Showing papers on "Electric power published in 2007"

Instantaneous power theory and applications to power conditioning

Abstract: Preface. 1. Introduction. 1.1. Concepts and Evolution of Electric Power Theory. 1.2. Applications of the p-q Theory to Power Electronics Equipment. 1.3. Harmonic Voltages in Power Systems. 1.4. Identified and Unidentified Harmonic-Producing Loads. 1.5. Harmonic Current and Voltage Sources. 1.6. Basic Principles of Harmonic Compensation. 1.7. Basic Principles of Power Flow Control. References. 2. Electric Power Definitions: Background. 2.1. Power Definitions Under Sinusoidal Conditions. 2.2. Voltage and Current Phasors and the Complex Impedance. 2.3. Complex Power and Power Factor. 2.4. Concepts of Power Under Non-Sinusoidal Conditions -Conventional Approaches. 2.5. Electric Power in Three-Phase Systems. 2.6. Summary. References. 3 The Instantaneous Power Theory. 3.1. Basis of the p-q Theory. 3.2. The p-q Theory in Three-Phase, Three-Wire Systems. 3.3. The p-q Theory in Three-Phase, Four-Wire Systems. 3.4. Instantaneous abc Theory. 3.5. Comparisons between the p-q Theory and the abc Theory. 3.6. Summary. References. 4 Shunt Active Filters. 4.1. General Description of Shunt Active Filters. 4.2. Three-Phase, Three-Wire Shunt Active Filters. 4.3. Three-Phase, Four-Wire Shunt Active Filters. 4.4. Shunt Selective Harmonic Compensation. 4.5. Summary. References. 5 Hybrid and Series Active Filters. 5.1. Basic Series Active Filter. 5.2. Combined Series Active Filter and Shunt Passive Filter. 5.3. Series Active Filter Integrated with a Double-Series Diode Rectifier. 5.4. Comparisons Between Hybrid and Pure Active Filters. 5.5. Conclusions. References. 6 Combined Series and Shunt Power Conditioners. 6.1. The Unified Power Flow Controller (UPFC). 6.2. The Unified Power Quality Conditioner (UPQC). 6.3. The Universal Active Power Line Conditioner (UPLC). 6.4. Summary. References. Index.

Complex systems analysis of series of blackouts: Cascading failure, critical points, and self-organization

Abstract: We give an overview of a complex systems approach to large blackouts of electric power transmission systems caused by cascading failure. Instead of looking at the details of particular blackouts, we study the statistics and dynamics of series of blackouts with approximate global models. Blackout data from several countries suggest that the frequency of large blackouts is governed by a power law. The power law makes the risk of large blackouts consequential and is consistent with the power system being a complex system designed and operated near a critical point. Power system overall loading or stress relative to operating limits is a key factor affecting the risk of cascading failure. Power system blackout models and abstract models of cascading failure show critical points with power law behavior as load is increased. To explain why the power system is operated near these critical points and inspired by concepts from self-organized criticality, we suggest that power system operating margins evolve slowly to near a critical point and confirm this idea using a power system model. The slow evolution of the power system is driven by a steady increase in electric loading, economic pressures to maximize the use of the grid, and the engineering responses to blackouts that upgrade the system. Mitigation of blackout risk should account for dynamical effects in complex self-organized critical systems. For example, some methods of suppressing small blackouts could ultimately increase the risk of large blackouts.

Moving towards a more electric aircraft

Abstract: The latest advances in electric and electronic aircraft technologies from the point of view of an "all-electric" aircraft are presented herein. Specifically, we describe the concept of a "more electric aircraft" (MEA), which involves removing the need for on-engine hydraulic power generation and bleed air off-takes, and the increasing use of power electronics in the starter/generation system of the main engine. Removal of the engine hydraulic pumps requires fully-operative electrical power actuators and mastery of the flight control architecture. The paper presents a general overview of the electrical power generation system and electric drives for the MEA, with special regard to the flight controls. Some discussion regarding the interconnection of nodes and safety of buses and protocols in distributed systems is also presented

Microgrids and Distributed Generation

Abstract: Application of individual distributed generators can cause as many problems as it may solve. A better way to realize the emerging potential of distributed generation is to take a system approach which views generation and associated loads as a subsystem or a “microgrid.” The sources can operate in parallel to the grid or can operate in island, providing utility power station services. The system will disconnect from the utility during large events (e.g., faults and voltage collapses), but may also intentionally disconnect when the quality of power from the grid falls below certain standards. Utilization of waste heat from the sources will increase total efficiency, making the project more financially attractive. University of Wisconsin laboratory verification of microgrid control concepts are included.

