Showing papers on "Electric power published in 1988"

Reliability Assessment of Large Electric Power Systems

Abstract: This book covers a wide range of relevant material related to present-day knowledge and application in power system reliability. Increasing socioeconomic pressures to create safe and reliable power systems are being exerted on utilities by government, environmental groups and society in general. The material presented in this book will play a role in finding acceptable solutions to such pressures and will encourage the increased use of reliability techniques in practical applications.

10 MW GTO converter for battery peaking service

Abstract: A bidirectional 18-pulse voltage-source converter utilizing gate-turnoff thyristors (GTOs) is described. The converter, which is rated 10 MVA, was placed in service in early 1988 to connect an energy storage battery to a utility grid. The converter is rated and controlled to operate in all four quadrants (discharge, charge, leading VAr, or lagging VAr) at the full 10 MVA rating. It is capable of independent rapid control of real and reactive power with a transient response of 16 ms to changes in commanded value of real or reactive power. Thus it is usable as a reactive power controller (static VAr control), voltage control, frequency control, power system stabilizer, or real power peaking station. For use as a reactive power controller only, no battery would be needed. The design, construction, control, and application of the converter are described, and performance data taken at factory power test and at the installation are given. >

The power system failure on July 23, 1987 in Tokyo

Abstract: A power system failure occurred at 1:19 p.m. on July 23, 1987, in the service area of the Tokyo Electric Power Company Inc. The unusually hot weather led to concentrated mass consumption of electricity, causing a failure which affected 2.8 million customers in the area. There were three major causes of this failure: the power demand level on that day was unusually high; the rate of demand increase exceeded previous levels; and air conditioners which have characteristics such that a fall in voltage leads to a rise in current are in widespread use in Japan. The failure is analysed and countermeasures to mitigate future power failures are presented. >

Non-contacting power supplying system

Abstract: Disclosed is a non-contacting power supplying apparatus (10), which couples electrical power to a portable power receiving apparatus (50) that is positionable on the top of the power supplying apparatus (10). In the disclosed embodiments, a power supplying coil (18) of the power supplying apparatus (10) is in spaced-apart juxtaposition with a power receiving coil (54) of the portable power receiving apparatus when the power receiving apparatus (50) is in a predetermined position relative to the power supplying apparatus (10). An electrical signal frequency is induced in the power supplying coil (18) by a frequency converter (16) and is coupled to the power receiving coil (54). A rectifier/filter circuit (56) connected to the power receiving coil (54) supplies a signal for charging a rechargeable battery (58). A control circuit (24), located in the power supplying apparatus (10) activates a switch (14) so that the rechargeable battery (58) can be charged only when the power receiving apparatus (50) is properly positioned on top of the power supplying apparatus (10). A capacitor (20) is connected in parallel with the power supplying coil (18) and resonates with the power supplying coil at a frequency greater than that of the frequency converter (16). In some embodiments, a monitoring circuit (64) is provided for supplying a signal representative of the charge status of the rechargeable battery (58). In these embodiments, the control circuit (28) of power supplying apparatus (10) activates the switch (14) only when the power receiving apparatus (50) is properly positioned relative to the power supplying apparatus (10) and charging of the rechargeable battery (58) is required.

Power control circuit for discharge lamp and method of operating same

Abstract: Circuits, and methods of using the same, are disclosed for controlling the power supplied to a discharge lamp of the type having a closed inductive loop, such as the resonant ballast circuit for a fluorescent lamp or the inductive ballast loop of a high pressure sodium lamp, wherein the closed inductive loop is operated by an electrical power supply having a d-c input stage and an output power controlled by the switching frequency of a switch means within the power supply itself whereby current flows to the closed inductive loop when the switch means is conductive and no current flows from the power supply to the closed loop when the switch means is non-conductive. This power control circuit comprises means for sensing the instantaneous current flowing through the switch means itself, means controlled by this instantaneous current for creating a first signal with a value that is proportional to the actual power being supplied by the power supply to the closed loop, means for creating a second signal with a value proportional to the desired set point power for the lamp, means for creating an error signal having a value indicative of the difference between the first and second signals, and means for adjusting the switching frequency of the switch means in accordance with the value of the error signal, whereby the output power of the power supply is continuously adjusted toward the set point power for controlling the power actually supplied to the lamp circuit irrespective of the parameters of the lamp circuit itself. The disclosed circuits provide for constant power to a high pressure discharge lamp to yield a constant color temperature. Further, the disclosed circuits provide for dimming of the discharge lamp to selective power levels.

