Showing papers on "Power station published in 1996"

Tracing the flow of electricity

Abstract: Continuing trend towards deregulation and unbundling of transmission services has resulted in the need to assess what the impact of a particular generator or load is on the power system. A new method of tracing the flow of electricity in meshed electrical networks is proposed which may be applied to both real and reactive power flows. The method allows assessment of how much of the real and reactive power output from a particular station goes to a particular load. It also allows the assessment of contributions of individual generators (or loads) to individual line flows. A loss-apportioning algorithm has also been introduced which allows the break down of the total transmission loss into components to be allocated to individual loads or generators. The method can be useful in providing additional insight into power system operation and can be used to modify existing tariffs of charging for transmission loss, reactive power and transmission services.

Boiler deposits from firing biomass fuels

Abstract: Alkali in the ash of annual crop biomass fuels creates serious fouling and slagging in conventional boilers. Even with the use of sorbents and other additives, power plants can fire only limited amounts of these fuels in combination with wood. The National Renewable Energy Laboratory (NREL). U.S. Department of Energy (DOE), and the biomass power industry conducted eight full-scale firing tests and several laboratory experiments to study the nature and occurrence of deposits. The goal was to increase the quantities of these biofuels which can be used. This paper describes the results of the laboratory and power plant tests which included: tracking and analyzing fuels and deposits by various methods; recording operating conditions; and extensive laboratory testing. These analyses have advanced the understanding of the role of minerals in the combustion of biomass, and their occurrence in biofuels. Deposits occur as a result of the boiler design, fuel properties and boiler operation. The limited furnace volume and high flue gas exit temperatures of most biomass boilers promote slag or deposits from biofuels which contain significant amounts of alkali, sulfur or chlorine and silica. All annual growth, whether from urban tree trimmings, annual crops and residues or energy crops contains sufficient volatile alkali, 0.34 kg GJ − (0.8 lb MMBtu −1 ) or more, to melt in combustion or vaporize and condense on boiler tubes and refractory. Special boiler designs are required for annual crops, including grasses and straws. Addition of magnesium oxide and other additives may be necessary to inhibit alkali volatilization while burning these biofuels.

Power plant engineering

Abstract: Introduction Engineering economics Thermodynamics and power plant cycle analysis Fossil fuels Coal and limestone handling Combustion processes Steam generators Steam turbine generators Steam cycle heat exchangers Fans Pumps Circulating water systems Cycle performance impacts Power plant atmospheric emissions control Water treatment Liquid and solid waste treatment and disposal Electrical systems Plant control systems Site/plant arrangements Gas turbines Fluidized bed combustion Resource recovery Nuclear power Emerging technologies Power plant planning and design Permitting and environmental review requirements Appendix: Conversion Table

Design and dynamic response characteristics of 400 MW adjustable speed pumped storage unit for Ohkawachi Power Station

Abstract: At 400 MW, the world's largest adjustable speed pumped storage unit for Ohkawachi Power Station, the Kansai Electric Power Co., Inc., Japan, was commissioned on Dec. 3, 1993. It can change power in steps of at least 32 MW in the generate mode and at least 80 MW in the pump mode, within 0.2 s. This paper describes principal design considerations for the control systems of the machine and presents actual performance of the machine with reference to some typical oscillograph charts.

Performance of a 10 kW power electronic interface for combined wind/PV isolated generating systems

Abstract: The hoped exploitation of pollution-free, low cost, renewable energy resources has always stirred up interest and inventiveness. The double-input single-output DC/DC power converter discussed in this paper, developed for combined wind-photovoltaic generating systems, aims to mitigate the output power fluctuations due to the intermittent nature of both solar and wind energy. Digital control of the whole apparatus also contributes to optimise the converter modes of operation, running both the energy input circuits at their maximum power level. The paper reports an overall description of the power interface characteristics and experimental results recorded in extensive laboratory tests of a 10 kW rated prototype.

A liquefied natural gas (lng) fueled combined cycle power plant and an lng fueled gas turbine plant

Abstract: A process and system which improves the capacity and efficiency of a power plant. A LNG supply system fuels the plant. Gasified LNG in a combustor mixes with the air from an air compressor to provide the hot combustion gas for a gas turbine. The expanding LNG is used to chill a heat exchange fluid, e.g. water, which heat exchange fluid cools and densifies the intake air for the air compressor. Subsequently, the heat exchange fluid is used in another heat exchange step and is then re-chilled and recycled to cool and densify the intake air.

