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Sustainable Alternative Energy (SAE), 2009 IEEE PES/IAS Conference on

Date 28-30 Sept. 2009

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Displaying Results 1 - 25 of 68
  • Distributed renewable generation: Interconnection and performance

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    Evaluation procedure for interconnection of distributed generation (DG) to distribution feeder is presented. Regulatory documents are used as guidelines for the approach. Three categories of interconnections are identified. Detailed interconnection studies are proposed to further investigation of prospective interconnections. Additional considerations for allocation and sizing of DG are discussed. As an example, Georgia Institute of Technology's Aquatic's Center PV system is presented, equipped with a 342kW roof-mounted photovoltaic array since 1996. This system is closely monitored and studied with the help of a data acquisition system. The relationship between certain parameters, as well as reliability of the system may be analyzed and forecasted. View full abstract»

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  • HVDC connection of off-shore wind farms based on synchronous generators

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    Modern wind turbines allow for tight control of terminal voltage, this is particularly true for synchronous generator (SG) based wind turbines. Therefore, an integrated design of wind turbine and HVDC link control can lead to a substantial simplification of the off-shore rectifier. This paper introduces an integrated control algorithm for line commutated thyristor (LCT) based HVDC transmission line whereby the offshore rectifier tap changer is eliminated and a cheaper and more efficient uncontrolled rectifier is used instead of a LCT-based rectifier. The presented control strategy allows for good performance during steady state and transient operation, including on-shore fault ride-through operation. View full abstract»

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  • Large-scale wind energy development in China and the relevant issues

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (139 KB) |  | HTML iconHTML  

    An in-depth investigation of China's large-scale wind energy development is conducted in the paper. In order to cater for the trend of abating carbon emissions and improving energy efficiency, wind power industry is developing at an astonishing speed in China. The characteristics of China's LSWD are analyzed in the context of its basic national conditions of energy. The mode of long-distance, large capacity and use of high voltage transmission lines is the option of the China's LSWD, which highlights the strategy of “constructing large wind power bases and integrating into bulk grids”. Also, major issues concerning LSWD are emphasized. Among the issues, wind resource data, the impacts of wind power on power systems and the institutional and legal issues are studied. From the point of view of LSWD, the coordinated relationship between the grid and the wind farm is very important in the long term. A grid of robustness and smartness will provide a sound platform for LSWD, and the unified, enhanced standards and rational policies will create effective competition in China's electricity market and improve the adaptability for the wind farm and the grid as well. View full abstract»

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  • Mitigation of output power fluctuations in wind farms with Opti-slip induction generator

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB) |  | HTML iconHTML  

    This paper presents an elegant technique for mitigating the output power fluctuations from a grid connected Opti-slip induction generator (OSIG), due to sudden wind gusts leading to input drive torque variations. The proposed technique has also been extended to control the amount of real power into the grid at the desired value. The control of OSIG is achieved using the basic principles of chopper control for varying the rotor resistance. The proposed control scheme has been simulated and tested in PSCAD/EMTDC. The performance of the control scheme is further validated experimentally. The results obtained both in simulation and experimentation are discussed in detail. View full abstract»

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  • Impact of WRIG and DFIG wind generation ramping down on independent power systems

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (619 KB) |  | HTML iconHTML  

    The generated power of wind turbine generators changes with wind speed. The higher the ratio of wind generation to all system generation is, the more wind turbine generators influence the power system due to variable characteristics of wind. In particular, independent power systems with small capacities, such as remote islands, will be greatly influenced. This paper adopts real system data of a remote island of Taiwan to investigate impacts on power systems under light load condition that are interconnected with wound rotor induction generators or doubly-fed induction generators in different power factor control modes and voltage control mode when wind speed ramps down. The results are very helpful for both system planning and operations. View full abstract»

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  • Feasibility of a 10 MW doubly fed induction generator for direct-drive wind turbines

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (438 KB) |  | HTML iconHTML  

    The study considers 10 MW, 600 poles, doubly fed induction generator, allowing direct-drive units with reduced size converter. The work relies on a lumped parameters design and on finite element verifications, and it compares some of its results to the findings of recent literature. The results of the paper evidenced a borderline feasibility of the considered generator. View full abstract»

