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Rose, Amy Michelle. "Prospects for grid-connected solar PV in Kenya." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81126.
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Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 187-195).
Kenya's electric power system is heavily reliant on hydropower, leaving it vulnerable during recurring droughts. Supply shortfalls are currently met through the use of expensive leased diesel generation. Therefore, plans for new generation focus on geothermal and conventional thermal sources. While these technologies offer a lower-cost alternative to leased diesel, they require large upfront capital investments in new infrastructure. I propose that grid-connected solar PV offers an alternative solution to displace expensive diesel generation, while capitalizing on Kenya's abundant solar resource and avoiding large upfront financing requirements. Coordinated operation of Kenya's extensive reservoir hydro capacity can overcome intermittency problems associated with solar generation and offer a low-cost path to grid-connected solar PV by eliminating the need for additional investment in storage. This study uses a static expansion planning model of Kenya's power system representing the years 2012 and 2017 to evaluate the feasibility of grid-connected solar PV under different price and hydrological conditions. These results reveal that high penetrations of solar PV can be integrated into the current system without increasing total system costs. By 2017 extensive planned investments in low-cost geothermal, imported hydro, and wind power will significantly reduce production from fuel oil plants and solar PV is no longer economically competitive at current prices. The 2017 analysis does not evaluate scenarios where the price of solar PV decreases, new capacity is delayed, or PV capacity eliminates the need for new transmission infrastructure required for planned generation assets. Any of these scenarios increases the competitiveness of solar PV in the 2017 system. The methodology developed in this study could be used for system level evaluation of solar and other intermittent renewables in other hydro-dominated electric power systems in Africa.
by Amy Michelle Rose.
S.M.in Technology and Policy
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Ramachandran, Jayaraman. "Modelling of grid connected geographically dispersed PV systems for power system studies." Thesis, Northumbria University, 2005. http://nrl.northumbria.ac.uk/3224/.
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The growth of the photovoltaic market indicates that in the near future PV electricity generation may rise to a significant power source. As the proportion of electric power generated from PV systems becomes significant, the effect of these sources on transmission and distribution networks must be considered. This research work has investigated suitable representations of the PV resource and the output power of dispersed PV systems to study the effects of large-scale deployment of PV systems on the grid operation. The representation of solar radiation is very important since this dictates the output power of PV systems. In this work, the simple and reliable Markov Transition Matrix (MTM) method was selected to generate synthetic horizontal solar radiation data. A single MTM was developed to generate half-hour horizontal solar radiation data for different locations in the UK. Large-scale inclusion of PV systems in the UK electricity supply is expected to take the form of a large number of small, geographically dispersed building integrated PV systems. The study also developed a detailed PV cluster model to represent these dispersed PV systems. The variation of PV output power may impact the demand and generation balance on the network requiring additional reserve generation to ensure the system security. In this work, the variation of PV output power and the impact on the reserve requirement was analysed for different penetration levels. This is also the first study to analyse the correlation of solar radiation for different locations in the UK in regard to the impact on reserve requirements. Using data from three locations and according to the National Grid Company (NGC) requirements, it was found that PV capacities of 3750 MW could be added to the present network without additional reserve requirements. The additional reserve required is not on the basis of "MW of reserve per MW of PV capacity". Rather it is based on the aggregation of load demand and of PV output from all regions. The reduction in the reserve requirement by forecasting the weather profile of the day was also illustrated. In this case, a PV capacity of 22,500 MW, which can generate a little over 5% of the UK electricity demand, can be added with minimal increase in system cost. Therefore, the variation of PV output power is unlikely to be a threat to the system security.
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Forrisi, Ivano. "Contribution to renewable systems grid connected : control, stability analysis and reliability." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0345/document.
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Cette thèse a pour but l'analyse d'un système photovoltaïque connecté au réseau électrique en prenant en compte le contrôle, l'étude de la stabilité et la fiabilité. Un onduleur de type 2-Niveau a été comparé avec un onduleur multi-niveaux appelé Neutral Point Clamped. Les avantages et désavantage de chaque topologie ont été analysé en considérant l'efficacité énergétique, l'optimisation de l'injection de l'énergie sur le réseau électrique et la fiabilité du système. Pour le contrôle du courant de sortie de l'onduleur, ont été proposées deux solutions : un contrôle basé sur la théorie de la platitude et un contrôle par passivité. Ces deux différents contrôles sont comparés par rapport à la robustesse, la complexité et le nombre de capteurs utilisés. Il a été montré que les deux contrôles sont capables de gérer la problématique de la résonance du filtre LCL. Pour augmenter l'efficacité de l'algorithme MPPT dans une configuration Distributed-MPPT avec la connexion en série des deux sorties des convertisseurs boost, une nouvelle technique a été proposé pour l'équilibrage des tension d'entrée d'un onduleur NPC. En utilisant un outil appelé TPtool, un étude de la stabilité large signal par "Higher-Order-Singular-Value-Decomposition" a été présenté et comparé avec une méthode basée sur les modèles Takagi-Sugeno pour des systèmes non-linéaires. Finalement, l'onduleur 2-Niveaux est comparé avec deux multi-niveaux différents (NPP et NPC) en termes de disponibilité, en prenant en compte les niveaux de redondance des convertisseurs. Pour analyser la disponibilité, a été considérée la théorie des chaines de Markov et pour l'implémentation, le logiciel GRIF a été utiliséThe aim of this PhD thesis is to analyze a PV-grid connected system in terms of control, stability and reliability. A comparison between a classical 2-Level inverter and a multilevel NPC is presented. The advantages and weakness of both the converters are analyzed with respect to the power efficiency, optimization of the energy injection to the grid and reliability of the system. In order to control the inverter output current, two different solutions are proposed: flatness-based control and passivity-based control. These controls are compared in terms of robustness, complexity and number of sensors used. It is shown that both the controls may manage the resonance problems due to a LCL filter. For increasing the efficiency of the MPPT in a configuration Distributed-MPPT with connections in series of the boost converters outputs, a novel technique for the dc voltages balancing of a NPC inverter is proposed. A large stability analysis using "Higher-Order-Singular-Value-Decomposition" is presented and compared with Takagi-Sugeno approach for nonlinear systems. Finally, 2-Level inverter is compared with two multilevel inverters (NPC and NPP) in terms of availability, considering the redundancy levels of the converters. To analyze the systems availability, the Markov chains theory is considered and it is implemented on GRIF
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Umana, Aniemi. "Module-level autonomous settingless protection and monitoring for standalone and grid-connected photovoltaic array systems using quadratic integration modeling." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54441.
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This research applies a recently developed dynamic state-estimation based protection scheme, the settingless protection, to the photovoltaic (PV) industry for the first time. At this time, the proposed protection algorithm has been implemented on traditional protection zones for individual power system devices, but this research extends this protection to a microgrid, specifically, a system of PV network composed of several PV modules. Several illustrative examples on various anomalies such as high impedance faults and shorted-out PV modules have been provided to demonstrate the effectiveness of this protection scheme. The detection of these anomalies has been demonstrated in the presence of changing atmospheric conditions, and with the operation of maximum power point tracking (MPPT) equipped dc-dc converters.
This protection scheme requires an accurate model of the PV module, therefore, a two-diode PV model has been developed using quadratic integration modeling. In this PV model development, a scaling factor is applied to the Taylor series expansion of the exponential terms of the model of the PV module. Then the higher order terms of the Taylor series expansion are reduced to at most second order terms using the quadratization technique.
Furthermore, a novel approach for extracting the PV parameters, namely, the ideality constants, leakage currents, PV module internal current, shunt and series resistances, has been presented. A comparison was performed between numerically generated data using the determined PV module parameters and data measurements from a physical PV module. It was shown that the maximum error from this comparison was below 0.12A, and less than 0.05A around the maximum power point region of the PV modules used for this research.
The residual data from the PV array protection scheme has been used to develop a method for identifying the location of faulted PV modules. Also, condition-based monitoring of the PV array system has also been presented with examples. From the PV array system monitoring, the shading and underperformance of a PV module have been identified.
From the contributions of this research, an accurate module of the PV array has been developed in a form that can be integrated with other power system devices. This accurate module can be used for state estimation of the PV array, load flow analysis, short circuit analysis, and other power system analytical studies. Also, by determining the location of the faulted PV module, the time to identify this faulted PV module in a large PV installation is drastically reduced. Lastly, by identifying shading conditions and underperforming PV modules, the PV system operator can quickly bring the underperforming module or modules to optimal performance, thereby, maximizing the power yield of the PV array, and maximizing the revenue of the PV system owner.
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Raji, Atanda Kamoru. "Performance evaluation and improvement of grid-connected technology." Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/1198.