The relative cost of biomass energy transport.

Abstract: Logistics cost, the cost of moving feedstock or products, is a key component of the overall cost of recovering energy from biomass. In this study, we calculate for small- and large-project sizes, the relative cost of transportation by truck, rail, ship, and pipeline for three biomass feedstocks, by truck and pipeline for ethanol, and by transmission line for electrical power. Distance fixed costs (loading and unloading) and distance variable costs (transport, including power losses during transmission), are calculated for each biomass type and mode of transportation. Costs are normalized to a common basis of a giga Joules of biomass. The relative cost of moving products vs feedstock is an approximate measure of the incentive for location of biomass processing at the source of biomass, rather than at the point of ultimate consumption of produced energy. In general, the cost of transporting biomass is more than the cost of transporting its energy products. The gap in cost for transporting biomass vs power is significantly higher than the incremental cost of building and operating a power plant remote from a transmission grid. The cost of power transmission and ethanol transport by pipeline is highly dependent on scale of project. Transport of ethanol by truck has a lower cost than by pipeline up to capacities of 1800 t/d. The high cost of transshipment to a ship precludes shipping from being an economical mode of transport for distances less than 800 km (woodchips) and 1500 km (baled agricultural residues).

Supplying Baseload Power and Reducing Transmission Requirements by Interconnecting Wind Farms

Abstract: Wind is the world’s fastest growing electric energy source. Because it is intermittent, though, wind is not used to supply baseload electric power today. Interconnecting wind farms through the transmission grid is a simple and effective way of reducing deliverable wind power swings caused by wind intermittency. As more farms are interconnected in an array, wind speed correlation among sites decreases and so does the probability that all sites experience the same wind regime at the same time. The array consequently behaves more and more similarly to a single farm with steady wind speed and thus steady deliverable wind power. In this study, benefits of interconnecting wind farms were evaluated for 19 sites, located in the midwestern United States, with annual average wind speeds at 80 m above ground, the hub height of modern wind turbines, greater than 6.9 m s 1 (class 3 or greater). It was found that an average of 33% and a maximum of 47% of yearly averaged wind power from interconnected farms can be used as reliable, baseload electric power. Equally significant, interconnecting multiple wind farms to a common point and then connecting that point to a far-away city can allow the long-distance portion of transmission capacity to be reduced, for example, by 20% with only a 1.6% loss of energy. Although most parameters, such as intermittency, improved less than linearly as the number of interconnected sites increased, no saturation of the benefits was found. Thus, the benefits of interconnection continue to increase with more and more interconnected sites.

Wireless Power Supply System and Wireless Power Supply Method

Abstract: An object is to provide a system for improving convenience for users, by which a portable electronic device or the like can be charged even in a place where utility power is not available. Another object is to provide a system which allows a service provider to easily perform customer management. A wireless power supply system includes a power storage device having a power storage portion, a terminal charging device for wirelessly supplying electric power to the power storage device, and a management server having user information. Electric power can be supplied to specified users by intercommunication of user information between the power storage device and the terminal charging device and between the terminal charging device and the management server.

