Modeling, Analysis and Design of Synchronous Buck Converter Using State Space Averaging Technique for PV Energy System

If we start forecasting in the view of electrical energy generation, in the upcoming decade all the fossil fuels are going to be extinct or the worst they are going to be unaffordable to a person living in typical circumstances, so renewable power energy generation systems are going to make a big deal out of that. It is extremely important to generate and convert the renewable energy with maximum efficiency. In this project, first we study the characteristics of low power PV array under different values of irradiance and temperature. And then we present the exquisite design of Synchronous Buck Converter with the application of State Space Modeling to implement precise control design for the converter by the help of MATLAB/Simulink. The Synchronous Buck Converter thus designed is used for portable appliances such as mobiles, laptops, iPod’s etc. But in this project our main intention is to interface the PV array with the Synchronous Buck Converter we designed, and we will depict that our converter is more efficient than the conventional buck converter in terms of maintaining constant output voltage, overall converter efficiency etc. And then we show that the output voltage is maintaining constant irrespective of fluctuations in load and source. And finally we see the performance of Synchronous Buck Converter, which is interfaced with PV array having the practical variations in temperature and irradiance will also maintain a constant output voltage throughout the response. All simulations are carried under MATLAB/Simulink environment. And at last experimental work is carried out for both conventional buck converter and also for synchronous buck converter, in which we observe the desired outputs obtained in simulations

Study and Analysis of Distributed Maximum Power Point Tracking Under Partial Shading Conditions

Photovoltaic (PV) energy generation is becoming an increasingly widespread means of producing clean and renewable power. In PV systems, long strings of photovoltaic modules are found to be vulnerable to shading effects, causing significant reduction in the system power output. To overcome this, distributed maximum power point-tracking (abbreviated as DMPPT) schemes have been proposed, in which individual dc–dc converters are connected to each PV module to enable module-wise maximum power extraction. The development of a distributed maximum power point tracking (DMPPT) photovoltaic (PV) system enables us to compensate the shading effect and the PV module mismatching as well as to increase the overall output power. The two main concepts to implement DMMPT systems are series and parallel configuration which describes the connection of the output terminals of the converters. Both systems are studied intensively. Output side sensor based DMPPT system has also been studied. It is also proved that parallel configuration is virtually free of any cross coupling effects

Fast‐converging robust PR‐P controller designed by using symmetrical pole placement method for current control of interleaved buck converter‐based PV emulator

In this study, the interleaved buck converter-based photovoltaic (PV) emulator current control is presented. A proportional-resonant-proportional (PR-P) controller is designed to resolve the drawbacks of conventional PI controllers in terms of phase management, which means balancing currents evenly between active phases to avoid thermally stressing and provide optimal ripple cancelation in the presence of parameter uncertainties. The resonant path of the controller (PR) with a constant proportional unity gain is designed considering the changing dynamics of a notch filter by pole placement method (adding mutually complementary poles to the notch transfer function) at PWM switching frequency. The proportional gain path (P) of the controller is used to determine the compatibility of the controller with parameter uncertainty of the phases and designed by utilizing loop-shaping method. The proposed controller shows superior performance in terms of 10 times faster-converging transient response, zero steady-state error with significant reduction in current ripple. Equal load sharing that constitutes the primary concern in multiphase converters is achieved with the proposed controller. Implementing of robust control theory involving comprehensive time and frequency domain analysis reveals 13% improvement in the robust stability margin and 12-degree bigger phase toleration with the PR-P controller. In addition to these, the proposed unconventional design process of the controller reduces the computational complexity and provides cost-effectiveness and simple implementation. Moreover, implementing of auxiliary resistor-capacitor (RC) circuits parallel with the inductors to sense the current in each phase removes the need for current measurement sensors that contribute to overall cost of the system

Design and Testing of High Frequency Converters for Photovoltaic System Integration

This thesis presents simulation, modelling, and testing for the complete photovoltaic (PV) system, including the PV panels themselves, the converters necessary for grid connection, and the testbed environments required for their testing. Investigating such systems is crucial, as PV systems are becoming increasingly prevalent. Converters are evolving and so too are the semiconductor devices of which they are comprised. Advanced topologies such as the modular multilevel converter (MMC) are allowing for radical changes in converter design and control, raising performance and efficiency ever higher. Buoying that growth is the development of wide bandgap (WBG) semiconductors, which are enabling faster, smaller, and more efficient converters. In light of these advancements, significant room for modeling and analysis of the various phenomena that occur in PV systems is critical. In order to address this need, this thesis will present analysis, simulation, and testing of a number of key elements within the PV system, such that the whole may be better understood. It will begin with the DC-DC converter itself, modeling transient events in synchronous buck converters, as well as demonstrating the implementation of maximum power point tracking (MPPT) in boost converters. Next, the inverter portion of the system will be examined, focusing on development of a single phase, low voltage version of the MMC topology that has been previously demonstrated in high voltage direct current (HVDC) systems. Finally, a design for a test bank and workbench will be discussed, shedding light on the laboratory apparatus necessary for proper evaluation and testing of new power electronic devices and systems. In short, the complete PV system is presented, its individual components are modeled and analyzed, and the conditions and materials necessary for testing are established, such that the understanding of PV integration in modern power systems can be better understood

