11,725 research outputs found
Data Acquisition and Control System of Hydroelectric Power Plant Using Internet Techniques
VodnĂ energie se nynĂ stala nejlepĆĄĂm zdrojem elektrickĂ© energie na zemi. VyrĂĄbĂ se pomocĂ energie poskytovanĂ© pohybem nebo pĂĄdem vody. Historie dokazuje, ĆŸe nĂĄklady na tuto elektrickou energii zĆŻstĂĄvajĂ konstantnĂ v prĆŻbÄhu celĂ©ho roku. Vzhledem k mnoha vĂœhodĂĄm, vÄtĆĄina zemĂ nynĂ vyuĆŸĂvĂĄ vodnĂ energie jako hlavnĂ zdroj pro vĂœrobu elektrickĂ© energie.NejdĆŻleĆŸitÄjĆĄĂ vĂœhodou je, ĆŸe vodnĂ energie je zelenĂĄ energie, coĆŸ znamenĂĄ, ĆŸe ĆŸĂĄdnĂ© vzduĆĄnĂ© nebo vodnĂ zneÄiĆĄĆ„ujĂcĂ lĂĄtky nejsou vyrĂĄbÄny, takĂ© ĆŸĂĄdnĂ© sklenĂkovĂ© plyny jako oxid uhliÄitĂœ nejsou vyrĂĄbÄny, coĆŸ ÄinĂ tento zdroj energie ĆĄetrnĂœ k ĆŸivotnĂmu prostĆedĂ. A tak brĂĄnĂ nebezpeÄĂ globĂĄlnĂho oteplovĂĄnĂ. PouĆŸitĂ internetovĂ© techniky k ovladĂĄnĂ nÄkolika vodnĂch elektrĂĄren mĂĄ velmi vĂœznamnĂ© vĂœhody, jako snĂĆŸenĂ provoznĂch nĂĄkladĆŻ a flexibilitu uspokojenĂ zmÄny poptĂĄvky po energii na stranÄ spotĆeby. TakĂ© velmi efektivnÄ ÄelĂ velkĂœm naruĆĄenĂm elektrickĂ© sĂtÄ, jako je napĆĂklad pĆidĂĄnĂ nebo odebrĂĄnĂ velkĂ© zĂĄtÄĆŸe, a poruch. Na druhou stranu, systĂ©m zĂskĂĄvĂĄnĂ dat poskytuje velmi uĆŸiteÄnĂ© informace pro typickĂ© i vÄdeckĂ© analĂœzy, jako jsou ekonomickĂ© nĂĄklady, predikce poruchy systĂ©mĆŻ, predikce poptĂĄvky, plĂĄny ĂșdrĆŸby, systĂ©mĆŻ pro podporu rozhodovĂĄnĂ a mnoho dalĆĄĂch vĂœhod. Tato prĂĄce popisuje vĆĄeobecnĂœ model, kterĂœ mĆŻĆŸe bĂœt pouĆŸit k simulaci pro sbÄr dat a kontrolnĂ systĂ©my pro vodnĂ elektrĂĄrny v prostĆedĂ Matlab / Simulink a TrueTime Simulink knihovnu. UvaĆŸovanĂĄ elektrĂĄrna sestĂĄvĂĄ z vodnĂ turbĂny pĆipojenĂ© k synchronnĂmu generĂĄtoru s budicĂ soustavou, generĂĄtor je pĆipojen k veĆejnĂ© elektrickĂ© sĂti. SimulacĂ vodnĂ turbĂny a synchronnĂho generĂĄtoru lze provĂ©st pomocĂ rĆŻznĂœch simulaÄnĂch nĂĄstrojĆŻ. V tĂ©to prĂĄci je upĆednostĆovĂĄn SIMULINK / MATLAB pĆed jinĂœmi nĂĄstroji k modelovĂĄnĂ dynamik vodnĂ turbĂny a synchronnĂho stroje. Program s prostĆedĂm MATLAB SIMULINK vyuĆŸĂvĂĄ k ĆeĆĄenĂ schematickĂœ model vodnĂ elektrĂĄrny sestavenĂœ ze zĂĄkladnĂch funkÄnĂch blokĆŻ. Tento pĆĂstup je pedagogicky lepĆĄĂ neĆŸ komplikovanĂ© kĂłdy jinĂœch softwarovĂœch programĆŻ. Knihovna programu Simulink obsahuje funkÄnĂ bloky, kterĂ© mohou bĂœt spojovĂĄny, upravovĂĄny a modelovĂĄny. K vytvoĆenĂ a simulovĂĄnĂ internetovĂœch a Real Time systĂ©mĆŻ je moĆŸnĂ© pouĆŸĂt budâ knihovnu simulinku Real-Time nebo TRUETIME, v prĂĄci byla pouĆŸita knihovna TRUETIME.Hydropower has now become the best source of electricity on earth. It is produced due to the energy provided by moving or falling water. History proves that the cost of this electricity remains constant over the year. Because of the many advantages, most of the countries now have hydropower as the source of major electricity producer. The most important advantage of hydropower is that it is green energy, which mean that no air or water pollutants are produced, also no greenhouse gases like carbon dioxide are produced which makes this source of energy environment-friendly. It prevents us from the danger of global warming. Using internet techniques to control several hydroelectric plants has very important advantages, as reducing operating costs and the flexibility of meeting changes of energy demand occurred in consumption side. Also it is very effective to confront large disturbances of electrical grid, such as adding or removing large loads, and faults. In the other hand, data acquisition systems provides very useful information for both typical and scientific analysis, such as economical costs reducing, fault prediction systems, demand prediction, maintenance schedules, decision support systems and many other benefits. This thesis describes a generalized model which can be used to simulate a data acquisition and control system of hydroelectric power plant using MATLAB/SIMULINK and TrueTime simulink library. The plant considered consists of hydro turbine connected to synchronous generator with excitation system, and the generator is connected to public grid. Simulation of hydro turbine and synchronous generator can be done using various simulation tools, In this work, SIMULINK/MATLAB is favored over other tools in modeling the dynamics of a hydro turbine and synchronous machine. The SIMULINK program in MATLAB is used to obtain a schematic model of the hydro plant by means of basic function blocks. This approach is pedagogically better than using a compilation of program code as in other software programs .The library of SIMULINK software programs includes function blocks which can be linked and edited to model. Either Simulink Real-Time library or TrueTime library can be used to build and simulate internet and real time systems, in this thesis the TrueTime library was used.