Power generation plant and control apparatus therefor

Abstract: The object of the invention is to provide an electric power plant and a control apparatus therefor which can obtain an emergency power supply reliably through use of the turbine starter. Another generator different from the main generator coupled to the rotor shaft of the turbine is provided to the input side of the starter via a motor, and a control apparatus is provided for electrically connecting the starter and the generators responsive to a bus voltage from the in-house power supply unit which supplies electricity to a plurality of auxiliary equipment operating in the electric power plant. Thereby, an emergency power supply can be obtained reliably by the simple configuration of the invention without installing emergency power generation facilities such as a diesel engine, gas turbine or the like. In addition, an LCI device which has been utilized only at the time of turbine start up can be utilized advantageously also at the time of emergency when the in-house power supply is lost.

Development of an advanced power system stabilizer using a strict linearization approach

Abstract: This paper presents a practical design for a power system stabilizer using the differential geometric linearization approach. This stabilizer uses the information at the secondary bus of the step-up transformer as input signals, enabling its application to multi-machine power systems. The stabilizer makes it possible to obtain all necessary information within its own power station without observing an equivalent reactance in other power systems. To evaluate the dynamic performance of this stabilizer, the authors tested it on a multimachine power system computer model. The simulation results showed that the stabilizer offered good dynamic performance and robustness compared with conventional power system stabilizers, thus confirming its very effective and practical application in power system stabilization.

An in-space wireless energy transmission experiment

Abstract: The concept for an orbiting power satellite capable of supplying the needs of several co-orbiting manufacturing satellites is similar to the central power station and distribution network found on Earth. An experiment for testing a portion of such an "Orbital Power and Light" space power utility system-a retrodirective phased array energy transmission system in space-is described. The experiment will demonstrate the ability of a wireless power transmission system to acquire and maintain a target in space. The experiment will consist of a planar phased array antenna on the Space Shuttle beaming to a target rectenna with a pilot guide beam on the free flying Wake Shield Facility (WSF).

The Cascaded Humidified Advanced Turbine (CHAT)

Abstract: This paper introduces the Cascaded Humidified Advanced Turbine (CHAT) plant, a gas turbine based power generation plant utilizing intercooling, reheat, and humidifi- cation. It is based upon the integration of an existing heavy duty gas turbine with an additional shaft comprising industrial compressors and high pressure expander. CHAT capitalizes on the latest proven gas turbine technology, which, combined with a sophisticated thermal cycle configuration, results in substantial improvement in gas turbine efficiency, compared to a simple cycle, while still maintaining typical advantages and merits of a combustion turbine plant. Built with a commercial combustion turbine and available industrial compressors and expanders, the CHAT plant does not require extensive product development and testing. As a result, the CHAT power plant can be offered with specific capital costs up to 20 percent lower than the combined cycle plant, and with competing efficiency. Compared to a combined cycle plant, the CHAT plant offers lower emissions (due to air humidification) and other significant operating advantages with regard to start-up time and costs, better efficiency at part load, lower power degradation at higher ambient temperatures, and simpler operations and maintenance due to elimination of the complexities and costs associated with steam production. The CHAT plant also integrates very effectively with coal gasification and particularly well with the water quench design. This feature has been discussed in previous publications.

A decentralized controller design for a power plant using robust local controllers and functional mapping

Abstract: This paper presents a design approach for a decentralized controller for a power plant. An electric power plant nonlinear model is decomposed into three subsystems: boiler, turbine, and generator. The interconnecting variables between the subsystems are treated as constant boundary conditions for the controller design. The local controllers are designed to be robust in order to accommodate fluctuations in the interaction variables once the overall system is considered. The drum pressure set-point is automatically obtained from the power demand through a functional mapping.

Wood cofiring evaluation at TVA power plants

Abstract: Foster Wheeler Environmental and Reaction Engineering International (REI) conducted site-specific case studies of cofiring wood-derived fuel and coal at existing fossil-fired boilers within the Tennessee Valley Authority (TVA) power generation system. The case studies were part of a one-year strategic biomass assessment of the TVA region, jointly funded by TVA Research and Development, the National Renewable Energy Laboratory (NREL/DOE), and the Electric Power Research Institute (EPRI). This paper addresses TVA's interest in utilizing biomass as a power generation option and the progress of the cofiring case studies through 1993. The analyses demonstrate that wood cofiring is economically feasible at cyclone boiler installations and may be a low-cost CO2 mitigation strategy for many pulverized coal boilers.