Energy controlling system for time shifting electric power use

Abstract: The disclosed system reduces power use during peak loads by automatically shifting the energization of the water heater to periods of off-peak power use. An energy controller maintains a calendar clock and controls the application of power to an electric water heater so that only on non-holiday weekdays, power to the water heater is interrupted during those periods of the day which have been predetermined to be the periods of peak power usage. The consumer whose water heater is controlled in accordance with the system is provided with an override button so that once a day the consumer may institute an override period to energize his water heater regardless of the peak power usage schedule. The energy controller contains in a microprocessor memory status data which includes the calendar time, a listing of the holidays, the schedule of peak power usage and the override interval. The energy controller is connected to an external module mounted outside the dwelling enclosure and by which a portable programming unit may be interconnected to the energy controller. By means of the portable programming unit, the accuracy of the status data can be verified or can be amended.

Electrical power transfer system for aircraft passenger entertainment system

Abstract: A conductor rail assembly parallel to an aircraft passenger seat track is coupled by direct electrical connection to the aircraft passenger entertainment system power supply. Passenger seat entertainment system power connectors are inserted into and retained in the conductor rail assembly to distribute power to the individual seat receivers.

The Effects of Competition on Transmission and Distribution Costs in the Municipal Electric Industry

Abstract: Dissatisfaction with rising electric rates, together with the success of deregulation in the transportation, communications, and financial sectors, have led to a number of recent proposals for the total or partial deregulation of the electric power industry.1 Many of these proposals envision an enhanced role for competition in the generation of electricity, with continued regulation or public ownership for the transmission and distribution of electric

Control system for turbocharger with rotary electric machine

Abstract: A control system for a turbocharger with a rotary electric machine on a motor vehicle detects the amount of depression of an accelerator pedal, calculates a maximum engine torque corresponding to the rotational speed of an engine on the motor vehicle when the accelerator pedal is fully depressed, calculates an amount of electric power, to be supplied to the rotary electric machine, required to produce a maximum boost pressure corresponding to the calculated maximum engine torque, and supplies the calculated amount of electric power to the rotary electric machine.

Power generating system

Abstract: A power supply system for developing electrical power from variable-speed motive power produced by a prime mover includes a differential speed summer having a first shaft coupled to the prime mover and further having second and third shafts coupled to first and second generators, respectively, a power conditioner coupled to the second generator for conditioning the power developed thereby and means for regulating the conditioned power developed by the second generator so that the first generator develops constant-frequency AC power.

Self-sustaining power module

Abstract: A self-sustaining power module (10) that combines the technologies of radioactivity with photovoltaic cells (12) to produce an electrical power supply having a useful life of over ten years. The radioactive source is a tritium capsule (22) that interfaces with the receptor surface of the photovoltaic cell (12). The capsule (22) has inside surfaces that are coated with a phosphor and is filled with tritium gas (26). The tritium gas produces beta particles that bombard the phosphor (18) causing the phosphor to luminesce and produce photons. The photons, in turn, strike and cause the photovoltaic cell (12) to generate a current flow that is then applied, via a pair of electrtodes (30), (32), to an external load. Also disclosed is a power pack (40) that houses a plurality of power modules (10). The power pack includes provisions that allow the power modules (10) to be electrically interconnected to provide various series, parallel and series-parallel power output combinations.

Constant power system and method

Abstract: A method and system for maintaining a substantially constant output of electrical power includes an engine for operating upon receipt of a signal, an electric motor, a flywheel mounted to rotate when either the engine or the motor is operated, a generator for producing electrical power when operated, and a hydraulic coupling system for driving the generator when the flywheel is rotated. A control unit allows application of power from a conventional power source to the electrical motor so long as the output power level from the conventional power source is adequate and thus the flywheel is rotated and the generator is driven to provide output power to a load. The control unit also allows application of power directly from the power source to the load. Upon interruption of power from the conventional power source, the control unit causes cut-off of power from the source to both the motor and the load, and applies a signal to the engine to start the engine. The engine then rotates the flywheel to again drive the generator to maintain the power output.

Device for controlling turbocharger with electric rotary machine

Abstract: A device for controlling a turbocharger having an electric rotary machine confirms present running conditions of a motor vehicle by detecting, at all times, the engine speed, the engine load, and the amount of depression of an accelerator pedal while the motor vehicle is running, and determines whether the electric rotary machine is to oper­ated in a generator mode or a motor mode. If the electric rotary machine is to operate in the motor mode, appropriate electric power is supplied to the electric rotary machine based on the engine load, the accelerator pedal depression, and the speed of rotation of the turbine of the turbocharger, for increasing the speed of rotation of the turbocharger to quickly increase the boost pressure developed by the turbocharger.

Modular AC output battery load levelling system

Abstract: An electric load levelling system includes a plurality of individual modules for storing and supplying AC electrical power. Each module is preferably contained within a separate enclosure and includes a plurality of individual electrochemical storage cells for storing DC electrical energy. Each enclosure includes a power conversion mechanism for converting input AC power for storage in the enclosed DC cells, and output DC power from the cells to AC for supply to an input/output line. The system is capable of storing electrical energy during periods of off-peak demand, and outputting such stored energy during periods of peak demand. The individual modules function as an "AC battery" having an AC input and output, and are adapted for mass production and ease of interchangeability.

