Showing papers on "Electric power published in 1987"

Electric discharge machine

Abstract: PURPOSE:To prevent the convergence electric discharge and stabilize electric discharge machining by installing a working electric power scurce for applying electric conduction into an electric discharge gap from two dieferent positions on an electrode through selecting the working pulses and improving the dispersiok performance at the electric discharge points which is generated in the electric discharge gap and permitting the easy transfer of the electric discharge points CONSTITUTION:In a voltage source 3, the pulse condensers 5A and 5B are charged through switches 4A and 4B, and electric conduction is applied into the electric discharge gap between a workpiece 1 and an electrode 2 from two different positions A and B on an electrode 2 by the turning-on/off of the switches 6A and 6B, selecting the working pulses Therefore, the dispersion performance of the electric discharge points generated in the electric discharge gap can be improved Further, the electric discharge current by the pulses alternately supplied into the electric discharge points A and B is detected by each detection coil 8A, 8B, and the both detection signals are compared in a comparison circuit 9, and the generation of the convergence electric discharge in the electric discharge gap is detected When the generation of the convergence electric discharge is detected, a control circuit 10 is automatically controlled by the convergence electric discharge detection signal, and the speedy preventive control for the convergence electric discharge is executed, and the stable precision working is carried out

Compressed gas system and method

Abstract: A system and method of selectively deployed and utilized compressed air energy storage satellite facilities within an electrical power grid network. The satellite facilities are independent of geological formations and provide means for increasing the load carrying capacity of an electrical power system without increasing the size of the baseload electrical power generation facility or of the power transmission lines. A portion of the compressed gas is circulated back through a compressor located in a gas flow circuit, causing turbulent flow in a series of tanks, thus slowing heat energy loss to the environment. A heat exchanger located in the circuit of gas flow cools the gas while it is being stored, thus reducing the work needed to compress a given mass of gas into the tanks. The system and method utilizes low cost electrical energy produced by a baseload facility during non-peak periods and converts such electricity into potential energy in the form of compressed air. The compressed air is deployed in outlying areas, away from the baseload facility, to provide ready electrical energy during peak demand periods from a location closer to the peak electrical demand consumer. The system and method may also be utilized to boost dropped and/or lagging voltage and/or current to reduce line loss during electrical power transmission.

Sodium-sulfur battery

Abstract: PURPOSE:To increase electric power storage efficiency by arranging latent heat storage equipment which stores heat energy generating from unit cells in an accommodation room in which sodium-sulfur unit cells are accommodated. CONSTITUTION:A latent heat storage equipment 3 which stores heat energy generating from unit cells 2 is arranged in an accommodation room 1 in which sodium-sulfur unit cells 2 are accommodated. When the electric power consump tion is large in the daytime, unit cells are discharged, and Joule heat and heat energy generated as reaction heat are stored in the heat storage equipment 3 and temperature is kept at 300-400 deg.C. When the electric power consumption is small in the nighttime, unit cells are charged. To supplement the heat loss caused by heat radiation of heat energy as the total of Joule heat and endothermic reaction heat from the accommodation room 1 and the heat loss caused by heat radiation when cells are not used in the daytime, heat energy stored is radiated to keep temperature at 300-400 deg.C.

Switching power supply

Abstract: A switching power supply, in which a series circuit consisting of a primary winding of a transformer (4) and a controllable switch (3) is connected with a DC power source (l0) and a secondary winding of the trans­former is connected with a first voltage source (50) outputting the voltage developed across the secondary winding during the on-period of the controllable switch and a second voltage source (60) storing the exciting energy of the transformer during the off-period of the controllable switch by using the exciting inductance of the transformer as a current source, a series circuit consisting of the first and the second voltage sources being connected with a load (70). Owing to this construction, even if voltage-current characteristic of a load having constant voltage chracteristic, such as a magnetron, vary due to variations in the temperature, etc., the output voltage is automatically compensated and a stable electric power can be supplied to the load.

