Showing papers on "Electric power published in 2006"

Power electronics intensive solutions for advanced electric, hybrid electric, and fuel cell vehicular power systems

Abstract: There is a clear trend in the automotive industry to use more electrical systems in order to satisfy the ever-growing vehicular load demands. Thus, it is imperative that automotive electrical power systems will obviously undergo a drastic change in the next 10-20 years. Currently, the situation in the automotive industry is such that the demands for higher fuel economy and more electric power are driving advanced vehicular power system voltages to higher levels. For example, the projected increase in total power demand is estimated to be about three to four times that of the current value. This means that the total future power demand of a typical advanced vehicle could roughly reach a value as high as 10 kW. In order to satisfy this huge vehicular load, the approach is to integrate power electronics intensive solutions within advanced vehicular power systems. In view of this fact, this paper aims at reviewing the present situation as well as projected future research and development work of advanced vehicular electrical power systems including those of electric, hybrid electric, and fuel cell vehicles (EVs, HEVs, and FCVs). The paper will first introduce the proposed power system architectures for HEVs and FCVs and will then go on to exhaustively discuss the specific applications of dc/dc and dc/ac power electronic converters in advanced automotive power systems

Power Electronics Handbook: Devices, Circuits and Applications

Abstract: Power electronics, which is a rapidly growing area in terms of research and applications, uses modern electronics technology to convert electric power from one form to another, such as ac-dc, dc-dc, dc-ac, and ac-ac with a variable output magnitude and frequency. It has many applications in our every day life such as air-conditioners, electric cars, sub-way trains, motor drives, renewable energy sources and power supplies for computers. This book covers all aspects of switching devices, converter circuit topologies, control techniques, analytical methods and some examples of their applications. Designed to appeal to a new generation of engineering professionals, "Power Electronics Handbook, 3rd Edition" features four new chapters covering renewable energy, energy transmission, energy storage, as well as an introduction to Distributed and Cogeneration (DCG) technology, including gas turbines, gensets, microturbines, wind turbines, variable speed generators, photovoltaics and fuel cells, has been gaining momentum for quite some time now. With this book readers should be able to provide technical design leadership on assigned power electronics design projects and lead the design from the concept to production involving significant scope and complexity. It contains 45 chapters covering all aspects of power electronics and its applications. It features three new chapters now including coverage Energy Sources, Energy Storage and Electric Power Transmission. It includes contributions from more than fifty leading experts spanning twelve different countries.

EPOCHS: a platform for agent-based electric power and communication simulation built from commercial off-the-shelf components

Abstract: This paper reports on the development and subsequent use of the electric power and communication synchronizing simulator (EPOCHS), a distributed simulation environment. Existing electric power simulation tools accurately model power systems of the past, which were controlled as large regional power pools without significant communication elements. However, as power systems increasingly turn to protection and control systems that make use of computer networks, these simulators are less and less capable of predicting the likely behavior of the resulting power grids. Similarly, the tools used to evaluate new communication protocols and systems have been developed without attention to the roles they might play in power scenarios. EPOCHS integrates multiple research and commercial off-the-shelf systems to bridge the gap.

Control and Performance Evaluation of a Flywheel Energy-Storage System Associated to a Variable-Speed Wind Generator

Abstract: The flywheel energy-storage systems (FESSs) are suitable for improving the quality of the electric power delivered by the wind generators and for helping these generators to contribute to the ancillary services. Supervisors must be used for controlling the power flow from a variable-speed wind generator (VSWG) to the power grid or to an isolated load. This paper investigates the control method and the energetic performances of a low-speed FESS with a classical squirrel-cage induction machine in the view of its association to a VSWG. A test bench is developed, and experimental results are presented and discussed

A system and method for contact free transfer of power

Abstract: A system and method is provided for the inductive transfer of electric power between a substantially flat primary surface and a multitude of secondary devices in such a way that the power transfer is localized to the vicinities of individual device coils. The contact free power transfer does not require precise physical alignment between the primary surface and the secondary device and can allow the secondary device or devices to be placed anywhere and in arbitrary orientation with respect to the primary surface. Such power transfer is realized without the need of complex high frequency power switching network to turn the individual primary coils on or off and is completely scalable to almost arbitrary size. The local anti-resonance architecture of the primary device will block primary current from flowing when no secondary device or devices are in proximity to the local RF power network. The presence of a tuned secondary device detunes the local anti-resonance on the primary surface; thereby enable the RF power to be transferred from the local primary coils to the secondary device. The uniformity of the inductive coupling between the active primary surface and the secondary devices is improved with a novel multi-pole driving technique which produces an apparent traveling wave pattern across the primary surface.