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Dissertation (DTech(Electrical Engineering))--Cape Peninsula University of Technology, 2012The confluence of the limited resources of fossil fuels (e.g. coal, oil and natural gas), environmental degradations leading to climate change, security of supplies and fossil fuels high costs have demanded a tremendous efforts on humanity to seek for a sustainable and unlimited natural energy sources. Amongst these renewable energy sources stands out solar energy because of its ubiquitousness. Solar energy is converted to DC electricity by the photovoltaic effect. Photovoltaic (PV) power systems installed in commercial and industrial buildings are a good example of distributed power generation. Here the energy consumption and production match and thus electricity taken from the grid during daytime peak hours can be reduced. This is beneficial as the transmission losses in the grid are avoided and also transmission need is reduced. The cost effectiveness of a solar energy system has hindered its wide adoption and deployment in terms of the initial capital cost even though it has a zero energy cost and very minimal operating and maintenance costs. Different governments have instituted many financial incentives for fast adoption of PV systems for both residential and commercial applications. However, all these incentives are not sustainable in the longer term forecast. For PV system to attain grid parity requires more than unsustainable approach of many governments providing time limited subsidies. The technical solution to the problem is to reduce the overall system cost through technical innovations. One such method is the adoption of transformerless inverter technology as the grid interface system. Transformerless inverter topology provides galvanic isolation through innovative inverter topology and switching strategies that eliminates problems created by not employing the service of transformer.
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KARLSSON, REBECCA, and EVA NILSENG. "The potential for centralized photovoltaicsystems in Sweden." Thesis, KTH, Hållbarhet och industriell dynamik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-189586.
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Considering the long term target set by the Swedish government of having an energy system basedexclusively on renewable sources, the potential for different renewable sources need to beinvestigated. When analyzing the sources used for electricity production in Sweden today, solarPV represents a very small share. This relatively small share also mainly consists of grid-connecteddistributed PV systems, and to analyze the possibilities of making solar energy a larger share inthe electricity production in Sweden this study will focus on grid-connected centralized PV farms.The main purpose of the study is to identify the potential for grid-connected centralized PVsystems for large scale production in Sweden. This will include an identification of the mostimportant key factors influencing the profitability, an investment calculation to be aware of theprofitability, a prediction of the future development of the PV industry in Sweden and lastly themain challenges that the PV industry is facing.To conduct this study a collaboration with Vattenfall Vind AB has been made, where a case studybased on three specific locations has been implemented when analyzing both the profitability andthe key factors. These three cases are based on places where Vattenfall has existing wind farms orhas assigned for upcoming ones. These areas could be seen as a potential benefit since the companyalready has started to inspect the land area, and that wind and PV farms might be able to sharenecessities such as infrastructure.The results of the study mainly indicate that the PV industry most likely will continue develop andgrow, but the profitability of investing in grid-connected centralized PV farms does not lookpromising today or in the next coming years. This mainly due to low prices for electricity anduncertainties in the future development of the financial support policy. The location is also veryimportant for this type of installation. There are places in southern Sweden with enough insolation,but these areas can be seen as limited. To make solar energy a larger share of the electricityproduction in Sweden in a profitable way today, more investments should be made in gridconnecteddistributed PV systems rather than grid-connected centralized PV farms. PV farms forlarge scale production might though be more profitable in the future when the prices for modulesand inverters will decrease further and when the spot price increases.
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Sultani, Jasim Farhood. "Modelling, design and implementation of D-Q control in single-phase grid-connected inverters for photovoltaic systems used in domestic dwellings." Thesis, De Montfort University, 2013. http://hdl.handle.net/2086/9631.
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This thesis focuses on the single-phase voltage-source inverter for use in photovoltaic (PV) electricity generating systems in both stand-alone and grid-tied applications. In many cases, developments in single-phase PV systems have followed developments in three-phase systems. Time-variant systems are more difficult to control than time-invariant systems. Nevertheless, by using suitable transformation techniques, time-variant systems can often be modelled as time-invariant systems. After the transformation, the control signals that are usually time-variant (often varying sinusoidally in time) become time-invariant at the fundamental frequency, and are hence much easier to deal with. With this approach, synchronous rotating frame control techniques have been previously proposed for high performance three-phase inverter applications. The transformation theory cannot be applied directly in single-phase systems without modification, and the d-q components would not be time-invariant in situations where harmonics, resonances or unbalance is present. Single-phase inverter controller designs based on the use of a synchronous rotating reference frame have been proposed, but such designs do not always perform as well as expected. This thesis aims to improve single-phase voltage-source inverters. The main objective is to address, in terms of cost, efficiency, power management and power quality, the problems found with single-phase designs based on a synchronous rotating frame single-phase inverter controller. Consequently, this thesis focuses on a novel controller approach in order to obtain a more reliable and flexible single-phase inverter. As the first step, this thesis investigates the single-phase inverter switching gate-drive algorithms and develops a form of space-vector pulse-width-modulation (SVPWM) in order to reduce total harmonic distortion. The results of the new SVPWM algorithm demonstrate its superior performance when compared with sinusoidal pulse-width-modulation (SPWM) which is often used with single-phase inverters. The second step, which is further reviewed and presented in this thesis, is the modelling of the single-phase inverter control based on the synchronous rotating frame. A mathematical analysis is conducted to determine the mechanism of the coupling that exists between the voltage phase and amplitude terms, and a new transformation strategy is proposed based on using the voltage phase as a reference at the Park transformation stages, and the current phase as a reference for the current at the transformation stages. The line-frequency components of the feedback signals are transformed to time-invariant components, thus eliminating the ripple and reducing the computational burden associated with the controller stage. Consequently, the inverter feedback controller stage is designed so that the coupling terms are decoupled within the controller itself. The effectiveness of the techniques proposed in this thesis are demonstrated by simulation using the MATLAB/SIMULINK environment. The proposed technique was also investigated through a practical implementation of the control system using a Digital Signal Processor (DSP) and a single-phase inverter. This practical system was tested up to 1 kW only (limited by the available inverter hardware). Nevertheless, the correlation between the simulation and the practical results is high and this gives confidence that the developed mechanism will allow the 2.5kW goal to be achieved. Practical test cases illustrate the effectiveness of the models. In addition, the comparisons between experimental and simulation results permit the system's behaviour and performance to be accurately evaluated. With the development of the new controller, small-scale single-phase renewable energy systems will become more useful in the field of power quality management through their ability to separately control the phase and amplitude of the output voltage. Consequently, incorporation of this type of generator within the national electrical distribution network, as distributed generators (DG) at low-voltage level, can assist with power quality management at the consumer side of the grid. In addition, such a generator can also operate in stand-alone mode if the grid becomes unavailable. The third step in this thesis investigates small-scale single-phase renewable energy systems operating as decentralized distributed generators within a local network. This operation is achieved by controlling the inverter side using the quantities measured at the common coupling point between the grid and the inverter, without requiring other extensive communications. Thus, the small-scale single-phase renewable energy distributed generator systems will contain only a local controller at each installation.
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Wilson, Jason Clifford. "A techno-economic environmental approach to improving the performance of PV, battery, grid-connected, diesel hybrid energy systems : A case study in Kenya." Thesis, Högskolan Dalarna, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:du-28542.
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Backup diesel generator (DG) systems continue to be a heavily polluting and costly solution for institutions with unreliable grid connections. These systems slow economic growth and accelerate climate change. Photovoltaic (PV), energy storage (ES), grid connected, DG – Hybrid Energy Systems (HESs) or, PV-HESs, can alleviate overwhelming costs and harmful emissions incurred from traditional back-up DG systems and improve the reliability of power supply. However, from project conception to end of lifetime, PV-HESs face significant barriers of uncertainty and variable operating conditions. The fit-and-forget solution previously applied to backup DG systems should not be adopted for PV-HESs. To maximize cost and emission reductions, PV-HESs must be adapted to their boundary conditions for example, irradiance, temperature, and demand. These conditions can be defined and monitored using measurement equipment. From this, an opportunity for performance optimization can be established. The method demonstrated in this study is a techno-economic and environmental approach to improving the performance of PV-HESs. The method has been applied to a case study of an existing PV-HES in Kenya. A combination of both analytical and numerical analyses has been conducted. The analytical analysis has been carried out in Microsoft Excel with the intent of being easily repeatable and practical in a business environment. Simulation analysis has been conducted in improved Hybrid Optimization by Genetic Algorithms (iHOGA), which is a commercially available software for simulating HESs. Using six months of measurement data, the method presented identifies performance inefficiencies and explores corrective interventions. The proposed interventions are evaluated, by simulation analyses, using a set of techno-economic and environment key performance indicators, namely: Net Present Cost (NPC), generator runtime, fuel consumption, total system emissions, and renewable fraction. Five corrective interventions are proposed, and predictions indicate that if these are implemented fuel consumption can be reduced by 70 % and battery lifetime can be extended by 28 %, net present cost can be reduced by 30 % and emissions fall by 42 %. This method has only been applied to a single PV-HES; however, the impact this method could have on sub-Saharan Africa as well as similar regions with unreliable grid connections is found to be significant. In the future, in sub-Saharan Africa alone, over $500 million dollars (USD) and 1.7 billion kgCO2 emissions could be saved annually if only 25 % of the fuel savings identified in this study were realized. The method proposed here could be improved with additional measurement data and refined simulation models. Furthermore, this method could potentially be fully automated, which could allow it to be implemented more frequently and at lower cost.
