Fractional Short Circuit Current Research Articles

Hybrid sensor-aided direct duty cycle control approach for maximum power point tracking in two-stage photovoltaic systems

A novel maximum power point tracking (MPPT) approach for two-stage photovoltaic (PV) systems is proposed, which is a hybridization of Perturb & Observe (P&O) with a modified version of the Fractional Open Circuit Voltage (FOCV) algorithm. Differently from other hybrid algorithms which merge P&O with FOCV or Fractional Short Circuit Current (FSCC), the proposed algorithm enables direct duty cycle control (DDCC), which significantly reduces efficiency losses due to steady-state oscillations. Also unlike similar methods, it provides a mechanism for tracking the global maximum power point during partial shading (PS). Validation of the proposed method is carried out via computer simulations and a practical experiment, whose results show that it yields superior performance compared to commonly used MPPT algorithms and, on more detailed analysis, improves standard P&O efficiency by a large margin (up to 15% at uniform irradiance and 27% during PS). Furthermore, it outperforms a similar hybrid, but non-DDCC, algorithm by up to 7% in efficiency.

Real-Time Experimental Assessment of a New MPPT Algorithm Based on the Direct Detection of the Short-Circuit Current for a PV System

To substantially increase the efficiency of photovoltaic (PV) systems, it is important that the Maximum Power Point Tracking (MPPT) system has an output close to 100%.This process is handled by MPPT algorithms such as Fractional Open-Circuit Voltage (FOCV), Perturb and Observe (P&O), Fractional Short-Circuit Current (FSCC), Incremental Conductance (INC), Fuzzy Logic Controller (FLC) and Neural Network (NN) controllers. The FSCC algorithm is simple to be implemented and uses only one current sensor. This method is based on the unique existence of the linear approximation between the Maximum Power Point (MPP) current and the short-circuit current in standard conditions. The speed of this MPPT optimization technic is fast, however this algorithm needs to short-circuit the PV panel each time in order to obtain the short circuit current. This process leads to energy losses and high oscillations. In order to improve the FSCC algorithm, we propose a method based on the direct detection of the shortcircuit current by simply reading the output current of the PV panel. This value allows directly calculating the short circuit current by incrementing or decrementing the solar irradiation. Experimental results show time response attenuation, little oscillations, power losses reduction and better MPPT accuracy of the enhanced algorithm compared to the conventional FSCC method.

The Transition to Renewable Energy for A Green Shoot of Economic Revival: Comparative Study of Four MPPT Control Algorithms for A PV System

This paper explains the need for renewable energies for “green revival” of the economy. First, we will analyze the overall context of the double crisis. Then we will focus on “green recovery” as a solution for these two crises. Finally, we will study the example of the photovoltaic system as a source of renewable energy by presenting and comparing four types of MPPT commands such as: Perturb and Observe, Incremental Conductance, Fractional Open-Circuit Voltage (FOV) and Fractional Short-Circuit Current (FCC). The Matlab-Simulink environment will be used to analyze and interpret the simulation results of these algorithms and therefore we show the performance and limits of each algorithm.

Online current-sensorless estimator for PV open circuit voltage and short circuit current

The suggested paper presents a new method for the estimation of short circuit current (Isc) and open-circuit voltage (Voc) of the photovoltaic (PV) system. Moreover, a modified relation of reverse saturation current (Is) is used to prevent the wrong estimation of Isc and Voc values at any point of the P-V curve. In addition, a new current-sensorless method of PV current estimation is used to further reduce the cost of the proposed technique. The accuracy of the proposed method is checked by testing on three different PV panels such as Yingli 245C-30b, Sharp NT-180U1, and Risen SYP-110S. Moreover, the fractional short circuit current (FSSC) and fractional open-circuit voltage (FOCV) algorithms are also implemented using the proposed and conventional analytical method and their results are compared with each other. The proposed method is validated in the Matlab/Simulink and hardware experimentation. The results of the proposed method indicate the following advantages: (1) accurate prediction of the Isc and Voc values at any point of the P-V curve, (2) interruption free output power during the Isc and Voc measurement, (3) accurate sensorless estimation of PV current, 4) no overshoot and undershoot in the tracked power of PV module, and 5) significant improvement in tracking efficiency by 38.33% for the FSSC algorithm and 28.2% for the FOCV algorithm, compared to the conventional analytical method.

