Showing papers on "Power station published in 2001"

Artificial neural networks in renewable energy systems applications: a review

Abstract: Artificial neural networks are widely accepted as a technology offering an alternative way to tackle complex and ill-defined problems. They can learn from examples, are fault tolerant in the sense that they are able to handle noisy and incomplete data, are able to deal with non-linear problems and, once trained, can perform prediction and generalisation at high speed. They have been used in diverse applications in control, robotics, pattern recognition, forecasting, medicine, power systems, manufacturing, optimisation, signal processing and social/psychological sciences. They are particularly useful in system modelling such as in implementing complex mappings and system identification. This paper presents various applications of neural networks mainly in renewable energy problems in a thematic rather than a chronological or any other order. Artificial neural networks have been used by the author in the field of solar energy; for modelling and design of a solar steam generating plant, for the estimation of a parabolic trough collector intercept factor and local concentration ratio and for the modelling and performance prediction of solar water heating systems. They have also been used for the estimation of heating loads of buildings, for the prediction of air flow in a naturally ventilated test room and for the prediction of the energy consumption of a passive solar building. In all those models a multiple hidden layer architecture has been used. Errors reported in these models are well within acceptable limits, which clearly suggest that artificial neural networks can be used for modelling in other fields of renewable energy production and use. The work of other researchers in the field of renewable energy and other energy systems is also reported. This includes the use of artificial neural networks in solar radiation and wind speed prediction, photovoltaic systems, building services systems and load forecasting and prediction.

System, method and computer program product for enhancing commercial value of electrical power produced from a renewable energy power production facility

Abstract: A method, system and computer program product enhance the commercial value of electrical power produced from a wind turbine production facility. Features include the use of a premier power conversion device that provides an alternative source of power for supplementing an output power of the wind turbine generation facility when lull periods for wind speed appear. The invention includes a communications infrastructure and coordination mechanism for establishing a relationship with another power production facility such that when excess electrical power is produced by the wind turbine facility, the excess may be provided to the power grid while the other energy production facility cuts back on its output production by a corresponding amount. A tracking mechanism keeps track of the amount of potential energy that was not expended at the other facility and places this amount in a virtual energy storage account, for the benefit of the wind turbine facility. When, the wind turbine power production facility experiences a shortfall in its power production output it may make a request to the other source of electric power, and request that an increase its power output on behalf of the wind turbine facility. This substitution of one power production facility for another is referred to herein as a virtual energy storage mechanism. Furthermore, another feature of the present invention is the use of a renewal power exchange mechanism that creates a market for trading renewable units of power, which have been converted into “premier power” and/or “guaranteed” by secondary sources of power source to provide a reliable source of power to the power grid as required by contract.

History of Power Plants and Progress in Heat Resistant Steels

Abstract: During the last fifty years steam pressure and temperature in fossil-fired power plants have been continuously raised to improve thermal efficiency. Recent efforts for raising steam conditions are in response to the social demand for environmental protection as well as energy conservation concerns. Today the steam temperature of 600°C for modern power plants equipped with swing load or sliding pressure demand functions has already been realized, and a goal for the future is the 630°C to 650°C class with ferritic steels.However the 600°C to 630°C class is possible for current construction, based on already developed materials that include ferritic steels for pipework and rotors. Numerous studies on heat resistant steels actively conducted since the early 1970s have allowed great progress in both 9–12% Cr steels and austenitic steels. This paper presents a historical view of developments in steam pressure and temperature of fossil-fired power plants and alloy design for heat resistant steels in the 20th century, particularly over the last severaldecades, as well as a survey of the current status of steel development for power plants, mainly with regard to creep strengthening and enhancement of corrosion resistance.

HVDC transmission for large offshore windfarms

Abstract: Onshore and offshore wind farms are a rapidly growing worldwide industry. The development of larger, more efficient turbines is opening up new frontiers in wind energy generation in the form of large offshore wind farms. The use of high-voltage direct current (HVDC) technology can fully realise the potential of these developments, overcoming the major technical challenges facing traditional AC solutions and providing an efficient, economic and reliable solution.

Solar-Hybrid Gas Turbine-based Power Tower Systems (REFOS)*

Abstract: Solar hybrid power plants have a significant potential for cost reduction when the solar energy is introduced into a gas turbine system. The introduction into gas turbine systems could be realized with pressurized volumetric air receivers heating the compressed air of the gas turbine before it enters the combustor. A receiver module, consisting of a secondary concentrator and a volumetric receiver unit, was tested at the Plataforma Solar de Almeria, Spain. Air exit temperatures up to 815°C and power levels of 410 kW were achieved. Total solar test time summed up to 400 hours. Receiver efficiencies were in the range of 70%. A new secondary concentrator with improved efficiency was designed and built. Based on an inexpensive manufacturing technology, the secondary concentrator geometry was optimized to reduce the optical losses: Performance tests with this new secondary concentrator and a cold-water calorimeter proved the expected increase in efficiency of about 10%. Maximum operation power was 450 kW at the exit aperture. The dependency of performance on the incidence-angle showed good agreement with the predictions, as well as the results of a special photographic measurement campaign. Several configurations of solar-hybrid gas turbine cycles in the low to medium power range are examined for performance and costs. The results confirm the promising potential of this technology to reach competitiveness in certain power markets; a comparison between a 30 MW solar-hybrid combined cycle plant and an ISCCS power plant are presented. Future developments for system improvement and cost reduction are discussed.