Solar cell fabrication method

Abstract: A solar cell fabrication method and solar cell made by the method wherein a grid of point electrical connections is made to a transparent first electrode layer of the cell through a layer of a-Si semiconductor material which is sandwiched between the first electrode layer and a second back electrode layer. A dielectric layer electrically insulates the back electrode layer and the grid of point electrical connections. An electrically conducting network is deposited on the dielectric layer and electrically interconnects the grid of point electrical connections. The resulting cell has a relatively low active area loss and a relatively low electrical power loss due to the electrical connections in the cell.

Generation scheduling and control

Abstract: Within an Energy Management System, the Generation Scheduling and Control function controls the electrical power output of generators so as to supply the continuously changing customer power demand in an economical manner. This function is largely provided by an Automatic Generation Control (AGC) program operating within the control center computer. Power system dispatchers also play an important role, interacting with the program to incorporate current operating conditions. This paper summarizes the system characteristics associated with AGC, as well as current practices of program design and operation. Topics of current interest are also discussed. Current technology in this area is fairly mature, and existing performance is good over-all. Current issues such as fuel scheduling, dispersed generation technologies, and advanced load management schemes may change the nature of the AGC problem in the future.

Method and device for generating electric power by use of wave force

Abstract: The invention relates to a method and device for generating electric power by use of wave force. According to the invention, it is possiblke to obtain the required power using the floatation bladders rising and falling repeatedly with waves as a power using the floatation bladders rising and falling repeatedly with waves as a power source and the rotation force of gears connected to the floatation bladders through ropes. The invention has advantages in that the construction of the power generating means and its supporting means are simple, execution of work is easy, a kinetic energy is convertable into an electric energy using the floatation bladders regardless of the magnitude of waves, and even in the deep sea, the base frame is not installed on the sea bed, but in a fixed depth under the mean sea level, and thereby the maintenance and repair of device is carried out without any difficulty.

SOLERGY; A computer code for calculating the annual energy from central receiver power plants

Abstract: The program SOLERGY was designed to simulate the operation and power output of a user-defined solar central receiver power plant for a time period of up to one year. SOLERGY utilizes recorded or simulated weather data and plant component performance models to calculate the power flowing through each part of the solar plant. A plant control subroutine monitors these powers and determines when to operate the various plant subsystems. Parasitic electrical power is computed on a 24-hour basis.

Computerized controller with service display panel for an oil well pumping motor

Abstract: An apparatus for controlling and monitoring an electrical motor used to pump petroleum from beneath the surface of the earth. A computerized metering apparatus is used to monitor overload power, underload power, as well as other conditions. When the demand power consumption of the electric motor exceeds or falls below preprogrammed limits, the computer provides an indication of the detected condition. A display panel with a particular combination of display lights is thus controlled by the computer to provide oil well service personnel with an indication of a detected problem, even from a distance. This allows service personnel to monitor the condition of a well without getting out of their service vehicle. Additionally, capability is provided to respond to signals provided from the company supplying electric power in order to control the pumping unit.

Poynting vector probe for measuring electrical power

Abstract: A new probe for measuring electric power flow from a source of supply to a load at high voltage and current, but at extremely low power factor is disclosed. The probe enables the direct measurement of electric power, in accordance with the Poynting theorem, by sensing the electric and magnetic fields associated with the high voltage and high current.

Optical modulation device

Abstract: An optical modulation device for effecting optical modulation by controlling the diffraction phenomenon of light, which not only consumes a small amouhnt of the driving energy employed, such as a electric power, but which is also capable of improvements in reliability

Pressure control for the fuel system of an internal combustion engine

Abstract: A fuel system for an internal combustion engine wherein the fuel pressure is maintained within a desired predetermined range. An electric fuel pump supplies fuel at a pressure proportional to the electric power applied to the pump. Control circuitry compares a voltage signal corresponding to the fuel pressure within a predetermined voltage range corresponding to a predetermined fuel pressure range. When the voltage signal is below the predetermined voltage range, the electric power applied to the electric pump is increased; when the voltage signal is above the predetermined voltage range, the electric power applied to the electric pump is decreased. The control circuit may further increase or decrease the electric power at a predetermined rate.