The most used MPPT algorithms: Review and the suitable low-cost embedded board for each algorithm

In order to increase the production of photovoltaic-based cleaner energy, the maximum power point tracking (MPPT) controller was employed. Because different MPPT algorithms have been adduced in the literature, it is mandatory to compare and differentiate them to select the most adequate MPPT for a particular application or to make suggestions for future research regarding MPPT. This paper reviews (extensively) the most used MPPT algorithms. They are classified into three groups: (1) direct, such as hill climbing (HC), perturb and observe (P&O), and incremental conductance (INC); (2) indirect, namely fractional short-circuit current (FSCC), Fractional Open-Circuit Voltage (FOCV), and pilot cell and (3); soft computing methods such as a Kalman filter, fuzzy logic control (FLC), neural network, partial swarm optimization (PSO), ant colony optimization (ACO), artificial bee colony (ABC), bat algorithm and hybrid PSO-FLC. A detailed principle of operation and the merits and downsides of each method are discussed. Also, the distributed MPPT and other MPPT methods are briefly presented. Finally, a recommendation of the most well-suited embedded board for the implementation of each method is presented and discussed. To complete these objectives, this manuscript focuses solely on the low-cost embedded board.

An Approximate Short Circuit Strategy for Transient MPPT Performance of Uniformly Irradiated Photovoltaic Modules

This paper presents an improved strategy to provide better maximum power point tracking (MPPT) performance and increase energy yield during transient state of MPPT process. This strategy is based on the estimation of short circuit current (SCC) of the photovoltaic (PV) system without short circuit. Besides that, this strategy aims to decrease convergence time to maximum power point (MPP) by preventing real short circuit of PV source and eliminating the additional switch requirement. To determine performance of the proposed strategy, simulation studies have been performed in MATLAB/Simulink and this strategy has been compared with fractional SCC (FSCC) technique and perturb and observe (P&O) algorithm. In addition, to make validation experimentally, a low powered single ended primary inductance converter (SEPIC) is realized. Both simulation and experimental results show that proposed strategy performs better transient MPPT performance than FSCC technique and P&O algorithm.

Real-Time Experimental Assessment of Hill Climbing MPPT Algorithm Enhanced by Estimating a Duty Cycle for PV System

Better functioning of maximum power point tracking (MPPT) can significantly increase the energy efficiency of photovoltaic systems. This process is provided by MPPT algorithms. Such as fractional open-circuit voltage, perturb and observe, fractional short-circuit current, hill climbing, incremental conductance, fuzzy logic controller, neural network controller, just to name a few. The hill climbing algorithm uses the duty cycle of the boot converter as a retraction parameter when the MPPT task is performed. However, this technique has disadvantages in terms of the stability of the system during periods of constant radiation. To overcome this disadvantage, A MPPT technique based on the estimation of the boost converter duty cycle associated with the conventional hill climbing, fractional open-circuit voltage and fractional short-circuit current algorithm is proposed. A comprehensive description of the experimental implementation hardware and software platforms is presented. On the basis of the measured data, the enhanced algorithm was compared to the conventional hill climbing MPPT technique according to various criteria, showing the disadvantages and advantages of each. Experimental results show advantage of the enhanced algorithm compared to the conventional hill climbing MPPT technique in time response attenuation (0.25s versus 0.6s), little oscillations (0.5 W versus 2.5 W), power loss reductions and better maximum power point tracking accuracy (98.45 W versus 92.75 W) of the enhanced algorithm compared to the conventional hill climbing MPPT technique.

HYBRID ALGORITHM AND ACTIVE FILTERING DEDICATED TO THE OPTIMIZATION AND THE IMPROVEMENT OF PHOTOVOLTAIC SYSTEM CONNECTED TO GRID ENERGY QUALITY

This work describes a photovoltaic generator connected to the grid by associating the features of a shunt active power filter to improve the energy quality. A command by hysteresis is proposed to eliminate the harmonious currents as well as the reactive power while injecting the active power into the grid. This power is extracted by hybrid command of Maximum Power Point Tracking (MPPT) which combines the conventional Perturb and Observe (P&O) and Fractional Short Circuit Current (FSCC). The boundary condition between FSCC and P&O is intensely decided by the proposed algorithm. The use of this method allows to exploit the speed of FSCC, to put the system around the approached maximum power point (MPP), and precision of the P&O to track the real PPM with a small step of disturbance. Another advantage achieved by this method, is that it does not require any sensor to measure irradiation because it detects intelligently the change of irradiation.

