Real Photovoltaic Panel Research Articles

Laboratory Tests in Cyber-Physical Mode for an Energy Management System Including Renewable Sources and Industrial Symbiosis

Abstract The aim of this paper regards the laboratory validation of an energy management system (EMS) for an industrial site on the Eigerøy island (Norway). It will be the demonstration district in the ROBINSON project for a consequent concept replication. This activity in cyber-physical mode is an innovative approach to finalize the EMS tool with real measurement data with prime movers available at laboratory level, considering the necessary EMS robustness and flexibility for replication on other industrial islands. This EMS was designed and developed to minimize variable costs, producing on/off and set-point signals that, through a model predictive control (MPC) software, establish the system status. This smart grid includes renewable sources (e.g., solar panels, a wind turbine, and syngas) and traditional prime movers, such as a steam boiler for the industry needs. Moreover, an energy storage device is installed composed of an electrolyzer with a hydrogen pressure vessel. The main results reported in this work regard 26-h tests performed in cyber-physical mode thanks to the real-time interaction of hardware and software. So, a real microturbine and real photovoltaic (PV) panels were managed by the EMS in conjunction with software models for components not physically present in the laboratory. Although the optimization target was cost minimization, significant improvement was also obtained in terms of efficiency increase and CO2 emission decrease.

PLL-Less Active/Reactive Power Control of Photovoltaic Energy Source with Applying pq-Theory in Single-Phase Grid System

Converter systems are applied to manage active/reactive power control of photovoltaic (PV) source during integration with the electric grid system. The control algorithm of the conventional converter system consists of a reference generation unit, a dc-link voltage control loop, two power control loops and a phase lock loop (PLL) system. PLL unit is used to lock in phase angle of the electric grid, and to perform the coordinate transformation for calculations of the active/reactive powers. However, the control algorithm has a slow dynamic response because of utilisation of a PLL structure. In addition, additional complex mathematical computations are required with the use of a PLL algorithm. Furthermore, the interaction of the PLL and the power control loops may lead power oscillation problems under weak grid, and also result in instability of the PV system. In this study, to avoid the aforementioned issues and to enhance the power flow capability of the grid-connected PV panels, a PLL-less control algorithm in pq-theory is studied for the active/reactive power management and the grid synchronization. In addition, the mathematical formulations of the current control algorithm are presented in detail. To show the effectiveness of the PLL-less controller, a PV system model with using real PV panel groups is designed and constructed in a simulation environment. The proposed control method is tested under various operation cases such as dynamic environmental conditions, reactive power support and voltage variations. The proposed method shows efficient performance under applications of the different operation situations.

Design a photovoltaic simulator system based on two-diode model with linear interpolation method

For an effective study of photovoltaic (PV) systems, precise current-voltage (I-V), power – voltage (P-V) curves of photovoltaic modules are required. However, conducting experiment on real panels faces with many difficulties such as needing large space, high cost, objective conditions of the environment. Therefore, it is essential to research an emulator producing the I-V, P-V characteristics of a PV system the same as those conducted on a real PV panel. This paper presents a two–diode model simulation replacing a photovoltaic panel to export precise current-voltage (I-V), power – voltage (P-V) curves based on the linear interpolation method. The proposed simulator shows many advantages of subjecting to changes in radiation and temperature. The accuracy of the emulator has been not only verified by the simulation results on Matlab software, but also evaluated, compared with the experiment model. The simulation results have coincided with the experimental ones, the output error of less than 4% is shown in the experiment.