Static converter, especially for an uninterruptible electrical power supply system

Abstract: A converter comprises a plurality of modules each having a heat-sink unit with a base-plate made of a good heat-conducting metal material, acting as a support for the electronic components, a pair of parallel flanges laterally fixed to the opposite edges of the base-plate, and a rear plate for connection of the draw-in contacts capable of cooperating with the studs of a fixed connecting base. Error prevention means, formed by pins and orifices prevent any module connection error. The draw-in contacts are achieved by tulip-fingers or grips capable of being housed in six holes of the connection plate. The assembly forms a rack which can be actuated by a handle.

Optimal planning of gas turbine co-generation plants based on mixed-integer linear programming

Abstract: An optimal planning problem of a co-generation plant is studied which is constructed by combining gas turbine generators, waste heat boilers, auxiliary boilers, etc. The planning problem proposed is to determine the optimal configuration of the plant equipment taking into account the optimal operational policy of the plant for the annual energy demands of electric power and heat given a priori. Based on the annual cost method, the long-term economics of the plant is evaluated by the annual total cost, which is the objective function to be minimized. This optimal planning problem is formulated as a mixed-integer linear programming problem, and the optimal solution is derived by adopting the branch and bound method. As a result, both the configuration of the plant equipment and the operational policy are optimally determined reflecting the difference in economics and efficiency of the scale of each equipment. In addition, both the power to be purchased and the value of maximum contract demand of the purchased power is optimally determined. Using a numerical example, the validity and effectiveness of the optimal planning method proposed here is ascertained.

Energy storing apparatus

Abstract: An electric energy storing apparatus comprising lead-acid storage battery means and flowing type battery means. The lead-acid storage battery means is connectable to power lines interconnecting electric power generating means and a load, and the flowing type battery is connectable to the lead-acid storage battery means in order to charge the storage battery means, execute an equalization charge, or act as an end cell for the storage battery means.

Circuit for supplying power to a dental photopolymerizing apparatus

Abstract: An electric lamp for the photopolymerization of dental materials is supplied with constant electric power so that constant light output is obtained. The control circuit used to this end operates with a triac (3) connected between an a.c. voltage supply (2) and the lamp (1), said triac being controlled by signal values stored in a read-only memory of a microprocessor (4). Said stored values are respectively allocated to pairs of instantaneous values of lamp current and lamp voltage, the instantaneous values being detected in each cycle of the a.c. supply voltage and being utilized to address the read-only memory.

Electric power supply unit, in particular for a motor vehicle, and an electric rotary machine for such a unit

Abstract: The electric power supply comprises an electric rotary machine intended to be driven by an engine in order to supply electrical energy to a battery and/or to various user units, and rectifier means combined with the machine for obtaining direct current. The machine is chosen in such a way that when it is driven by the engine at its idling speed, the voltage at the terminals of the machine is insufficient to ensure charging of the battery; the unit comprises means to make it possible to establish periodically a voltage surge at the terminals of the machine and a current for charging the battery.

Control apparatus for variable-speed hydraulic power generating system

Abstract: Disclosed is a control apparatus for a variable-speed hydraulic power generating system comprising a variable-speed a.c. electric generator connected to an a.c. electric power system and a hydraulic machine system including a water turbine for driving the generator and a guide vane for controlling an amount of water supplied to the water turbine. The control apparatus comprises a frequency converter connected between the electric power system and the generator for controlling electric power supplied from the generator to the electric power system, control means operating in response to at least an externally applied power generation command signal for controlling, on one hand, the frequency converter thereby controlling the electric power supplied from the generator to the electric power system and generating, on the other hand, a guide-vane opening command signal for controlling the guide vane thereby controlling the amount of water supplied to the water turbine, and means for reducing resonance which may occur in the hydraulic machine system when the rotation speed of the water turbine changes in response to a change of the externally applied power generation output command signal.

