Showing papers on "Electric power published in 1995"

Analysis Of A Micro-electric Generator For Microsystems

Abstract: Supplying power to remote microsystems that have no physical connection to the outside world is difficult, and using batteries is not always appropriate. A solution is offered by the device proposed in this paper, which generates electricity from mechanical energy when embedded in a vibrating medium. This micro-generator has dimensions of around 5x5x1mm. Analysis predicts that the power produced is proportional to the cube of the frequency of vibration, and that to maximise power generation the mass deflection should be as large as possible. Power generation of 1/spl mu/W at 70Hz and 0.1mW at 330Hz are predicted for a typical device, assuming a deflection of 50/spl mu/m.

Electrical Power Systems

Abstract: The various Codes applicable to the University's electrical power system are mainly based upon a model of a single utility service, connected to a single premise. The University’s electrical system, however, consists of multiple utility services, a cogeneration facility, and a comprehensive primary distribution network connected to hundreds of premises. Thus applying the codes to the University's electrical system is not straightforward as it would be in other locations.

A survey of distribution system power quality-preliminary results

Abstract: This paper presents preliminary results from a national monitoring program designed to characterize power quality levels on electric distribution systems. The monitoring program is being sponsored by the Electric Power Research Institute. Initial stages of the project resulted in the development of a new power quality monitoring instrument (designated the PQNode). This instrument permits simultaneous monitoring of steady state quantities (RMS voltage and current, harmonic distortion levels, power factor, etc.) and disturbances (voltage sags, overvoltages, transients, etc.). Approximately 200 PQNodes have been installed on distribution systems of 24 different utility companies. Monitoring data is being compiled by Electrotek Concepts in Knoxville, TN. The paper describes the monitoring system and presents preliminary results of the monitoring effort. >

Electrical power distribution monitoring system and method

Abstract: An electrical power distribution monitoring system is provided for a power distribution line (4) having a plurality of sections with a plurality of electrical loads (6a-e, 7, 25, 26) connected to the power distribution line to form a power distribution network. The monitoring system has at least one sensor (8, 10, 27, 28) for at least one present electrical value at at least one point of the network, and calculating means (14, 16, 17) arranged to estimate electrical values for at least one section of the line in dependence on both of present electrical values measured by the sensor and data relating to past power consumption by loads connected to the line. Improved prediction of actual conditions in the distribution line can be obtained.

Application of auctions as a pricing mechanism for the interchange of electric power

Abstract: The expected move to a market-based electric power industry will significantly change electric utility operations. These changes will fundamentally alter the pricing of electric power. How this pricing will be accomplished is a key issue. Traditionally, embedded cost based methods have been used. Spot-pricing has received attention as a possible approach in a market-based electric power environment. Another market-based approach is the use of auctions. This paper presents the application of a sequential sealed-bid and sealed-offer auction to the pricing of electric power by using linear programming. >

Coordination between the reactive power scheduling function and the hierarchical voltage control of the EHV ENEL system

Abstract: The paper presents the control strategies adopted at ENEL (the Italian Electric Power Company) for the automatic voltage regulation and for the short and very short term reactive power scheduling. The advanced project is based upon a three level hierarchical control of voltage and reactive power (primary, secondary and tertiary regulation) and a reactive power dispatch procedure. The three levels are characterized by specific control actions which affect systems of different size and complexity, operating in three steps. In particular, the slowest third level executes the optimal voltage profile defined by the short or very short term reactive power scheduling. The need of an effective co-ordination between the off-line reactive scheduling procedures and the on-line voltage control is pointed out in the work. Besides, the paper presents a computation procedure realized in order to simulate the steady state behaviour of the electric power system submitted to the hierarchical voltage control system and its interaction with the VAr optimisation program. >

Electrical energy meters having real-time power quality measurement and reporting capability

Abstract: A revenue accuracy meter and a method are provided for measuring the amount and quality of power received by a power customer across electrical power lines. The revenue accuracy meter preferably has a variation determiner for determining undesired variations in an electrical signal representative of power received by the power customer during a plurality of predetermined time periods. A power usage measurer is coupled in electrical communication with the variation determiner for measuring the power usage of a customer responsive to an electrical signal representative of a customer load. The meter further has a communications interface coupled in electrical communication with the variation determiner and the power usage measurer for communication signals representative of the power variations and the power usage. An energy management controller also preferably is connected to the communications interface for controlling power usage responsive to predetermined electrical command signals received from the power customer through the communications interface.