A life cycle assessment of biomass cofiring in a coal-fired power plant

Abstract: The generation of electricity, and the consumption of energy in general, often result in adverse effects on the environment. Coal-fired power plants generate over half of the electricity used in the U.S., and therefore play a significant role in any discussion of energy and the environment. By cofiring biomass, currently operating coal plants have an opportunity to reduce the impact they have, but to what degree, and with what trade-offs? A life cycle assessment has been conducted on a coal-fired power system that cofires wood residue. The assessment was conducted in a cradle-to-grave manner to cover all processes necessary for the operation of the power plant, including raw material extraction, feed preparation, transportation, and waste disposal and recycling. Cofiring was found to significantly reduce the environmental footprint of the average coal-fired power plant. At rates of 5% and 15% by heat input, cofiring reduces greenhouse gas emissions on a CO2-equivalent basis by 5.4% and 18.2%, respectively. Emissions of SO2, NOx, non-methane hydrocarbons, particulates, and carbon monoxide are also reduced with cofiring. Additionally, total system energy consumption is lowered by 3.5% and 12.4% for the 5% and 15% cofiring cases, respectively. Finally, resource consumption and solid waste generation were found to be much less for systems that cofire.

A Simplified Dynamic Model of Grid-Connected Fuel-Cell Generators

Abstract: This paper describes a reduced-order dynamic model for a grid-connected fuel-cell power plant that is suitable for preliminary stability assessment. Generic voltage and power control loops are included. The model is applied to a distributed utility that uses fuel cells and gas turbines to investigate the nature and magnitude of their interaction. The studies presented in the paper show the effect of the mix between the fuel cell and gas turbine generation on the system stability. The developed model, being simple, could provide a useful tool for the planning of distributed generation.

Power Systems Harmonics : Computer Modelling and Analysis

Abstract: Deregulation has presented the electricity industry with many new challenges in power system planning and operation. Power engineers must understand the negative effect of harmonics on an electrical power network resulting from the extensive use of power electronics-based equipment. Serving as a complete reference to harmonics modelling, simulation and analysis, this book lays the foundations for optimising quality of power supply in the planning, design and operation phases. Features include: MATLAB function codes to aid the development of harmonic software and provide a hands-on approach to the theory presented; Insight into the use of alternative, increased efficiency, harmonic domain techniques; Examination of the harmonic modelling and analysis of FACTS, along with conventional and custom power plant equipment; Clear presentation of the basic analytical approaches to harmonic theory and techniques for the resolution of harmonic distortion. Advanced undergraduate and postgraduate students in electrical engineering will benefit from the unique combination of practical examples and theoretical grounding. Practising power engineers, managers and consultants will appreciate the detailed coverage of engineering practice and power networks world-wide.

Handbook for Cogeneration and Combined Cycle Power Plants

Abstract: This comprehensive Handbook has been fully updated and expanded for the second edition. It covers all major aspects of power plant design, operation, and maintenance. It covers cycle optimization and reliability, technical details on sizing, plant layout, fuel selection, types of drives, and performance characteristics of all major components in a cogeneration or combined cycle power plant. The author discusses design, fabrication, installation, operation, and maintenance. Many illustrations, curves, and tables are used throughout the text. Special features include: comparison of various energy systems; latest cycles and power augmentation techniques; reviews and benefits of the latest codes; detailed analysis of available equipment; descriptions of all major equipment in CCPP; techniques for improving plant reliability and maintainability; testing and plant evaluation techniques; and, advantages and disadvantages of fuels.

Power reserve in interconnected systems with high wind power production

Abstract: A capacity of installed wind power of 40 GW in Europe, control areas with a wind power production exceeding the maximum load-these are serious plans that may come true in several years. Due to the high fluctuations and the limited predictability of wind power, this development will cause a severe change in the demands on the power reserve. Therefore, this paper introduces an investigation that quantifies the technical consequences of the increasing wind power in Europe on the primary, secondary, and long-term reserve.

High density combined cycle power plant process

Abstract: A process for increasing the specific output of a combined cycle power plant and providing flexibility in the power plant rating, both without a commensurate increase in the plant heat rate, is disclosed The present invention demonstrates that the process of upgrading thermal efficiencies of combined cycles can often be accomplished through the strategic use of additional fuel and/or heat input In particular, gas turbines that exhaust into HRSGs, can be supplementally fired to obtain much higher steam turbine outputs and greater overall plant ratings, but without a penalty on efficiency This method by and large defines a high efficiency combined cycle power plant that is predominantly a Rankine (bottoming) cycle Exemplary embodiments of the present invention include a load driven by a topping cycle engine, powered by a topping cycle fluid which exhausts into a heat recovery device

Functional integration of multiple components for a fuel cell power plant

Abstract: A fuel cell power plant having a plurality of functionally integrated components including a fuel cell assembly provided with a fuel stream, an oxidant stream and a coolant stream. The fuel cell power plant functionally integrates a mass and heat recovery device for promoting a transfer of thermal energy and moisture between a first gaseous stream and a second gaseous stream, and a burner for processing the fuel exhausted from the fuel cell assembly during operation thereof. A housing chamber is utilized in which the oxidant stream exhausted from the fuel cell assembly merges with a burner gaseous stream exhausted from the burner. The resultant airflow from the common chamber is directed back to the mass and heat recovery device as the first gaseous stream.