Electrically compensated constant speed drive with prime mover start capability

Abstract: An electrically compensated constant speed drive includes a mechanical differential having first and second input shafts and an output shaft wherein a prime mover is coupled to the first input shaft, a brushless generator is coupled to the differential output shaft and includes a control permanent magnet generator (PMG) and a main generator which develops output power and a speed compensation link is coupled between the control PMG and the second differential shaft. The speed compensation link includes a dynamoelectric machine coupled to the second differential input shaft and a power converter which interconnects armature windings of the control PMG and electrical power windings of the dynamoelectric machine. A generator control unit controls the flow of power between the control PMG and the dynamoelectric machine so that the dynamoelectric machine develops compensating speed of a magnitude sufficient to maintain the output shaft of the differential at a desired speed so that the brushless generator develops constant frequency AC power. The present constant speed drive is lighter and smaller than prior electrically compensated constant speed drives.

A.C. induction motor energy conserving power control method and apparatus

Abstract: Electric power consumed by an a.c. induction motor is measured and sensed changes in power factor are used to modulate the combined magnetic flux produced in the motor field by two sets of RUN windings. A main RUN winding set, which normally couples fully with the a.c. power, is engineered to have sufficient ampere-turns to produce just enough magnetic flux to operate the motor with a light load and maintain a moderately high power factor. Motor driven load increases are determined by sensing a corresponding increase in the power factor of the main RUN winding set, whereupon power flow to a secondary RUN winding is proportionately increased. Considerable energy savings occurs when the motor drives a fluctuating load due to reduced magnetic field excitation under all but full load conditions, with the result that energy ordinarily wasted by eddy currents, copper losses, and poor power factor operation is considerably lessened. Other possible losses due to harmonic distortion of the a.c. power waveform brought about by the phase-delayed thyristor control of the second run winding power are mostly swamped out and masked by the parallel, always-on major power draw by the main run winding. A motor speed-sensitive switch or relay may divert current around the thyristor and fully excite the second run winding during motor start-up, thereby producing full available motor torque during start-up while negating any electrical stress on the control thyristor.

Electric power supply circuit monitoring systems

Abstract: Monitoring an electric power distribution circuit having a rated load capacity includes continually sensing an intensity of electric power supplied through that circuit. In response to that sensing a first signal indicating when electric power is supplied through that circuit at a predetermined maximum current usage below rated load capacity is provided. A second signal indicating a safe loading condition is provided when the sensed intensity is substantially below that maximum current usage. A third signal is provided when the mentioned intensity is at a value between the safe loading condition and the maximum current usage.

Control and protection assembly connecting a local area communication network to an industrial process

Abstract: The control and protection assembly according to the invention comprises several channel units, for example a motor channel unit, a jack channel unit and an inputs-outputs channel unit, directly connected to the process to be controlled, each unit comprising a microprocessor preprogrammed so as to perform control, decentralized protection and monitoring of the associated channels Each unit is connected to an electrical power supply system and to an internal serial network A connecting unit acts as interface between the internal serial network and a local area communication network The configuration and parameter setting information relevant to the process to be controlled is supplied to the various units by means of a console connected to the connecting unit

Sensing devices utilizing magneto electric transducers

Abstract: A sensing device for measuring electric current and electric power including a plurality of magneto-electric transducers for detecting a magnetic field about a conductor carrying the electric current. The magneto-electric transducers can include Barber-Pole type elements, each element being positioned on a substrate at approximately the same distance from the central point of a substrate.

Laser oscillator device

Abstract: A laser oscillator device applies a high-frequency voltage to a plurality of discharge regions (1a, 1b) through a dielectric to produce a high-frequency discharge for laser pumping. The laser oscillator device includes high-frequency power supplies (26a, 26b) for converting a DC power supply into high-frequency power supply outputs, output transformers (22a, 22b) for boosting the high-frequency power supply outputs and transmitting high-frequency electric power to the discharge regions, the output transformers having secondary windings with grounded midpoints, and current detectors (CT1a, CT1b) for detecting currents flowing through discharge tubes. Output currents of the high-frequency power supplies are controlled by feeding back the detected currents. Since the detected currents are not affected by mutual currents between electrodes, alarm conditions due to uncontrollable operation of a feedback loop and damage of parts are prevented from occurring, and stable current control is achieved.