Instantaneous reactive power p-q theory and power properties of three-phase systems

Abstract: This paper investigates how power phenomena and properties of three-phase systems are described and interpreted by the Instantaneous Reactive Power (IRP) p-q Theory. This paper demonstrates that this theory misinterprets power properties of electrical systems or provides some results that at least defy a common sense or meaning of some notions in electrical engineering. For example, it suggests the presence of an instantaneous reactive current in supply lines of purely resistive loads and the presence of an instantaneous active current in supply lines of purely reactive loads. Moreover, it suggests that line currents of linear loads with sinusoidal supply voltage contain a nonsinusoidal component. This paper shows, moreover, that the IRP p-q Theory is not capable to identify power properties of three-phase loads instantaneously. A pair of instantaneous values of p and q powers does not allow us to conclude whether the load is resistive, reactive, balanced, or unbalanced. It is known that a load imbalance reduces power factor. However, the IRP p-q Theory does not identify the load imbalance as the cause of power factor degradation.

Electrical power distribution control systems and processes

Abstract: In one aspect, the present disclosure describes a power adjustment process. The process for power distribution regulation includes filtering data from electrical sensors to provide conditioned data representative of a portion of a power distribution grid and determining, by a controller and based in part on the conditioned data, when an increase or decrease in an output parameter from one regulator of a plurality of regulators in the power distribution grid will reduce system power consumption. The process also includes increasing or decreasing the associated output electrical parameter in response to the controller determining that such will reduce system power consumption.

Feasibility of structural monitoring with vibration powered sensors

Abstract: Wireless sensors and sensor networks are beginning to be used to monitor structures. In general, the longevity, and hence the efficacy, of these sensors are severely limited by their stored power. The ability to convert abundant ambient energy into electric power would eliminate the problem of drained electrical supply, and would allow indefinite monitoring. This paper focuses on vibration in civil engineering structures as a source of ambient energy; the key question is can sufficient energy be produced from vibrations? Earthquake, wind and traffic loads are used as realistic sources of vibration. The theoretical maximum energy levels that can be extracted from these dynamic loads are computed. The same dynamic loads are applied to a piezoelectric generator; the energy is measured experimentally and computed using a mathematical model. The collected energy levels are compared to the energy requirements of various electronic subsystems in a wireless sensor. For a 5 cm3 sensor node (the volume of a typical concrete stone), it is found that only extreme events such as earthquakes can provide sufficient energy to power wireless sensors consisting of modern electronic chips. The results show that the optimal generated electrical power increases approximately linearly with increasing sensor mass. With current technology, it would be possible to self-power a sensor node with a mass between 100 and 1000 g for a bridge under traffic load. Lowering the energy consumption of electronic components is an ongoing research effort. It is likely that, as electronics becomes more efficient in the future, it will be possible to power a wireless sensor node by harvesting vibrations from a volume generator smaller than 5 cm3.

Optimal price and quantity determination for retail electric power contracts

Abstract: Considering the viewpoint of a retailer, this paper analyzes the problem of setting up contracts on both the supplier and end-user sides to maximize profits while maintaining an acceptable level of settlement risk. The proposed stochastic optimization model can assist retailers with these efforts and guide them in their contractual arrangements. A realistic example illustrates the capabilities of the methodology proposed.