Fuel cell power conditioning for electric power applications: a summary

Abstract: Fuel cells are considered to be one of the most promising sources of distributed energy because of their high efficiency, low environmental impact and scalability. Unfortunately, multiple complications exist in fuel cell operation. Fuel cells cannot accept current in the reverse direction, do not perform well with ripple current, have a low output voltage that varies with age and current, respond sluggishly to step changes in load and are limited in overload capabilities. For these reasons, power converters are often necessary to boost and regulate the voltage as a means to provide a stiff applicable DC power source. Furthermore, the addition of an inverter allows for the conversion of DC power to AC for an utility interface or for the application of an AC motor. To help motivate the use of power conditioning for the fuel cell, a brief introduction of the different types, applications and typical electrical characteristics of fuel cells is presented. This is followed by an examination of the various topologies of DC-DC boost converters and inverters used for power conditioning of fuel cells. Several architectures to aggregate multiple fuel cells for high-voltage/high-power applications are also reviewed.

Marine Tidal Current Electric Power Generation Technology: State of the Art and Current Status

Abstract: The potential of electric power generation from marine tidal currents is enormous. Tidal currents are being recognized as a resource to be exploited for the sustainable generation of electrical power. The high load factors resulting from the fluid properties and the predictable resource characteristics make marine currents particularly attractive for power generation and advantageous when compared to other renewable energies. Moreover, international treaties related to climate control have triggered resurgence in development of renewable ocean energy technology. Therefore, several demonstration projects in tidal power are scheduled to capture the tidal generated coastal currents. Regarding this emerging and promising area of research, this paper reviews marine tidal power fundamental concepts and main projects around the world. It also report issues regarding electrical generator topologies associated to tidal turbines. Moreover, attempts are made to highlight future issues so as to index some emerging technologies mainly according to relevant works that have been carried out on wind turbines and on ship propellers.

Power plant conceptual studies in Europe

Abstract: The European fusion programme is ‘reactor oriented’ and it is aimed at the successive demonstration of the scientific, the technological and the economic feasibility of fusion power. The European Power Plant Conceptual Study (PPCS) has been a study of conceptual designs of five commercial fusion power plants and the main emphasis was on system integration. It focused on five power plant models which are illustrative of a wider spectrum of possibilities. They are all based on the tokamak concept and they have approximately the same net electrical power output, 1500 MWe. These span a range from relatively near-term, based on limited technology and plasma physics extrapolations, to an advanced conception. The PPCS allows one to clarify the concept of DEMO, the device that will bridge the gap between ITER and the first-of-a-kind fusion power plant. An assessment of the PPCS models with limited extrapolations highlighted a number of issues that must be addressed to establish the DEMO physics and technological basis.

System and method for assessing vehicle to grid (v2g) integration

Abstract: A method for calculating power available for sale from an electric vehicle to an electric power market on a grid includes determining maximum DC power available from the electric vehicle; determining an electrical conversion efficiency related to a conversion of DC power from the electric vehicle to AC power; accounting for a time period in which the DC power is available from the electric vehicle; and calculating the power available for sale from the electric vehicle. A method of assessing economic value of a vehicle to grid arrangement includes calculating a total revenue amount due to providing one or more of peak power, spinning reserves, and regulation services; calculating a cost for each of producing energy, degradation due to wear, and annualized capitalization; summing the calculated costs; and determining the economic value of the vehicle to grid arrangement by comparing the summed calculated costs to the total revenue amount. A computer-implemented system for assessing economic value of a vehicle to grid arrangement includes a computer circuit configured to calculate a total revenue amount due to providing one or more of peak power, spinning reserves, and regulation services; calculate a cost for each of producing energy, degradation due to wear, and annualized capitalization; sum the calculated costs; and determine the economic value of the vehicle to grid arrangement by comparing the summed calculated costs to the total revenue amount.