Power plant performance management systems and methods

Abstract: A steam powered electric power generating station to provide electricity comprises a steam turbine positioned in a steam turbine shell, equipment, such as a heater, a first and a second temperature detector, and a computer. The steam turbine has necessary blades and a rod to turn an electrical generator to create electricity. The steam turbine shell mechanically coupled to receive steam to turn the at least one blade steam turbine. The equipment is mechanically coupled to the steam turbine shell to receive steam from the steam turbine shell and receives feed water through an entry port and releases feed water heater through an exit port. The first temperature detector is positioned to detect a first temperature of the feed water prior to entering the equipment via the entry port. The second temperature detector is positioned to detect a second temperature of the feed water after exiting the first piece of feed water via the exit port. The computer is electrically coupled to the first temperature detector and to the second temperature detector and compares the first temperature to the second temperature to generate a temperature difference which is used to monitor station performance. Related processes comprise detecting a first temperature of feed water immediately before the feed water has entered heating equipment and a second temperature of the feed water immediately after the feed water has entered the heating equipment; comparing the first temperature to the second temperature to generate a temperature difference therebetween comparing the temperature difference with a preferred temperature difference to determine whether the temperature difference is within an approved range from the preferred temperature difference; generating a warning signal to alert the power plant operator if the temperature difference is not within the approved range; and taking corrective action to keep the station operating at desired efficiency levels.

Rotary wing model aircraft

Abstract: A model rotary wing aircraft is provided that includes a fuselage, a power plant, a main rotor, a tail rotor, and a drive apparatus. The power plant includes a passive cooling system to transfer heat produced by the power plant to the atmosphere. The passive cooling system consumes less than about five percent of the power produced by the power plant. The main rotor is driven by the power plant at a main rotor speed of rotation and the tail rotor is driven by the power plant at a tail rotor speed of rotation. The drive apparatus transfers power from the power plant to the main rotor and tail rotor to rotate the tail rotor at a tail rotor speed of rotation that is about three times greater than the main rotor speed of rotation to minimize the amount of power used by the tail rotor.

A numerical method for power plant simulations

Abstract: This paper describes a highly flexible computerized method of calculating operating data in a power cycle. The computerized method presented here permits the study of steam, gas and combined plants. Its flexibility is not restricted by any defined cycle scheme. A power plant consists of simple elements (turbine, compressor, combustor chamber, pump, etc.). Each power plant component is represented by its typical equations relating to fundamental mechanical and thermodynamic laws, so a power plant system is represented by algebraic equations, which are the typical equations of components, continuity equations, and data concerning plant conditions. This equation system is not linear, but can be reduced to a linear equation system with variable coefficients. The solution is simultaneous for each component and it is determined by an iterative process. An example of a simple gas turbine cycle demonstrates the applied technique. This paper also presents the user interface based on MS-Windows. The input data, the results, and any characteristic parameters of a complex cycle scheme are also shown.

Remote cranking of steam electric stations

Abstract: This paper focuses industry attention on power system restoration. During the initial phase of restoration, black-start combustion turbines are often considered as remote cranking sources for the start-up of steam electric stations. In general, remote cranking operation is carefully planned, simulated and then verified by field tests. This paper describes the planning and simulation used in black-start of two coal-fired generating units utilizing remote combustion turbines. It discusses a number of constraints which have to be considered and simulated in preparation for testing and verification. The paper concludes that, in order to minimize the possibility of damage to equipment during testing or actual restoration, it is necessary to undertake extensive simulation of the procedure. It recommends that the realistic generator reactive capability models be made a part of the network models to allow: optimum selections of tap positions for all the transformers within the remote cranking power system, thus providing adequate lead/lag reactive powers and to maintain acceptable voltage profile while proceeding through various stages of operation.

The Equivalence of Maximum Power and Minimum Entropy Generation Rate in the Optimization of Power Plants

Abstract: It is shown that to maximize the power output of a power plant is equivalent to minimizing the total entropy generation rate associated with the power plant. This equivalence is illustrated by using two of the oldest and simplest models of power plants with heat transfer irreversibilities. To calculate the total entropy generation rate correctly, one must recognize that the optimization process (e.g., the variability of the heat input) requires ``room to move,`` i.e., an additional, usually overlooked, contribution to the total entropy generation rate.

Reliability‐centred maintenance applied to power plant auxiliaries

Abstract: Availability of auxiliary equipment for coal‐based power plants is very important for the achievement of maximum generation and the improvement of plant load factor (PLF). In this context a realistic maintenance programme based on plant‐specific failure data will help to achieve an optimum performance level. Reliability‐centred maintenance (RCM) is a recent technique which is limited to a few areas and has implementation difficulties. Presents a realistic RCM‐based maintenance methodology for coal‐based power plant auxiliaries. Applies the methodology to the bowl mill, an item of auxiliary equipment. Presents results and savings that have been achieved with the application of the methodology.

Relocatable static var compensators help control unbundled power flows

Abstract: In competitive electricity markets, the operators of electricity transmission networks may no longer have direct control over the siting of power plant nor of the timing of plant retirement. Combined with variability in load patterns, these changes lead to new requirements for reactive power control and power system planning. In England and Wales, the National Grid Company plc (NGC) has identified the need for reactive power plant that can be relocated at short notice, and GEC Alsthom's T&D division has been commissioned to design and install three relocatable static var compensators at NGC's Iron Acton substation near Bristol.