 Advances in Technology Innovation, vol. 5, no. 4, 2020, pp. 230-247 Simulation and Implementation of a Modified ANFIS MPPT Technique Bachar Meryem * , Naddami Ahmed, Fahli Ahmed Department of Electrical Engineering, Hassan First University, Settat, Morocco Received 19 Nobember 2019; received in revised form 06 March 2020; accepted 06 June 2020 DOI: https://doi.org/10.46604/aiti.2020.4987 Abstract The maximum power point tracking (MPPT) algorithms ensure optimal operation of a photovoltaic (PV) system to extract the maximum PV power, regardless of the climatic conditions. This paper exposes the study, design, simulation and implementation of a modified advanced neural fuzzy inference system (ANFIS) MPPT algorithm based on fuzzy data for a PV system. The studied system includes a PV array, a DC/DC buck converter, the ANFIS controller, a proportional-integral (PI) controller, and a load. The simulation and experimental tests are carried out with the MATLAB/Simulink software and LabVIEW, respectively. Moreover, the obtained results are compared with previously published results by incremental conductance (IC) and fuzzy logic (FL) algorithms under different climatic conditions of irradiation and temperature. The results show that the proposed ANFIS algorithm is able to track the maximum power point for varying climatic conditions. Furthermore, the comparison analysis reveals that the PV system using ANFIS algorithm has more efficient and better dynamic response than FL and IC. Keywords: PV panel, MPPT algorithm, Buck converter, ANFIS 1. Introduction Nowadays, the demand for energy is constantly rising; however, the availability of fossil energy is rapidly declining. As a result, the cost of energy increasing becomes a hurdle to social development [1-2]. Solar energy with multiple benefits [3] is an effective solution to the production of green energy and also an alternative source. One of the most important solar technologies is photovoltaic (PV), which comes from converting sunlight into electricity within semiconductor materials such as silicon under the PV effect [4-5]. The association of the PV cells gives a PV panel that produces direct electrical energy. It can be stored in batteries or injected into the network. Hence, PV panels can be used for a stand-alone and grid-connected system [6]. However, PV energy is unstable because of its dependence on the load impedance and climatic conditions such as irradiation and temperature [7-8]. The PV cell characteristic has only one point where the power is maximum called maximum power point (MPP) [9]. As a consequence , researchers are developing approaches to extract as much power as possible from PV panels. Maximum power point tracking (MPPT) algorithms are used to extract the maximum power and improve the productivity of the PV system regardless of the change in climatic conditions. They are used to adjust the duty cycle (D) to a power conversion system, for example, DC/DC converters act as an impedance matching circuit between the PV array and the load [10-11]. Up to today, several MPPT algorithms have been used to rise above these problems. They can be classified according to the number of the used sensors, the cost, the complexity, and the efficiency. * Corresponding author. E-mail address: meryem.bachar@gmail.com Tel.: +2126501753; Fax: +212(0)523490354 Advances in Technology Innovation, vol. 5, no. 4, 2020, pp. 230-247 231 There are two types of MPPT techniques. First, the conventional MPPT techniques like the perturb and observe (P&O) [12-13], incremental conductance (IC) [14-15], the look-up table [16] Second, the intelligent MPPT techniques such as fuzzy logic (FL) [17], the fuzzy logic type 2 (FLT2) [18], neural network (NN) [19], and advanced neural fuzzy inference system (ANFIS). NN and FL systems are universal intelligent approximators. NNs have an interesting learning ability, while FL systems are built from human knowledge and have a high capacity for description through its use of linguistic values. These advantages have suggested a hybrid solution that combines the two cited approximators: FL and NN algorithm. This hybrid solution can be called a neuro-fuzzy approach or the ANFIS approach. In general, the used output power of the PV panel in the ANFIS system is obtained after monitored the behavior of the PV panel in different climatic conditions for a long time. The objective of this paper is to predict the power of the PV panel by the FL algorithm simulations and use the obtained data in the proposed ANFIS system to make up for the