Extremum Seeking Maximum Power Point Tracking for a Stand-Alone and a Grid-Connected Photovoltaic Systems

Energy harvesting from solar sources in an attempt to increase efficiency has sparked interest in many communities to develop more energy harvesting applications for renewable energy topics. Advanced technical methods are required to ensure the maximum available power is harnessed from the photovoltaic (PV) system. This dissertation proposed a new discrete-in-time extremum-seeking (ES) based technique for tracking the maximum power point of a photovoltaic array. The proposed method is a true maximum power point tracker that can be implemented with reasonable processing effort on an expensive digital controller. The dissertation presented a stability analysis of the proposed method to guarantee the convergence of the algorithm. Two-types of PV systems were designed and comprehensive framework of control design was considered for a stand-alone and a three-phase grid connected system. Grid-tied systems commonly have a two-stage power electronics interface, which is necessary due to the inherent limitation of the DC-AC (Inverter) power converging stage. However, a one stage converter topology, denoted as Quasi-Z-source inverter (q-ZSI), was selected to interface the PV panel which overcomes the inverter limitations to harvest the maximum available power A powerful control scheme called Model Predictive Control with Finite Set (MPC-FS) was designed to control the grid connected system. The predictive control was selected to achieve a robust controller with superior dynamic response in conjunction with the extremum-seeking algorithm to enhance the system behavior. The proposed method exhibited a better performance in comparison to conventional Maximum Power Point Tracking (MPPT) methods and required less computational effort than the complex mathematical methods

DESIGN OF AN EFFECTIVE CONTROL FOR GRID-CONNECTED PV SYSTEM BASED ON FS-MPC

This paper is deals in part of research that has been conducted on modern means in the basis of power electronics. Harmonic cancellation of distribution network is currently a serious problem, especially in high electrical industry. The main source of harmonic currents injected into the network requires attention to reduce the current harmonic levels. Energy quality is a fairly broad concept which covers both, the quality of power supply (voltage wave) and these of the currents injected into the electrical grid. In this context, a modern approved preventive solution in purpose to limit the rate of harmonic disturbance caused by the deferent power electronics systems connected to the grid must take action. It appears necessary to develop the quality and stability of the grid and develop curative devices such as converters provided with a control device making the current drawn on the most sinusoidal network possible. This paper proposes a control of tow stage grid tied PV system established on finite set model predictive control (FS-MPC). The design of FS-MPC is developed depending on the structure and operating principle associated to three-phase inverter tied to the grid.  In this context, we have also employed the structure of MPPT controller (P&O) and PI controller for adjustment of the DC-bus voltage. To set the proposed control scheme, numerical simulations are carried out using Matlab/Simulink 2013b. The obtained results demonstrate that the proposed control scheme assure the tracking of MPP and the injection of extracted PV power into the grid with high current quality under irradiation changes

Power Loss Analysis of Solar Photovoltaic Integrated Model Predictive Control Based On-Grid Inverter

This paper presents a finite control-set model predictive control (FCS-MPC) based technique to reduce the switching loss and frequency of the on-grid PV inverter by incorporating a switching frequency term in the cost function of the model predictive control (MPC). In the proposed MPC, the control objectives (current and switching frequency) select an optimal switching state for the inverter by minimizing a predefined cost function. The two control objectives are combined with a weighting factor. A trade-off between the switching frequency (average) and total harmonic distortion (THD) of the current was utilized to determine the value of the weighting factor. The switching, conduction, and harmonic losses were determined at the selected value of the weighting factor for both the proposed and conventional FCS-MPC and compared. The system was simulated in MATLAB/Simulink, and a small-scale hardware prototype was built to realize the system and verify the proposal. Considering only 0.25% more current THD, the switching frequency and loss per phase were reduced by 20.62% and 19.78%, respectively. The instantaneous overall power loss was also reduced by 2% due to the addition of a switching frequency term in the cost function which ensures a satisfactory empirical result for an on-grid PV inverter

Receding-horizon model predictive control for a three-phase VSI with an LCL filter

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a Continuous Control Set Model Predictive Control with receding horizon for a threephase voltage source inverter with LCL filter, using a reduced model of the converter. The main advantages of using this reduced model is that an active damping can be achieved while the computational burden is reduced. Besides, in order to eliminate the model uncertainties, and also to achieve a zero steady state error, the proposed converter model includes an embedded integrator. Regarding the control scheme, a Kalman filter is used in order to estimate the three-phase currents without oscillation. The objective is to find the control signals vector that minimizes the error between the current and its reference. It is important to remark that the control signals obtained fromthe cost function can be used directly in a space vector modulator, without the use of additional controllers such as proportionalintegral or proportional-resonant. Compared with the Finite Control Set Model Predictive Control, the proposedmethod operates at fixed switching frequency without using any restriction in the cost function. Simulation and experimental results show that this proposalworks correctly even in case of grid harmonics and voltage sags.Peer ReviewedPostprint (author's final draft

A Comparative Study of Vector Control and Model Predictive Control Technique for Grid Connected Battery System

Advancements made to battery energy storage technologies have led to increasing integration of battery systems with the grid. This paper presents a comparative study of the well-established vector control technique and the model predictive current control technique as applied to the grid connected battery systems. An electrical equivalent model of the battery is modeled and integrated with the grid using a three- phase bidirectional converter. The comparative study is shown for bidirectional flow of power to charge/discharge the battery from the grid. Also, the effects of model predictive control versus vector control technique are analyzed at an event of grid fault. Asymmetrical and symmetrical grid fault is considered for the comparison. All the modeling and simulation is performed in PSCADTM/EMTDCTM. The results are plotted using MATLAB R2017a. The results show that the model predictive control technique performs as good as the vector control technique for a battery connected grid system

Inverter-Side Current Control of Grid-Connected Voltage Source Inverters With LCL Filter Based on Generalized Predictive Control

In this paper, an inverter-side current (ISC) control strategy for grid-connected voltage source inverter with LCL filters is proposed based on a generalized predictive control (GPC) formulation as it has the advantages of fixed switching frequency, a systematic design procedure and low computational complexity. As the GPC strategy is a subtype of continuous-control-set model predictive control strategies, a proper model for controlling the ISC is obtained, showing that a full-order model is preferred to its first-order counterpart. The controller is designed taking into consideration harmonic distortion limits and robustness against filter component variations. To this end, a complete three-wire LCL filter model is obtained and impedance sensitivity to each component variation is analyzed. Finally, its performance is evaluated by means of experimental results and compared with a predictive deadbeat controller.Fil: Judewicz, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica; ArgentinaFil: González, Sergio Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica; ArgentinaFil: Fischer, Jonatan Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica; ArgentinaFil: Martínez, Juan Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica; ArgentinaFil: Carrica, Daniel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica; Argentin