Showing papers on "Electric power published in 2004"

Power electronics as efficient interface in dispersed power generation systems

Abstract: The global electrical energy consumption is rising and there is a steady increase of the demand on the power capacity, efficient production, distribution and utilization of energy. The traditional power systems are changing globally, a large number of dispersed generation (DG) units, including both renewable and nonrenewable energy sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave generators, and gas/steam powered combined heat and power stations, are being integrated into power systems at the distribution level. Power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems. This paper reviews the applications of power electronics in the integration of DG units, in particular, wind power, fuel cells and PV generators.

Power Electronics as Efficient Interface in Dispersed Power Generation Systems

Abstract: The global electrical energy consumption is rising and there is a steady increase of the demand on the power capacity, efficient production, distribution and utilization of energy. The traditional power systems are changing globally, a large number of dispersed generation (DG) units, including both renewable and nonrenewable energy sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave generators, and gas/steam powered combined heat and power stations, are being integrated into power systems at the distribution level. Power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems. This paper reviews the applications of power electronics in the integration of DG units, in particular, wind power, fuel cells and PV generators.

Renewable and Efficient Electric Power Systems

Abstract: Preface.1 Basic Electric and Magnetic Circuits.1.1 Introduction to Electric Circuits.1.2 Definitions of Key Electrical Quantities.1.3 Idealized Voltage and Current Sources.1.4 Electrical Resistance.1.5 Capacitance.1.6 Magnetic Circuits.1.7 Inductance.1.8 Transformers.2 Fundamentals of Electric Power.2.1 Effective Values of Voltage and Current.2.2 Idealized Components Subjected to Sinusoidal Voltages.2.3 Power Factor.2.4 The Power Triangle and Power Factor Correction.2.5 Three-Wire, Single-Phase Residential Wiring.2.6 Three-Phase Systems.2.7 Power Supplies.2.8 Power Quality.3 The Electric Power Industry.3.1 The Early Pioneers: Edison, Westinghouse, and Insull.3.2 The Electric Utility Industry Today.3.3 Polyphase Synchronous Generators.3.4 Carnot Efficiency for Heat Engines.3.5 Steam-Cycle Power Plants.3.6 Combustion Gas Turbines.3.7 Combined-Cycle Power Plants.3.8 Gas Turbines and Combined-Cycle Cogeneration.3.9 Baseload, Intermediate and Peaking Power Plants.3.10 Transmission and Distribution.3.11 The Regulatory Side of Electric Power.3.12 The Emergence of Competitive Markets.4 Distributed Generation.4.1 Electricity Generation in Transition.4.2 Distributed Generation with Fossil Fuels.4.3 Concentrating Solar Power (CSP) Technologies.4.4 Biomass for Electricity.4.5 Micro-Hydropower Systems.4.6 Fuel Cells.4.6.7 Electrical Characteristics of Real Fuel Cells.4.6.8 Types of Fuel Cells.4.6.9 Hydrogen Production.5 Economics of Distributed Resources.5.1 Distributed Resources (DR).5.2 Electric Utility Rate Structures.5.3 Energy Economics.5.4 Energy Conservation Supply Curves.5.5 Combined Heat and Power (CHP).5.6 Cooling, Heating, and Cogeneration.5.7 Distributed Benefits.5.8 Integrated Resource Planning (IRP) and Demand-Side Management (DSM).6 Wind Power Systems.6.1 Historical Development of Wind Power.6.2 Types of Wind Turbines.6.3 Power in the Wind.6.4 Impact of Tower Height.6.5 Maximum Rotor Efficiency.6.6 Wind Turbine Generators.6.7 Speed Control for Maximum Power.6.8 Average Power in the Wind.6.9 Simple Estimates of Wind Turbine Energy.6.10 Specific Wind Turbine Performance Calculations.6.11 Wind Turbine Economics.7 The Solar Resource.7.1 The Solar Spectrum.7.2 The Earth's Orbit.7.3 Altitude Angle of the Sun at Solar Noon.7.4 Solar Position at any Time of Day.7.5 Sun Path Diagrams for Shading Analysis.7.6 Solar Time and Civil (Clock) Time.7.7 Sunrise and Sunset.7.8 Clear Sky Direct-Beam Radiation.7.9 Total Clear Sky Insolation on a Collecting Surface.7.10 Monthly Clear-Sky Insolation.7.11 Solar Radiation Measurements.7.12 Average Monthly Insolation.8 Photovoltaic Materials and Electrical Characteristics.8.1 Introduction.8.2 Basic Semiconductor Physics.8.3 A Generic Photovoltaic Cell.8.4 From Cells to Modules to Arrays.8.5 The PV I -V Curve Under Standard Test Conditions (STC).8.6 Impacts of Temperature and Insolation on I -V Curves.8.7 Shading impacts on I-V curves.8.8 Crystalline Silicon Technologies.8.9 Thin-Film Photovoltaics.9 Photovoltaic Systems.9.1 Introduction to the Major Photovoltaic System Types.9.2 Current-Voltage Curves for Loads.9.3 Grid-Connected Systems.9.4 Grid-Connected PV System Economics.9.5 Stand-Alone PV Systems.9.6 PV-Powered Water Pumping.APPENDIX A: Useful Conversion Factors.APPENDIX B: Sun-Path Diagrams.APPENDIX C: Hourly Clear-Sky Insolation Tables.APPENDIX D: Monthly Clear-Sky Insolation Tables.APPENDIX E: Solar Insolation Tables byCity.APPENDIX F: Maps of Solar Insolation.Index.