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  • Method of inferring operation status of distributed generation systems in distribution section

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (181 KB) |  | HTML iconHTML  

    Recently, many distributed generation systems have been installed in power distribution networks. In the case of an extensive penetration of distributed generation systems, serious problems such as overvoltage at the customer receiving end as a result of surplus photovoltaic generation and islanding phenomena at a fault in a distribution line may occur. In particular, the distribution line may become overloaded during fault recovery because all distributed generation systems must stop operating instantly to prevent islanding at the fault; then, generation cannot be resumed instantly in accordance with the grid interconnection code in Japan. However, distribution network operators can prevent overload if the operation status of distributed generators can be estimated in advance. As a first step of inferring the operation status of distributed generators, we developed two methods of inferring the operation status of distributed generators at the customer receiving end. One was a method for low-voltage customers, in which the change in power factor measured at the customer receiving end was used. The other was a method for medium-voltage customers, in which both the active power and power factor measured at the customer receiving end were used. These two methods could infer that the distributed generators are “in operation” or “not in operation” at the customer receiving ends. However, the operation status in a distribution section, which is sectioned by two pole-mounted gas switches, should be inferred from the viewpoint of distribution operation. As the active power and power factor in the distribution section are affected by the loads of other customers, it is difficult to adopt the method for medium-voltage customer's receiving ends using the active power and power factor. This method could not infer the numbers of operating distributed generators. Therefore, we develop a new method of inferring both the status and number of distrib- - uted generators. This method uses the change in phase current unbalance due to the distributed generator operation. We apply this method to three distribution lines including medium-voltage customers. The correct answer rates of inference of the status and number of operating distributed generators for three different distribution sections were ranged from 95.7% to 98.1%, and from 86.1% to 97.0%, respectively.. View full abstract»

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  • Investigation of the torsional vibration and transient stability margin for doubly-fed induction generators

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (191 KB) |  | HTML iconHTML  

    This paper presents the results obtained from a PSCAD/EMTDC dynamic fault simulation of a grid connected Doubly-fed Induction Generator (DFIG). The transient stability performance of the DFIG is investigated; case studies which demonstrate the possibility of wind turbine generator torsional vibration, and the concept of Critical Clearing Time (CCT) for the DFIG are presented and the results are compared to those of a Fixed Speed Induction Generator (FSIG). View full abstract»

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  • Enhancement of fault ride-through capability and damping of torsional oscillations for a distribution system comprising induction and synchronous generators

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (246 KB) |  | HTML iconHTML  

    The dynamic interaction of a Distributed Synchronous Generator (DSG) with Fixed-speed (FSIG) and Doubly-Fed induction generator (DFIG)-based wind turbines during network fault conditions is presented in this paper. The objective is to enhance the damping of the wind turbine torsional oscillations, and the transient stability margin of the distributed generators measured by their respective Critical Clearing Times (CCTs). Power System Stabilizer (PSS), Static Var Compensator (SVC), Transient Gain Reduction (TGR) and high-speed exciters including static and solid-state exciters are investigated as candidate solutions to the system subjected to multiple-fault conditions. Impact of various factors such as fault location, SVC location, SVC size, PSS gain, exciter type and increased ceiling voltage are discussed using the results obtained from the PSCAD/EMTDC simulation. View full abstract»

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  • Power distribution protection scheme enhanced with communication

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (393 KB) |  | HTML iconHTML  

    The paper proposes a communication-based protection scheme for distribution networks with distributed generators. Emphasis is put on making the scheme flexible for various network configurations. Extensive simulation studies demonstrate the proper operation of the protection scheme. The paper looks additionally at the current capabilities in communication-enhanced protection made possible by standardized protocols (IEC 61850) and mechanisms (Ethernet). It finally discusses techniques to encompass intersubstation communications and examines issues that need to be addressed to create a successful, secure and dependable communication network. View full abstract»

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  • An interactive simulation of grid-connected DFIG units for protective relaying studies