Temporary power/data tap

Abstract: A temporary power/data tap for delivering both electrical power and data service line to a work surface from a distant standard wall or floor mounted electrical receptacle and data port. The power/data tap is designed to be selectively moved between retract and extended positions to provide electrical power and data service line to the work surface. The power/data tap is a self-contained unit designed for easy installation on the work surface which meets or exceeds United Laboratory standards. At least one electrical receptacle and one data port is mounted on a pivoting outlet enclosure housed inside an enclosure assembly. The electrical receptacle and data port are disposed in two separate compartments formed in the outlet enclosure. A power cord capable of being plugged into a standard wall or floor receptacle delivers electrical power to one side of the enclosure assembly. A power distribution assembly located inside the enclosure assembly then safely distributors the electrical power inside the enclosure assembly. Optional electrical connectors and interconnecting cable is provided for electrical power from one power/data tap to another.

Fuzzy logic integrated electrical control to improve variable speed wind turbine efficiency and performance

Abstract: A control system utilizing fuzzy logic adaptive control to control the operation of a wind turbine driven electric power generator to control power generator speed and hence power frequency while maximizing the power output of the power generator. Wind turbulence effects are eliminated and airgap magnetic flux of the power generator is controlled.

Environmental Implications of Electric Cars

Abstract: California and the Northeast states have passed laws requiring 2% of 1998 cars be `0` emissions vehicles such as electric cars. Electric vehicle technology also can move emissions to less crowd and less polluted locations. However, some other problems remain. The authors focus on the environmental consequences of producing and reprocessing large quantities of batteries to power electric cars, including discussions of both characteristics of Electric Vehicles and batteries and the life cycle of lead and the problems of environmental releases. The authors conclude that electric vehicles will not be in the public interest until they pose no greater threat to public health and the environment than do alternative technologies such as vehicles using low-emission gasoline. 19 refs., 1 tab.

Application of distribution system capacitor banks and their impact on power quality

Abstract: This paper presents a summary of the power quality related concerns associated with the application of electric utility distribution system capacitor banks. These concerns include distribution capacitor switching transients and power system harmonics. Methods for identifying these problems, determining their impact on electric utility and customer systems, and developing suitable solutions are provided. >

Improved secondary and new tertiary voltage control

Abstract: In this paper the basic role of a secondary (regional level) voltage control in a multi-regional electric power system is reviewed. Specifically, certain limitations of presently implemented control schemes are described. Next an improved secondary voltage control (ISVC) scheme is proposed. In the second part of the paper, possible enhancements of a multi-regional power system operation by means of scheduled, tertiary voltage control (TVC) interactions are proposed. It is shown that the prime role of a TVC is in managing limits on voltage control devices, such as generators. The theoretical developments are illustrated on two regions of the French electric power network.

A new method of harmonic power detection based on the instantaneous active power in three-phase circuits

Abstract: This paper presents a new method of harmonic power detection based on the instantaneous active power in three-phase circuits, and its applications to search for dominant harmonic sources in power systems. The proposed method requires only band elimination filters and a three-phase active power meter to detect the harmonic active power, and it is able to deal with harmonic power flow more easily and precisely than a conventional meter which is based on Fourier series of single-phase circuits. In addition, measurement errors of the harmonic power are discussed theoretically. The validity of the proposed method is demonstrated by digital simulation. >

Islanding-operation prevention apparatus, and dispersed power generation apparatus and power generation system using the same

Abstract: Even when a plurality of dispersed power generation systems are connected to a utility gride, an islanding-operation prevention apparatus can easily and assuredly prevent an islanding operation of each dispersed power supply constituting the corresponding dispersed power generation system. The apparatus includes a breaker provided between the utility gride and a dispersed power supply, an electric-power-value detector for detecting a value of electric power from a power line connected to the utility gride, a switch for electrically connecting or disconnecting an electric-power changing device for changing the value of electric power to the power line in accordance with an output from a pulse circuit, and a controller for controlling the breaker in accordance with the width of fluctuations of the value of electric power during the connection or the disconnection. A dispersed power generation apparatus and a dispersed power generation system uses such an apparatus. By further providing a synchronous circuit for synchronizing the output of the pulse circuit with a signal output from a reference-signal source, even if the amount of the generated power and the amount of a load are in a complete equilibrium state during an islanding operation, the islanding operation can be assuredly prevented with a short time period until the stop of the islanding operation and without using large-scale equipment.

