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Igic P.,University of Swansea | Zhou Z.,University of Swansea | Knapp W.,TU Munich | MacEnri J.,ESB International | And 2 more authors.
IET Renewable Power Generation | Year: 2011

Considerations of the electrical system configuration and the control strategy for the wave dragon (WD) multi-megawatt (MW) offshore wave energy converter (WEC) are presented in this study. The electrical system consists of 16-20 turbine-generator-AC/DC/AC converter units. The characteristics of the low-head water-turbine and generator control strategy enabling maximum energy capture and the best performance for the MW offshore wave energy power take-off system are described in detail. Simulation results from a single turbine-generator-frequency converter unit at different turbine heads are presented at the end of the study. © 2010 The Institution of Engineering and Technology.

Scully S.,ESB International | O'Dowd N.P.,University of Limerick
Journal of Pressure Vessel Technology, Transactions of the ASME | Year: 2013

This paper is concerned with the development of a methodology for thermomechanical analysis of high temperature, steam-pressurized P91 pipes in electrical power generation plant under realistic (measured) temperature and pressure cycles. In particular, these data encompass key thermal events, such as "load-following" temperature variations and sudden, significant fluctuations in steam temperatures associated with attemperation events and "trips" (sudden plant shut-down), likely to induce thermomechanical fatigue damage. An anisothermal elastic-plastic-creep material model for cyclic behavior of P91 is employed in the transient finite element (FE) model to predict the stress-strain-temperature cycles and the associated strain-rates. The results permit characterization of the behavior of pressurized P91 pipes for identification of the thermomechanical loading histories relevant to such components, for realistic, customized testing. This type of capability is relevant to design and analysis with respect to the evolving nature of power plant operating cycles, e.g., associated with more flexible operation of fossil fuel plant. © 2013 American Society of Mechanical Engineers.

Agency: GTR | Branch: EPSRC | Program: | Phase: Research Grant | Award Amount: 2.46M | Year: 2012

The Gas-FACTS programme will provide important underpinning research for UK CCS development and deployment on natural gas power plants, particularly for gas turbine modifications and advanced post combustion capture technologies that are the principal candidates for deployment in a possible tens-of-£billions expansion of the CCS sector between 2020 and 2030, and then operation until 2050 or beyond, in order to meet UK CO2 (carbon dioxide) emission targets. Gas CCS R&D is an emerging field and many of the concepts and underlying scientific principles are still being invented. But on-going UK infrastructure investments and energy policy decisions are being made which would benefit from better information on relevant gas CCS technologies, making independent, fundamental studies by academic researchers a high priority. In addition, the results of this project will provide an essential basis for further work to extract the maximum research benefits from the UK CCS demonstration programme and help to develop more advanced gas CCS technologies for a second tranche of CCS deployment. The programme will also develop rigorous assessment methods and a framework to maximise pathways to impact that could support other RCUK research activities on gas CCS. Globally, there is already interest in gas CCS in Norway, California and the Middle East, and this is likely to become more widespread if cheaper gas leads to more widespread use. This work will be undertaken through work packages with the following aims: WP1: To quantify the scope of gas turbine modifications to improve the technical, environmental and economic performance of integrated CO2 capture on CCGT plants. Small gas turbines will be modified to run with steam or recycled flue gas replacing some of the normal air feed to increase back-end CO2 concentrations (which will help make the CO2 easier to capture). WP2: To quantify through modelling and experimental testing the scope for improving post-combustion capure system performance on CCGT plants through a combination of advanced liquid solvents, including novel amine mixtures, and improved transient performance. Solvents that are used to take up CO2 and then release it in a pure form that can be stored underground will be modified so that the amount of energy required to do this is reduced. The equipment the solvents are used in will also be designed to turn on and off quickly to allow CCS power plants to compensate for fluctuations in output from wind turbines. WP3: In close collaboration with an external Experts Group to undertake integration and whole systems performance assessments. This will include a Gas-FACTS Impact Handbook combining impact tables with state-of-the-art surveys to ensure that pathways to impact pursued by Gas-FACTS researchers are co-ordinated with other significant activities, including excellent science and stakeholder plans, to maximise their effectiveness. Gas-FACTS results will be implemented in the freely-available IECM package for access by any potential users. WP4: Impact delivery and expert interaction activities will be based on establishing an Experts Group including representatives of the UK CCS academic community, global academic community, UK policymakers, UK Regulators, NGOs, power utilities, Original Equipment Manufacturers (OEMs), SMEs (Small and Medium Enterprises). WP4 will also run a programme of engagement activities to impact, including project meetings, specialist meetings on topical issues and results, web-based dissemination and document publication (reports, responses to Parliamentary inquiries, journal papers, articles etc.)

MacEnri J.,ESB International | Reed M.,Marine Current Turbines | Thiringer T.,Chalmers University of Technology
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2013

This paper presents the analysis of the study of the flicker emitted fromthe 1.2MWtidal energy converter (TEC), SeaGen, against varying tidal parameters. This paper outlines the main elements of the TEC itself, the environment it is located in and the measurement set up. In this paper, the flicker emitted by the TEC is compared with the different tidal parameters, including flood and ebb tides, tidal speed, water depth and turbulence strength and intensity. Flicker emissions have been calculated from measured data in over 90 measurement (10min) periods, and all of the tidal parameters vary significantly over that testing period. This allows for a detailed statistical and graphical analysis of the variation of flicker with the variation of the tidal parameters outlined above. It is found, with the exception of tidal speed, that there is no strong relationship between flicker emissions and any other tidal parameter. As SeaGen is an asymmetrical TEC with full blade pitching for flood and ebb generation, it was also found that the expected difference of flicker emissions owing to the effect of the submersed crossbeam was not significant. The TEC harmonic performance versus tidal speed is also presented. © 2013 The Author(s) Published by the Royal Society. All rights reserved.