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (322 KB) |  | HTML iconHTML  

    Doubly-Fed Induction Generators (DFIG) are commonly utilized in wind farms nowadays due to their advantages as compared with single-fed ones. Control complexities and their unique characteristics may, however, raise different problems during abnormal or faulty operating conditions. In this paper, an integrated simulation for DFIGs in wind farms is presented for protection application purposes in particular. The developed simulation describes the dynamic behavior of the DFIG in an interactive manner incorporating the interaction of the machine unit, the control system, rotor protection circuitry and the utilized Current Limiting Fuses (CLFs) simultaneously. CLF is modeled by aggregating the fusing action with the power system simulation running employing the S-M function with level-2 M-file code in MATLAB-Simulink. The developed simulation enables effectively to explore the behavior of the aforementioned units when working together in the field. Different simulation examples are illustrated to emphasize the broad abilities of the developed simulation. View full abstract»

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  • Voltage control in networks with distributed generation — A case study

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (675 KB) |  | HTML iconHTML  

    This paper analyzes the influence of distributed energy resources (DER) on distribution network voltage profile. A general description of the impact of DER on voltage profile is given and three advanced voltage control techniques are discussed: central voltage control with multiple voltage measurements, reactive power control with sources that enable such operation and the use of an autotransformer as a voltage regulator. The aim was to maximize and to facilitate DER integration. The influence of DER on voltage profile and the effectiveness of the investigated solutions were evaluated by means of simulation in DIgSILENT. The simulated network was an actual distribution network in Slovenia with a relatively high penetration of distributed generation. Recommendations for voltage control in networks with DER penetration are given at the end. View full abstract»

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  • Application of distributed generation to enhance loadability of distribution system, a case study

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (98 KB) |  | HTML iconHTML  

    There has been a great interest in integration of distributed generation (DG) units at distribution level in the recent years. DGs can provide cost-effective, environmentally friendly, higher power quality and more reliable energy solutions than conventional generation. Understanding the wide variety of DG options available along with their technical benefits in today's changing electric market environment can be daunting. Technical benefits of DGs can range from loss reduction to reduction in feeder loading. Loadability enhancement is another benefit that DG can add to distribution system, if properly placed and appropriately sized. This paper presents a simple methodology for placing a distributed generation with the view of increasing loadability and voltage stability of distribution system. Effectiveness of the proposed placement technique is demonstrated in a practical distribution system of Pujon in Malang, Indonesia. View full abstract»

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  • Operation optimization for a virtual power plant

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (222 KB) |  | HTML iconHTML  

    In the 21st century the concept of electrical power supply is morphing gradually from centralized into decentralized system, indicated by increasing the Installation of distributed generation on the main grid. With emerging of advanced Communication and information technology, the aggregation of several small size, environmentally compatible, generators close to the loads can be developed as virtual power plant in order to provide added-value to the electric Power system. In this paper an operation optimization algorithm is proposed to integrate two DGs and a micro grid into a VPP control area, containing several loads, which will be able to generate and sell electrical energy to loads and power market. Suitable models are proposed to simulate electric production, and the energy exchange between VPP and Grid. The optimization problem is here formulated as a non-liner maximization algorithm with constraints, where the objective function is profit of the VPP with supply of electric energy for all the loads. Solving the VPP optimization problem in two different scenarios with GAMS software will complete the paper. View full abstract»

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  • Virtual power producers simulation — Negotiating renewable distributed generation in competitive electricity markets

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (723 KB) |  | HTML iconHTML  

    Sustainable development concerns made renewable energy sources to be increasingly used for electricity distributed generation. However, this is mainly due to incentives or mandatory targets determined by energy policies as in European Union. Assuring a sustainable future requires distributed generation to be able to participate in competitive electricity markets. To get more negotiation power in the market and to get advantages of scale economy, distributed generators can be aggregated giving place to a new concept: the Virtual Power Producer (VPP). VPPs are multi-technology and multisite heterogeneous entities that should adopt organization and management methodologies so that they can make distributed generation a really profitable activity, able to participate in the market. This paper presents ViProd, a simulation tool that allows simulating VPPs operation, in the context of MASCEM, a multi-agent based electricity market simulator. View full abstract»

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  • A multi-input power converter for hybrid renewable energy generation system