SOFC Power Plants, the Siemens-Westinghouse Approach

Abstract: In 1998 Siemens AG (SAG) took over the tubular Solid Oxide Fuel Cell (SOFC) technology from Westinghouse. This merger placed SAG under the responsibility of Siemens Westinghouse Power Corporation (SWPC), and gave them the opportunity to concentrate on this technology as the most promising fuel cell option for the emerging distributed power market. A first full scale 100 kW demonstration plant in a “district heating” cycle, without integrated micro gas turbines, accumulated more than 15000 hours and is still working. All the expectations with respect to the design parameters and the operation behavior have been met or even exceeded. The first 220 kW “all electric” cycle demonstration plant with integrated micro gas turbine has successfully passed the factory tests. Additional field units are under contract which together with the above two pioneering demonstration plants will accumulate all the necessary learning experience to design a standardized SOFC product. In addition to the demonstration program, a research and development (R&D) program is being pursued. The outcome of both programs, the demonstration as well as the R&D, is expected to close the gap between the current high cost and the market price in order to enable substantial market penetration.

CO2 Capture via Oxyfuel Firing: Optimisation of a Retrofit Design Concept for a Refinery Power Station Boiler

Abstract: A previous study by the present authors demonstrated that the capture of carbon dioxide (CO2) from an existing large refinery power station boiler by conversion to oxygen firing with flue gas recycle is feasible and could be based on proven, available equipment. The study covered the systems for air separation, firing, boiler operation and CO2 separation and compression, and predicted the overall performance of the plant, the requirements for major new items of equipment and budget capital and operating costs. Further work has now been carried out to resolve key remaining uncertainties and to optimise the design. The new work reported here has considered in more detail the sensitivity of the plant performance and costs of conversion to such critical factors as the purity of the oxygen supply and the extent to which the boiler plant can be sealed against air ingress (tramp air). The effect of different levels of furnace modelling and the potential for plant integration have been reviewed. Significant opportunities for cost reduction compared with the previous study have been identified and the results will allow more cost effective oxyfuel plant designs and more reliable comparisons with alternative CO2 capture technologies.

Optimum distribution of heat exchanger inventory for power density optimization of an endoreversible closed Brayton cycle

Abstract: In this paper, the power density (defined as the ratio of the power output to the maximum specific volume in the cycle) is taken as the objective for performance optimizations of an endoreversible closed Brayton cycle coupled to constant-temperature heat reservoirs in the viewpoint of finite-time thermodynamics (FTT) or entropy generation minimization (EGM). The optimum heat conductance distribution corresponding to the optimum power density of the hot- and cold-side heat exchangers for the fixed heat exchanger inventory is analysed using numerical examples. The influence of some design parameters on the optimum heat conductance distribution and the maximum power density and the optimum pressure ratio corresponding to the maximum power density are provided. The power plant design with optimization leads to higher efficiency and smaller size.} \fnm{3}{Author to whom correspondence should be addressed.

Influence of gas flow rate and reactor length on NO removal using pulsed power

Abstract: A short duration of 100-ns pulsed power has been used to remove nitric oxide (NO) in a mixture of nitrogen, oxygen, water vapor, and NO, simulating flue gases from a power station. The effects of the gas flow rate, the reactor length, and the pulse repetition rate on the percentage of NO removal and its energy efficiency are reported. The percentage of NO removal at a fixed gas flow rate increased with increasing pulse repetition rate due to the increased energy into the discharge. At a fixed pulse rate, the removal of NO increased with decreasing gas flow rate due to the increased residence time of the gas in the discharge reactor, thus facilitating the creation of increased radicals of O and N which then decreased NO. The energy removal efficiency of NO (in mol/kWh) decreased with increasing gas flow rate and increasing removal ratio of NO. The removal of NO increased with increasing energy density (J/I), input into the discharge at different reactor length.

Power plant operation control system and a power plant maintaining and managing method

Abstract: Quick recovery or recovery support of a faulty power generating facility by real time diagnoses such as facility failure diagnosis, supervision for failure symptoms, facility diagnosis by evaluation of performance using databases between the power generating facilities and an operation control system. The operation control system transfers information on operating status and secular characteristic changes of apparatus from power generating facilities or information from operators of selected power generating facilities. The level of a failure of a power generating facility which has a failure is evaluated and repairing information (e.g. recovery procedures, processes, required parts, inventory of the parts, possible failure causes, etc.) is automatically created from repairing information prepared in advance for each evaluation condition. The repairing information is then sent to the operation supporting section of the power generating facility.