121 research outputs found

    A series facts controller as a voltage fluctuation mitigation equipment: an experimental investigation

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    This research project addresses the mitigation of voltage fluctuations using a series-connected power electronics-based controller, which belongs to the family of Flexible AC Transmission Systems (FACTS) controllers. These are emerging technologies which have been under continuous development for over a decade, and are now available to the electricity supply industry world-wide, helping to ameliorate a wide range of power system phenomena, to increase power transfers and stability margins. Voltage fluctuation is a complex phenomenon affecting adversely transmission and distribution networks. Bulky fluctuating load, wind farms and large induction motor are the major sources of voltage fluctuations. As the phenomenon propagates, it interacts with other voltage fluctuations contributed by different sources, and affecting neighbouring lighting circuits, giving raise to a phenomenon termed light flicker. To ameliorate such a problem, a well-coordinated operation of advanced voltage mitigation equipment, control strategy and specialised measurements instruments are required. Considerable progress has been made in voltage fluctuations mitigation using shunt FACTS controllers. However, very little work has been reported in tackling the very complex issue of mitigation of voltage fluctuation propagating in the network using series FACTS controllers. To advance this area of research, this project addresses the design and construction of a three-phase scaled-down TCSC prototype and a voltage fluctuations experimental environment, suitable for real-time hardware-in-the-loop testing. The research work carries out a fundamental study of TCSC resonances, which are termed resonance modes. It is found that a non-explicit resonance mode at a=90° exists, and it is termed intrinsic resonance mode. For a well-designed TCSC, only the fundamental and the intrinsic resonance mode should be active. To facilitate the design, a procedure has been identified, based in the synchronisation of resonance modes. To achieve mitigation successfully, a new tailor-made TCSC control strategy, named RT-DIMR, and a flexible virtual flickermeter based on the IEC-61000-4-15 standard are thoroughly developed and integrated under the same real-time computing platform. The RT-DIMR demonstrates its capability for controlling the TCSC under different voltage fluctuation conditions. The lEC-Flickermeter provides online flicker severity indices, information which may be used to asses whether or not the electrical network has been effectively improved. The aim of this research work is to experimentally evaluate the TCSC capabilities to mitigate travelling voltage fluctuations. A scaled-down network and voltage fluctuation sources are constructed to mimic a voltage fluctuations propagation environment. A comprehensive number of experiments are carried out to test the mitigation scheme under a wide range of conditions. The robustness and effectiveness of the mitigation schemes have been thoroughly demonstrated. The newly developed TCSC prototype, scaled-down testing environment and RT-DIMR control strategy recommend themselves not only as an imaginative voltage fluctuations mitigation research tool, but also as a general advanced FACTS research tool

    A UPFC for Voltage Regulation in LV Distribution Feeders With a DC-Link Ripple Voltage Suppression Technique

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    The large-scale integration of distributed photovoltaic generation causes several power quality issues in low voltage (LV) distribution networks. Network voltage profile variations severely affect the LV distribution networks. The four-leg unified power flow controller (4L-UPFC) has series and shunt converters that can address the power quality issues. However, instantaneous power theory shows that second-order harmonic voltage (2ωHV) appears at the dc-link capacitor of the 4L-UPFC during any unbalanced operations. This article proposes control strategies for series and shunt converters that will simultaneously regulate the load voltages of a distribution feeder while suppressing the 2ωHV term on the dc-link of the UPFC. A controlled negative sequence current from the shunt converter is used to suppress the 2ωHV term on the dc-link. The active suppression of the 2ωHV term allows electrolytic capacitors to be replaced with small long life ceramic or film capacitors, and this does not require additional passive compensation. Stability analysis of the control loops demonstrates the overall stability of the converter system. The proposed control methods have been implemented on a Texas DSP (F28377D). An experimental demonstration on a laboratory scale prototype shows that the proposed control methods can effectively regulate the load voltages at LV distribution feeders and suppress the 2ωHV on the dc-link of UPFC during unbalanced loads and supply conditions. © 1972-2012 IEEE

