An Extremely Low-Cost Multi-Panel PV Emulator for Research and Education

Photovoltaic (PV) emulator (PVE) allows the development and testing of the PV equipment and system effectively. The PVE is an alternative to controllable light source that requires a large space and highly inefficient. The PVE requires a power converter and the buck converter is preferred due to the control simplicity and high efficiency. Nonetheless, the conventional design of the buck converter cannot be used since the output voltage of the PVE highly dependent on the output resistance. A proper design of the buck converter specified for the PVE application is needed to maintain continuous current mode operation and the output voltage ripple factor below the desired specification. This paper proposed the design for the passive components for the PVE using buck converter, which includes the output resistor, inductor, and capacitor. The single diode model is used to produce the current-resistance characteristic curves of the PV. The control strategy of the PVE is not included in this paper. The results show that the passive components for the buck converter obtained from the derivation able to maintain continuous current mode and has the output voltage ripple factor lower than the desired specification when operates as the PVE. This proves the derivation of the passive components is accurate.

Photovoltaic (PV) sources are inherently nonlinear power devices and maximum power derivation depends on Maximum Power Point Tracking (MPPT) algorithms. The algorithms require testing in real time situation using PV source which will be troublesome due to higher dependency on environmental factors and larger space requirements for higher power rating. The increased and faster testing lead to develop a PV emulator with desired performance and lower price compare to the commercially available PV emulators. In this paper, design of a digitally controlled PV emulator with varying resistive load is proposed to replicate the behaviour of real PV sources. The power stage of the PV emulator is realized using dc-dc buck converter topology and the controller stage uses an algorithm-in-loop Newton-Raphson (NR) method. Finally, the PV emulator is tested with MPPT controlled dc-dc boost converter for battery charging. The design of the power and control stages of the PV emulator has been compared with the real PV source and it is observed that the obtained V-I characteristic is in good agreement. Moreover, an analysis is presented for different switching frequencies of the boost converter connected as load to the fixed switching frequency buck converter, i.e., PV emulator. Further, a schematic hardware circuit diagram has been given to realize the proposed digitally controlled PV emulator.

<span>A Photovoltaic (PV) emulator is a device that produces a similar output as the PV module and it is useful for testing the PV generation system. This paper present a new and simple control strategy for the PV emulator using the combination of the Resistance Comparison Method with the Integral Controller. The closed-loop buck converter system with the current-mode controlled and the single diode model are used for the PV emulator. The results obtained from the proposed PV emulator are compared with the conventional PV emulator using the Direct Referencing Method as the control strategy. The proposed PV emulator produces a more accurate output, 74 % faster transient response, and a lower output voltage ripple compared to the conventional PV emulator.</span>

With increasing solar photovoltaic-based power generation, a photovoltaic emulator (PVE) is necessary to experimentally validate new control strategies without the influence of external factors such as irradiance and temperature. However, two significant challenges with PVEs are (i) solving the nonlinear equation of photovoltaic (PV) panel and (ii) oscillations in constant current (voltage) region with voltage (current) control. Thus, in this paper, a PVE with the ability to mimic both uniformly irradiated and partially shaded PV panels is proposed by employing artificial neural network (ANN) and piecewise-linearization technique. Based on the input operating conditions (irradiance, temperature, and partial shading), the ANN breaks the nonlinear I-V curve into piecewise-linear segments and outputs their boundary points. Then, with these boundary points, piecewise-linear equations of the segments relating PVE’s voltage and current are formed. Subsequently, using these piecewise-linear equations, the reference PVE voltage corresponding to PVE’s output current is calculated and given to the PI controller of a synchronous buck converter to mimic a PV panel. Thus, the proposed PVE overcomes the problem of solving nonlinear I-V equation by piecewise linearization which in turn aids an impedance-matching technique to mitigate the aforementioned oscillations. The generation of training data and development of ANN were carried out in MATLAB. Finally, the simulation studies performed in MATLAB/Simulink and hardware experiments validated the steady-state accuracy and the transient response which settled within 10 ms endorsing the real-time application of the proposed PVE.

A photovoltaic (PV) emulator replicates the exact I-V and P-V output characteristics of a PV module or array. This replication should have occurred in such a way the same output characteristics in different ambient conditions, including different temperature and irradiation levels, mismatching, or partial shading, have been obtained. In this paper, a PV emulator based on a DC-DC converter with a novel control method has been presented. The proposed controller is a fractional PI one optimized with Grasshopper Optimization Algorithm (GOA). It has one degree of freedom more than the conventional PI controller, which is the main advantage of this control approach. Also, a fractional-order lag compensator is used to decrease the output ripple of the converter. On the other hand, the Lambert W function models the PV characteristics which this modeling approach reduces computational burden and time. The simulation results in MATLAB/Simulink validate the performance of the proposed PV emulator.

