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The boosting factor has become a vital feature for a multilevel inverter to be connected with the low voltage PV system. In this paper, an inverter topology with 9 levels has been introduced. With the use of 10 switches and one switched capacitor unit, the proposed 9L-SC-BMLI has achieved nine different voltage states, and it has twice voltage gain. Without any auxiliary circuits, the voltage of the floating capacitor can maintain self-balanced. The additional feature of the proposed 9L-SC-BMLI has been the lower number of switches, voltage stress of reduced magnitude, and inherent polarity reversal of the output voltage without any H-bridge. The 9L-SC-BMLI has been controlled using the PD-PWM technique, i.e., phase-disposition pulse width modulation technique. In order to show the merits of the 9L-SC-BMLI, a detailed comparative study has been provided in the paper with several similar topologies. A number of simulation results have been provided in the paper with different working environments, and these results have been validated with the real-time results accomplished from a laboratory prototype. 1972-2012 IEEE. Scopus

Maldivians have sustainably been exploiting tuna using hook and line in the Indian Ocean for over a millennium, with 20% of the total Indian Ocean tuna catches currently landed in the Maldives. After four decades using on average 55 anchored fish aggregating devices (AFADs) spread over the entire archipelago, this thesis aims to improve our knowledge on the fishery ecology of tuna within the Maldivian AFAD array in order to better understand the drivers of the sustainability of the fishery for the coming years. The ecology of tuna around these AFADs was studied by collecting local ecological knowledge from 54 pole and line fishers and by acoustically tagging 65 skipjack and 57 yellowfin tuna within an instrumented 21-AFAD array. Most fishers consider that slight currents, suitable sea temperature, prey and attractants enhance the aggregations while strong currents, high sea temperatures and stormy conditions make tuna leave AFADs. They also consider that tuna tend to stay associated with AFADs 3 to 6 days, which is comparable to results from acoustic tagging (from 2 to 5.5 days on average). Acoustic tagging showed that tuna do not have a specific preference in the direction of movement, and very few fish moved from one FAD to another. Therefore, the 55 AFADs in the Maldives do not act like a network but appear to be relatively independent. The Maldives FAD network can be considered as a case study to examine the pros and cons of sparse FAD networks as supports for fisheries, while minimizing potential negative impacts. More research on the ecological, social and economic aspects of the pole and line fishery must be conducted to support the Maldives in their science-based management.Keywords: Anchored Fish Aggregating Device, Tropical tunas, Pole and Line, Maldives, Local Ecological Knowledge, Residence Time., Les Maldiviens exploitent durablement le thon dans l'océan Indien depuis plus d'un millénaire, avec 20% des captures totales de thon de l'océan Indien actuellement débarquées aux Maldives. Après quatre décennies d'utilisation d'une moyenne de 55 dispositifs de concentration de poissons ancrés (DCPA-) répartis sur l'ensemble de l'archipel, cette thèse vise à améliorer nos connaissances sur l'écologie de la pêche au thon au sein du réseau de DCP des Maldives afin de mieux comprendre les moteurs de la durabilité de la pêche pour les années à venir. L'écologie du thon autour de ces DCP a été étudiée en recueillant les connaissances écologiques locales de 54 pêcheurs à la canne et en marquant acoustiquement 65 listaos et 57 albacores dans un réseau de 21 DCP instrumentés. La plupart des pêcheurs considèrent que des courants faibles, une température de la mer adaptée, des proies et des attractifs favorisent les agrégations tandis que des courants forts, des températures de la mer élevées et des conditions orageuses font que les thons quittent les DCP. Ils considèrent également que les thons ont tendance à rester associés aux DCP de 3 à 6 jours, ce qui est comparable aux résultats du marquage acoustique (de 2 à 5,5 jours en moyenne). Le marquage acoustique a montré que les thons n'ont pas de préférence spécifique dans la direction du mouvement, et que très peu de poissons se déplacent d'un DCP à l'autre. Par conséquent, les 55 DCP des Maldives ne fonctionnent pas comme un réseau mais semblent être relativement indépendants. Le réseau de DCP des Maldives peut être considéré comme une étude de cas pour examiner les avantages et les inconvénients des réseaux de DCP peu denses comme supports pour les pêcheries, tout en minimisant les impacts négatifs potentiels. Des recherches supplémentaires sur les aspects écologiques, sociaux et économiques de la pêche à la canne doivent être menées pour soutenir les Maldives dans leur gestion basée sur la scie nce.Mots clés: dispositif de concentration de poissons ancré, thons tropicaux, canne et ligne, Maldives, connaissances écologiques locales, temps de résidence