    Power Quality of Grid-Connected Wind Turbines with DFIG and Their Interaction with the Grid

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    Analysis of end use electrotechnology in mining and minerals processing as a determinant for electricity growth with special reference to the RSA

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    A project report submitted to the Faculty of Engineering, University of Witwatersrand, Johannesburg, In partial fulfilment of the requirements for the degree of Master of Science in Engineering George, 1996. The history of electricity growth in South Africa. has been one of rapid growth.' This reached as high as 13%in one year with the increase in electrification of mining and lndustry from the -1960's to 1980ts. In addition the development of new mines and new minerals beneficiation plants, especially metals beneficiation, accelerated electricity growth due to the electricity intensive end use technologies implemented that were specific to those industriesGR 201

    Modeling and Simulation of Metallurgical Processes in Ironmaking and Steelmaking

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    In recent years, improving the sustainability of the steel industry and reducing its CO2 emissions has become a global focus. To achieve this goal, further process optimization in terms of energy and resource efficiency and the development of new processes and process routes are necessary. Modeling and simulation have established themselves as invaluable sources of information for otherwise unknown process parameters and as an alternative to plant trials that involves lower costs, risks, and time. Models also open up new possibilities for model-based control of metallurgical processes. This Special Issue focuses on recent advances in the modeling and simulation of unit processes in iron and steelmaking. It includes reviews on the fundamentals of modeling and simulation of metallurgical processes, as well as contributions from the areas of iron reduction/ironmaking, steelmaking via the primary and secondary route, and continuous casting

    Best Available Techniques (BAT) Reference Document:for:Iron and Steel Production:Industrial Emissions Directive 2010/75/EU:(Integrated Pollution Prevention and Control)

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    The BREF entitled ‘Iron and Steel Production’ forms part of a series presenting the results of an exchange of information between EU Member States, the industries concerned, non-governmental organisations promoting environmental protection and the Commission, to draw up, review, and where necessary, update BAT reference documents as required by Article 13(1) of the Directive. This document is published by the European Commission pursuant to Article 13(6) of the Directive. This BREF for the iron and steel production industry covers the following specified in Annex I to Directive 2010/75/EU, namely: • activity 1.3: coke production • activity 2.1: metal ore (including sulphide ore) roasting and sintering • activity 2.2: production of pig iron or steel (primary or secondary fusion) including continuous casting, with a capacity exceeding 2.5 tonnes per hour. The document also covers some activities that may be directly associated to these activities on the same site. Important issues for the implementation of Directive 2010/75/EU in the production of iron and steel are the reduction of emissions to air; efficient energy and raw material usage; minimisation, recovery and the recycling of process residues; as well as effective environmental and energy management systems. The BREF document contains 13 chapters. Chapter 1 provides general information on the iron and steel sector. Chapter 2 provides information and data on general industrial processes used within this sector. Chapters 3 to 8 provide information on particular iron and steel processes (sinter plants, pelletisation, coke ovens, blast furnaces, basic oxygen steelmaking and casting, electric arc steelmaking and casting). In Chapter 9 the BAT conclusions, as defined in Article 3(12) of the Directive, are presented for the sectors described in Chapters 2 to 8.JRC.J.5-Sustainable Production and Consumptio

    Nuclear Fusion Programme: Annual Report of the Association Karlsruhe Institute of Technology (KIT)/EURATOM ; January 2009 - December 2009 (KIT Scientific Reports ; 7548)

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    The Karlsruhe Institute of Technology (KIT) is working in the framework of the European Fusion Programme on key technologies in the areas of superconducting magnets, microwave heating systems (Electron-Cyclotron-Resonance-Heating, ECRH), the deuterium-tritium fuel cycle, He-cooled breeding blankets, a He-cooled divertor and structural materials, as well as refractory metals for high heat flux applications including a major participation in the preparation of the international IFMIF project
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