Power supply system

Abstract: A power supply system is capable of feeding electric power from a power adapter to a plurality of load devices The power adapter includes a primary core; and a primary coil wound around the primary core for serving as a output port of the power adapter to output an alternating current The load devices include secondary cores for simultaneously forming magnetic circuits between the primary core and the load devices; and secondary coils wound around the secondary cores for feeding output power to the load devices The primary core has two pairs of protrusions, and the secondary cores are arranged on opposite sides of the primary core in such a manner that the primary core lies between the secondary cores to feed electric power simultaneously to the load devices

Derivation and Experimental Validation of a Power-Split Hybrid Electric Vehicle Model

Abstract: Hybrid electric vehicles (HEVs) have attracted a lot of attention due to environmental and efficiency reasons. Typically, an HEV combines two power trains, a conventional power source such as a gasoline engine, a diesel engine, or a fuel cell stack, and an electric drive system (involving a motor and a generator) to produce driving power with a potential of higher fuel economy than conventional vehicles. Furthermore, such vehicles do not require external charging and thus work within the existing fueling infrastructures. The power-split power train configuration of an HEV has the individual advantages of the series and parallel types of HEV power train configurations. A sophisticated control system, however, is required to manage the power-split HEV power trains. Designing such a control system requires a reasonably accurate HEV system plant model. Much research has been done for developing dynamic plant models for the series and parallel types, but a complete and validated dynamic model for the power-split HEV power train is still in its infancy. This paper presents a power-split power train HEV dynamic model capable of realistically replicating all the major steady-state and transient phenomena appearing under different driving conditions. A mathematical derivation and modeling representation of this plant model and its components is shown first. Next, the analysis, verification, and validation through computer simulation and comparison with the data actually measured in the test vehicle at the Ford Motor Company's test track is performed. The excellent agreements between the model and the experimental results demonstrate the fidelity and validity of the derived plant model. Since this plant model was built by integrating the subsystem models using a system-oriented approach with a hierarchical methodology, it is easy to change subsystem functionalities. The developed plant model is useful for analyzing and understanding the dominant dynamics of the power train system, the interaction between subsystems and components, and system transients due to the change of operational state and the influence of disturbances. This plant model can also be employed for the development of vehicle system controllers, evaluation of energy management strategies, issue resolution, and verification of coded algorithms, among many other purposes

Automotive Waste Heat Conversion to Electric Power using Skutterudite, TAGS, PbTe and BiTe

Abstract: BSST began development of a high efficiency Thermoelectric Waste Energy Recovery System for passenger vehicle applications in November 2004 under a contract [Contract No. DE-FC26-04NT42279] awarded by the U.S. Department of Energy Freedom Car Office. The system reduces fuel consumption by replacing a significant portion of the required electric power normally produced by the alternator with electric power produced from exhaust gas waste heat conversion to electricity in a Thermoelectric Generator Module (TGM). BSST team members include BMW, Visteon and Marlow Industries. In Phase 1, the team created a system architecture, developed a system model to predict performance and established system and subsystem design requirements. The Phase 1 effort resulted in a predicted fuel efficiency increase of 10%. Phase 2 is scheduled to be completed in December, 2006 in which key subsystem components will be built and tested and the system model updated to provide a new performance prediction. This paper presents the current status of the system architecture, modeling and key technologies

Thermoelectric waste heat recovery as a renewable energy source

Abstract: A thermoelectric converter is a solid-state heat engine in which the electron gas serves as the working fluid and converts a flow of heat into electricity. It has no moving components, is silent, totally scalable and extremely reliable. In the early 1960’s a requirement for autonomous long‐ life sources of electrical power arose from the exploration of space, advances in medical physics, deployment of marine and terrestrial surveillance systems and the exploitation of the earth’s resources in increasingly hostile and inaccessible locations. Thermoelectric devices employing radioactive isotopes as a heat source (Radioisotope Powered Thermoelectric Generators, referred to as RTGs) provided the required electrical power. Total reliability of this technology has been demonstrated in applications such as the Voyager space crafts with Voyager 1 passing into the Heliosheath some 8.3 billion miles from Earth on May 24th 2006. However, employing radioisotopes as sources of heat has remained restricted to specialised applications where the thermoelectric generator’s desirable properties listed above outweighed its relatively low conversion efficiency (typically 5%). The fivefold increase in the price of crude oil in 1974, accompanied by an increased awareness of environmental problems associated with global warming, resulted in an upsurge of scientific activity to identify and develop environmentally friendly sources of electrical power. Thermoelectric generation in applications, which employ waste heat as a heat source, is a totally green technology and when heat input is free, as with waste heat, the system’s generating power density is of greater importance than its conversion efficiency in determining the system’s economic viability. Over the past ten years or so effort has focused on developing thermoelectric generating systems which can recover waste heat from the human body, computer chips, automobile engines, and industrial utilities. In this paper the basic concepts of thermoelectric generation are outlined. An overview is presented of recent advances in the development of high performance thermoelectric materials, novel devices and applications, both macro and micro/nano. Finally, the potential of thermoelectric recovery of waste heat as a renewable energy source is assessed.