Techno-economic assessment of clean hydrogen production and storage using hybrid renewable energy system of PV/Wind under different climatic conditions

Techno-economic assessment is presented of using hybrid renewable energy system of wind turbine and photovoltaic (PV) panels for hydrogen production and storage at different climate conditions of five different Egyptian cities. The water electrolyzer and compressor for hydrogen production and storage are driven by electricity produced from real PV panels and wind turbines. A transient mathematical model of the overall system is presented and solved using MATLAB/Simulink. The system performance is examined in terms of energy storage, system efficiency, and cost. Results reveal that the annual produced electricity equals 84,096, 107,285, 104,761, 69,836.5, and 118,115 kWh for Cairo, Aswan, Asyout, El Arish, and Mersa Matruh, respectively. PV panels and wind turbines are suitable for hydrogen production for the studied cities, except El Arish where the wind turbine is not recommended. In addition, the compressor consumes about 3.13% to 3.3% of the produced electricity from the PV/wind system. The annual hydrogen production reaches 1,972 kg for Mersa Matruh, 1,795 kg for Aswan, 1,749 kg for Asyout, 1,418 kg for Cairo, and 1,196 kg for El Arish. Finally, the overall system efficiency and production cost range from 7.69% to 9.37% and from 4.54 $/kg to 7.48 $/kg, respectively.

Fault detection and diagnosis in photovoltaic panels by radiometric sensors embedded in unmanned aerial vehicles

AbstractPhotovoltaic solar energy is increasing its capacity in the global electric market due to its lower operating costs and higher efficiency, together with the support of the governments. Photovoltaic solar panels require high initial investments, and it is necessary to use advanced and efficient methods that lead to the maintainability and reliability of these systems, extending their life cycle and productivity. New condition monitoring systems are being applied to reduce the cost of inspections and ensure efficient data collection. The main contribution of this paper is a new efficient and low‐cost condition monitoring system based on radiometric sensors. The thermal patterns of the main photovoltaic faults (hot spot, fault cell, open circuit, bypass diode, and polarization) are studied in real photovoltaic panels. Different scenarios are considered, analyzing online the main patterns of the faults by Internet of Things. The accuracies of the results are statistically analyzed and compared with fault‐free scenarios. The validation of the approach is done by thermographic analysis of the experiments and employing a different radiometric sensor. The detection of faults with statistical analysis is achieved in 100% of the cases, and the identification of the specific fault in 96% of the scenarios. An artificial neural network and classification learner algorithms are employed to validate the results, obtaining similar results for fault identification, 95% and 94%, respectively, and 100% for fault detection.

Behavioral Analysis of Potential Induced Degradation on Photovoltaic Cells, Regeneration and Artificial Creation

Many photovoltaic (PV) parks suffer from a decrement in their generated power capability due to a phenomenon called potential induced degradation (PID). In this paper, a regenerative system using a high step-up DC–DC converter is proposed, for regenerating PV cells that have been degraded due to the PID effect. The same device also can be used for artificially creating PID on PV panels in order to study the effects of the PID under controlled conditions. The power converter offers multiple voltage levels at the output to adapt to various voltage ratings of PV parks. The device has plug-and-play features, ultra-low cost, small size and is simple in operation. Experimental tests are conducted in real PV panels and comparative results verify the operational principles of the proposed system. The artificial creation of the PID phenomenon and the regeneration of the PV cells are successfully proven experimentally.

Simple and Fast Dynamic Photovoltaic Emulator based on a Physical Equivalent PV‐cell Model

Photovoltaic emulators are a specific type of power electronics system to mimic the behaviour of a photovoltaic (PV) panel or array and facilitate the testing of energy systems. Existing solutions usually require sophisticated hardware design and fast computing. This paper presents a simple, reliable, and effective circuit-based photovoltaic (PV) emulator based on the equivalent PV stacked cells. The PV emulator can be used for solar system testing and analysis, such as maximum power point tracking (MPPT) and partial shading effect. The I– V and P– V characteristic curves of the emulator have been generated by using an LTspice simulator. It is experimentally investigated and compared with a real PV panel and existing emulator products. The experiment results show good agreement with the mimicked actual PV panel. The proposed PV emulator shows a better dynamic response and shorter settling time than several benchmarked commercial products. The enhancement in the time response is due to the simplicity of the emulator, where a few power diodes and some resisters are used. In addition to simplicity, the PV emulator is very cost-effective.