Relevance of the P & O MPPT Technique in an Original PV-Powered Water Pumping Application

Many papers exploiting the various MPPT (maximum power point tracking) techniques in PV (photovoltaic) applications, from the simple to the most complicated, can be found in literature. However, these techniques may not always be easy to implement in industrial applications. The main challenge of this paper is to model and implement the P & O (perturb and observe) algorithm in a low-cost PV-powered pumping system. To that end, a comparative investigation of the performance characteristics of the most popular MPPT methods, such as FOCV (fractional open circuit voltage), FSCC (fractional short circuit current), FLC (fuzzy logic control), ANN (artificial neural network) and INC (incremental conductance) is presented. This analysis is helpful to highlight the relevance of the P & O technique taking better account of complexity, difficulty of implementation and cost considerations in water pumping applications. The targeted PV-powered pumping system is based on a single-phase induction motor supplied by a three-phase inverter controlled by the DTC (direct torque control) technique. This stand-alone PV system is dedicated to water pumping, especially in rural areas that have no access to national grids but have sufficient amount of solar radiation. Simulation modeling (Matlab/Simulink) and experimental results are presented to demonstrate the relevance of the system.

A New Sensorless Hybrid MPPT Algorithm Based on Fractional Short-Circuit Current Measurement and P&O MPPT

This paper presents a new maximum power point tracking (MPPT) method for photovoltaic (PV) systems. The proposed method improves the working of the conventional perturb and observe (P&O) method in changing environmental conditions by using the fractional short-circuit current (FSCC) method. It takes the initial operating point of a PV system by using the short-circuit current method and later shifts to the conventional P&O technique. The advantage of having this two-stage algorithm is rapid tracking under changing environmental conditions. In addition, this scheme offers low-power oscillations around MPP and, therefore, more power harvesting compared with the common P&O method. The proposed MPPT decides intelligently about the moment of measuring short-circuit current and is, therefore, an irradiance sensorless scheme. The proposed method is validated with computer software simulation followed by a dSPACE DS1104-based experimental setup. A buck-boost dc-dc converter is used for simulation and experimental confirmation. Furthermore, the reliability of the proposed method is also calculated. The results show that the proposed MPPT technique works satisfactorily under given environmental scenarios.

An intelligent control strategy of fractional short circuit current maximum power point tracking technique for photovoltaic applications

This paper presents an improved Fractional Short Circuit Current (FSCC) Maximum Power Point Tracking (MPPT) technique in which an additional control loop is used to find the proper moment to measure the SCC. The target is to reduce the power losses in MPPT process that occur as a result of intermittent time based short circuit current measurements. The proposed modification enables the conventional FSCC MPPT to decide intelligently about the measurement of SCC thus reduces the number of times the photovoltaic (PV) module is isolated from the load. Although number of algorithms for tracking MPPT has been reported, the proposed method suits well for low cost PV applications. A Matlab/Simulink based model is employed to test the functional abilities of the proposed method. The comparison of the proposed method and conventional time based FSCC method is also presented in the simulation analysis. Finally, a 130 W prototype based on the dSPACE DS1104 controller and experimental results are presented to verify the effectiveness of the proposed method. The technique is verified under uniform shading conditions. The results show satisfactory performance against test conditions.

MPPT of a Photovoltaic Panel Based on Takagi-Sugeno and Fractional Algorithms

A new algorithm which provides continuously the optimal operating point of a photovoltaic panel is presented. As the power generated by a photovoltaic panel depends on climatic variables such as temperature and irradiation, control of a DC/DC converter connected to the panel is needed to extract the maximum power from the photovoltaic panel, by deciding continuously which the optimal operating point is. This amounts to selecting the duty cycle of the DC/DC converter. The proposed algorithm is based on combining the Takagi-Sugeno approach with Fractional Open-circuit Voltage (FOV) and Fractional Short-circuit Current (FSC) algorithms. To illustrate the performance of the new algorithm we compare with standard FOV and FSC algorithms. The simulation results show the improved performance of the proposed algorithm.