Power electronics options for large wind farm integration : VSC-based HVDC transmission
This paper describes the use of voltage source converter based HVDC transmission (VSC transmission) system for grid integration of large wind farms over long distance. The wind farms can be based on either doubly-fed induction generator (DFIG) or fixed speed induction generator (FSIG). The paper describes the operation principles and control strategies of the proposed system. Automatic power balancing during network AC fault is achieved without communication between the two converters. PSCAD/EMTDC simulations are presented to demonstrate the robust performance and to validate the proposed system during various operating conditions such as variations of generation and AC fault conditions. The proposed VSC transmission system has technical and economic advantages over a conventional AC connection for integrating large wind farms over long distanc
International White Book on DER Protection : Review and Testing Procedures
This white book provides an insight into the issues surrounding the impact of increasing levels of DER on the generator and network protection and the resulting necessary improvements in protection testing practices. Particular focus is placed on ever increasing inverter-interfaced DER installations and the challenges of utility network integration. This white book should also serve as a starting point for specifying DER protection testing requirements and procedures. A comprehensive review of international DER protection practices, standards and recommendations is presented. This is accompanied by the identiïŹ cation of the main performance challenges related to these protection schemes under varied network operational conditions and the nature of DER generator and interface technologies. Emphasis is placed on the importance of dynamic testing that can only be delivered through laboratory-based platforms such as real-time simulators, integrated substation automation infrastructure and ïŹ exible, inverter-equipped testing microgrids. To this end, the combination of ïŹ exible network operation and new DER technologies underlines the importance of utilising the laboratory testing facilities available within the DERlab Network of Excellence. This not only informs the shaping of new protection testing and network integration practices by end users but also enables the process of de-risking new DER protection technologies. In order to support the issues discussed in the white paper, a comparative case study between UK and German DER protection and scheme testing practices is presented. This also highlights the level of complexity associated with standardisation and approval mechanisms adopted by different countries
Increasing security of supply by the use of a local power controller during large system disturbances
This paper describes intelligent ways in which distributed generation and local loads can be controlled during large system disturbances, using Local Power Controllers. When distributed generation is available, and a system disturbance is detected early enough, the generation can be dispatched, and its output power can be matched as closely as possible to local microgrid demand levels. Priority-based load shedding can be implemented to aid this process. In this state, the local microgrid supports the wider network by relieving the wider network of the micro-grid load. Should grid performance degrade further, the local microgrid can separate itself from the network and maintain power to the most important local loads, re-synchronising to the grid only after more normal performance is regained. Such an intelligent system would be a suitable for hospitals, data centres, or any other industrial facility where there are critical loads. The paper demonstrates the actions of such Local Power Controllers using laboratory experiments at the 10kVA scale
PRISM: a tool for automatic verification of probabilistic systems
Probabilistic model checking is an automatic formal verification technique for analysing quantitative properties of systems which exhibit stochastic behaviour. PRISM is a probabilistic model checking tool which has already been successfully deployed in a wide range of application domains, from real-time communication protocols to biological signalling pathways. The tool has recently undergone a significant amount of development. Major additions include facilities to manually explore models, Monte-Carlo discrete-event simulation techniques for approximate model analysis (including support for distributed simulation) and the ability to compute cost- and reward-based measures, e.g. "the expected energy consumption of the system before the first failure occurs". This paper presents an overview of all the main features of PRISM. More information can be found on the website: www.cs.bham.ac.uk/~dxp/prism
Distributed photovoltaic systems: Utility interface issues and their present status. Intermediate/three-phase systems
The interface issues between the intermediate-size Power Conditioning Subsystem (PCS) and the utility are considered. A literature review yielded facts about the status of identified issues
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