Efficiency Improvement Scheme for PV Emulator Based on a Physical Equivalent PV-Cell Model

Recently, a photovoltaic (PV) emulator is proposed which is based on a combination of a constant current source and a one-diode photovoltaic model. Its superior dynamic performance is compatible with that of a real PV system. Although it is power efficient at the maximum power point (MPP), it suffers from high power loss around and at the open-circuit voltage (OCV) operation condition. The PV emulator can be used for PV system analysis and testing, such as maximum power point tracking (MPPT). This paper presents a new switching circuit which is placed in parallel with the diode string to minimize the power loss. The switching circuit consists of a two-switch non-inverting buck-boost DC/DC converter. When the operating point of the PV emulator moves from the current source region to the voltage source region, the converter, which is more efficient, switches in to replace the diode string seamlessly to maintain the circuit operation of the emulator. Experimental results show that in the worst case scenario, i.e. OCV condition, the efficiency and temperature of the proposed solution reach 81.47% and 30.1 °C respectively, as compared with 2.8% and 94.2 °C respectively for the diode string only case. In terms of dynamic response, the proposed PV emulator lags the real PV panel by only 3.5 ms as compared with 120 ms by a commercial emulator under the 30% to 60% insolation change test.

Моделювання роботи фотоелектричних панелей з використанням середовища Matlab/Simulink

Modeling of the photovoltaic panels’ parameters makes it possible to predict in the shortest time the performance of a photovoltaic station in the context of specific days, months and along the year for any area and the method of solar panels arranging. One of powerful tools of computer mathematics, which recently has been widely used to simulate various technical systems, is the MATLAB environment. Due to the built-in Simulink package, MATLAB allows to realize visual-oriented block simulation of dynamic systems, in particular, various devices of functional electronics, solar cells and photovoltaic modules. This paper proposes an approach to modeling the operation of real photovoltaic panels in the MATLAB/Simulink environment using information from the panel technical documentation as input data for the Solar Cell block. The method for determining the input parameters of the Solar Cell block, which are not specified in the technical documentation of the solar panel, is presented. This method is based on the analysis of the light current-voltage characteristic of the panel for standard test conditions in the approximation of a single-diode equivalent circuit of a photovoltaic cell. Proposed method was tested on the example of JAP6(BK) 60-250/3BB, AS-6P30-270W and LG290N1C panels from the world's leading manufacturers. A visual-oriented model based on Solar Cell block was created in the MATLAB/Simulink environment to build the light characteristics of photovoltaic panels. The light characteristics of the JAP6(BK) 60-250/3BB, AS-6P30-270W and LG290N1C panels were simulated using created model, and main parameters of the panels under standard test conditions were calculated. Comparison of the panels parameters determined from the simulated light characteristics with the data presented in the technical documentation showed that for all panels the deviation of the simulation results from the documentation parameters is less than permissible 3%. This indicates the acceptability of the proposed approach to modeling the operation of real photovoltaic panels in the MATLAB / Simulink environment.

Simulation and Experimental Investigation into a Photovoltaic and Fuel Cell Hybrid Integration Power System for a Typical Small House Application

The paper addresses the simulation of a novel real-time implementation of a photovoltaic (PV) and fuel cell (FC) hybrid integration power system. The hybrid system has the potential of reducing the dependency on batteries, leading to reduced cost and increased life span of the whole system using the Proton Exchange Membrane (PEM) fuel cell. The interface structure of the hybrid system has been explored incorporating the Maximum Power Point Technique (MPPT) for maximum power extraction. The simulation of the hybrid system including fuel cell, PhotoVoltaic panels (PVs) and battery has been carried out using SimPowerSystems. An innovative Real Time Interface (RTI) approach using the concept of the Hardware-In-the-Loop (HIL) has been presented for a fast dynamic response of a closed loop control of the hybrid system. The corroboration of the hybrid system is validated experimentally, using a real photovoltaic panel connected to a PEM fuel cell emulator and battery. The PVs are controlled by the perturbation and observation Maximum Power point (MPP) technique and the PEM fuel cell is controlled through a boost DC-DC converter using current mode control. The whole system is implemented on the dSPACE 1103 platform for real-time interface and control strategies. The overall behavior of the hybrid system has been critically analyzed and corroboration of the simulated and experimental results have been presented.