Estratégias de Operação para Sistemas Fotovoltaicos com Armazenamento Híbrido de Energia Elétrica

Na sociedade atual a energia elétrica é considerada um bem essencial para a vida de cada indivíduo. De modo a acompanhar esta crescente tendência na utilização de energia elétrica, surge cada vez mais uma implícita responsabilidade da sociedade na procura de fontes de energia mais limpas. Uma das mais atrativas soluções neste momento passa pela produção fotovoltaica. A utilização desse tipo de energia, obtida por meio da transformação direta de recursos naturais, é atualmente estudada com grande interesse pela comunidade científica, devido à sua complexidade, tanto pelas diferentes fontes de produção, quanto pela sua variabilidade e imprevisibilidade. No entanto, essa falta de previsibilidade poderia ser compensada pela complementaridade entre recursos ou pela introdução de sistemas de armazenamento de energia elétrica. Os sistemas de armazenamento de energia elétrica são reconhecidos como uma das abordagens mais promissoras. No entanto, estes sistemas sofrem de alguns problemas operacionais, como por exemplo a degradação do desempenho quando sujeitos a altas correntes de carga / descarga e uma consequente redução da sua vida útil. Para mitigar estas desvantagens, começaram a surgir os sistemas de armazenamento híbridos de energia. Estes sistemas combinam benefícios de duas ou mais tecnologias diferentes. A ligação de super-condensadores e baterias de Li-ion, que combina a alta densidade de potência de super-condensadores com a alta densidade energética das baterias de Li-ion, é a topologia mais usual neste tipo de sistema. Esta dissertação tem como objetivo o dimensionamento, construção e controlo de um sistema isolado da rede elétrica, com extração de energia fotovoltaica e armazenamento híbrido de energia elétrica.In today's society, electricity is considered an essential asset for the life of each individual. In order to keep up with this growing trend, in the use of electric energy in previously manually performed tasks, there is an increasing implicit responsibility of society to seek cleaner sources of energy. One of the most attractive solutions, at this moment, is photovoltaic production. The use of this type of energy, obtained through the direct transformation of natural resources, is currently studied with great interest by the scientific community, due to its complexity, as well as its variability and unpredictability. However, this lack of predictability can be eliminated by the complementarity between resources or by the introduction of electrical energy storage systems. Energy storage systems are recognized as one of the most promising approaches. However, these systems suffer from some operational problems, such as degradation of performance when subjected to high load/discharge currents and a consequent reduction in their useful life. To mitigate these drawbacks, hybrid power storage systems began to emerge. These systems combine the benefits of two or more different technologies. The connection of super capacitors and Li-ion cells, thus combining the high power density of super capacitors with the high energy density of Li-ion cells, is the most common topology in this type of system. This dissertation aims at the design, construction and control of an isolated grid system, with extraction of photovoltaic energy and hybrid storage of electric energy

Sistema de monitorização remota de parâmetros internos e da envolvente de árvores

Atualmente, com o aumento populacional, a sociedade agropecuária viu-se na responsabilidade de acompanhar este crescimento. Com a sobreexploração desta área e a consequente utilização de meios fitossanitários para a fazer subsistir, cada vez mais nos deparamos com o aumento da degradação ambiental e com o aparecimento frequente de doenças e pragas muito mais resistentes. Como consequência disto, os produtos têm vindo a sofrer uma redução da qualidade para além de apresentarem um risco crescente de toxicidade prejudicial para a saúde do ser humano. Uma das soluções mais atrativas neste momento passa pela monitorização direta e em tempo real de parâmetros como a temperatura e a humidade, tanto da própria árvore como também do meio que a envolve. Desta forma, é possível prever o aparecimento dos infestantes, evitando a utilização excessiva, e em muitos casos desnecessária, de pesticidas. Contudo, ainda não existem muitos estudos desenvolvidos para solucionar este problema. Assim, esta dissertação visa o projeto e construção de um dispositivo de monitorização remota que permita ao utilizador conhecer parâmetros com impacto na saúde das árvores como sejam a temperatura interna; a humidade do solo e a temperatura, humidade e concentração de gases da atmosfera envolvente. Sabendo ainda que dois dos requisitos fundamentais dos sistemas de monitorização remota se prendem com o alcance de comunicação e sua autonomia, todos os dados monitorizados são transmitidos para um repetidor central, também desenvolvido nesta dissertação, por meio da tecnologia LoRaWAN, sendo todo o sistema alimentado por energia solar via conversão fotovoltaica. Adicionalmente, o utilizador pode aceder aos dados monitorizados em tempo real em qualquer lugar, devido a uma aplicação móvel desenvolvida para essa finalidade. Por fim, para validar o bom funcionamento do dispositivo, são apresentados os resultados de ensaios experimentais, em forma de gráfico, realizados numa oliveira sob diferentes condições ambientais.With the population increase experienced presently the agricultural society felt obligated to following up with this growth. Over exploration of this area and the consequent use of phytosanitary products to make it subsist are leading us to increasingly face environmental degradation growth and the frequent occurrence of much more resistant diseases and pests. As result, products have been suffering from a reduction in quality as well as an increasing risk of harmful toxicity to human health. One of the most attractive solutions right now is the direct and real-time parameters monitoring such as temperature and humidity of both the tree itself and the surrounding environment. Thereby, we can predict the forthcoming of diseases and pests avoiding the excessive and, in many cases, unnecessary pesticide use. However, there are not many studies developed to solve this problem. Thus, this dissertation aims the design and construction of a monitoring device that allows the user to know parameters related to tree’s health as inner temperature; soil humidity and temperature, humidity and gas concentration of the surrounding atmosphere. Knowing that two remote monitoring systems fundamental requirements are related to communication range and autonomy all monitored data will be transmitted to a central repeater, also developed in this dissertation, via LoRaWAN technology and the entire system will be powered from photovoltaic power extraction. Moreover, to see the monitoring results the user can access them anywhere in the world due to a mobile application developed for this purpose. Lastly, to validate the proper functioning of the device, tests are performed on an olive tree under different environmental conditions and graphs with the results are presented