The photovoltaic (PV) technology has been increasingly used in our energy generation. Therefore, it is essential to have a good PV testing facility during the development process. The PV emulator (PVE) is a voltage or current source that mimic the current-voltage characteristic as a PV module that requires proper control strategy to work. The resistance feedback method (RFM) control strategy has many good attributes, except the transient response, which is caused by the proportional-integral (PI) controller. This paper proposed a new fuzzy logic PI (FLPI) controller to improve the transient performance of the RFM PVE. It is based on the error adjustment method that founded on the transient state and load of the PVE. The performance of the proposed PVE is compared with the original PVE that used RFM with the PI controller. The finding of the research shows that the transient performance of the proposed PVE has improved 2.3 times compared to the original PVE without affecting its accuracy.

This paper presents the design, simulation, and experimental implementation of a photovoltaic (PV) emulator based on a buck converter controlled using the dynamic evolution control (DEC) technique. The proposed system accurately reproduces the nonlinear current-voltage (I-V) and power-voltage (P-V) characteristics of a commercial GREEN CELL SM100-18P (100 Wp) PV module under standard test conditions (1000 W/m2, 25 °C). The electrical characteristics of the reference module are embedded in the controller through a lookup table (LUT), which is integrated with the DEC algorithm to enable adaptive real-time regulation of output voltage and current. System modeling and validation are first conducted in MATLAB/Simulink to analyze steady-state and transient performance. A hardware prototype based on an XL4016 buck converter and Arduino Nano microcontroller is then implemented, with real-time monitoring provided via an ILI9341 TFT display. Experimental results show that the emulator achieves a maximum power deviation of 0.8%, a normalized root mean square error (RMSE) of 0.015, a settling time of approximately 12 ms, overshoot below 1.5%, voltage ripple under 2%, and peak conversion efficiency of 94% near the MPP region. These results confirm that the proposed PV emulator provides accurate static and dynamic reproduction of PV characteristics, offering a low-cost, stable, and repeatable platform for laboratory-scale evaluation of PV-related power electronic converters.

The aim of this paper is to achieve the efficient control design for a single phase grid tie inverter (GTI)using PROTEUS Professional software and its practical implementation. Unique thought is given to theway that, dissimilar to customary standalone inverters, GTI are required to satisfy the demandsassociated with each phase of the grid. Photovoltaic module and single-phase GTI both are tied togetherusing an inverter. In this paper we have got the reference voltage from the main grid using operationalamplifier, Wave Shape Coping Pulse Width Modulation (WSPWM) technique is applied withPIC16F877A microcontroller and IR2110 gate driver which drive the MOSFET IRF840 afterappropriate filtering and control the power supply to the grid with appropriate isolation. The functionaltesting of the single phase GTI has been performed successfully when DC-AC conversion occurs. Besidethe ability of GTI, its frequency and output voltage had consistent fluctuations due to the change infrequency and grid voltage. Another feature of the GTI is that if the power from electrical grid is zero,the inverter will stop the process of inversion and just supply zero voltage output at that time.Accordingly, quick shut down of DC-AC process of inversion happens if there arises a sudden dark outperiod. It is worth mentioning that the designed GTI cannot be operated without reference voltage of thegrid and connected directly to PV solar panels.

Due to the variation of solar irradiance, temperature and shading conditions, the power generated by a photovoltaic (PV) module and hence the power delivered to the load changes drastically, which imposes the need for analysis of a complete PV system to get the maximum power under these natural variable conditions. In this paper, a complete off-grid PV module based power generation system has been designed and simulated using MATLAB/Simulink and performance has been scrutinized using the value of standard solar irradiance about 1 KW/m-2 for Bangladesh. The simulation model includes solar PV module, the converter power stage with MPPT control and charge controlling functions and here performance of each block has been examined conspicuously. Eventually, it has been found that the model is quite competent to simulate both the I-V and P-V characteristics of a PV module and based on the result it has been predicted that the performance of several modules or even PV array connected in series and/or in parallel with the delivery of maximum power can be tested under different solar irradiance and temperature conditions. DOI: http://dx.doi.org/10.3329/dujs.v62i2.21977 Dhaka Univ. J. Sci. 62(2): 127-132, 2014 (July)

In this paper proposes a new digital control scheme for a photovoltaic (PV) system using fuzzy-logic and a dual (MPPT) controller. To obtain the maximum electricity from the solar cells, the PV modules have two MPPT controllers. The dc voltage and current are controlled to track the maximum power point, where the PV modules feed the maximum output power. A MPPT technique is used to operate in the optimum power condition. The first MPPT controller is an astronomical two-axis sun tracker, which is designed to track the sun over both the azimuth and elevation angles and obtain maximum solar radiation at all times. The second MPPT controller controls the power converter between the PV panel and the load and also it implements a new fuzzy-logic controller (FLC) based perturb and observe (P&O) scheme to keep the system power operating point at its maximum. The proposed control scheme achieves stable operation in the entire region of the PV panel and eliminates the resulting oscillations around the maximum power operating point.

