http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<<ETX>>

Multi-level conversion : high voltage choppers and voltage-source inverters

We investigated the effects of inhibitors of clathrin-mediated endocytosis (chlorpromazine and K(+) depletion) and of caveolae-mediated uptake (filipin and genistein) on internalization of FITC-poly-l-lysine-labeled DOTAP/DNA lipoplexes and PEI/DNA polyplexes by A549 pneumocytes and HeLa cells and on the transfection efficiencies of these complexes with the luciferase gene. Uptake of the complexes was assayed by fluorescence-activated cell sorting. Lipoplex internalization was inhibited by chlorpromazine and K(+) depletion but unaffected by filipin and genistein. In contrast, polyplex internalization was inhibited by all four inhibitors. We conclude that lipoplex uptake proceeds only by clathrin-mediated endocytosis, while polyplexes are taken up by two mechanisms, one involving caveolae and the other clathrin-coated pits. Transfection by lipoplexes was entirely abolished by blocking clathrin-mediated endocytosis, whereas inhibition of the caveolae pathway had no effect. By contrast, transfection mediated by polyplexes was completely blocked by genistein and filipin but was unaffected by inhibitors of clathrin-mediated endocytosis. Fluorescence colocalization studies with a lysosomal marker, AlexaFluor-dextran, revealed that polyplexes taken up by clathrin-mediated endocytosis are targeted to the lysosomal compartment for degradation, while the polyplexes internalized via caveolae escape this compartment, permitting efficient transfection.

Role of clathrin- and caveolae-mediated endocytosis in gene transfer mediated by lipo- and polyplexes

It has become imperative for the power and energy engineers to look out for the renewable energy sources such as sun, wind, geothermal, ocean and biomass as sustainable, cost-effective and environment friendly alternatives for conventional energy sources. However, the non-availability of these renewable energy resources all the time throughout the year has led to research in the area of hybrid renewable energy systems. In the past few years, a lot of research has taken place in the design, optimization, operation and control of the renewable hybrid energy systems. It is indeed evident that this area is still emerging and vast in scope. The main aim of this paper is to review the research on the unit sizing, optimization, energy management and modeling of the hybrid renewable energy system components. Developments in research on modeling of hybrid energy resources (PV systems), backup energy systems (Fuel Cell, Battery, Ultra-capacitor, Diesel Generator), power conditioning units (MPPT converters, Buck/Boost converters, Battery chargers) and techniques for energy flow management have been discussed in detail. In this paper, an attempt has been made to present a comprehensive review of the research in this area in the past one decade.

Hybrid renewable energy systems for power generation in stand-alone applications: A review

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

https://cyberleninka.org/article/n/696659.pdf

Comparative assessment of maximum power point tracking procedures for photovoltaic systems

Maximum power point trackers (MPPT) are used to operate a solar photovoltaic (PV) panel at its maximum power point (MPP) A number of tracking algorithms have been used in the past A simple and cheap analog MPPT has been simulated and constructed The MPP tracking algorithm is based on the fact that the MPP voltage is approximately a fixed percentage of the open circuit voltage of the PV panel The PV panel is usually disconnected from the load after regular intervals, to record the open circuit voltage In the present work, an unloaded pilot PV panel, with characteristics similar to those of the main PV panel and installed under similar conditions, is used to measure the open circuit voltage The main PV panel is never disconnected from the load, resulting in increased energy output The simulation and experimental results show that the panel tracks the MPP under changing atmospheric and load conditions

Development of an Analog Maximum Power Point Tracker for Photovoltaic Panel

Standalone photovoltaic (SAPV) systems are widely used in remote areas after development of photovoltaic cell industry in recent years. But as the load and insolation conditions vary the efficiency of the PV system decreases. A maximum power point tracker (or MPPT) is a high efficiency DC to DC converter which functions as an optimal electrical load for a photovoltaic (PV) cell, most commonly for a solar panel or array, and converts the power to a voltage or current level which is more suitable to whatever load the system is designed to drive. A PV cell has an exponential relationship between current and voltage, and the maximum power point (MPP) occurs at the knee of the curve. In this work, a MPPT has been proposed which works in conjunction with a power electronic converter to shift the operating point to obtain maximum power from a PV Panel with load and insolation conditions varying . MPPT first tracks the MPP and sets the operating point. The modeling and simulation has been done in Simulink software available with MATLAB. The efficiency of the proposed MPPT has also been evaluated. It has been shown how the efficiency of the system increases when we use MPPT for a resistive load .

/pdf/simulink-based-modeling-simulation-and-performance-4scyk8p4jm.pdf

Simulink based modeling, simulation and Performance Evaluation of an MPPT for maximum power generation on resistive load

Multilevel line commutated inverters for renewable energy systems have gained popularity in recent times, especially in the distributed generation where a number of batteries, fuel cells, solar cell, and micro-turbines can be connected through a MLC to feed the grid. They can synthesize higher output voltage levels and can generate near sinusoidal voltages. This paper presents analysis of a grid connected MLC as an inverter having variable dc sources(which can be the output of wind farms, solar panels etc.). A Computer simulation analysis using SIMULINK/ MATLAB has been done to minimize total harmonic distortion (THD) by increasing the stages and by varying the delay angles for varying dc input to the multilevel inverter. A comparative study of different stages of MLC for different value of dc input has also been studied. The results has been tabulated and discussed.

Simulation and study of a grid connected multilevel converter (MLC) with varying DC input

Maximum power point trackers (MPPT) are used to operate a solar photovoltaic (PV) panel at its maximum power point (MPP). In this paper a microcontroller based MPPT is realized. Two tracking algorithms, namely, perturb and observation (PAO) algorithm and maximum power point voltage (MPPV) algorithm have been implemented. The MPPT is tested under varying insolation and load conditions. It has been shown that with PAO algorithm, the controller takes significant time to track the MPP. Moreover, the operating point oscillates around the MPP. The large tracking time and oscillations around the MPP result in significant energy loss during the tracking process. The wastage of power is more significant in rapidly changing atmospheric condition, as the controller has to search for new operating point more frequently. On the other hand, with the MPPV algorithm, the MPP is tracked very quickly with no oscillations around the MPP.

Abu Tariq

Papers

Comparative assessment of maximum power point tracking procedures for photovoltaic systems

Development of an Analog Maximum Power Point Tracker for Photovoltaic Panel

Simulink based modeling, simulation and Performance Evaluation of an MPPT for maximum power generation on resistive load

Simulation and study of a grid connected multilevel converter (MLC) with varying DC input

Development of microcontroller-based maximum power point tracker for a photovoltaic panel