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Ly, Noriko Jia Yong Claudine. "Self-sufficiency of the vineyard of Château de la Chaize : Design and Simulation of a grid-connected PV system in South of France." Thesis, KTH, Energiteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263902.
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The task of this master thesis is to evaluate the potential and economic feasibility of a solar photovoltaic project at the Castle Château de la Chaize, situated near Lyon in France. The domain of the Château de la Chaize aims to be more ecologically responsible, by producing organic wine, using geothermal energy and producing its own electricity, using solar energy. The solar system would hence be used to produce the electricity that the castle and the vineyard would use. Since the whole domain is changing in order to be more sustainable, the energy consumption is still unclear. Three consumption scenarios are thus studied to model: the current situation (108 MWh), the change in energy needs due to the renewal of the wine making process (568 MWh), and finally the additional energy demand due to the construction of a spa on the domain lands (1056 MWh). The project site is also situated in the domain, near the Castle. The meteorological data and the shading scene are gathered from databases and site visits. Since the site is oriented towards the North-West and the South and East sides are blocked by a forest, significant shading losses are expected. In order to maximize the potential of the PV system, the use of Li-Ion batteries, to increases the self-generated part of the consumed electricity, is also considered. Simulations for the system production and the matching of the consumption and production is lead using the PVsyst software. Standard modules and inverters are used to run the simulation. The different configurations (energy consumption, size of the PV system, battery,...) are compared using the self-generation rate (part of the energy that is consumed that comes from the PV system) and financial criteria such as the Internal return rate or the profit at year 20. The results show that using a solar system to provide electricity for the current scenario would not be financially viable. For the renovation scenario, the best system design is the southward oriented fixed tilted plane at 350 kWp. It generates a profit of 71 k€ and has a self-generation ratio of 31.5 %. For the spa scenario, the 350 kWp south-oriented system is also the most interesting, with a self-generation rate of 29.8 % and IRR of 9.33 %. The financial analysis of the systems with batteries shows that the investment costs of the storage system are too high, and its lifetime is too short to be profitable. It would be interesting to see the evolution of the energy storage market, that is expected to develop, to see the economic interest of installing storage systems.Uppgiften för detta examensarbete är att utvärdera potentialen och den ekonomiska genomförbarheten för ett solcellsfotovoltaikprojekt vid slottet Château de la Chaize, beläget nära Lyon i Frankrike. Domänen för Château de la Chaize syftar till att vara mer ekologiskt ansvarig, genom att producera ekologiskt vin, använda geotermisk energi och producera sin egen elektricitet med solenergi. Därför skulle solsystemet användas för att producera den elektricitet som slottet och vingården skulle använda. Eftersom hela området utvecklas för att bli mer hållbar är energiförbrukningen fortfarande oklar. Tre konsumtionsscenarier studeras sålunda för att modellera: den aktuella situationen (108 MWh), förändringen i energibehov på grund av förnyelsen av vinframställningsprocessen (568 MWh) och slutligen den extra energibehovet på grund av ett nytt spa på domänen landar (1056 MWh). Projektplatsen ligger också i domänen, nära slottet. Meteorologiska data och skuggningsscenen samlas in från databaser och webbplatsbesök. Eftersom platsen är inriktad mot nordväst, och södra och östra sidan blockeras av en skog, förväntas betydande skuggningsförluster. För att maximera PV-systemets potential övervägs också användning av Li-Ion-batterier för att öka den självgenererade delen av den förbrukade elen. Simuleringar för systemproduktion och matchning av konsumtion och produktion är bly med hjälp av PVsyst-programvaran. Standardmoduler och inverterare används för att köra simuleringen. De olika konfigurationerna (energiförbrukning, storleken på PV-systemet, batteriet, ...) jämförs med hjälp av självproduktionshastigheten (en del av energin som förbrukas som kommer från PV-systemet) och ekonomiska kriterier som intern avkastning eller vinsten vid år 20. Resultaten visar att användning av ett solsystem för att tillhandahålla el till det aktuella scenariot inte skulle vara ekonomiskt hållbart. För renoveringsscenariot är den bästa systemdesignen det söderutorienterade fasta lutningsplanet med 350 kWp. Det ger en vinst på 71 k € och har en egenproduktionsgrad på 31,5 %. För spa-scenariot är det sydorienterade systemet med 350 kWp också det mest intressanta, med en egenproduktionshastighet på 29,8 % och IRR på 9,33 %. Den ekonomiska analysen av systemen med batterier visar att investeringskostnaderna för lagringssystemet är för höga och att dess livslängd är för kort för att vara lönsam. Det skulle vara intressant att se utvecklingen av energilagringsmarknaden, som förväntas utvecklas, att se det ekonomiska intresset av att installera lagringssystem.
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Bartel, Kyle. "Allocating Optimal Grid-Connected Solar Photovoltaic Power Plant Sites : GIS-Based Multi-Criteria Modeling of Solar PV Site Selection in the Southern Thompson-Okanagan Region, British Columbia, Canada." Thesis, Högskolan i Gävle, Akademin för teknik och miljö, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-15859.
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Fossil fuels and non-renewable resources are being replaced with, as modern day society has coined the term, green energy. This movement towards green energy creates a demand for renewable energy resources, such as solar photovoltaic (PV) systems. This study used Geographic Information Systems (GIS) in conjunction with Remote Sensing (RS) practices and two weighting systems the Analytical Hierarchy Process (AHP) and Rank-Order methods for PV site selection. Six multi-criteria models were developed using spatial factors and constraining images to locate potential photovoltaic power plant sites for three settings of fixed axis PV arrays. This analysis was performed at a macro regional scale and further analysis is encouraged for micro site selection.
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TerÃn, Eldin Mario Miranda. "Sistema Fotovoltaico de Pequeno Porte Interligado à Rede ElÃtrica." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7563.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoA necessidade de obter uma matriz energÃtica menos poluente e em harmonia com o meio ambiente à um tÃpico muito importante no sÃculo XXI. Este trabalho apresenta um conversor cc-ca de dois estÃgios para injetar a energia de um arranjo de painÃis fotovoltaicos à rede elÃtrica. O primeiro estÃgio à um conversor elevador, isolado, baseado na CÃlula de ComutaÃÃo de TrÃs Estados (CCTE), responsÃvel por elevar a tensÃo dos painÃis fotovoltaicos de 48 Vcc para 400 Vcc e de extrair a mÃxima potÃncia disponÃvel deles. O segundo estÃgio consiste em um conversor monofÃsico cc-ca, ponte completa, responsÃvel por injetar a energia na rede elÃtrica de baixa tensÃo (220 Vca, 60 Hz). SÃo apresentados estudos teÃricos e exemplos de projeto dos circuitos de potÃncia e controle para ambos os estÃgios e, com o objetivo de validar a anÃlise, sÃo apresentados resultados de simulaÃÃo computacional, complementados com resultados experimentais, correspondentes a um protÃtipo de laboratÃrio de 850 W. O rendimento global obtido experimentalmente à aproximadamente 86,5% enquanto que a distorÃÃo harmÃnica total da corrente entregue à rede elÃtrica obtida via simulaÃÃo computacional à 3,8% a plena carga.
In the 21st century, the need of a more clean and environment friendly power matrix has become a very important issue. Therefore this work presents a two stage cc-ac converter for connecting a photovoltaic array to the electrical grid. The 1st stage itâs an isolated boost converter, based in the Three Stage Switching Cell (TSSC), in charge of boosting the photovoltaic array voltage from 48 Vcc to 400 Vcc and to track its maximum power point. The 2nd stage is a single-phase cc-ac Full-Bridge converter responsible of injecting the photovoltaic power into the low voltage power grid (220 Vac, 60 Hz). Both, theoretical analysis and designs examples of power and control circuits are presented for the two stages and, in order to validate the analysis, simulation results complemented with experimental results from an 850 W laboratory prototype are presented. The overall efficiency obtained from the prototype was 86.5% while the total harmonic distortion of the current obtained via simulation was 3.8% at full load.
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Showers, Obu Samson. "Enhanced frequency regulation functionality of grid-connected PV system." Thesis, Cape Peninsula University of Technology, 2019. http://hdl.handle.net/20.500.11838/3070.