Performance Improvement of PV-Fed Hybrid Modular Multilevel Converter Under Partial Shading Condition

This article presents a hybrid modular multilevel converter (HMMC) for large-scale photo voltaic (PV) integration to grid. PV panels are directly connected to each submodule of the converter without using any dc–dc converter. A distributed maximum power point tracking (D-MPPT) method is used to extract maximum power from each PV-string under normal, as well as, shading (uniform/nonuniform) condition. Power unbalance among the phases during partial shading is a major issue of such type of converter, which needs to be properly handled for satisfactory operation. To address this issue in a cascaded H-bridge converter, zero sequence voltage (ZSV) injection based methods have been utilized. In this work, ZSV injection is integrated with D-MPPT and the combined method is applied on HMMC to address both interphase and intraphase partial shading satisfying MPPT operation in each submodule. The feasibility of the proposed control method is first verified through PSCAD/EMTDC simulation. Thereafter, a dSPACE Micro-Lab-Box-based experimental prototype is developed to check the performance at 10 kW power level under the presence of real PV panels. A comparative assessment of the proposed system with available topologies has been performed to highlight the notable features. The capability of ZSV controlled HMMC is evaluated under various shading conditions to explore its usefulness to deal with power unbalance conditions. It may be predicted that an HMMC-based PV system with the aforesaid control methods has sufficient merits to become a potential candidate for high power PV integration.

Effective in-laboratory test method for PV power generation with enhanced PV emulation accuracy

Photovoltaic (PV) systems require outdoor experiments to verify their functionality and reliability. However, outdoor experiments require complicated experimental set-ups including PV panels, power conversion circuits and controllers. In addition, the experimental data obtained from such systems can be easily affected by environmental conditions such as weather, temperature and season. Recently, PV emulation methods have been proposed that can emulate PV characteristics in the laboratory by connecting a DC supply to PV modules in parallel. However, the voltage characteristics of the conventional PV emulator are different from those of real PV panels, which degrades the accuracy of the PV emulator. This paper proposes an effective PV emulation method with accuracy improvements at the maximum power point of the PV panel, which is based on a simple circuit analysis. Using the proposed PV emulation method, the performance verification of a target PV system can be easily and accurately obtained. The proposed emulation method for PV power generation is experimentally verified by comparisons between it, the conventional emulation method and results obtained from outdoor experiments.

Characterization of a polycrystalline photovoltaic cell using artificial neural networks

This article presents a method to estimate the parameters of a photovoltaic cell model in its equivalent circuit of a single-diode using artificial neural networks; more specifically, the multilayer perceptron concept is used. The data required to estimate the parameters are based solely on the information available in the manufacturer’s data sheet. The neural network has two hidden layers and the selected training method was Bayesian regularization. The training data were produced synthetically to ensure that a large part of the range of possible parameter values is covered. The network performance is validated with a data set not included in the training set, making the comparison with a recognised method from the literature, and even more, with experimental data obtained from a real photovoltaic panel. The main advantage of this method is that, once the network is trained, the parameters returned by the network will always be unique for each input provided, which is not the case with other artificial intelligence methods such as genetic algorithms or differential evolution. In addition, this method can be directly applied to other similar problems, only by modifying the inputs and outputs of the network.