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    This paper studies the dc power supply system to combine with the hybrid renewable energy sources. A multi-input power converter (MIPC) which operates in four types: an operation type wherein power is delivered to dc Bus from hybrid renewable energy sources; a single type wherein only one renewable energy source supplies power to the dc Bus; an inverter type wherein power is delivered to dc Bus from ac grid via inverter module, and a battery type wherein power is delivered to dc Bus from batteries without renewable energy source. In this paper, the integration of the dc Bus and a hybrid renewable power supply system is proposed. A hybrid renewable power energy which integrates the solar energy, wind-power, and city power, etc will be exploited to supply the household appliance and loads. View full abstract»

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  • Integration of distributed energy resources in the operation of energy management systems

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB) |  | HTML iconHTML  

    The presence of distributed generation poses new challenges in the management and operation of electrical grids. Distributed generation (wind, combined heat and power, etc.) already accounts for 20% or more of total generation in some electric utilities and this figure is constantly increasing worldwide. TSOs, DSOs and energy markets need to have some visibility on a large number of small power injections. This paper presents solutions to adapt classical tools and processes so that energy management systems can efficiently supervise and manage distributed generation. View full abstract»

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  • Evaluation of control strategies in HVAC split systems

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB) |  | HTML iconHTML  

    The important and continuous increment in the global electricity consumption is doing that energy saving strategies have turned into a crucial solution. Efficient heating, ventilation and air conditioning controls are generally the most cost-effective ways to minimize the use of energy in buildings. In this framework, an energy management and control system has been developed to schedule electric end-uses in the campus of the Polytechnic University of Valencia, Spain. As a result, each system or device in the campus is able to be switched on/off by using a web platform. This paper presents an evaluation of different control strategies for HVAC split systems, which have been performed by using an energy management and control system, developed in a similar way by UPV. In order to adapt and compare several schedules, this paper analyzes the effect of these actions in a common air conditioning device. Not affecting the comfort level and the indoor air quality is an important requirement. For that reason, a multi criteria comparison must be drawn. Demand response strategies are tested in several situations, and the economic saving is calculated taking into account the electricity contract clauses. Finally, a test is realized for the control of a group of similar devices in order to reduce the maximum peak power and obtain a flexible load shape with the HVAC loads. The studies are then extrapolated on a large system, the whole university campus, for which energy and economic savings are quantified. View full abstract»

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  • Wind energy integration and the Ireland-Wales interconnector

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (207 KB) |  | HTML iconHTML  

    In a small electricity grid such as the all Ireland system of Northern Ireland and the Republic of Ireland, managing with the variability of high levels of wind power generation will be crucial to ensuring the economic success of wind energy generation and the overall stability of the electricity system. Storage and interconnection are frequently proposed to manage this variability and total flexibility of the interconnector is assumed. This paper examines how market and meteorological effects could constrain interconnector operation. Currently an interconnector between the Republic of Ireland and Wales officially referred to as the East West Interconnector is in planning. The split between energy transfer and reserve provision through the interconnector will be dictated by energy prices and relative value of reserve services. The levels of wind power generation in each connected region may limit the mutual support expected from interconnection. In this regard wind forecasting and wind correlations in the connected regions are extremely relevant and are discussed in this paper. View full abstract»

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  • A hybrid programming for distribution reconfiguration of dc microgrid

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (189 KB) |  | HTML iconHTML  

    This paper presents a hybrid programming (HP) technique to solve the dc microgrid reconfiguration problem for loss reduction and service restoration. By using the proposed algorithm, a more efficient network configuration can be obtained to reduce loss. The problem is optimized in a stochastic searching manner similar to that of the evolutionary programming (EP). The initial population is determined by opening the switches with the lowest current in every mesh derived in the optimal power flow (OPF) with all switches closed. To avoid prematurity, HP technique was applied to adjust the number of mutant elements adaptively. Tabu Lists with heuristic rules were employed in the searching process to enhance performance. Simulation results show that the proposed algorithm has advantages than the earlier developed algorithms. The optimization strategy is general and can be used to solve other power system optimization problems as well. View full abstract»

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  • Decomposing objectives and functions in power system operation and control