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Thesis (MEng (Electrical Engineering))--Cape Peninsula University of Technology, 2019Electric utilities are confronted with challenges like rising fuel costs, aging equipment, increasing energy demand, frequency regulation and the difficulty to integrate renewable energy resources into the grid. The presence of photovoltaic (PV) penetration on the utility grid is also increasing significantly in recent years. With the recent rise in PV penetration and the advancement of the global PV industry, there is an urgent and a necessary need to introduce features in PV systems that will make them respond smartly. However, much of these can be addressed without negatively affecting the total performance and power quality of the grid. Hence, engaging smart Grid technologies, and leveraging the benefits of the distributed nature of PV, new prospects to unearth value can be created. Through the implementation of progressive energy storage techniques, efficient two-way communications, a grid-tied PV system can create significant value, mostly through improved PV contribution in grid support functions like frequency regulation. An enhanced frequency regulation functioning scheme for a grid-connected photovoltaic (PV) system is modelled in MATLAB/Simulink software environment. The system is designed to operate in grid ancillary services precisely, frequency regulation function. The model consists of a Photovoltaic (PV) plant with a battery connected to the grid through a three-phase inverter. A bi-directional DC-DC converter between the grid and the battery system is included. The model has a battery storage system that provide steady and regular active/reactive powers available while the grid transmit specific amounts of power needed for a specific duration. According to the design, either the grid or the PV system depending on the dominant energy situation charges the battery. The battery is designed to discharge only when the grid demands energy from the PV and if the PV system fails to meet the demanded active power or reactive power. The PV system and the battery storage is integrated with the grid with the aid of dc-ac inverter in such a manner that bi-directional flow of active and reactive power is achieved. A 1 MW PV system is connected to the utility grid through a three-phase voltage source inverter system. The grid nominal frequency is set at 50 Hz under normal operation. However, the frequency decreased when the PV was not producing required power hence, the battery responded almost instantaneously and returned the frequency to the nominal frequency. The effectiveness of battery storage system for utility grid frequency regulation was substantiated from the simulation results attained.
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Mansouri, Seyed Akbar. "Circuit Topology Study of Grid-Connected Photovoltaic System." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308328627.
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Simonsen, Silje Odland. "Development of a Grid Connected PV System for Laboratory Use." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9064.
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To support the teaching in digital signal processing and control in power electronics a laboratory setup of a PV (photovoltaic) converter system is currently under development at NTNU. The equipment consists of a general reconfigurable power converter and a DSP (Digital Signal Processor) control card with system software for software development and testing. The finished system is intended for implementation in an African University to be used in teaching of PV systems. The power converter stage will be a dual stage consisting of a DC-DC converter and a DC-AC inverter connected to the grid through a transformer stage. For this particular master thesis the input stage comprising the PV panel and the DC-DC converter will be of main focus. A control design will be developed, comprising voltage mode control (with feedback from the input of the converter) and Maximum Power Point Tracking (MPPT). The DC link voltage level is set to be 48 V, while the input voltage will vary from 0 to 45 V. In the experiments the setup will consist of DC source simulating the PV-panel, a DC-DC converter and an electronic load representing the grid connection through an inverter and a transformer. The DC-DC converter was built and tested in a previous master project and can be configured as a buck, boost or buck-boost converter. For this thesis the boost topology was chosen, as this topology is the one most frequently used in PV systems. The control was implemented through C code programming. A regular voltage mode controller was developed and tuned through utilization of Ziegler-Nichols ultimate sensitivity method. At first a P-controller was implemented, but it was not able to cancel out the error between the reference voltage and the input voltage. This was expected, and an integral part was added to form a PI-controller. Now the closed loop control of the system turned out to be rather good for the whole range of the input voltage. The MPPT algorithm Perturb & Observe was chosen to track the maximum power point of operation. The MPPT was tested for both step changes in irradiance and temperature levels. When varying the irradiance level the current was the parameter most affected. Even though the MPP was tracked rather well there was uncertainty regarding the MPPT algorithm capability since the voltage was only exposed to minor changes. When the temperature was changed, the voltage was affected in higher degree. The MPPT was able to track the MPP rather well, and tracking in the wrong direction only happened right after a step change. In real life the temperature will normally not change in steps, so this test was said to be done under extreme conditions.
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Perez, de la Mora Nicolas. "Energy Storage for a Grid-Connected PV-System: A Feasibility Study." Thesis, Högskolan Dalarna, Maskinteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:du-12794.
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The work presented in this thesis concerns the dimensioning of an Energy Storage System (ESS) which will be used as an energy buffer for a grid-connected PV plant. This ESS should help managing the PV plant to inject electricity into the grid according to the requirements of the grid System Operator. It is desired to obtain a final production not below 1300kWh/kWp with a maximum ESS budget of 0.9€/Wp. The PV plant will be sited in Martinique Island and connected to the main grid. This grid is a small one where the perturbations due clouds in the PV generation are not negligible anymore. A software simulation tool, incorporating a model for the PV-plant production, the ESS and the required injection pattern of electricity into the grid has been developed in MS Excel. This tool has been used to optimize the relevant parameters defining the ESS so that the feed-in of electricity into the grid can be controlled to fulfill the conditions given by the System Operator. The inputs used for this simulation tool are, besides the conditions given by the System Operator on the allowed injection pattern, the production data from a similar PV-plant in a close-by location, and variables for defining the ESS. The PV production data used is from a site with similar climate and weather conditions as for the site on the Martinique Island and hence gives information on the short term insolation variations as well as expected annual electricity production. The ESS capacity and the injected electric energy will be the main figures to compare while doing an economic study of the whole plant. Hence, the Net Present Value, Benefit to Cost method and Pay-back period studies are carried on as dependent of the ESS capacity. The conclusion of this work is that it is possible to obtain the requested injection pattern by using an ESS. The design of the ESS can be made within an acceptable budget. The capacity of ESS to link with the PV system depends on the priorities of the final output characteristics, and it also depends on which economic parameter that is chosen as a priority.
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Di, Vincenzo Maria Carla. "Improving the efficiency of grid connected PV system for real operating conditions." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=17983.
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Ruiz, Bello Elsa. "Design of a PV-system with batteries connected building for a grid." Thesis, Högskolan i Gävle, Energisystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-25506.
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Lo, Franco Francesco. "Integrazione di sistemi di accumulo a batterie e impianti fotovoltaici di grande taglia per applicazioni grid-connected." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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In un impianto fotovoltaico connesso alla rete elettrica, l’ integrazione di un sistema di accumulo permette di raccogliere l’ energia dal solare nelle ore di minor richiesta di rete (di giorno), ed erogarla nei momenti di bassa produzione e di maggiore richiesta di rete (la sera).
In collaborazione con ENGIE Eps, è sorta l’ esigenza di confrontare tre diverse tipologie di accoppiamento delle batterie in un impianto ibrido PV+Batteria connesso alla rete elettrica.
La prima architettura è chiamata AC coupling poiché il BESS (Battery Energy Storage System) è connesso tramite opportuni convertitori, direttamente alla rete elettrica. La terza e la seconda
architettura sono denominate DC Coupling poiché il BESS è collegato tramite un convertitore o senza, al lato DC dell’ impianto.
Il confronto è stato realizzato analizzando i flussi di potenza
dell’ impianto facendo riferimento a dati di produzione reali forniti da ENGIE Eps. Più in particolare, sono stati forniti i dati di produzione e di irraggiamento di un impianto reale di potenza massima pari a 285 MW, con storage di capacità pari a 275 MWh. La valutazione della potenza richiesta all’ impianto è stata ottenuta dall’analisi del segnale AGC relativo alla rete nella quale l’ impianto è inserito. Tale segnale `e stato generato a partire da dati di frequenza di rete forniti dall’ azienda.
Dall’ analisi precedentemente descritta si è individuata l’ architettura migliore in termini di rendimento, che risulta essere la DC coupling con DC/DC sulla batteria.
Nell’ ultima parte della tesi si è inoltre svolto su richiesta di ENGIE Eps, lo studio del controllo dei convertitori relativi all’ architettura in esame. La strategia di controllo
individuata è descritta nel dettaglio in questo documento.
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Schilla, Thomas Johann. "Development of a network model of a PV array and electrical system for grid-connected applications." Thesis, Northumbria University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275735.
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Kabir, MD Ahsan. "Techno-economic study of grid connected residential PV system with battery storage - A review of the Local System Operator (LSO) model." Thesis, KTH, Elektroteknisk teori och konstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205594.