Electric Power Generation, Transmission, and Distribution

Abstract: ELECTRIC POWER GENERATION: NONCONVENTIONAL METHODS Wind Power Gary L. Johnson Advanced Energy Technologies Saifur Rahman Photovoltaics Roger A. Messenger ELECTRIC POWER GENERATION: CONVENTIONAL METHODS Hydroelectric Power Generation Steven R. Brockschink, James H. Gurney, and Douglas B. Seely Synchronous Machinery Paul I. Nippes Thermal Generating Plants Kenneth H. Sebra Distributed Utilities John R. Kennedy TRANSMISSION SYSTEM Concept of Energy Transmission and Distribution George G. Karady Transmission Line Structures Joe C. Pohlman Insulators and Accessories George G. Karady and R.G. Farmer Transmission Line Construction and Maintenance Wilford Caulkins and Kristine Buchholz Insulated Power Cables used in Underground Applications Michael L. Dyer Transmission Line Parameters Manuel Reta-Hernandez Sag and Tension of Conductor D.A. Douglass and Ridley Thrash Corona and Noise Giao N. Trinh Geomagnetic Disturbances and Impacts upon Power System Operation John G. Kappenman Lightning Protection William A. Chisholm Reactive Power Compensation Rao S. Thallam Environmental Impact of Transmission Lines George G. Karady DISTRIBUTION SYSTEMS Power System Loads Raymond R. Shoults and Larry D. Swift Distribution System Modeling and Analysis William H. Kersting Power System Operation and Control George L. Clark and Simon W. Bowen Hard to Find Information (on Distribution System Characteristics and Protection) Jim Burke Real-Time Control of Distributed Generation Murat Dilek and Robert P. Broadwater ELECTRIC POWER UTILIZATION Metering of Electric Power and Energy John V. Grubbs Basic Electric Power Utilization-Loads, Load Characterization and Load Modeling Andrew Hanson Electric Power Utilization: Motors Charles A. Gross POWER QUALITY Introduction S.M. Halpin Wiring and Grounding for Power Quality Christopher J. Melhorn Harmonics in Power Systems S.M. Halpin Voltage Sags Math H.J. Bollen Voltage Fluctuations and Lamp Flicker in Power Systems S.M. Halpin Power Quality Monitoring Patrick Coleman INDEX

System and method for transferring electrical power between grid and vehicle

Abstract: The present invention discloses a system for transferring electrical power between a grid and at least one vehicle. The vehicle can be Battery Electric Vehicle (BEV), Plug-in Hybrid Electric Vehicle (PHEV) or Fuel Cell Vehicle (FCV). The type of vehicle will be recognized and controlled by the system to support demand response and supply side energy management. Vehicle recognition can be carried out by load signature analysis, power factor measurement or RFID techniques. In an embodiment of the invention, the grid is a Smart Grid. The present invention also discloses a method for facilitating electrical power transfer between the grid and the vehicle.

Cognitive electric power meter

Abstract: An electric power meter includes an embedded decomposition module that is configured to decompose a power meter signal into constituent loads to segregate and identify energy consumption associated with each individual energy consumption device within a plurality of energy consumption devices coupled to the power meter.

The p-q theory in three-phase systems under non-sinusoidal conditions

Abstract: The conventional theory of active and reactive power in single-phase or three-phase systems is based on an average value concept, thus making it impossible to define instantaneous active and reactive power in a real sense. On the basis of an instantaneous value concept, the authors have already proposed a new definition of instantaneous active and reactive power in three-phase circuits for arbitrary voltage and current waveforms without any restriction. This is called the instantaneous reactive power theory or the p-q theory, which is considered a basic theory of active power line conditioners such as reactive power compensators and active power filters for harmonic compensation

Experimental results from sea trials of an offshore wave energy system

Abstract: A full-scale prototype of a wave power plant has been installed off the Swedish west coast and the overall wave energy converter concept has been verified. Initial results have been collected and s ...

Interactive battery charger for electric vehicle

Abstract: A method for recharging an electric storage battery in the charging system of an electric vehicle from an electric utility power grid includes determining the length of time required to recharge the battery, determining the desired time when the recharge is to be completed, transmitting to the electric power utility the length of time required to recharge the battery and the desired time, and recharging the battery from the utility grid during a period when projected load demand is lower than peak demand and ending no later than the desired time.