Design and Implementation of Control Techniques of Power Electronic Interfaces for Photovoltaic Power Systems

The aim of this thesis is to scrutinize and develop four state-of-the-art power electronics converter control techniques utilized in various photovoltaic (PV) power conversion schemes accounting for maximum power extraction and efficiency. First, Cascade Proportional and Integral (PI) Controller-Based Robust Model Reference Adaptive Control (MRAC) of a DC-DC boost converter has been designed and investigated. Non-minimum phase behaviour of the boost converter due to right half plane zero constitutes a challenge and its non-linear dynamics complicate the control process while operating in continuous conduction mode (CCM). The proposed control scheme efficiently resolved complications and challenges by using features of cascade PI control loop in combination with properties of MRAC. The accuracy of the proposed control system’s ability to track the desired signals and regulate the plant process variables in the most beneficial and optimised way without delay and overshoot is verified. The experimental results and analysis reveal that the proposed control strategy enhanced the tracking speed two times with considerably improved disturbance rejection. Second, (P)roportional Gain (R)esonant and Gain Scheduled (P)roportional (PR-P) Controller has been designed and investigated. The aim of this controller is to create a variable perturbation size real-time adaptive perturb and observe (P&O) maximum power point tracking (MPPT) algorithm. The proposed control scheme resolved the drawbacks of conventional P&O MPPT method associated with the use of constant perturbation size that leads to a poor transient response and high continuous steady-state oscillations. The prime objective of using the PR-P controller is to utilize inherited properties of the signal produced by the controller’s resonant path and integrate it to update best estimated perturbation that represents the working principle of extremum seeking control (ESC) to use in a P&O algorithm that characterizes the overall system learning-based real time adaptive (RTA). Additionally, utilization of internal dynamics of the PR-P controller overcome the challenges namely, complexity, computational burden, implantation cost and slow tracking performance in association with commonly used soft computing intelligent systems and adaptive control strategies. The experimental results and analysis reveal that the proposed control strategy enhanced the tracking speed five times with reduced steady-state oscillations around maximum power point (MPP) and more than 99% energy extracting efficiency.Third, the interleaved buck converter based photovoltaic (PV) emulator current control has been investigated. A proportional-resonant-proportional (PR-P) controller is designed to resolve the drawbacks of conventional PI controllers in terms of phase management which means balancing currents evenly between active phases to avoid thermally stressing and provide optimal ripple cancellation in the presence of parameter uncertainties. The proposed controller shows superior performance in terms of 10 times faster-converging transient response, zero steady-state error with significant reduction in current ripple. Equal load sharing that constitutes the primary concern in multi-phase converters has been achieved with the proposed controller. Implementing of robust control theory involving comprehensive time and frequency domain analysis reveals 13% improvement in the robust stability margin and 12-degree bigger phase toleration with the PR-P controller. Fourth, a symmetrical pole placement Method-based Unity Proportional Gain Resonant and Gain Scheduled Proportional (PR-P) Controller has been designed and investigated. The proposed PR-P controller resolved the issues associated with the use of the PI controller which are tracking repeating control input signal with zero steady-state and mitigating the 3rd order harmonic component injected into the grid for single-phase PV systems. Additionally, the PR-P controller has overcome the drawbacks of frequency detuning in the grid and increase in the magnitude of odd number harmonics in the system that constitute the common concerns in the implementation of conventional PR controller. Moreover, the unprecedented design process based on changing notch filter dynamics with symmetrical pole placement around resonant frequency overcomes the limitations that are essentially complexity and dependency on the precisely modelled system. The verification and validation process of the proposed control schemes has been conducted using MATLAB/Simulink and implementing MATLAB/Simulink/State flow on dSPACE Real-time-interface (RTI) 1007 processor, DS2004 High-Speed A/D and CP4002 Timing and Digital I/O boards