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The grid connected solar PV system with battery storage is one of the promising alternativeenergy solutions for electricity consumers. The Local System Operator (LSO) will be a newactor to operate its own energy system by integrating PV and battery system with other technicalsolutions. This thesis investigates the technical and economic viability of a grid connected PVsystem with battery storage in behind-the-meter approach for aggregated residential load toassess the LSO model for the present conditions in Sweden.The system model is developed using the System Advisory Model (SAM) – a simulationsoftware for renewable energy system analysis. The PV system model is designed using solarirradiation profile and fifty multi-dwelling aggregated residential load data from Sweden. Theappropriate design inputs of solar PV module, inverter and system loss are taken from previousstudies. The electricity price is analysed from the comparative study of Nord-pool wholesaleprice, market retail price and distribution grid tariffs. The financial metrics such as discountrate, inflation rate, system cost and currently available PV incentives are considered to make anaccurate model. To help with the assessment, three cases are formed; the first case representsonly the PV system and the other cases include storage - using a lithium-ion or lead-acid battery.This comparative study helps to determine the optimum PV and battery size at two differentlocations in Sweden.The optimum net present value (NPV) and profitability index (PI) is found at the 40 kW PVand 3 kWh battery system at Karlstad, Sweden. The optimum case is considered for furtherinvestigation to evaluate the system life time energy profile, electricity bill saving capabilityand battery performance. The system peak shaving potential is investigated by making twoother scenarios with higher battery capacity. Sensitivity analysis is also performed to assess thesystem’s technical and financial input parameters. The system capacity factor at the site locationis found as an influential parameter to the annual production and profitability. The optimumsize of PV system with a lithium-ion battery investment is found feasible for the LSO realimplementation only considering the current PV incentives and electricity price in Sweden. Thereport concludes with the assessment, the technical and economic feasibility of the studied PVand battery storage system profitability depends on the system site location, residential loadsize, consumer electricity cost and available PV incentives.solcellsystem (PV) med batterilagring är en lovande alternativenergilösning förslutkonsumenten. Den 'local system operator', LSO, blir en ny aktör som driver egetenergisystem genom att integrera PV- och batterisystem med andra tekniska lösningar. Dennaavhandling undersöker det tekniska och ekonomiska genomförbarhetet i ett nätanslutet PVsystem med batterilagring i 'bakom mätaren' scenario för aggregerade bostäder i ettflerbostadshus, för att urvärdera LSO modellen.Systemmodellen är utvecklat med 'system advisory model' (rådgivande modell), SAM, ettsimuleringsprogram för förnybara energisystem. PV systemparametrarna beräknas med hänsyntill väderprofiler och lastdata från Sverige. Lämpliga parametrar för solcellsmoduler, omriktareoch systemförluster tas från tidigare studier. Slutkonsumenternas elpriser analyseras frånjämförande studie av NordPool grosshandelspris, konsumentpris och distributionnätstariffer.Finansiella mått såsom system kostnad, rabatt och inflationstakten och tillgängliga incitamentför PV investeringar används för att göra modellen noggrannare. Tre fall undersöks; det förstarepresenterar systemet med bara PV, och de övriga fallen lägger till lagring, genom antingenlitiumjon eller bly-syre batterier. Denna jämförande studie är ett underlag för att bestämma denoptimala PV och batteristorleken för anläggninar på två olika område i Sverige.Den optimala netto nuvarande värde (NPV) och lönsamhet index (PI) är på 40 kW PV systemetoch 3 kWh batteri på Karlstad, Sverige. Ytterligare undersökning av detta fall används för attutvärdera energiprofilen under systemets livstid, möjlighet till minskad elräkning, och batterietsprestanda. Potential för utjämning av systemets topplast utreds genom att skapa två andrascenarier med högre batterikapacitet. Känslighetsanalys utförs också för att bedöma de tekniskaoch ekonomiska parametrarna. Den optimuma storleken på PV system med ett litium-jonbatterifinns rimligt för LSO riktiga genomförande med tanke på incitamenten. Simuleringsresultatenoch systemkonsekvenserna av LSO modellen diskuteras. Rapporten visar att den tekniska ochekonomiska genomförbarheten av det studerade PV systemet med litium-jon batteri beror påslutkonsumentelpriset, PV incitament och globala trender i kostnaderna försystemkomponenter, samt på valet av lämplig plats med en effektiv analys av väder profil ochsystemetförluster.
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Sahoo, Smrutirekha. "Impact Study: Photo-voltaic Distributed Generation on Power System." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-32369.
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The grid-connected photo-voltaic (PV) system is one of the most promising renewable energy solutions which offers many benefits to both the end user and the utility network and thus it has gained the popularity over the last few decades. However, due to the very nature of its invariability and weather dependencies, the large scale integration of this type of distributed generation has created challenges for the network operator while maintaining the quality of the power supply and also for reliable and safe operations of the grids. In this study, the behavioral impact of large scale PV system integration which are both steady and dynamic in nature was studied. An aggregate PV model suited to study the impacts was built using MATLAB/Simulink. The integration impacts of PV power to existing grids were studied with focus on the low voltage residential distribution grids of Mälarenergi Elnät AB (10/0.4 kV). The steady state impacts were related to voltage profile, network loss. It was found that the PV generation at the load end undisputedly improves the voltage profile of the grid especially for the load buses which are situated at farther end of the grid. Further, with regard to the overvoltage issue, which is generally a concern during the low load demand period it was concluded that, at a 50% PV penetration level, the voltage level for the load buses is within the limit of 103% as prescribed by the regulator excepting for few load buses. The voltage level for load buses which deviate from the regulatory requirement are located at distance of 1200 meter or further away from the substation. The dynamic impact studied were for voltage unbalancing in the grid, which was found to have greater impact at the load buses which is located farther compared to a bus located nearer to the substation. With respect to impact study related to introduction of harmonics to the grid due to PV system integration, it was found that amount of harmonic content which was measured as total harmonic distortion (THD) multiplies with integration of more number of PV system. For a 50 % penetration level of PV, the introduced harmonics into the representative network is very minimal. Also, it was observed from the simulation study that THD content are be less when the grid operates at low load condition with high solar irradiance compared to lower irradiance and high load condition.
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Wu, Hsu-Chin, and 吳旭晉. "AC Line Current Regulation Strategy for Grid-Connected PV Systems." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/83901772759886008730.
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博士國立中正大學
電機工程所
97
The objective of this dissertation is to propose an ac line current regulation strategy for a grid-connected photovoltaic (GCPV) system. The GCPV system consists of a multiple-input dc-dc converter, a dc link filter, and a dc-ac inverter. Because the dc link voltage depends on the difference between the input power from the PV array and the output power injected into the ac mains, a dc link voltage based voltage controller is needed to generate the ac reference current for the dc-ac inverter. A good ac current regulation strategy can minimize the change of the ac reference current amplitude while regulating the dc link voltage without using a large dc link capacitor. The power flow of the GCPV system and the operational principles of different ac line current regulation strategies are presented. In this dissertation, the optimal ac line current regulation is defined to be able to achieve dc link voltage regulation in one line cycle while minimizing the injected ac line current variation. The analytical expressions for the proposed optimal ac line current regulation strategy are derived thoroughly. The derived equations also explain the behavior of the dc link voltage responding to the power variation of the GCPV system. As a result, the selection criteria of the dc link capacitor can be established. In this dissertation, operational principle and analytical expression derivation of the proposed optimal ac line current regulation strategy have been presented. Hardware experimental results have verified the validity of the proposed strategy. The main contribution of this dissertation includes: 1) presenting the optimal ac line regulation strategy to stabilize dc link voltage for the GCPV system, 2) improving the power quality of the ac mains for the GCPV system, and 3) providing appropriate dc link capacitor selection criteria to reduce the size and cost of the GCPV system.
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Silva, Leonardo Candido da. "Power interface for grid-connected pico-hydro systems using PV inverters." Master's thesis, 2018. http://hdl.handle.net/10198/19869.
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Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáThe electrical energy is a contemporaneous paradigm, the demand for electrical energy is evergrowing, and so is the energy supply; By bringing the energy production closer to the end-users, either in urban centers or people in remote areas have a chance to exploit renewable energy resources to produce electrical energy, and become self-sufficient. Hydropower has since long been a reliable power source, as well as being the most cost-effective. Although, it has its issues, e.g., its synchronization to the utility grid depends on the continuous operation mode of the generator. Commercially available low-power inverters, up to 1.5 kW, are designed to be applied in either solar power generation, or wind power generation. These inverters were not designed to be used with hydropower generation. This work evaluates two current-controlled power interface solutions, boost and C´ uk converters, to make a hydropower generator and a commercial photovoltaic inverter compatible. The models, simulations and tests of the proposed power structures along with a commercial photovoltaic inverter emulation are made with Matlab® Simulink®, facilitating the evaluation of the power structure and its controller in a discrete-time domain in a Simulation-in-the-Loop environment, as well as, an implementation using a Real-Time controller board from dSPACE interfacing between the power structure and the controller built-in Simulink® in a Hardwarein- the-Loop test platform with Commercial Phtovoltaic Inverter (CPVI), which allows for rapid prototyping, data acquisition and processing and experimental validation of the proposed solutions.