Booster unit for diesel electric locomotive

Abstract: A booster unit for diesel electric locomotive having a frame-mounted diesel engine, a main traction generator and a series of traction motors connected to said generators is disclosed. It is comprised of a gas turbine mounted on the frame adjacent to the diesel engine, a high speed alternator connected directly with the turbine and a series of rectifiers connected at the output of the high speed alternator. The alternator and rectifiers form a high speed electric generator. A load control means connected at the output of the alternator is provided for controlling the output power thereof. The high speed generator is connected in parallel with the main traction generator such that the traction motors can be supplied with extra electrical power when required.

Solid state relay

Abstract: A solid-state relay having a photo-coupler for controlling supply of AC power to a load is improved so as to eliminate the problem of counterelectromotive force which could happen when the load contains an inductive component and the power to the load is turned off. The solid-state relay of the present invention typically comprises a first and a second light emitting diode which are adapted to be lighted up by an input signal; a photo-diode which is optically coupled to the first light emitting diode and is adapted to selectively supply AC electric power from a power source to the load depending on whether the light from the first light emitting diode is being received or not; a photo-triac which is optically coupled to the second light emitting diode and is adapted to supply the AC electric power from the power source to the load depending on whether the light from the second light emitting diode is being received or not; a time delay circuit which maintains the second light emitting diode lighted up for a certain time interval after the input signal is terminated; and a triac for terminating the supply of the AC electric power to the load when voltage of the power source is below a certain level.

System for maximizing efficiency of power transfer

Abstract: A system for maximizing the efficiency of power transfer from a photovoltaic source to a load element, such as a fluid pump to circulate fluid in a swimming pool system. The system is operative to maximize the power output by the photovoltaic power source, or, alternatively, to maximize the amount of work performed by the load element. A microprocessor controller receives input information concerning the voltage and current levels of the electrical power generated by the photovoltaic source, and input information concerning the work performed by the load element. When the load element is a fluid pump, the input information includes the flow rate of the fluid pumped by the fluid pump. The controller generates an output signal causing a power convertor to increase the current of the signal output by the power converter until the output power is maximized, or, alternatively, until the efficiency of the work performed by the load element is maximized. The controller provides overload protection to the load element by responding to an appropriate sensor output with an appropriate control signal.

Intrinsic safety module interface

Abstract: An interface system interconnects a common power supply and plural data communications paths located in a safe environment to a plurality of load devices located in a flammable atmosphere. A module power attenuator attenuates the electrical power output level of the common power supply to a first predetermined level for application to the load devices. A digital signal attenuator attenuates the electrical power level between data communications paths to a second predetermined level for application to the load devices. Coupling devices are utilized to maintain electrical segregation but allow communication to and from the safe environment.

Electric power deregulation: background and prospects

Abstract: The incentive failures of rate-of-return regulation are well known and thus raise the question of whether to deregulate electric power. The development of long-distance transmission and of alternative power sources in networks has spawned several institutions that would or could allow markets to substitute for such regulation. These include long-term contract sales, spot power exchange, contract power pooling, shared facility ownership, and economic dispatch. Because of the current surplus of power, the existence of such institutions has caused increasing competition in the electric power market and has catalyzed the movement to deregulate generators from state authority and to restructure utility assets. By encouraging this movement, regulators can further the discipline that markets already exert on prices and costs. By making counterproposals to the utilities, regulators can influence asset restructuring so that some of the capital gains inherent in such restructuring can be shared with consumers in the form of rate relief. Finally, for the future, the cotenancy agreement—which is antitrust supervised and competitively ruled—has promising possibilities for deregulating transmission and distribution.

A motor-driven cable reel assembly

Abstract: A motor-driven electric cable reel assembly comprises a rotatable cable take-up drum (7), and an electric motor (2) for driving the drum (7) in its cable take-up direction. The cable reel assembly also includes a storage battery provided with a battery charger which is connected to the cable in a manner such that the battery is recharged when the cable is connected to an electric power source. Also provided is a switch arrangement (10) which is effective to stop the motor (2) in response to torque generated by the motor.

Safety electrical tap

Abstract: An electrical power tap is provided with at least one shutter mechanism to block spurious insertion of a foreign object through one blade slot short of the power circuit contacts of an adjacent pair of plug receptacles. This mechanism includes a pair slides supported for independent movement between closed-latched and open positions. Access to the contacts of either power tap plug receptacle requires that its slide first be unlatched by a blade penetrating one slot and then cammed to the open position by another blade penetrating the other slot, as occurs incident to the insertion of a standard electrical plug.

Exhaust energy recovery apparatus for engine

Abstract: An exhaust energy recovery apparatus for an engine has an induction generator (6) drivable by exhaust gases emitted from the engine (1), and an induction motor (11) drivable by electric power generated by the induction generator The frequency of an exciting current supplied to the induction generator (6) and the load on the induction motor (11) are controlled (7) so that the operation efficiency of the turbine (2) will be maximized