the simple SP array by connecting ties across each row ofjunctions and which may be characterized as the scheme with the highest possible redundancy; and bridge-linked (BL) array, in which all cells are interconnected in bridge rectifier fashion. The explicit computer simulations for the energy yield and current-voltage distributions in the array are presented, which seem to favor cross-tied configurations (TCT and BL) in coping with the effects of mismatch losses.
Reconfigurable architectures are of great interest to system designers to improve the system’s operation and efficiency. In this paper, we propose an adaptive utility interactive photovoltaic (PV) system based on a novel Flexible Switch array Matrix topology. This proposed system maximizes the generated power in real-time in response to operational conditions such as shading, soiling, mismatches, and module failure among others. The proposed system is a compromise in the utilization of power conditioning equipment to maximize energy capture and system efficiency. Simulation results demonstrate an average 13% improvement in efficiency when compared with the central inverter topology performance. A prototype system has been designed and tested. The experimental results validate the proposed topology and its benefits for a wide range of applications.
This paper proposes an adaptive reconfiguration scheme to reduce the effect of shadows on solar panels. A switching matrix connects a solar adaptive bank to a fixed part of a solar photovoltaic (PV) array, according to a model-based control algorithm that increases the power output of the solar PV array. Control algorithms are implemented in real time. An experimental reconfiguration PV system with a resistive load is presented and is shown to verify the proposed reconfigurations.