Charge induction apparatus of robot cleaner and method thereof

Abstract: The present invention relates to a charging apparatus for a robot cleaner and a method for charging the robot cleaner by which the robot cleaner can be accurately induced to a power source supplier to receive a battery charge when a battery power source drops below a predetermined level. The apparatus includes a control unit for controlling an overall operation, a memory which stores a driving program including structures for various rooms for which cleaning operations may be performed, and a driving unit for moving the robot cleaner in forward, reverse, left and right directions according to control signals of the control unit. A travel distance detecting unit is provided for detecting a travel distance covered by the driving unit and a travel direction detecting unit is provided for detecting a travel direction varied by the driving unit. An obstacle detecting unit is also provided for detecting whether or not there is an obstacle with a cleaning area and for detecting a distance to the obstacle from the cleaner. A charged level detecting unit detects a charge voltage level of a battery and an electric power source supplier is provided for charging the battery to above a predetermined level when the charge voltage level of the battery detected by the charge level detecting unit drops below the predetermined level. An electric power source receiving unit is also provided for electrically connecting the electric power source supplier to the battery so that the power source supplied from the electric power source supplier can be applied to charge the battery.

General Electric ATS Program technical review Phase 2 activities

Abstract: The Advanced Turbine Systems (ATS) Program Phase 2 objectives are to select a cycle, and to identify and resolve technical issues required to realize the ATS Program goals of 60% net combined cycle efficiency, single digit NOx, and a 10% electric power cost reduction, compared to current technology. The Phase 2 efforts have showns that the ATS Program goals are achievable. The GE Power Generation advanced gas turbine will use closed-loop steam cooling in the first two turbine stages and advanced coatings, seals and cooling designs to meet ATS performance and cost of electricity goals.

System for measuring electrical power interruptions

Abstract: A system for measuring electrical power interruptions in an electrical power distribution system to a customer premises, controlling the restoration of loads to the electrical power grid after power is restored following an outage, and facilitating preventive maintenance on the electrical power distribution system so that the reliability of power distribution is enhanced. A load control module is associated with each load whose power restoration is to be controlled. Following the occurrence of a power outage, when power is restored, an instruction is transmitted to each load control module by a controller at the premises to enable reconnection of the associated load to the power distribution system in a predefined sequence. At each customer premise, the power feed cable is monitored for the presence of a power signal thereon. When a power interruption occurs, the elapsed time is measured; and upon resumption of power delivery on the cable, a message is transmitted to the energy provider containing an indication of the occurrence of the interruption and the time thereof.

Data carrier system

Abstract: A data carrier system allows data to be transmitted and received The data is transmitted using weak radio waves of suitable frequencies, such as frequencies in a high frequency band (HF) or a very high frequency band (VHF) The transmitters and receivers need not physically contact each other, be located in any particular position, or be oriented in any particular direction The data carrier system does not suffer deficiencies in electric power supply, and therefore there exists no need to exchange batteries Individual transmitters and receivers are positively discriminated one from another The receivers are in the form of a plurality of tags The transmitters are in the form of a plurality of reader-writers Both are controlled by microcomputers, and each tag is equipped with a secondary battery as the power source

Expandable modular computer system

Abstract: An expandable system such as a computer system includes a plurality of stacked functional modules with each module engaging an abutting module in a physically locked relationship. Electric power for the modular system is provided to all modules through power lines within each module housing for EMI shielding with abutting modules having mating electric power connectors.

Portable computer/radio power management system

Abstract: An electrical power management system for supplying power to a computer peripheral having a relatively high intermittent power demand, such as a packet-switched data radio. A first self-contained rechargeable power supply, outputting power appropriate for the electrical appliance, stores electrical energy and supplies power to the appliance. A second self-contained rechargeable power supply stores electrical energy and supplies electrical power to intermittently recharge the first power supply. The first and the second power supplies can be such self-contained units as single or multicell batteries or capacitors. Preferably, the first power supply is a battery or a capacitor and the second power source is an internal power supply of a portable personal computer.