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SUKESH, NIKHIL. "Single Stage Grid-Connected Micro-Inverter for Photovoltaic Systems." Thesis, 2012. http://hdl.handle.net/1974/7317.
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This thesis presents a novel Zero Voltage Switching (ZVS) approach in a grid connected single-stage flyback inverter without using any additional auxiliary circuits. The soft-switching of the primary switch is achieved by allowing negative current from the grid-side through bidirectional switches placed on the secondary side of the transformer. Basically, the negative current discharges the MOSFET’s output capacitor thereby allowing turn-on of the primary switch under zero voltage. In order to optimize the amount of reactive current required to achieve ZVS a variable frequency control scheme is implemented over the line cycle. In addition, the bi-directional switches on the secondary side of the transformer have ZVS during the turn-on times. Therefore, the switching losses of the bi-directional switches are negligible. A 250W prototype has been implemented in order to validate the proposed scheme. Experimental results confirm the feasibility and superior performance of the converter compared to the conventional flyback inverter.Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-07-06 16:24:13.385
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Silva, Mário Filipe Aires da. "Analysis of new indicators for fault detection in grid connected PV systems for BIPV applications." Master's thesis, 2014. http://hdl.handle.net/10451/11392.
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Tese de mestrado integrado em Engenharia da Energia e do Ambiente, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2014Neste trabalho apresentamos um novo procedimento para deteção automática de falhas em sistemas fotovoltaicos (PV) ligados à rede. A maioria dos métodos de diagnóstico para deteção de falhas em sistemas PV já conhecidos são consumidores de tempo e precisam de equipamento caro. De forma a evitar completamente o uso de modelação e simulação do sistema PV no processo de deteção de falhas, nós definimos dois novos indicadores de corrente e voltagem, NRc e NRv, respetivamente, no lado DC do inversor do sistema PV. Este método é baseado na avaliação desses novos indicadores. Foram definidos limites para esses indicadores de forma a ter em conta a configuração do sistema PV: número de módulos PV incluídos em série e em paralelo que formam o PV array. A definição desses limites para os indicadores de voltagem e corrente têm que ser adaptados ao sistema PV específico a supervisionar e um período de treino é recomendado de forma a garantir um diagnóstico correto e reduzir assim a probabilidade de falsas falhas detetadas. Um estudo de simulações foi feito em MatLab e usando informação monitorizada pelo inversor, piranómetros, termopares e células de referência instaladas no sistema PV conectado à rede localizado no Centro de Desenvolvimento das Energias Renováveis (CDER), Algéria. O método proposto é simples mas eficaz na deteção das falhas principais de um sistema PV e foi experimentalmente validado e demonstrou a sua eficácia na deteção de falhas presentes em aplicações conectadas à rede.
In this work we present a new procedure for automatic fault detection in grid connected photovoltaic (PV) systems. Most diagnostic methods for fault detection of PV systems already known are time consuming and need expensive hardware. In order to completely avoid the use of modeling and simulation of the PV system in the fault detection procedure we defined two new current and voltage indicators, NRc and NRv respectively, in the DC side of the inverter of the PV system. This method is based on the evaluation of these indicators. Thresholds for these indicators are defined taking into account the PV system configuration: Number of PV modules included in series and parallel interconnection to form the PV array. The definition of these thresholds for the voltage and current indicators must be adapted to the specific PV system to supervise and a training period is recommended to ensure a correct diagnosis and reduce the probability of false faults detected. A simulation study was carried using MatLab and the data used was monitored by the inverter, pyranometers, thermocouples and reference cells installed in a grid connected PV system located in the Centre de Développement des Energies Renouvelables (CDER), Algeria. The proposed method is simple but effective detecting the main faults of a PV system and was experimentally validated and has demonstrated its effectiveness in the detection of main faults present in grid connected applications.
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FONG, YUAN-JYUN, and 馮垣鈞. "A Study on Power Quality Measurement and Analysis for Flexible Active Power Controls of Grid-Connected PV Systems." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/64837358113016115209.
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Jiang, Gang-Lin, and 蔣岡霖. "Grid-Connected PV System of KSU Green Office." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/96284150924095750753.
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碩士崑山科技大學
電子工程研究所
99
The Kun-Shun University(KSU) has installed photovoltaic(PV) generator system in green office since 2010. The system consists of two different solar cell systems. One is multi-crystalline silicon photovoltaic modules, and the other is CIGS thin film (PV) modules. The thesis uses a useful analysis tool for such system under actual operation process. Thus the KSU-PV system is taken as an example to examine different conditions such as shading, and changes operating points of cell. Furthermore, it is also used to simulation control of PV systems, voltage, current, and power calculation. The main issue is devoted to the simulation of the grid-connected PV system application. Finally, comparisons of the simulation results and actual field test are also presented in this thesis.
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Chen, Ching-Heng, and 陳敬恆. "Improvements for single phase grid connected PV system." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/53215136024663793701.
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碩士明志科技大學
電機工程研究所
100
Two technology improvements in the grid-connected PV generation system were proposed in the thesis. One is a variable step-size maximum power point tracking method with noise interference reduction for the PV array. The other is a digital phase locked loop improvement for single-phase grid-connected inverters. Eventually, a DSP-based test system was built and tested to validate the performance of the methods. In the thesis, a PV model was built and simulated. From the results of simulations, some useful conclusions were found. The experiments in the PV system were also performed. Based on the conclusions of the simulations and experiments, a variable step size maximum power point tracking method using |dPpv/dVpv| and |dPpv/dIpv| to determine step size for noise interference reduction was proposed. This method can increase the speed of maximum power point tracking, and the output power and utility of PV modules. Using synchronous frame to obtain essential parameters from the utility power such as frequency, phase and amplitude in a single phase grid-connected systems, how to convert a single phase signal into orthogonal two phase signals by using memory table method and SOGI-QSG method are discussed. In addition, an improved synchronizing signal-detecting circuit was also proposed. Finally, a digital phase-lock-loop (DPLL) was built and tested to validate the performance of the system. The experimental results show that a high performance DPLL with harmonic and noise rejection and wide frequency variation stability have been realized and validated.
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Lin, Chung-Hsin, and 林仲信. "Islanding Prevention with Grid-Connected PV Power System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/40548180575950049753.
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碩士國立中正大學
電機工程所
94
A grid-connected PV power system with islanding prevention is proposed in this thesis. The proposed PV power system co¬n¬sists of a power stage and a control stage. In the power stage, a boost dc/dc converter incorporated with the perturba-tion-and-observation algorithm can draw the maxi¬mum power from the PV array. Then, a full-bridge dc/ac inverter will deliver real power to the utility line. Also the RLC parallel load for islanding test described in IEEE 929 and UL 1741 are estab-lished. In the control stage, the control circuit is realized by using two microcon-trollers. One is used to achieve the maximum power point tracking for the PV array by using the perturbation-and-observation algorithm. The other one is used to im-plement the function of grid-connection. Finally, experimen¬tal re¬sults have been conducted to verify the performance of the grid-connected PV power system with islanding prevention.
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Guanhan_Chen and 陳冠翰. "Power Control for Single-Phase Grid-Connected PV System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/64212644936169415625.
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碩士明志科技大學
電機工程系碩士班
102
A single-phase grid-connected PV system is developed in this project. In the maximum power point tracking (MPPT), a variable step-size MPPT method is used to maximize the output power of PV with faster response, smaller perturbance, and reducing noise interference. The synchronizing signals are detected by a second-order generalized integrator quadrature-signal generator (SOGI-QSG), a synchronous frame transformation, and digital phase-lock loop (DPLL) with faster response and smaller noise interference. Using the synchronous frame transformation power control, active power and reactive power are controlled independently and respectively. In the right side of the maximum power point(MPP), the derivative of PV output current with respect to the duty cycle of push-pull converter is larger , so the interference of measurement noise is relative smaller and the is getting smaller as the output power approaches to maximum power point, finally to zero. Conversely, the output voltage of PV has the same characteristic in the left side of MPP. Therefore, the value of multiplied by gain is used as a variable step-size during the MPPT procession in the right side of the MPP and the value of multiplied by gain is used as a variable step-size in the left side of the MPP. The single-phase voltage and current are transferred to two phase orthogonal signals, , , ,and , by SOGI-QSG. Then, the frequency, phase angle, and amplitude of the grid voltage are obtained by synchronous frame conversion and DPLL. Moreover, the active power and reactive power can be calculated using the signals, , , ,and . PI controllers are used to regulate the output of active power and reactive power from the system. The outputs of PI controllers are taken inverse park transfer and voltage drop compensation to get the need of the inverter output voltage. A DSP TMS320F28335 is used to realize the control system by writing program for sampling data, performing the calculation and control algorithms, and generating the trigger signals of power devices. Finally, the performance of the system is validated by simulations and experiments.