The Feasibility of Small-Scale Residential DC Distribution Systems

Abstract: The application of DC distribution of electrical power has been suggested as an efficient method of power delivery This concept is inspired by the absence of reactive power, the possibility of efficient integration of small distributed generation units and the fact that, internally, many appliances operate using a DC voltage A suitable choice of rectifier facilitates the improvement of the power quality as well as the power factor at the utility grid interface Stand-by losses can be largely reduced However, because of the inherent danger associated with DC voltages and currents, it is imperative that a considerable amount of design effort is allocated for risk analysis and the conception of protective devices and schemes, in order to guarantee personal and material (especially fire) safety This paper consists of the following topics: topological design, buffering of the DC bus, interfacing distributed generators, efficiency analysis and safety measures The conclusion of this work is that (at the moment) it is generally not efficient to implement a DC distribution system exclusively at the level of the end-user Rather, further research should focus on the extension of DC power delivery to higher levels of the electricity grid

Remote meter monitoring and control system

Abstract: An automated server based system for monitoring, reading, controlling as well as switching gases, liquids and electric power is provided for use in remote Automated Meter Reading (AMR) industry for water, gas and electric power utilities, Supervisory Control and Data Acquisition (SCADA); Security, Safety and Fire Alarm Systems (SSFA) and Home and Industrial Automation (HIA), in connection with appliances and equipment of all kinds.

Cost of Power Interruptions to Electricity Consumers in the United States (U.S.)

Abstract: The massive electric power blackout in the northeastern U.S. and Canada on August 14-15, 2003 catalyzed discussions about modernizing the U.S. electricity grid. Industry sources suggested that investments of $50 to $100 billion would be needed. This work seeks to better understand an important piece of information that has been missing from these discussions: What do power interruptions and fluctuations in power quality (power-quality events) cost electricity consumers? We developed a bottom-up approach for assessing the cost to U.S. electricity consumers of power interruptions and power-quality events (referred to collectively as reliability events ). The approach can be used to help assess the potential benefits of investments in improving the reliability of the grid. We developed a new estimate based on publicly available information, and assessed how uncertainties in these data affect this estimate using sensitivity analysis.

Electrical power contacts and connectors comprising same

Abstract: Electrical connectors and contacts for transmitting power are provided. One power contact embodiment includes a first plate that defines a first non-deflecting beam and a first deflectable beam, and a second plate that defines a second non-deflecting beam and a second deflectable beam. The first and second plates are positioned beside one another to form the power contact.

System and method for powering accessories in a hybrid vehicle

Abstract: A system and method for providing power to vehicle accessories having operational power requirements in excess of 1 kilowatt. The system is employed in conjunction with a vehicle comprising a main power unit and an electric motor, the main power unit providing more than 42 volts of power to a DC power bus from which the electric motor draws power to propel the vehicle. The system comprises a vibration dampening mounting structure affixed to the vehicle. A vehicle accessory requiring operational power in excess of 1 kilowatt and an electric accessory motor are affixed to the mounting structure. The electric accessory motor is mechanically coupled to the vehicle accessory. The electric accessory motor draws electric power from the DC power bus to provide operational power to the vehicle accessory. The vehicle accessory can be a scroll type air compressor.

Stand-alone wind turbine system, apparatus, and method suitable for operating the same

Abstract: This invention provides a wind turbine-battery-dump load stand-alone renewable energy system and an optimal control of the same. The system may include both power conversion and control units. In one embodiment, the power conversion unit features a wind-turbine-driven three-phase induction generator, a diode rectifier, a battery charger, a boost dc/dc converter, a battery bank (48V), and a dc/ac inverter. A dump load is also used to dissipate excess power that is not required for either the battery charging or for the load. The integrated control unit may use the TMS320LF2407A DSP microcontroller from Texas Instruments, which allows operations of the wind power system and the battery storage system to be merged into a single package under a master controller. An embodiment of the control system features battery-charging control, battery voltage-boost control, dump load control, PWM inverter control, and system protection. It enables the use of renewable energy resources, while at the same time facilitating an efficient management of energy dispatch. This integrated control system offers remote villages the potential to fully supply their electrical power needs.