Neural network based sensorless maximum wind energy capture with compensated power coefficient

Abstract: This work describes a small wind generation system where neural network principles are applied for wind speed estimation and robust maximum wind power extraction control against potential drift of wind turbine power coefficient curve. The new control system will deliver maximum electric power to a customer with lightweight, high efficiency, and high reliability without mechanical sensors. A turbine directly driven permanent magnet synchronous generator (PMSG) is considered for the proposed small wind generation system in this paper. The new control system has been developed, analyzed and verified by simulation studies. Performance has then been evaluated in detail. Finally, the proposed method is also applied to a 15 kW variable speed cage induction machine wind generation (CIWG) system and the experimental results are presented.

Power line communications

Abstract: This article overviews the power line communication, which is originally devised to transmit electric power from a small number of sources to a large number of sinks. Initially the first data transmission were over power lines were primarily done only to protect sections of the power distribution system in case of faults. This paper also studies the performance of power lines for high bit rate applications. DMT technology is adopted by the homeplug standard can theoretically provide data rates of 100Mb/s. However, products based on the standard only have achieved data rates up to 14 Mb/s. To protect against the severe noisy conditions and fading in the powerline channel, very high levels of error control coding need to be provided. The efforts of the homeplug alliance and home networking technology's growth in the US portend a very bright future for DMT-based PLC home networking.

System and method for assigning an identity to an intelligent electronic device

Abstract: A power management architecture for an electrical power distribution system, or portion thereof, is disclosed. The architecture includes multiple intelligent electronic devices (“IED's”) distributed throughout the power distribution system to manage the flow and consumption of power from the system. The IED's are linked via a network to back-end servers. Security mechanisms are further provided which protect and otherwise ensure the authenticity of communications transmitted via the network in furtherance of the management of the distribution and consumption of electrical power by the architecture. In particular, public key cryptography is employed to identify components of the architecture and provide for secure communication of power management data among those components. Further, certificates and certificate authorities are utilized to further ensure integrity of the security mechanism.

Efficiency of energy conversion for devices containing a piezoelectric component

Abstract: Recent developments in miniaturized sensors, digital processors and wireless communication systems have many desirable applications. The realization of these applications however, is limited by the lack of a similarly sized power source. Micro-scale concepts to generate electrical power include devices which use the stored energy in fuels to those which harvest energy from the environment. Many proposed power generation systems employ a piezoelectric component to convert the mechanical energy to electrical energy. Of primary importance is the efficiency of power conversion. In this paper, an exact formula is developed that predicts the power conversion efficiency for a device that contains a piezoelectric component. This formula transparently and quantitatively reveals a trade-off effect on efficiency caused by the quality factor and electromechanical coupling factor of the device. In particular, decreasing the structural stiffness leads to the largest gains in efficiency, followed by decreasing the mechanical damping and increasing the effective mass.

System and method for securing energy management systems

Abstract: A power management architecture for an electrical power distribution system, or portion thereof, is disclosed The architecture includes multiple intelligent electronic devices (“IED's”) distributed throughout the power distribution system to manage the flow and consumption of power from the system The IED's are linked via a network to back-end servers Power management application software and/or hardware components operate on the IED's and the back-end servers and inter-operate via the network to implement a power management application The architecture provides a scalable and cost effective framework of hardware and software upon which such power management applications can operate to manage the distribution and consumption of electrical power by one or more utilities/suppliers and/or customers which provide and utilize the power distribution system Security mechanisms are further provided which protect and otherwise ensure the authenticity of communications

Micromachined CMOS thermoelectric generators as on-chip power supply

Abstract: As the power consumption of a large number of microelectronic devices has been continuously reduced in recent years, power supply units of a few microwatts have become sufficient for their operation. Our improved micro-scale thermoelectric generator (μ-TEG) is based on polysilicon surface micromachining and is designed to convert waste heat into electrical power. Since this device is compatible with standard CMOS fabrication processes, it can be easily integrated on chip level and matches the needs for low-cost and small-size systems. As thermoelectric materials, both, pure poly-Si and poly-Si 70% Ge 30% have been investigated. Emphasis was placed on a thermally optimized design and the reduction of the total electrical resistance of the generator. As a result of these improvements, a voltage of 5 V and an electrical power output of 1 μW for a matched consumer is achieved with generators of 1 cm 2 in size at a temperature drop of about 5 K.