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Lu, Kuang-Chin, and 呂光欽. "Intelligent Power Control System of Three-Phase Grid-Connected PV System." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/90117545732400970594.
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博士國立中央大學
電機工程學系
104
A PC-based intelligent power control system of the three-phase grid-connected photovoltaic (PV) system for active and reactive power control during grid faults is developed in this dissertation. Two fuzzy-neural-network (FNN) based intelligent controllers are proposed to perform the intelligent power control system to regulate the active and reactive power of the grid-connected PV system satisfying the low voltage ride through (LVRT) requirements and ensuring the injected currents within the safety value of the three-phase inverter. The first proposed intelligent controller is the probabilistic wavelet fuzzy neural network (PWFNN) controller, which combines the merits of probabilistic FNN (PFNN) and wavelet FNN (WFNN). The other is the Takagi-Sugeno-Kang type probabilistic fuzzy neural network with asymmetric membership function (TSKPFNN-AMF) controller, which is the combination of the characteristics of the Takagi-Sugeno-Kang type fuzzy neural network (TSKFNN), asymmetric membership function (AMF) and probabilistic neural network (PNN). Both PWFNN and TSKPFNN-AMF controllers are good at dealing with a complex nonlinear system with uncertainty, complexity, and strong nonlinearities. Since the three-phase grid-connected PV system, which includes PV panel, boost converter, three-phase inverter and grid, can be regarded as a nonlinear system with uncertainty, it is very difficult to develop a physical nonlinear model for the system. Traditional controller such as proportional-integral (PI) controller is difficult to guarantee the desired control performance with the presence of plant parameter variations and unknown external disturbances due to the linearity characteristic of a PI controller. Therefore, the proposed PWFNN and TSKPFNN-AMF controllers can be adopted to develop a system with learning capability for nonlinear systems with uncertainties and be adopted to control the active and reactive power of the grid-connected PV system during grid faults. Moreover, a formula for evaluating the percentage of voltage sags is derived to determine the ratio of the injected reactive current to satisfy the regulations. To reduce the risk of over-current during LVRT operation, a current limit is predefined for the injection of reactive current. Furthermore, a dual mode operation control method of the converter and inverter of the three-phase grid-connected PV system is proposed to balance the active power between the PV panel and the three-phase inverter and maximize the three-phase inverter power capability via injecting the full-rated current during grid fault. To achieve this objective, the control system applies the mode II operation strategy to curtail the active power to ensure the maximum rated current is not surpassed. In addition, the network structure, online learning algorithm, and convergence analysis of the proposed intelligent controllers are described in detail. An emulated 1kW grid-connected three-phase PV system is settled and tested to verify the performance of the proposed intelligent power control system. Various types of voltage sags and test scenarios are designed to investigate the LVRT capability of the grid-connected PV system. The experimental results show that although the control performances of the proposed controllers are superior to other controllers such as PI, FNN and WFNN, higher complexity of structure and current harmonic distortion of injected current during grid faults are the main defects. Additionally, some benchmarks of these controllers are also provided to evaluate the control performances.
32
Wen, Shu-Hsien, and 溫書賢. "Power Control for a Single-Phase Grid-Connected PV System." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/80976572390076208009.
Full textAbstract:
碩士明志科技大學
電機工程研究所
100
In this work it implements a power control for a single-phase grid-connected PV System. The power control consists of a digital phase-lock-loop (DPLL) and synchronous frame current regulator. Based on the DPLL, the frequency, phase angle, and amplitude of the grid voltage are obtained by the second-order generalized integrator quadrature-signal generator (SOGI-QSG), synchronous frame transfer, and phase angle control loop. The DPLL can reduce the interference of the harmonics. The DPLL has provided the orthogonal voltage Signals, and in the stationary frame, phase angle , , and the rotating d-axis voltage, . Involving in the orthogonal voltage Signals, and , the active power and reactive power can be calculated easily. The inverter output current setting is obtained through the power control loop and inverse Park transform. The inverter output current controller is implemented by a proportional-resonant control strategy (PR). The PR controller can achieve zero steady-state errors in an AC current control system. Single-phase grid-connected inverter circuit had twice frequency power pulsation inherently. It is affected dc bus voltage which causes the output current distortion. It also produces PV module voltage and current fluctuation and interfere Maximum Power Point Tracking, hence reducing the utility of PV module. In this work the power pulsation is discussed and a method for compensating this problem is proposed.
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Cheng, Chung-Sheng, and 鄭仲聖. "Grid-Connected Power Converter System for PV/Wind Energy Source." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/82503191812533352471.
Full textAbstract:
碩士國立中正大學
電機工程所
93
A grid-connected power converter system fed by solar energy source and wind en¬ergy source is presented in this thesis. The proposed power converter system co¬n¬sists of a power stage and a control stage. In the power stage, a multi-input dc/dc converter incorporated with the perturbation-and-observation method can draw the maxi¬mum power from the two renewable energy sources simultaneously or indi¬vidu¬ally. Then, a full-bridge dc/ac inverter will transmit the power to the utility line. In the control stage, the control circuit is realized by using two microcontrollers and auxiliary analog circuits. For practical applications, func¬tions of soft-start and circuit protection are implemented. Finally, a 1.5 kW proto¬type fed by solar energy source and wind energy source is built and tested. Experimen¬tal re¬sults are shown to verify the performance of the proposed power converter system.
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Lu, Tung-shuan, and 呂東軒. "Effects of PV Grid-Connected System on an Isolated Island Power System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/50178493980240014959.
Full textAbstract:
碩士國立臺灣科技大學
電機工程系
96
This thesis analyzes the effects of a grid-connected photovoltaic (PV) generation system on the voltage and frequency of a real isolated island power system in Taiwan. A 350 kW PV system to be connected with the electric utility of the island is investigated in this thesis. Simulations of the isolated island power system and the PV grid-connected system are realized using Matlab/Simulink. A complete transient and dynamic stability analysis is investigated. Impacts of PV system connection locations in the isolated island power system, solar irradiation variation and optimal operational mode of diesel governors are studied. PV system dynamic behavior during three-phase fault is also included and proper connection capacity of PV system is estimated. Simulation results show a considerable effect of the PV system on voltage and frequency fluctuations. It provides a suggestion of generator locations on the isolated island power system in the future.
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Lin, Sheng-Hsien, and 林聖賢. "Design and Implementation of Grid-Connected PV-Wind Power Converter System." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/26292432119439986548.
Full textAbstract:
碩士國立中正大學
電機工程研究所
91
This thesis presents a grid-connected power converter system fed by the photovoltaic(PV) arrays and the wind turbine. The proposed power converter sys-tem consists of an input stage, a two-input dc/dc converter, and an output stage, a full-bridge inverter. By using the perturbation-and-observation method, the two-input dc/dc converter can draw the maximum power from the PV arrays and the wind turbine simultaneously or individually. The power is then transmitted to the full-bridge inverter for grid connection. Based on the principle of input and output power balancing, the full-bridge inverter will regulate its output current by using sinusoidal-pulse-width-modulation control and deliver the electric power to the utility line. Finally, a 1.2 kW, digital signal processor controlled, grid-connected power converter system fed by the PV arrays and the wind turbine is implemented. Experimental measurements are presented to verify the feasibility and the performance of the proposed grid-connected power converter system.
36
Chien, Hung-Cheng, and 錢弘承. "Implementation of a Grid-Connected Three-Phase Three-Wire PV Generation System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/50198172015992258837.
Full textAbstract:
碩士國立中正大學
電機工程所
96
A grid-connected three-phase three-wire PV generation system is presented in this thesis. The proposed PV generation system consists of a first-stage converter and a second-stage one. The first-stage converter is a DC/DC boost converter using the perturbation and observation method to draw the maximum power from the solar array. For the second-stage converter, a three-phase full bridge inverter is adopted to inject sinusoidal current into the utility line. The proposed system also provides several protection functions, such as over/under voltage protection and over current protection. Two microcontrollers are adopted in the PV generation system to realize the maximum power point tracking algorithm, and the grid-connection function. Finally, a 1kW grid-connected three-phase three-wire PV generation system has been built, and experimental measurements have been conducted to verify the performance of the proposed PV generation system.
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Chang, Chia-Yuan, and 張佳源. "Design and Implementation of Grid-Connected Solar PV System with Active Power Filter." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/53905350171060053228.
Full textAbstract:
碩士中原大學
電機工程研究所
96
The objective of this thesis is to develop a grid-connected solar photovoltaic (PV) system with active power filter. For solar cells, the system adopts the dc/dc boost power converter as well as the improved incremental conductance algorithm for to accelerate the maximum power point speed and the chattering phenomena around maximum power points are reduced and reducing power losses. In addition, the bi-directional dc/dc power converter is designed to charge or discharge batteries in order to regulate the power flow between solar cells, grid power and loads so that it can accomplish the management of energy balance control and enhance the reliability of the whole system. Finally, the system adopts the bi-directional dc/ac power converter as well as the improved fixed-frequency hysteresis current-controlled (HCC) PWM control scheme, being able to reduce the current harmonic, and the DC Change into AC supplies load or carry grid. Experimental and simulated results to verify the performance of the proposed system, this thesis changes the load demand, effectiveness of the energy automatic balancing among solar PV, grid power and load is examined.
