Ghias Farivar

An Analytical Solution for Tracking Photovoltaic Module MPP

In this paper, a new method for estimating the maximum power point (MPP) of a solar array based on its characteristic equation is introduced. The proposed method is simple fast and returns the MPP accurately. Moreover, the sensitivity of the introduced scheme to the model parameters is analyzed. Finally, the practicability of the proposed method is demonstrated by both simulation and experimental results on REC-AE220 solar modules.

A Voltage Balancing Strategy With Extended Operating Region for Cascaded

In this paper, a generalized switching technique for cascaded H -bridge (CHB) converters is proposed. To take advantage of both low- and high-frequency modulation techniques, a hybrid modulation method is utilized. The proposed technique employs the low-frequency switching for voltage balancing of the dc-link capacitors, and the high-frequency sinusoidal pulse-width modulation switching for shaping the input ac current. Using the proposed technique, the stable operating region of CHB converters is extended. The proposed technique is capable of maintaining the dc voltages balanced even under critical operating conditions in which the load of one H-bridge cell is removed. The validity and effectiveness of the proposed method is confirmed by several simulation and experimental tests on a seven-level CHB rectifier.

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In this paper a new approach to find all the single diode model parameters of a Photovoltaic (PV) array is demonstrated. Unlike the other methods, the proposed method in this paper is straightforward and does not need any additional information more than the manufacturer datasheet. In the selected model the effect of temperature coefficients is also considered. By using the proposed approach, PV system designers and researchers would be able to model the PV arrays without any considerable effort.

-Bridge Converters

Due to relatively high initial cost of the PV arrays, full utilization of the arrays output power is highly demanded in photovoltaic (PV) systems. The high tracking accuracy and perfect steady state characteristics of the PV model-based maximum power point tracking (MPPT) techniques has drawn a great attention toward these schemes in the past few years. Despite of the accuracy, the model-based MPPT methods suffer from heavy computational burden due to nonlinear characteristics of the PV arrays. In this paper, a novel model-based MPPT strategy for fast and precise tracking of the MPP in PV arrays is introduced. Simplicity and at the same time, accuracy, are the main features of the proposed MPPT scheme. Performance of the proposed MPPT method is evaluated based on digital time domain simulation studies in the MATLAB/SIMULINK environment. The studies demonstrate the capability of the proposed MPPT technique to rapidly and accurately track the MPP. The effectiveness of the proposed scheme is also validated through the experimentation on the 250W MPPT buck-converter.

Photovoltaic module single diode model parameters extraction based on manufacturer datasheet parameters

This paper introduces an improved predictive current control strategy for reducing the output current harmonic content of single-phase grid-connected inverters, based on nonlinear filter inductor model. The proposed control strategy, takes both saturation and hysteresis loop effects into account to produce an appropriate voltage to mitigate unwanted harmonic contents of injected current. Also, it only uses the grid voltage and a simple PI controller to produce the switching times and maintain the DC-bus voltage on its nominal value. Performance of the grid connected inverter and the proposed control method are evaluated based on digital time domain simulation studies in the MATLAB/SIMULINK environment. The studies demonstrate the capability of the proposed control strategy to fulfill the IEEE 929 – 2000 standard for the current total harmonic distortion.

A novel analytical solution for the PV-arrays maximum power point tracking problem

In this paper, an effective approach for estimating the operating temperature of a photovoltaic (PV) module is presented. The developed method is simple and does not need any additional hardware. The proposed approach uses an analytical formula to derive the temperature from the maximum power point (MPP) voltage and current. The effectiveness of the new method is investigated through some conducted simulations in MATLAB/Simulink environment and its validity is verified by experiment on REC-AE220 solar modules.

An improved predictive current control method for grid-connected inverters

In this paper, the feasibility of using stationary super-capacitors to store the metro network regenerative braking energy is investigated. In order to estimate the required energy storage system (ESS), a very simple model for metro network is developed. Using the model of metro network for a particular station, a new approach is proposed to find an appropriate cost function for sizing the ESS components. By minimizing the proposed cost function, the optimum rating of components and appropriate control strategy for dc-dc converter can be realized. A case study is provided and simulated for station five of line three of Tehran metro network using Matlab software optimization toolbox.

A novel temperature estimation method for solar cells

This paper presents a maximum power point tracking (MPPT) method based on fuzzy logic theory. A comparative study of conventional fuzzy methods is carried out and advantages and disadvantages of each one are explained. Additionally, different situations that may cause a fuzzy logic control (FLC) system fail to track or degrade in performance are analyzed. Accordingly, the theory and concept of a new algorithm that ensures satisfactory operation is explained. To evaluate the validity and effectiveness of the suggested method, different situations are simulated in MATLAB/SIMULINK environment. The results confirm the effectiveness of proposed method.

Optimal stationary super-capacitor energy storage system in a metro line

This paper investigates the feasibility of indirect controller for a cascaded H-bridge rectifier. Using this method, the converter can connect directly to the medium voltage levels and eliminates the necessity to current sensors. In order to have a good approximation to the real current and to improve the converter performance, the dynamics of output capacitors are entered to the PWM procedure. In this study, the controller is designed to maintain voltage balance among different H-bridge cells, even if the attached loads to the dc links are different. The controller should also program the input current to be sinusoidal and in-phase with the input voltage. The performance of the controller is verified by different simulations on a 7-level cascaded H-bridge rectifier, in Matlab/Simulink environment.