Spacecraft Power Systems

Abstract: POWER SYSTEM FUNDAMENTALS Satellite Overview Near-Earth Space Environment Power System Options Photovoltaic-Battery System Environmental Effects Power System Requirements Design Process and Trades PV-BATTERY SYSTEM Solar Array Battery Power Electronics and Magnetics Distribution Harness and Protection Ancillary Components POWER SYSTEM PERFORMANCE Energy Balance and Power Management Dynamic Performance and Stability Electromagnetic Interference and Compatibility Electrostatic Discharge Reliability and Derating Integration and Testing SPECIAL POWER SYSTEMS Interplanetary and Deep-Space Missions Radioisotope Thermoelectric Generator Dynamic Systems with Alternator High-Power High-Voltage Systems Electric Propulsion Fuel Cell Power Flywheel Energy Storage Superconductors in Space Microwave Beam Power Satellite

Power generation system

Abstract: A system for generating an electrical power output from a subsea installation that includes at least one flowline, wherein the system includes a turbine that is operatively connected to the flowline, the turbine being rotatable by fluid flowing through the flowline, and the turbine generating the electrical power output when the turbine is rotated.

Electric vehicles charge forward

Abstract: This article reviews the status of electric vehicles/hybrid electric vehicles (EV/HEVs) worldwide and their state of the art, with emphasis on the engineering philosophy and key technologies. The importance of the integration of technologies of automobile, electric motor drive, electronics, energy storage and controls, and the importance of the integration of society strength from government, industry, research institutions, electric power utilities, and transportation authorities are addressed. The challenged of EV commercialization is discussed. EV is a multidisciplinary subject involving broad and complex aspects. However, it has core technologies; chassis and body technology, propulsion technology, and energy source technology. The electric propulsion system is the heart of the EV. It consists of motor drive, transmission and controller, plus the integration with engine power train in the case of the HEV.

System and methods for maintaining power usage within a set allocation

Abstract: An electric power management system includes a monitor for the total power usage of a facility that monitors a history of power consumption during a set time interval of a distribution system having at least one electric load. Predictions of available power are generated through out the time interval by comparing the history of power consumption to a set allocation. Available power predictions are transmitted to the at least one electric load. The at least one load control receives the power capability predictions and controls the energy usage of the at least one electric load such that the total energy usage of the facility does not exceed the set allocation.

Executive overview: energy storage options for a sustainable energy future

Abstract: Sustainability of electric power systems will involve very large use of renewable energy sources for power production. Some of these sources, e.g. wind and solar, have a characteristic stochastic behaviour, which makes their output power production difficult to predict and have high power output fluctuations. Energy storage devices will be needed at different locations in the power system, to level the mismatch between renewable power generators and consumption and/or to store the surplus of power from renewable sources for later use during nongeneration time periods or low power generation time periods. This presentation will give an overview of different storage technologies and how they can be used in a sustainable power system.

Optimization of electrical distribution feeders using simulated annealing

Abstract: The planning of electrical power distribution systems strongly influences the supply of electrical power to consumers. The problem is to minimize both the investment cost for feeder and substations, and the power-loss cost. When the substations can already provide enough power flow, then the problem reduces to minimize the total cost related to the feeders and their power-loss. The difficulty of dealing with this problem increases rapidly with its size (i.e., the number of customers). It seems appropriate to use heuristic methods to obtain suboptimal solutions, since exact methods are too much time consuming. In this paper, a simulated annealing algorithm is used. A set of numerical results are provided.

Electric power applications of superconductivity

Abstract: The development of superconducting systems for electric power is driven by the promise of improved efficiency, smaller size, and reduced weight as compared to existing technologies and by the possibility of new applications. Superconducting power components can also contribute to improved power quality and increased system reliability. This paper addresses historical developments and technology status of four superconducting power applications: cables, superconducting magnetic energy storage (SMES), fault-current limiters, and transformers. Today, SMES is the only fully functional superconducting system and it has seen only limited use at grid power levels. A few model or demonstration units exist for each of the other three applications. Superconductivity faces several hurdles on the path to widespread use. Perhaps the most important is the need for operating voltages of 100 kV or more. Though progress in this and other areas has been rapid, considerable development is needed before superconducting devices perform reliably in the utility environment. As a result, today, most initial installations are aimed at niche applications and will be installed where space is limited, where power demands are increasing over existing corridors, and/or where initial development costs can be offset by enhanced power grid performance.