In order to commercialize & utilize the PV energy properly, connect it to the grid is a more viable option. Therefore, the study of grid-connected solar PV generation system has gained wide attention. Optimizing output power from a solar photovoltaic module and simultaneous reduction in the harmonics in the line current is of special attention because the efficiency of the solar PV cell is quite low. The conventional line-commutated inverter (commonly used in grid-connected inverter) introduces line current of square-shaped which contains the higher-order harmonics and causes heating of the core of the transformer. The thyristors/SCR based switches have low switching losses and their power handling capability and reliability increases in comparison to the MOSFET/IGBT switches. Nevertheless, for PWM applications, the traditional thyristor-based forced commutated inverters are not appropriate due to the issue of commutation circuits. In this work, a three-phase cascaded full bridge inverter (Rectifier operating in inversion mode) topology has been utilized to produce the seven levels in the input grid current, which is closer to a sinusoidal wave and hence has lower total harmonic distortion (THD). The modular nature of cascaded bridge type configuration is suitable for grid connected solar PV inverter. The results of the proposed scheme have been verified successfully in the MATLAB Simulink environment. The performance of the cascaded configuration is tested for THD in line current, power factor and power transfer capability (PV to the grid). The enhanced performance is obtained by applying a metaheuristic algorithm and meticulous selection of performance parameter.

The main function of MARX generator is to produce a high potential pulse for testing the insulation of the electrical instruments such as transformers and electrical lines. However, power losses in conventional Marx generator due to capacitor and resistor are still a challenging task. A very few papers are reported in this direction. To fill this gap, method to implement the other static devices in place of conventional components is discussed. The presented topology comprises of a MOSFET, a capacitor, and two diodes. A 555 timer has been used to give pulses to the passive elements (capacitors) to be charged in parallel during ON interval. During OFF interval, charge storage devices are connected in series with the help of solid-state switches. Hence, MOSFET is used as a switching device; lossless charging of capacitors is done with the help of diodes. A comparison between different level generators is made and result is presented. The performance of the system is evaluated with the help of simulation results of PROTEUS software.

In modern energy system, the load frequency control (LFC) is the main operation which is done at system at daily basis. The purpose of the load frequency control is to maintain the power balance between the interconnected systems and to control the tie lines power flow. In this chapter, we provide an overview of the different LFC technique which is based on different controllers. The conventional and soft computing techniques of load frequency control techniques have been compared for reheat turbine system and non-reheat turbine system.

The 9 switch inverter (9SI) configuration is capable to control the power for two independent 3-phase loads simultaneously. However, this 9SI has the limitation on modulation index (M.I) since each inverter leg is controlled with 2 reference waves and one carrier wave. This lower M.I result in higher magnitude requirement of DC-link voltage. In addition to this, the load gets 2 level voltage only. For addressing these issues, in this paper, the 9 switch inverter (9SI) configurations for multiphase (>3) Induction motor (MIM) drives is explored. The 9SI configurations with split winding will generate the 3-level voltage across the effective phase winding of 6-phase and 9-phase IM drives. The phase reconfiguring techniques for enhancing the modulation index of proposed 9SI based multilevel inverter (MLI) fed 6-phase as well as 9-phase machines is proposed, where the phase difference between two identical voltage profile coils (IVPC) excited with same Inverter leg is minimized. The possible phase reconfiguring concepts for both symmetrical and asymmetrical configurations of the 6-phase and 9-phase machines are presented. The generalized adaptability and analysis of the proposed 9SI configurations with phase reconfiguring techniques for a machine with any number of phases is presented. The carrier based space vector pulse width modulation is implemented for proposed 9SI based MLI configurations which enhances the M.I further by 15.4%. The 9SI based MLI fed symmetrical 9-phase IM drive is validated by using Ansys Maxwell 2D.

The boosting factor has become a vital feature for a multilevel inverter to be connected with the low voltage PV system. In this paper, an inverter topology with 9 levels has been introduced. With the use of 10 switches and one switched capacitor unit, the proposed 9L-SC- BMLI has achieved nine different voltage states, and it has twice voltage gain. Without any auxiliary circuits, the voltage of the floating capacitor can maintain self-balanced. The additional feature of the proposed 9L-SC-BMLI has been the lower number of switches, voltage stress of reduced magnitude, and inherent polarity reversal of the output voltage without any H-bridge. The 9L-SC-BMLI has been controlled using the PD- PWM technique, i.e., phase-disposition pulse width modulation technique. In order to show the merits of the 9L-SC-BMLI, a detailed comparative study has been provided in the paper with several similar topologies. A number of simulation results have been provided in the paper with different working environments, and these results have been validated with the real-time results accomplished from a laboratory prototype.