Thiringer T.,Chalmers University of Technology | MacEnri J.,ESB International | Reed M.,Marine Current Turbines
IEEE Transactions on Sustainable Energy | Year: 2011

This paper presents the power quality evaluation of a 1.2-MW tidal power plant. The results show that the unit works well and that the power quality impact is moderae to low and for future units which most likely will have more turbines, the power quality impact will be very low. The wind turbine power quality standard IEC 61400-21 was used in this investigation, and was adequate; however, regarding the connecting transients, there could be a need for a specific standard. It is found that the power level is well controlled at higher water speeds; the maximum 10-min power is found to be 1.21 MW. The maximum 2-s value is found to be 1.46 MW and the maximum 60-s value is found to be 1.30 MW. The reactive power exchange with the grid is negligible; at full load, the power factor is 0.99. The flicker coefficient is between 1 and 5, depending on the grid impedance angle. Finally, it can be said that the maximum total harmonic distortion (THD) for the voltages is found to be 1.2% and for the current 0.65% during operation with the complete power plant. © 2011 IEEE.

O'Riordan J.,ESB International
IET Conference Publications | Year: 2015

Using a case study outlined below the paper will demonstrate how an atypical distribution network configuration was employed to ensure security and continuity of supply in response to an increase in demand from a major single point load. The paper will highlight the options considered and the formalised process involved in delivering this request as well as the upgrades required to the protection on the local distribution and transmission networks.

Farragher T.P.,Marine Institute of Ireland | Scully S.,ESB International | O'Dowd N.P.,University of Limerick | Leen S.B.,Marine Institute of Ireland
International Journal of Fatigue | Year: 2013

A finite element methodology for thermo-mechanical fatigue analysis of a subcritical power plant outlet header under realistic loading conditions is presented. The methodology consists of (i) a transient heat transfer model, (ii) a sequential anisothermal cyclic viscoplastic model and (iii) a multiaxial, critical-plane implementation of the Ostergren fatigue indicator parameter. The methodology permits identification of the local thermo-mechanical stress-strain response at critical locations and prediction of fatigue life and cracking orientation for complex transient, anisothermal, cyclic elastic-plastic-creep material behaviour. Measured plant data, in the form of steam and pipe temperature transients and steam pressure data, are employed to identify heat transfer constants and validate the predicted thermal response, with particular attention given to plant start-up and attemperation effects. The predictions indicate out-of-phase temperature-strain response at the header inside surface and in-phase response on the outside surface. Cooling transients are predicted to control damage and crack initiation at the inner bore, whereas heating transients are predicted to have a more damaging effect at weld locations. A representative test cycle is presented, which is shown to capture the salient thermo-mechanical cyclic damage of the realistic cycle. The predicted results correlate well with industrial experience in terms of crack (initiation) orientation, location and life. © 2012 Elsevier Ltd. All rights reserved.

McGrath A.,ESB International
Proceedings of the Universities Power Engineering Conference | Year: 2013

Voltage regulators were originally implemented as a cost effective means of improving power quality on network spurs where embedded generation was not considered economically or technically feasible. Their main function in maintaining local network stability is achieved by way of increasing voltage during periods of short-time over-loading and reducing voltage during periods of load shedding. This paper gives a brief introduction to the mode of operation and network installation configuration of voltage regulators. This paper also gives an insight into modern regulator controls which enable voltage regulators to perform a variety of new tasks and functions such as local operation and data storage alongside real-time communication with utility operation centres. One of the latest features of voltage regulation control is voltage reduction mode, which enables utilities to tap down regulators to reduce the local voltage by up to 3% to increase the current available in the network. Voltage regulators are tailor-made for individual utility's requirements and manufacturers must examine the key internal components of the regulator when designing a regulator for a specific utility. A review of some of the factors utilities must examine when procuring regulators is contained in this paper. New directives which apply to all oil-immersed transformers imported into the EU have come into effect that restrict and regulate the substances contained in transformer mineral oil and the amount of which can be imported into the EU. Certain substances which have been deemed carcinogenic have been subject to heavy restrictions on import into the EU and manufacturers of transformers have introduced new products that not only comply with EU legislation but are also environmentally sound. This paper examines a number of aspects of voltage regulators from the development of new control features, new environmentally-friendly oils and, communication and control design and test criteria. © 2013 IEEE.

Bednarik J.,ESB International
Proceedings of the Universities Power Engineering Conference | Year: 2013

This paper describes the design and project decisions taken in a project which successfully uprated a 38 kV distribution substation to a 110 kV transmission substation within a compact urban environment on the west coast of Ireland. It describes the phasing of the project and the measures taken to ensure service continuity and to reduce the risk of substation outages during construction. The paper includes details of the project scope, site and network constraints and issues encountered during the planning and construction periods. The construction on a compact site located in a busy urban location required detailed planning of the logistics for switchgear delivery and assembly. © 2013 IEEE.

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