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1768 KB) |  | HTML iconHTML  

    The introduction of many new energy solutions requires the adaptation of classical operation paradigms in power systems. In the standard operation paradigms, a power system is seen as some equivalent of a synchronous generator, a power line and an uncontrollable load. This paradigm is being questioned by a diverse mix of challenges posed by renewable energy sources, demand response technologies and smart grid concepts, affecting all areas of power system operation. Both, new control modes and changes in market design are required eventually. A proper redesign should starts with a coherent approach to modeling. This paper presents a mean-ends perspective to the analysis of the control structures and operation paradigms in present power systems. In a top-down approach, traditional frequency-and area-control mechanisms are formalized. It is demonstrated that future power system operation paradigms with different generation control modes and controllable demand can be modeled in a coherent way. Finally, the discussion is opened up toward a formalization of service-exchange between market participants. View full abstract»

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  • Modeling the stochastic dependencies in a probabilistic load flow including wind generation

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (167 KB) |  | HTML iconHTML  

    Nowadays, the implementation of environmentally-friendly and uncontrollable primary energy sources in the electrical power system production is increasing, introducing abatement in generation dispatchability. The incorporation of high levels of small-scale non-dispatchable distributed generation leads to the transition from the traditional 'vertical' power system structure to a 'horizontally-operated' power system, where the distribution networks contain both stochastic generation and load. This leads to a large number of stochastic system inputs and complex dependencies between them being involved in the analysis. In this paper, a Monte Carlo Simulation approach is used for the power system multivariate uncertainty analysis problem. The Stochastic Bounds Methodology is applied in order to tackle this problem through the definition of extreme dependence structures that can bound all real cases. On the other hand, the Joint Normal Transform models the exact dependence structure between the clusters based on the mutual correlations obtained by data analysis and provide more accurate results. View full abstract»

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  • Extension of a probabilistic load flow calculation based on an enhanced convolution technique

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (501 KB) |  | HTML iconHTML  

    Traditional algorithms used in grid operation and planning only evaluate one deterministic state. Uncertainties introduced by the increasing utilization of renewable energy sources have to be dealt with when determining the operational state of a grid. From this perspective the probability of certain operational states and of possible bottlenecks is important information to support the grid operator or planner in their daily work. From this special need the field of application for Probabilistic Load Flow methods evolved. Uncertain influences like power plant outages, deviations from the forecasted injected wind power and load have to be considered by their corresponding probability. With the help of probability density functions an integrated consideration of the partly stochastic behaviour of power plants und loads is possible. In this context an extension to a convolution based probabilistic load flow is present in this paper. The extension reduces the already limited inaccuracy introduced by network model simplifications. Aspects like accuracy improvement and computation time in comparison to existing method are covered in detail. View full abstract»

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  • Sizing and analysis of big scale and isolated electric systems based on renewable sources with energy storage

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (455 KB) |  | HTML iconHTML  

    A considerable number of institutions, companies and societies demand and trust the possibility of a sustainable world where the energetic production is based on renewable sources. Most likely future problem of the no-controllable renewable electric production (mainly wind and solar) may be the temporally variability. To follow the power demand is necessary controllable generation. The paper analyses based on hypothetical situations how to manage through storage systems the no-controllable productions to get the complete substitution of the no-renewable power plants. Data from real renewable plants has been used to explore in big electric systems (Spain) the optimal sizing of said storage systems. It is shown that with a potential renewable overproduction around 150% versus a yearly demand only a 1.5% energy storage capacity versus demand should be necessary. View full abstract»

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  • Improved model of photovoltaic sources considering ambient temperature and solar irradiation

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    The aim of the present work is to propose a complete Photovoltaic (PV) Direct Current (DC) source model, considering non linear effects with ambient temperature and solar irradiance. The main advantage of this model is that all non ideal characteristics of the PV source are taking into account, and complex weather conditions patterns can be considered. This model includes: The PV array and boost-buck DC-DC converter that operates to assure maximum power extraction. The Maximum Power Point Tracking (MPPT) algorithm, which is based on the incremental conductance method, is also described. The model can be used for example, as a DC source to supply grid connected or islanded inverters, to study the interaction of PV generators with the power system. View full abstract»

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