Solar energy is becoming a very fast and important means of renewable sources of energy. The output of solar panels varies with movement of the sun. In order to track maximum power, maximum power point trackers are used to track maximum power from the solar panel. With the solar tracking, more energy generation is possible, since the solar panel can maintain a perpendicular profile to the rays of the sun. Hence, increasing the overall efficiency of the solar panel.

Solar panel or solar photovoltaic array helps in maximum utilization of energy during daytime that is from sunrise to sunshade. However, shading on solar panels can have a huge impact on the performance of solar photovoltaic panels. This shading has severed effects on the output of solar cells. But most of the time a common misconception occurs that the partial shading does not make any impact on the output of solar panels. But solar photovoltaic panels are highly susceptible to changing atmospheric conditions and the shades falling on it. Solar insolation, the surrounding temperature, array configuration and shading on solar panels affect the performance of the solar photovoltaic array. Basically, the solar photovoltaic panel consists of several cells that are connected to each other in a series circuit. Because of this series connection, the performance of the solar panel is significantly reduced even if the smallest section of the solar panel is shaded. Due to any of the factors such as passing of the clouds, neighbouring buildings, towers, trees and the presence of the telephones poles which can exert its complete or partial shadow on the solar panels, performance of solar array can be affected. It can be investigated that the P-V characteristic curve varies under different atmospheric conditions and changing number of shaded modules of the solar photovoltaic string. Overheating of shaded cells is the major effect caused by partial shading of the photovoltaic module. It leads to the reduction of energy of the entire solar module. Here we are studying the harmful effects and variations caused by partial shading on the overall solar photovoltaic module’s performance. PSPICE and MATLAB are types of simulation models to test the performance of PV module and to present the result.

Solar PV systems are increasingly becoming an indispensable source of energy owing to their simple construction, pollution free operation, and comparatively low operating costs. The solar PV systems provide an eco-friendly, cheap and almost omnipresent availability of energy throughout the world. Although, seemingly a very lucrative and easily available source of energy, these systems are not very widely implemented as Solar PV systems are not very efficient and major power losses occur. Due to clouds, skyscrapers in metropolitan cities, huge trees in rural areas etc. the sunlight is inhibited this leads to the sun rays striking the surface of the PV cell in an uneven fashion thereby leading to high power losses where the intensity of light is low and high power peaks where the intensity of light is high. Bypass diodes are employed to mitigate the effect of partial shading, but their application causes multiple peaks of power at the output. To track and determine the maximum power amongst all the available power peaks in this paper a Nature-Inspired algorithm (PSODTVAC) is employed. This algorithm is compared with other established algorithms like the gravitational search algorithm (GSA), Standard PSO (PSOSTD) and PSO with time varying acceleration (PSOTVAC) and it was observed that the proposed algorithm outperformed these existing algorithms.

Various power generation technologies, such as wind turbines and solar power plants, have been increasingly installed in renewable energy projects as a result of rising demand and ongoing efforts by global researchers to mitigate environmental effects. The sole source of energy for such generation is nature. The incorporation of the green unit into the power grid also results in volatility. The stabilization of frequencies is critical and depends on the balance of supply and demand. An efficient monitoring scheme called Load Frequency Monitoring (LFM) is introduced to reduce the frequency deviation from its natural state. Specific energy storage systems may be considered to improve the efficiency of the control system. The storage system contributes to the load rate, peak rushing, black start support, etc., in addition to high energy and rapid responsive features. A detailed study of different power storage systems, their current business scenario, and the application of LFM facilities, as well as their analysis and disturbance, is presented in this paper. According to the literature analysis, the current approaches can be divided into two categories: grid and load scale structures. This article also distinguishes between the organized aggregate system and the uncoordinated system control scheme, both of which have advantages and disadvantages in terms of technology. Funding: The authors would like to acknowledge the financial support from Taif University Researchers Supporting Project Number (TURSP-2020/278), Taif University, Taif, Saudi Arabia. Scopus

In this paper, a performance comparison of three-level neutral point clamped (NPC) inverter using different modulation schemes are presented. Different level shifted carrier based PWM schemes and space vector modulation scheme for three-level NPC inverter is modeled and analyzed. The performance analysis is presented in order to understand its interaction with solar photo-voltaic (SPV) system. The power quality of the inverter output is compared using total harmonic distortion (THD). The whole system comprises a solar PV array (Waaree Energies WSM- 315), a boost converter (operated at MPPT using incremental conductance technique), a multi-level inverter (NPC), and a three-phase load (R and L). Then, the system is modeled in MATLAB®/ Simulink and the results obtained are presented and discussed in this paper.