Maximum Perturbation Step Size in MPP-Tracking Control for Ensuring Predicted PV Power Settling Behavior

The heuristic perturb-and-observe-based maximum-power-point tracking (MPPT) algorithm of photovoltaic (PV) generator is still the most popular technique in use, despite the broad spectrum of developed other MPPT algorithms. The correct direction of the next perturbation step requires that the previous perturbation is settled down properly and the applied perturbation step size is large enough to overcome the PV-power changes induced by the varying irradiation level and/or the power-grid-originated PV-voltage ripple. The requirements for the minimum perturbation step size are well defined in the available literature. The design equations to predict the PV-power settling time are derived by assuming that the PV-interfacing converter operates in continuous conduction mode (CCM). A large perturbation step size may drive the interfacing converter to enter into discontinuous conduction mode (DCM), which will delay the PV-power settling process and destroy the validity of the predicted settling times. In order to avoid confusing the MPPT process, the maximum perturbation step size has to be limited as well. This paper provides theoretical foundations for the proper design of the maximum step size based on the DC-DC interfacing-converter dynamic behavior. The theoretical findings are validated with experiments as well as by simulations by means of a boost-type DC-DC converter and real PV panel.

Design of a Low-Cost PV Emulator Applied for PVECS

Applied tests on a real photovoltaic panel for a consolidated analysis require complex experiment setup and permanent availability of climatic conditions. This method is ineffective and can damage the PV system. As a result, PV emulators are highly requested in solar energy conversion and generation research, which rests essentially on a maximum power point tracking control algorithm (MPPT) and an adapting power stage as the DC-DC converter and PV inverter. The PV emulator guarantees a controllable light source environment to act as a real PV system in the laboratory. This paper deals with the study and development of an experimental PV emulator based on logarithmic approximation of the ideal single diode model (ISDM), which is implemented using analog electronic components. Mainly, the PV model, the controller, and the power stages, forming the PV emulator, are described. This simple, low-cost, and efficient device is considered as a nonlinear power supply template replacing the real PV system for any operating point irrespective of the environmental condition changes. The emulated current-voltage and power-voltage curves are validated via resistive load and batteries. Then, the performance of the proposed PV emulator is evaluated by its ability to recharge properly two 12V 7 Ah batteries.

Performance Evaluation of Variable Structure Controller Based on Sliding Mode Technique for a Grid-Connected Solar Network

Generating electric power from solar energy is a vastly growing technology worldwide. This paper investigates and evaluates the performance of a solar power generation system utilizing variable structure control with sliding mode for maximum power point tracking (MPPT). This controller is implemented on a buck–boost dc–dc power converter to track the maximum power point (MPP). The suggested controlled solar energy system also includes a dc-link capacitance, a voltage-source inverter, and a grid filter. Energy-based control is performed for the voltage of the dc-link capacitor. Space vector pulsewidth modulation (SVPWM) with current control in dq rotating frame is utilized to govern the inverter. The suggested system is simulated and subjected to various operating conditions. The results demonstrate the power captured from photovoltaic (PV) panels and delivered to the grid while tracking the MPP. For more confidence on the MPPT controller, practical experimentation is introduced using a real PV panel and power circuit with interfacing to a personal computer (PC). The proposed design is subjected to various experimental tests to ensure its validity.

Modeling the output power of heterogeneous photovoltaic panels based on artificial neural networks using low cost microcontrollers

Many implementations of artificial neural networks have been reported in scientific papers. However, few of these implementations allow the direct use of off-line trained networks. Moreover, no implementation reported the use of relatively small network adequate to run on low cost microcontroller. Hence, this work, which presents a small artificial neural network, which models the output power of heterogeneous photovoltaic panel. In addition, the work discuss the hardware implementation that allows such network to run on low cost microcontroller. The hardware implementation has the ability to model heterogeneous photovoltaic panel's output power with very high accuracy and fast response time. Feedforward back propagation has been used because of its high resolution and accurate activation function. Real-time measured parameters can be used as inputs for the developed system. The resulting hardware data is tested with data from real photovoltaic panels; to confirm that it can efficiently implement the models prepared off-line with Matlab. The comparison revealed the robustness of the proposed heterogeneous photovoltaic model system at different conditions. The proposed heterogeneous photovoltaic model system offer a proper and efficient tool that can be used in monitoring photovoltaic panels, such as the ones used in smart-house applications.