Power Systems Modelling and Fault Analysis: Theory and Practice

Abstract: Power Systems Modelling and Fault Analysis: Theory and Practice, Second Edition, focuses on the important core areas and technical skills required for practicing electrical power engineers. Providing a comprehensive and practical treatment of the modeling of electrical power systems, the book offers students and professionals the theory and practice of fault analysis of power systems, covering detailed and advanced theories and modern industry practices. The book describes relevant advances in the industry, such as international standards developments and new generation technologies, such as wind turbine generators, fault current limiters, multi-phase fault analysis, the measurement of equipment parameters, probabilistic short-circuit analysis, and more. Includes a fully up-to-date guide to the analysis and practical troubleshooting of short-circuit faults in electricity utilities and industrial power systemsPresents sections on generators, transformers, substations, overhead powerlines and industrial systemsCovers best-practice techniques, safety issues, power system planning and economics

Device having multiple graphics subsystems and reduced power consumption mode, software and methods

Abstract: Many computing device may now include two or more graphics subsystems. The multiple graphics subsystems may have different abilities, and may, for example, consume differing amount of electrical power, with one subsystem consuming more average power than the others. The higher power consuming graphics subsystem may be coupled to the device and used instead of, or in addition to, the lower power consuming graphics subsystem, resulting in higher performance or additional capabilities, but increased overall power consumption. By transitioning from the use of the higher power consuming graphics subsystem to the lower power consuming graphics subsystem, while placing the higher power consuming graphics subsystem in a lower power consumption mode, overall power consumption is reduced.

Communication apparatus and method

Abstract: A communication apparatus (1) for communicating over an electrical power cable (3). The communication apparatus (1) comprises a transmitter circuit (5) adapted to transmit a communication signal; and a receiver circuit (6) adapted to receive a communication signal from another communication apparatus (1). The communication apparatus (1) is adapted to transmit and receive communication signals over the power cable (3) both when said power cable (3) is conducting electricity and when said power cable (3) is not conducting electricity.

Optimizing scheduling of post‐earthquake electric power restoration tasks

Abstract: This paper presents a stochastic integer program developed to determine how to schedule inspection, damage assessment, and repair tasks so as to optimize the post-earthquake restoration of the electric power system. The objective of the optimization is to minimize the average time each customer is without power, and a genetic algorithm is used to solve it. The effectiveness of the schedules recommended by the optimization are evaluated by running a detailed discrete event simulation model of the restoration process with both the optimization-generated schedules and the power company's original schedules, and comparing the resulting restorations according to three measures—average time each customer is without power, time required to restore 90 of customers, and time required to restore 98 of customers. The optimization and simulation models both consider all the earthquakes that could affect the power system and represent the uncertainty surrounding expected restoration times. he models were developed through an application to the Los Angeles Department of Water and Power (LADWP) electric power system, but the general approach is extendable to other electric power systems, other lifelines, and other hazards. Copyright © 2006 John Wiley & Sons, Ltd.

Source Energy and Emission Factors for Energy Use in Buildings (Revised)

Abstract: This document supports the other measurement procedures and all building energy-monitoring projects by providing methods to calculate the source energy and emissions from the energy measured at the building Energy and emission factors typically account for the conversion inefficiencies at the power plant and the transmission and distribution losses from the power plant to the building The energy and emission factors provided here also include the precombustion effects, which are the energy and emissions associated with extracting, processing, and delivering the primary fuels to the point of conversion in the electrical power plants or directly in the buildings

Evaluating Strategies for Defending Electric Power Networks Against Antagonistic Attacks

Abstract: We show how concepts from game theory can be used to find and evaluate strategies for defending an electric power system against antagonistic attacks. Consequently, the interaction between the antagonist and the defender of the system is envisaged as a game. In a numerical example, we study the performance of different defense strategies against a number of attack scenarios. Particularly, we study whether there is a dominant defense strategy and an optimal allocation of resources between protection of components and recovery

Distribution of network communications based on server power consumption

Abstract: A network device is described that load-balances network traffic among a set of network servers based on electrical power consumption of the network servers. The network device may measure electrical power consumption in a variety of ways, and may generate and maintain a power consumption profile for each of the network server. The power consumption profile may describe the respective server power consumption in increasing granularity. For instance, each power consumption profile may specify electrical power consumption according to watts consumed by a server per average transaction, watts consumed per transaction for a specific type of software application, watts consumed per transaction for a software application for individual network resources, and so on. Furthermore, the profiles may be maintained for individual servers or aggregated for groups or sequences of servers.