38
Liu, Ming-Tai, and 劉銘台. "Power Control and LCL Filter Design for Three-Phase Grid-Connected PV System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/55603650581678945847.
Full textAbstract:
碩士明志科技大學
電機工程系碩士班
102
The major object of this research is to implement a three-phase gird-connected PV system with the power decoupled control. The system integrates with dc to dc converter, dc to ac converter, and LCL filter, and the system also have implemented a three-phase synchronous-reference frame digital phase-lock-loop (DPLL) and three-phase grid-connected power decoupled control. The major structure of three-phase synchronous-reference frame DPLL includes Clark、Park transformation, and DPLL. The Clark transfers grid voltage to two phase orthogonal voltage v_α and v_β, then the Park transfers the two phase orthogonal voltage to two orthogonal voltage v_d and v_q, finally the amplitude, frequency, and phase angle of the grid voltage can be obtained by DPLL. In adding the current i_α and i_β transferred by Clark transformation of grid current, the active power and reactive power can be calculated by the parameters v_α,v_β, i_α,and i_β. Furthermore, the active power and reactive power are controlled by proportional-integrated control loop and the power decoupling control is achieved by inverse Park and inverse Clark transformation. The switching strategy of the voltage-source inverter (VSI) is a unipolar sine pulse width modulation (SPWM).The SPWM technique will cause the high order harmonics in the output voltage. Moreover, the dead time also causes the odd order harmonics. In this research, LCL filters are designed to attenuate those harmonics. A three-phase LCL filter is designed to meet the interconnection standard requirement.
39
Xavier, José Maria. "Performance Analysis of a PV Grid-connected System at the Universidade Nacional Timor Lorosa'e." Master's thesis, 2019. https://hdl.handle.net/10216/119366.
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Dash, Prajna Paramita. "A High-Performance Three-Phase Grid-Connected PV System Based On Multilevel Current Source Inverter." Thesis, 2013. http://hdl.handle.net/10012/7356.
Full textAbstract:
Current Source Inverter (CSI) topology is gaining acceptance as a competitive alternative for grid interface of renewable energy systems due to its unique and advantageous features. Merits of CSI over the more popular Voltage Source Inverter (VSI) topology have been elaborated on by a number of researchers. However, there is a dearth of quality work in modeling and control of CSI topology interfacing renewable energy resources to the grid. To enrich the study focussing on application of CSI for renewable energy interface, this thesis develops a multilevel structure based on CSI for three-phase grid-connected Photovoltaic (PV) application. In the first part of research, a single-stage CSI interfacing to PV array is developed. The CSI-based PV system is equipped with Maximum Power Point Tracker (MPPT), DC-link current controller, and AC-side current controller. To eliminate the nonlinearity introduced by the PV array, a feed-forward control is introduced in the DC-link current controller. The AC-side current controller is responsible for maintaining unity power factor at the Point of Common Coupling (PCC). To verify the performance of the developed CSI-based PV system, a number of simulation studies are carried out in PSCAD/EMTDC environment. To illustrate the performance of the CSI-based PV system during transients on the grid side, simulation studies are carried out for four kinds of faults. Results obtained from fault studies are highly in favor of CSI topology and provide illustrative evidence for short-circuit current protection capability of the CSI. On the other hand, the VSI-based PV system performs poorly when subjected to similar grid transients.
To extend the research on CSI-based PV system further, a multilevel structure based on CSI is developed. The multilevel structure is a parallel combination of $n$ CSI units and capable of producing $2n+1$ levels of current at the terminal of the inverter. Each unit in the multilevel structure has its own MPPT, DC-link current controller. However, on the AC-side a combined current controller is proposed. The design results in a high power rating with reduced number of filters, sensors and controllers. The developed multilevel structure can operate with PV arrays exposed to equal and unequal insolation level. However, when the PV arrays are operating under unequal insolation level, low order harmonics are generated in the sinusoidal current that is injected into the grid. Elimination of these harmonics is performed by implementing a modified control strategy in stationary reference frame that corresponds to the harmonic component that needs to be minimized. The modified control strategy operates in coordination with the existing DC-side and AC-side current controllers, and MPPTs. Therefore, real-time suppression of current harmonics can be ensured. Performance of the multilevel structure is verified by different transient studies.
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Clark, Ronald. "A predictive optimal dispatch and optimal sizing method for a grid-connected PV-diesel-storage system." Thesis, 2015. http://hdl.handle.net/10539/17665.
Full textAbstract:
Hybrid energy systems are becoming a popular means of exploiting natural sources
of energy and increasing electrical efficiency in urban settlements. However, effective
implementation of these systems relies on a means of optimally sizing and operating the
system to ensure the lifetime costs of the system are minimised.
This dissertation addresses the problem of minimising the lifetime costs of a gridconnected
hybrid system with diesel generation, photovoltaic array (PV) and an energy
storage component.
To minimise the operational costs a predictive generator-storage scheduling strategy is
proposed. The dispatch strategy seeks to minimise the operational costs by scheduling
the generator and storage unit to: 1) Minimise the total energy requested from the
grid; 2) Minimise the peak energy requested from the grid; 3) Minimise the fuel used by
the generator. The dispatch strategy is developed in two papers. In the first paper a
demand prediction algorithm is developed which is required by the proposed predictive
dispatch strategy. In the second paper, the actual dispatch strategy for the generator
and storage unit is formulated. The dispatch strategy takes the form of an integrated
convex optimisation model which, when solved, provides the dispatch strategy for the
generator and storage.
An optimal sizing method is then developed to take into account the capital costs of
the components. The purpose of the optimal sizing method is to balance the trade-off
between the increased capital costs incurred by larger PV and storage units and the
corresponding decrease in operational costs.
The optimal dispatch strategy and sizing method are then tested on an example case
study which investigates the possibility of operating a hybrid on the campus of the
University of the Witwatersrand.
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Hong-ZhangWang and 王宏彰. "Design and Implementation of Multi-Input Grid-Connected PV Power System with Soft-Switching and MPPT Functions." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/87978014264621956552.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
98
Effects of the partial shading or different installing angles of the solar photovoltaic (PV) modules often result in problems of PV module mismatch and operations of power converter being not at maximal power point. The overall output efficiency of the solar PV generation system is thus reduced. So how to solve the PV module mismatch problems and improve system efficiency of the power converter is one of the crucial technologies for the PV generation system. In order to reduce the shading effects and mismatch problems, this thesis implements a multi-input grid-connected PV system and accomplish distributed maximum power point tracking (MPPT) strategy by using digital signal processor. The structure of the circuit is divided into two-stage converter system. The front end of the system is a boost converter performing MPPT and resonant soft-switching functions with synchronous rectification to improve the efficiency of the system. The back end of the system is a full-bridge inverter which is connected to grid using current-control mode by unipolar PWM switching. The power output has lower current total harmonic distortion (THD) and near-unity power factor. On the hardware implementation of the proposed system, this thesis takes two input converters for an example to verify the feasibility of the proposed method. Each converter on the system input side is realized with the capacity of 600W, and the total system output capacity is 1.2 kW. The simulated and experimental results show that promising power factors and efficiencies of the system can be achieved for both on-grid and off-grid operations.
43
Gu, Yu-Song, and 辜昱崧. "Implementation of a Single-Phase Quasi Z-Source Inverter with Voltage Dip Mitigation for a Grid Connected PV System." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/61730302081156937415.
Full textAbstract:
碩士國立高雄應用科技大學
電機工程系博碩士班
101
Based on single-phase Quasi Z-source inverter, a grid-connected PV system was built; besides, a Digital Signal Processor (DSP) is used to implement the power control and improve the voltage quality problem caused by voltage dip. The zero-point detector circuit by PLL control is used to facilitate the parallel connection of the inverter to grid; in the meantime, the DC bus and the output voltage can be effectively regulated by shoot-through and non-shoot-through modes. In addition, the power angle and the voltage amplitude are used to regulate active and reactive power injected to the utility. To verify the feasibility of the system, the system model was built by MATLAB/Simulink, and the operation of the system was simulated. Finally, a prototype of Quasi Z-source inverter was tested, and the results illustrate that the parallel connection of inverter to grid and the power control of the system can be satisfied.
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Lu-AnChen and 陳律安. "Design of a Novel High Step-Up Multiple-Output Converter with Digital Control Chip Applied to a Grid-Connected PV System." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/70929538652068176892.
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