An excellent operating point tracker of the solar-cell power supply system

Abstract: When the solar array is used as an input power source, the excellent operating point tracker is often employed to exploit more effectively the solar array as an electric power source and to obtain the maximum electric power at all times even when the light intensity and environmental temperature of the solar array are varied. Usually, the excellent operating point is determined by computing the electric power from the solar-array power supply with a microcomputer, digital signal processor, etc. However, such a method has the following problems: 1) complex control-circuit configuration; 2) high cost; and 3) low control speed. From this viewpoint, this paper proposes a new excellent operating point tracker of the solar-cell power supply system, in which inexpensive p-n junction diodes are used to generate the reference voltage of the operating point of the solar array. Using the proposed method, the high degree of the solar-array excellent point tracking performance can be obtained even when the light intensity and environmental temperature of the solar array are varied. Furthermore, this paper provides the operation principle, design-oriented analysis, etc., of the proposed solar-cell power supply system.

Power system for electric and hybrid vehicles

Abstract: A power system for an electric vehicle, the power system comprising at least one power generating device selected from a group consisting of a solar panel, a wind turbine capable of producing electrical power, an auxiliary generator driven by an internal combustion engine, and a generator for producing electrical power mechanically connected to, and driven by the rotational force of an axle of a vehicle. The power system being further comprised of a charging device, a battery control device, at least one battery, a motor control device, an electric drive motor electrically connected to the motor control device, and a driver interface connected to the motor control device. The electric drive motor may be used to generate power through regenerative braking. The wind turbine may be raised outside the body of a vehicle while the vehicle is not in motion. The solar panel may be disposed outside the vehicle while remaining electrically connected to the charging device.

Method for operation of a converter system

Abstract: The present invention relates to a method for operating a converter system of a wind turbine, wherein the converter system includes converter modules capable of converting electric power produced by a generator to electric power applicable to a utility grid. The converter modules include generator inverters and grid inverters. The method determines the enabling/disabling of the converter modules in response to a parameter related to the variable amount of electric power being produced by the generator. Advantages of the present invention are optimisation of power efficiency of the converter modules and improved reliability of the converter modules. Another advantage is the capability of fast enabling and disabling of the converter modules.

Offshore wind turbine with multiple wind rotors and floating system

Abstract: A wind energy conversion system optimized for offshore application. Each wind turbine includes a semi-submersible hull with ballast weight that is moveable to increase the system's stability. Each wind turbine has an array of rotors distributed on a tower to distribute weight and loads and to improve power production performance where windshear is high. As much of the equipment associated with each rotor as possible is located at the base of the tower to lower the metacentric height. The equipment that may be emplaced at the bottom of the tower could include a power electronic converter, a DC to AC converter, or the entire generator with a mechanical linkage transmitting power from each rotor to the base of the tower. Rather than transmitting electrical power back to shore, it is contemplated to create energy intensive hydrogen-based products at the base of the wind turbine. Alternatively, there could be a central factory ship that utilizes the power produced by a plurality of wind turbines to create a hydrogen-based fuel. The hydrogen based fuel is transported to land and sold into existing markets as a value-added "green" product.

Electrical Power Supply Arrangement and Use Thereof

Abstract: A power supply arrangement is specified in which a capacitor with a low internal resistance, in particular a supercap ( 3 ), is connected via a means for charging ( 4 ) to an input ( 1 ) and via a load current regulator ( 9 ) to a connecting means ( 7 ) for an electrical load ( 8 ). Together with a feedback path, a control loop is formed for the load current through the electrical load ( 8 ). It is therefore possible to allow flash operation in applications such as mobile telephones with rechargeable batteries with a high internal resistance, with provision for high energy utilization from the capacitor, with controlled discharging with a regulated current.