lost time. In this study, the ANFIS MPPT algorithm was used to extract the MPP from the PV array with a PI controller based on the fuzzy data. The authors tested the performance of the proposed algorithm and compared the simulation and experimental results using MATLAB/Simulink environment and laboratory virtual instrument engineering workbench (LabVIEW) software. The obtained results will be compared by the FL and IC MPPT algorithms results used in the previously published papers. To expose that, this paper is arranged as follows: The second section presents an electrical model of the PV cell that was used in the simulation and the effect of irradiation and temperature on the PV array. The third part gives details about the DC/DC converters, especially DC/DC buck ones. The fourth part shows the ANFIS MPPT algorithm and explains the principle of operation of this proposed technique. The fifth section represents the simulation results with the MATLAB/Simulink environment. The sixth part displays the experimental results with the LabVIEW software and CompactRio. Finally, the last part discusses and compares the results. 2. Photovoltaic Cell A solar cell is a basic element in the PV system. It converts the incident light into electrical energy. To model a photovoltaic (PV) panel, it is the most important to model a PV cell [20]. Generally, the PV cell is presented by four elements: a current generator Iph, a diode D, a parallel resistance Rsh, and a series resistance Rs. Iph models the conversion of light radiation into electricity. D represents the PN junction. Rsh symbolizes the leakage current and Rs models the internal losses due to connections between cells. Fig. 1 presents the equivalent circuit of the PV cell. Fig. 1 The equivalent circuit of PV cell The current generated by the solar cell is obtained by Eqs. (1)-(2): Dph shI I I I   (1) 0 s sh V IR Rq s ph sh V IR I I I e R              (2) D Rs Rsh Iph I V Advances in Technology Innovation, vol. 5, no. 4, 2020, pp. 230-247 232 Iph, I0, and q are the photodiode current, the inverse saturation current, the charge of the electron, the ideality factor of the PN junction, the Boltzmann constant, and the temperature of the PV cell, respectively. The PV cell generates only 0.6V. Consequently, the PV cells are connected in series or (and) in parallel to gain the desired voltage to supply the load. Figs. 2-3 indicate the I-V and P-V curve of the used PV array at 1000W/m² and 30°C. Fig. 2 I-V curve of the studied PV array Fig. 3 P-V curve of the studied PV array The characteristic of the PV array is influenced by climatic conditions such as irradiation and temperature. Fig. 4 shows the I-V and P-V curves of the used PV array for variant irradiation. Fig 5 shows the PV characteristics for variant temperature during 0 and 75 °C. In Figs. 4-5, it is seen that the current is produced by the PV panels increases when the irradiation increases. However, the voltage increases when the temperature decreases. (a) I-V curves of the PV array Fig. 4 I-V and P-V curve of the PV array for variant irradiation and constant temperature 1 kW/m² 0.8 kW/m² 0.6 kW/m² 0.2 kW/m² 0.4 kW/m² Advances in Technology Innovation, vol. 5, no. 4, 2020, pp. 230-247 233 (b) P-V curves of the PV array Fig. 4 I-V and P-V curve of the PV array for variant irradiation and constant temperature (continued) (a) I-V curves of the PV array (b) P-V curves of the PV array Fig. 5 I-V and P-V curve of the PV array for variant temperature and constant irradiation 3. A DC/DC Converter Fig. 6 The DC/DC Buck converter 1 kW/m² 0.8 kW/m² 0.6 kW/m² 0.2 kW/m² 0.4 kW/m² 75°C 50°C 25°C 0°C 75°C 50°C 25°C 0°C C S D Ve L o ad L D Advances in Technology Innovation, vol. 5, no. 4, 2020, pp. 230-247 234 A DC/DC converter is used to transform the DC voltage supplied by the PV panel into a DC voltage suitable for supplying DC voltage receivers. Currently, different types of DC/DC converters are used such as the buck converter, the boost converter, the buck-boost converter, and the Full-bridge converter [21]. In this study, the buck converter is used to diminish output voltage as shown in Fig. 6. The Ve is the input voltage, S is a metal-oxide-semiconductor field-effect transistor (MOSFET) controlled by the MPPT controller, D is a diode, L is inductance, and C is a capacitor. When the switch S is closed, the voltage across the inductor is given by: L e sV V V  (3) The relationship between the input voltage and the output voltage of the buck converter can be found by: s eV DV (4) where D is the duty cycle with 0