Power distribution center

Abstract: An electric power distribution center for use on aircraft comprises a space frame having a first surface defining a plurality of sockets, and a second, generally parallel, surface defining a plurality of connector ports; a plurality of conducting bus bars utilizing a three dimensional routing configuration encapsulated within the space frame; current sensors integrally mounted within the space frame for monitoring the flow of electrical current through the conducting bus bars; and a printed circuit board encapsulated within the space frame for providing electrical circuit pathways within the power distribution center. Further, a plurality of load protection and control devices, seated within the sockets of the first surface, provide a switchable coupling between the bus bars and the printed circuit board to control the distribution of electric power to the individual aircraft loads. Connectors mounted on the second surface of the power distribution center provide the interface connection from the internal circuit connection means and current sensing means to external devices.

A new unified approach to power quality management

Abstract: A new control algorithm for a power converter-based device that is capable of alleviating the problems of harmonic interference and voltage regulation on radial distribution lines is introduced. It comprises a relocatable converter in series with a passive filter and is known as the Power Quality Manager. Simulation results based on an existing 88-kV line are presented. Experimental results are presented, based on a three-phase 200-VA scaled model of the existing 88-kV system. It is a cost-effective and flexible solution to improving power quality.

Interpretation and analysis of power quality measurements

Abstract: This paper describes advances in power quality monitoring equipment and software tools for analyzing power quality measurement results. Power quality monitoring has advanced from strictly problem solving to ongoing monitoring of power system performance. The increased amount of data being collected requires more advanced analysis tools. Types of power quality variations are described and the methods of characterizing each type with measurements are presented. Finally, methods for summarizing the information and presenting it in useful report formats are described.

Discharge lamp lighting device

Abstract: Disclosed herein is a discharge lamp lighting device which realizes the minute control of the lighting sequence and electric power of a high-pressure discharge lamp and the control of various anti-error protecting functions by mounting a microcomputer. However, since microcomputer processing-typically progresses in accordance with the programs previously recorded on a ROM, various actions of the discharge lamp are controlled in accordance with ROM-recorded data settings. To modify these settings, the contents of the ROM need to be updated. Therefore, a function for communicating with an external device is assigned to the microcomputer so that various data settings can be modified.

Electric power unit and power transmitting unit for electric vehicles

Abstract: An electric power apparatus and a power transmitting apparatus of an electric vehicle are each constructed as a unit structure to improve the overall range and reliability of the electric vehicle. In the electric vehicle including, as a power system, a battery power supply, a motor, and a controller for controlling rotation of the motor, an electric power unit comprises a plurality of storage cells making up the battery power supply, a case housing the storage cells, a motor driving circuit and a charger both mounted on the case, a plate substrate covering the storage cells, and sockets for connecting respective terminals of the storage cells, the motor driving circuit and the charger. Also, in the electric vehicle including, as a driving system, a motor, a clutch, a transmission, and a power transmitting mechanism, a power transmitting unit comprises an automatic multiple-speed clutch transmission including a dog clutch, and the dog clutch comprises a clutch movable portion including a permanent magnet, and a clutch driving portion including excitation coils.

Performance-based ratemaking for electric utilities: Review of plans and analysis of economic and resource-planning issues. Volume 1

Abstract: This document contains summaries of the electric utilities performance-based rate plans for the following companies: Alabama Power Company; Central Maine Power Company; Consolidated Edison of New York; Mississippi Power Company; New York State Electric and Gas Corporation; Niagara Mohawk Power Corporation; PacifiCorp; Pacific Gas and Electric; Southern California Edison; San Diego Gas & Electric; and Tucson Electric Power. In addition, this document also contains information about LBNL`s Power Index and Incentive Properties of a Hybrid Cap and Long-Run Demand Elasticity.

Solid state optically coupled electrical power switch

Abstract: Solid state optically coupled power switch with light induced or modified voltage applied or removed at one or more MOSFET gate and source electrode pairs to shift each MOSFET between its high and low impedance states and in various circuit arrays for ac or dc switching and/or cross points switching or mechanical Form C relay substitution or other purposes