This paper presents the modeling, analysis and control of different DC-DC converter topologies to emulate the photovoltaic (PV) system. A PV emulator is basically a DC-DC converter having same electrical characteristics that of solar PV panel. The emulator helps to achieve real characteristics of PV system in a better way in an environment where using actual PV systems can produce inconsistent results due to variation in weather conditions. The paper describes different types of DC-DC converters like buck, Resonant and Quasi Resonant Converter. The complete system is modelled in MATLAB ® Simulink SimPowerSystem software package. The Simulation results obtained from the MATLAB ® Simulink SimPowerSystem software package for different topologies under steady and dynamic conditions are analyzed and presented. An evaluation table is also presented at the end of the paper, presenting the effectiveness of each topology.

The single-phase inverters with higher-order filters are popular for grid interface of photovoltaic (PV) systems. Increasing penetration of these systems coupled with nonlinear loads impact grid voltage quality. The grid code restricts the injection of harmonic currents into the grid. To reduce the harmonic distortions in the current that is fed to the grid, this article presents a Proportional-Resonant (PR) controller for a HERIC inverter topology with an integrated input side dc-dc converter. The traditional controllers cannot restrict the injected current harmonic content when the grid voltage is polluted. To solve this problem a PR controller with Harmonic Compensators (HC) has been presented to limit the harmonic distortions. A 1.5kVA single-phase grid-tied inverter with an LCL filter on the output side has been simulated in MATLAB. Simulation studies on a grid-tied PV inverter have been carried out, and performance has been investigated and compared with other controllers for different levels of the injected grid current. The developed grid-tied inverter with a PR controller with HC is suitable for achieving low total harmonic distortion which guarantees that the system provides satisfactory performance according to the grid standards.

This paper presents experimental analysis of Genetic Algorithms (GAs) based Maximum Power Point Tracking (MPPT) for photovoltaic (PV) systems. This method, presented by another paper [1], uses GAs to track the maximum power point (MPP) of PV panels. Comparison with the famous Perturb and Observe (P&O) and Incremental Conductance (Inc-Cond) are given, we tested stability (power oscillation) with real panels (Conergy PowerPlus 214P), to compare response time (rapidity) we used a PV emulator [2] so we can inject the same irradiance profile and see output PV power evolution. The response time, of P&O and Inc-Cond, and the PV power oscillation varies with the duty cycle increment step; with a small step, we get less power oscillation but this needs an important time response, we can improve system rapidity with a bigger duty increment step but important power oscillation will result. With GAs based MPPT we can get more stability with rapid response time. The results obtained show better stability and less oscillation around the MPP with the new method.

In order to achieve optimum point tracking (MPPT) for the selection of the highest power consumption, the photovoltaic (PV) system was improved. The output power of the PV effect depends on external solar irradiation and the ambient temperature. In the existing MPPT approaches, most take only radiation fluctuations into account, with limited consideration of the consequences of temperature shifts. But the temperature coefficients (TCs), especially in applications where changes in ambient temperature are relative high, play an important role in the PV system. A correct study for the MPPT method was performed with a PV system which considers the temperature change using a variable universe fuzzy logic control (VUFLC). Taking account of the changing atmosphere temperature in photovoltaic panels, the proposed control method will regulate VUFLC contraction and expansion, removing the effect of temperature fluctuations and improving MPPT efficiency and thus achieving a quick and accurate tracking control. The proposed strategy was tested under different environmental conditions for a PV module and its control efficiency is compared with simulation and experimental results to other MPPT strategies. Compared with fossil fuels, the best alternative is to generate photovoltaic energy every day. In future, because of the above developments the thermal and nuclear power plant will probably withdraw. The cost of development and installation are rising in comparison with other renewable options. The article addresses a better configuration with an MPPT controller for a PV solar power system compared to other strategies dealing with the non-shaded, partial shading of variable sun-irradiance. This helps designers and maintainers build maintenance processes and phases.

Solar PV energy: From material to use, and the most commonly used techniques to maximize the power output of PV systems: A focus on solar trackers and floating solar panels