Real-Time Genetic Algorithms-Based MPPT: Study and Comparison (Theoretical an Experimental) with Conventional Methods

Maximum Power Point Tracking (MPPT) methods are used in photovoltaic (PV) systems to continually maximize the PV array output power, which strongly depends on both solar radiation and cell temperature. The PV power oscillations around the maximum power point (MPP) resulting from the conventional methods and complexity of the non-conventional ones are convincing reasons to look for novel MPPT methods. This paper deals with simple Genetic Algorithms (GAs) based MPPT method in order to improve the convergence, rapidity, and accuracy of the PV system. The proposed method can also efficiently track the global MPP, which is very useful for partial shading. At first, a review of the algorithm is given, followed with many test examples; then, a comparison by means Matlab/Simulink© (R2009b) is conducted between the proposed MPPT and, the popular Perturb and Observe (PO) and Incremental Conductance (IC) techniques. The results show clearly the superiority of the proposed controller. Indeed, with the proposed algorithm, oscillations around the MPP are dramatically minimized, a better stability is observed and increase in the output power efficiency is obtained. All these results are experimentally validated by a test bench developed at LIAS laboratory (Poitiers University, Poitiers, France) using real PV panels and a PV emulator which allows one to define a profile insolation model. In addition, the proposed method permits one to perform the test of linearity between the optimal current I mp (current at maximum power) and the short-circuit current I sc , and between the optimal voltage V mp and open-circuit voltage V oc , so the current and voltage factors can be easily obtained with our algorithm.

Bat algorithm based maximum power point tracking for photovoltaic system under partial shading conditions

This paper presents a maximum power point tracking (MPPT) method for photovoltaic system under partial shading conditions using bat algorithm (BA). The bat algorithm is a swarm intelligence based method which was inspired by the echolocation behaviour of bats. BA have a high accuracy in the global optimisation and it can provide good dynamic performance and very quick convergence rate by automatically switching between exploration and exploitation stages during the MPPT process. To verify the performance of the proposed method, several simulations have been carried out in Matlab/Simulink environment for various shading patterns. The simulations results highlight the accuracy of the proposed scheme for optimal management of the energy available at the output of the photovoltaic panels. In addition, the comparison with the P&O and the PSO methods shows that the proposed method outperforms them in term of global search ability and dynamic performance. To verify the practical implementation of the proposed method, a modular reconfigurable architecture is designed using very high speed integrated circuit hardware description language (VHDL) and implemented on Xilinx Virtex-5 (XC5VLX50-1FFG676) Field Programmable Gate Array (FPGA). The use of FPGA for designing the MPPT controller provides high performance, increases the robustness and makes the hardware implementation more flexible. The algorithm is tested in real time application on a buck-boost converter using a real photovoltaic panel. Experimental results confirm the efficiency of the proposed method in the global peak tracking and its high accuracy to handle the partial shading.

Modeling, simulation and hardware implementation of a bond graph-maximum power point tracker for a photovoltaic panel under partially shaded conditions

The electric power generated by a photovoltaic module can be greatly reduced compared with optimal production due to weather conditions and factors such as partial shade. The main defect of a conventional maximum power point tracking control algorithm is its misinterpretation of the location of the maximum power point during a sudden change in climatic conditions because of the existence of several local maxima on the power–voltage characteristic curve. This work presents a preliminary study on the modeling, simulation and implementation of a new algorithm for power output maximization of photovoltaic generators under partially shaded conditions using a bond graph approach. The idea is to use a buck-boost converter and to test experimentally the performance of the proposed algorithm on a real photovoltaic panel. We imposed ten patterns of irradiance on the photovoltaic panel, of which more than half were patterns of partial shading. The proposed controller performed excellently under all shading conditions compared with the classical direct duty cycle technique. The control part and the proposed algorithm were implemented on a microcontroller, and the efficiency of the developed algorithm was demonstrated as a function of the real position of the maximum power point through the results of a simulation performed using Symbols (SYstem Modeling by BOnd graph Language and Simulation) software. The results obtained from the simulation were compared with experimental results obtained from real measurements using a Photowatt PW1650 photovoltaic panel under the same operating conditions and climatic environment.