Modular power distribution system for use in computer equipment racks

Abstract: A modular power distribution system is provided for distributing power within an equipment rack. One particular power distribution system has a control unit that is mounted proximate a rack including a power input for receiving power from a power source located outside the rack. The control unit includes a power converter for converting the received power to an output electrical power, and a plurality of power outlets for providing an electrical connection to the control unit and outputting the output electrical power. This particular power distribution system also includes an extension means mounted proximate the rack and having an electrical power input for input of electrical power to the extension means and a plurality of power outlets adapted to couple with and distribute electrical power to conducting elements that electrically connect the extension means to the mounted equipment. This particular power distribution system further includes an electrical power cable connected to one of the power outlets in the control unit and to the electrical power input of the extension means.

Method and system for improved reliability in storage devices

Abstract: A method of preventing data loss in a data storage system includes supplying write data to a high speed volatile write buffer and supplying electrical power from an energy storage device upon detection of a primary power loss event. The backup electrical power is supplied to the write buffer and nonvolatile cache. Under backup power, the write data is transferred into the nonvolatile cache and the backup power is removed. Upon regaining main power, a data presence indication triggers a transfer of the write data from the nonvolatile cache to the long term storage media. The method may be implemented for a system to protect it from inadvertent power losses or it may implemented in a system where the long term storage device is power cycled to save power. The energy storage device is not necessarily needed in the power cycled system unless power failure protection is also desired.

Ultra-wideband communication through local power lines

Abstract: A system, method and apparatus structured to transmit a plurality of ultra-wideband pulses through an electric power medium (305) are provided. One embodiment of the method comprises an ultra-wideband transmitter (302) structured to transmit the plurality of ultra-wideband pulses through the electric power medium (305) and an ultra-wideband receiver (302) structured to receive the plurality of ultra-wideband pulses from the electric power medium (305). Another embodiment of the present invention comprises a power supply that provides ultra-wideband communications to devices that obtain power from the power supply.

A microturbine for electric power generation

Abstract: A single-stage axial microturbine has been developed with a rotor diameter of 10 mm. This turbine is a first step in the development of a microgenerator that produces electrical energy from fuel. The turbine is made of stainless steel using die-sinking electro-discharge machining. It has been tested to speeds up to 160,000 rpm and generates a maximum mechanical power of 28 W with an efficiency of 18%. When coupled to a small generator, it generates 16 W of electrical power, which corresponds to an efficiency for the total system of 10.5%.

Method for operating or controlling a wind turbine and method for providing primary control power by means of wind turbines

Abstract: A method for operating at least one wind turbine with a rotor and an electric generator coupled to the rotor for delivering electrical power into an energy distribution system with the aid of a control device ensures that the wind turbine operates within its operating range. The wind turbine is controlled in response to the change of a system operating parameter and for a period of time, in such a manner that a higher power is fed into the system than belongs to the operating range of the steady-state operation. The same conditions also apply to a method for providing control power or primary control power for an electric energy generator and distributor system to which a multiplicity of power stations including wind turbines is connected, and to a wind turbine.

Inductively coupled plasma/partial oxidation reformation of carbonaceous compounds to produce fuel for energy production

Abstract: Inductively coupled plasma (ICP) reforming converts carbonaceous compounds into a fuel for use in generating electrical power. Energy rich hydrocarbon fuels, such as coal, marine diesel, oils, and hydrocarbon wastes are employed as a feedstock for the ICP, which transforms the feedstock into a fuel that can be used by fuel cells and gas turbines for the production of electricity. The overall efficiency of an ICP-based electrical power system can be increased by providing partial oxidation within the reaction vessel. The partial oxidation conditions consume a small amount of the reformed fuel gas, thereby liberating sufficient thermal energy to reduce the electrical power requirements of the ICP to maintain desired reactor temperatures, and providing an increase in the overall net electrical power production. The integrated power production system can also adjust to meet an increased requirement for process heat and steam by balancing the effect of partial oxidation.

Valuation and Optimal Operation of Electric Power Plants in Competitive Markets

Abstract: We present an algorithm for the valuation and optimal operation of hydroelectric and thermal power generators in deregulated electricity markets. Real options theory is used to derive nonlinear partial-integro-differential equations (PIDEs) for the valuation and optimal operating strategies of both types of facilities. The equations are designed to incorporate a wide class of spot price models that can exhibit the same time-dependent, mean-reverting dynamics and price spikes as those observed in most electricity markets. Particular attention is paid to the operational characteristics of real power generators. For thermal power plants, these characteristics include variable start-up times and costs, control response time lags, minimum generating levels, nonlinear output functions, and structural limitations on ramp rates. For hydroelectric units, head effects and environmental constraints are addressed. We illustrate the models with numerical examples of a pump storage facility and a thermal power plant. This PIDE framework can achieve high levels of computational speed and accuracy while incorporating a wide range of spot price dynamics and operational characteristics.