The concept of multilevel inverter arrived from the conventional two-level inverter. Two-level inverter is not suitable for the high-power, medium-voltage, and high-voltage industrial and commercial application. Multilevel inverters fulfill the above requirement. Control of multilevel inverter is done by adjusting the time average of their voltage levels. Generally, this is performed by pulse-width modulation (PWM) techniques. Output performance in terms of the power quality, common mode voltage, etc., greatly depends on the types of the modulation schemes applied. The aim of this paper is to present the different carrier-based modulation schemes that are available in the literature for five-level inverter. The detailed mathematical analysis of modulation techniques is presented to better understand the five-level inverter.

Induction motor is the backbone of current industrial applications. Multiphase machines can handle high power application easily. With the use of five-phase induction motor, advantage of both multi-phase and induction motor can be achieved. This paper presents analysis of five-phase seven level-based Induction motor system fed by packed U-cell based inverter. Modelling of five-phase induction motor is done with the help of mathematical equations using d-q axis transformation. Inverter voltage output comes to be approximately sinusoidal with 18.07% Total Harmonic Distortion (THD). Induction motor with specified parameters is simulated under no-load condition and attains steady state conditions after transient state.

During the international symposium on “Regional Applications and Nexus of the Ocean Health Index” at The University of Tokyo in Japan in July 2015, a range of experts, practitioners and researchers discussed the potential for assessing the current state of ocean health at different scales, as well as changes over time. Discussions focused on how the successful assessment and implementation of projects aimed at fostering ocean health and resilient coastal ecosystems strongly depends on a multi-stakeholder approach and local leadership. In addition, recent examples of regional independent assessments conducted using the Ocean Health Index were introduced, with an accompanying explanation of how the Index goals can be adjusted, specified or weighted in line with a local context or policy direction. This manuscript introduces key points raised during the symposium as well as relevant supplementary materials.

Ever increasing demand of energy and continuous depletion of accessible standard energy resources has diverted the mind of researchers towards the efficient utilization of renewable resources of energy like sun, wind & sea water movement etc. for generation of electrical energy. Among all the renewable energy resources, solar energy is abundantly and almost uniformly available in most part of the world and is seen as a potential player in future energy market around the world. The advantages of electrical energy generation through sun include pollution free electricity generation, negligible maintenance and free availability. Electrical energy can be generated from sun by either directly converting the sunlight into dc electricity or through solar thermal energy. Energy through solar photovoltaic[SPV] has seen an enormous funding in research and development with ministry of new and renewable energy sources [MNRE], government of India, pumping in vital funds for its effective utilization in India. Electrical energy can be extracted from solar photovoltaic module or array during sunny days in the form of dc and can be converted to ac by the use of inverters and can be stored by using batteries for the use in night or in durations of unavailability of solar irradiations in rainy seasons. Solar PV module or array could be a combination of PV cells that can be connected in either series or parallel or combination of both to enhance the power output to the match the load demand. The output power of these photovoltaic modules is affected by varying environmental conditions like variation in irradiations and operating cell temperatures etc. The present work pertains to reviewing the development of solar PV emulator for testing and carrying out research activities on solar PV based system thereby providing the problems posed by its intermittent nature of dependence on the weather conditions. A through and critical analysis of various power electronic and conventional analog technologies in development of solar PV emulator has been carried out. The performance comparison of solar PV emulator presented in literature based on various parameters has also been presented.

Five-phase supply is needed for supplying five-phase motor drive systems. Special transformer connection schemes have been developed over the years and reported in the literature to convert three-phase supply from the grid to obtain a balanced five-phase output which can be used to supply multiphase motor. In this paper, two existing transformer connections have been investigated and a new connection scheme has been proposed. Similar to the existing connection schemes, the proposed transformation system also employs three separate cores, each consisting of one primary and several secondary coils. The secondary coils comprise of different numbers of turns and are connected in specific ways so as to achieve the desired 72 degrees phase shift with equal magnitudes. The feasibility of the proposed scheme is proved using simulation and experimental approach. Moreover, a comparative analysis of the three solutions is presented. This work was supported by the Qatar University [grant number QUST-CENG-SPR-14/15-8]. Scopus

In this paper the performance of a split-phase motor and a three-phase induction motor drives for soft starting is evaluated. The paper systematically investigates and compares the characteristics of a variable voltage fed induction motor drive for two different types of soft starters; one based on IGBT and another based on Thyristor. Experimental validation is done using analogue circuit based system, developed in the laboratory. The novelty of the work lies in the development of simple and flexible models for simulation purpose and their experimental validation. Keywords: Variable speed electric drives, Soft starter, Thyristor, IGBT