Twin break transfer switch

Abstract: An electrical transfer switch for providing electrical power from either one of two sources of electrical power to a load, and characterized by at least a pair of spaced power contacts disposed on a base which contacts are electrically connected to different sources of power; a load contact on the base and interconnected with a load; an electrically conductive bridge pivotally supported intermediate the ends thereof on the base for rotation between different angular positions as power for the load is transferred from one power source to another power source.

Turbine helper drive apparatus

Abstract: A turbine helper drive apparatus has an induction motor coupled to a turbine, and a power converter for power-controlling the motor. Part of the load of the turbine is shared by the motor in accordance with preset power for power control, so that auxiliary drive to compensate for the insufficient capacity of the turbine is performed and cheaper, late-night electric power is effectively utilized.

The Effects of Reduced Voltage on Distribution Circuit Loads

Abstract: This study quantifies the changes in real and reactive power on distribution circuit loads as a function of supply voltage. A total of eight distribution circuit segments representing residential, commercial, and industrial loads were monitored and controlled over a 20-month period. The data collected were used to validate a computer model developed by The University of Texas at Arlington under Electric Power Research Institute project RP-1419. The data shown in this paper are the results of an independent analysis conducted by The Detroit Edison Company.

Integrated mechanical vapor recompression apparatus and process for the cogeneration of electric and water-based power having a recirculation control system for part-load capacity

Abstract: Disclosed are a method and apparatus for selectively generating different amounts of electric power and high pressure steam power according to the user's needs, using a fluid-cooled engine and a dual-function screw machine that may be operated as either a compressor or an expander. Fluid from a cooling jacket fluid is separated into vapor and liquid portions and, to increase the amount of high pressure steam delivered by the apparatus, low pressure steam from a separator is compressed by the screw machine and liquid from the separator is heated to a high temperature and high pressure. When additional electric power is desired, the low pressure steam from the separator is diverted from the screw machine. High pressure steam, manufactured by compressing and heating the liquid of the separator, is expanded in the screw machine, which adds its power to the main drive shaft, thereby adding to the available electric power. Various combinations of amounts of electric power and steam power are possible by controlling the amounts of material presented to the screw machine as either a compressor or an expander. The apparatus also includes a recirculation system used when the screw machine is employed as a compressor during periods of off-design point engine load and which facilitates driving the screw machine without drawing down the pressure of the apparatus.

Development of New Diagnostic Method for Hot-Line XLPE Cables with Water Trees

Abstract: A new insulation diagnostic method for XLPE cables containing water trees is presented. A dc component in the ac charging current of these cables was found to be a significant sign of the existence of water trees. The dc component has good correlations with such insulation characteristics of aged XLPE cables as ac breakdown voltage and dc leakage current. Criteria for insulation diagnosis of 6.6kV XLPE cables have been established. An automatic insulation diagnostic device has been developed. It is now being applied to hot-line XLPF cables in distribution systems of TEPCO (The Tokyo Electric Power Co., Inc.).

Simultaneous Production of Desalinated Water and Power Using a Hybrid-Cycle OTEC Plant

Abstract: A systems study for simultaneous production of desalinated water and electric power using the hybrid-cycle OTEC system was carried out. The hybrid cycle is a combination of open and closed-cycle OTEC systems. A 10 MWe shore-based hybrid-cycle OTEC plant is discussed and corresponding operating parameters are presented. Design and plant operating criteria for adjusting the ratio of water production to power generation are described and their effects on the total system were evaluated. The systems study showed technical advantages of the hybrid-cycle power system as compared to other leading OTEC systems for simultaneous production of desalinated water and electric power generation.

Renewable energy technologies for developing countries

Abstract: Electric power for developing countries is essential for economic growth and total spending is approaching $50 billion each year. Although a 3% annual increase in electric power capacity is projected for the U.S., the demand in most developing countries is growing at a more rapid pace-between 5% and 15% annually. Electricity planners for developing countries in the past have focused on large centralized power plants fired by fossil fuels. Dependency on imported fuels, long lead times and the inability to project demand load requirements dictate that small decentralized renewable energy technologies should be explored as a viable alternative.

Electric power panelboard adapter module

Abstract: An adapter module allows circuit breakers and disconnect switches of varying ratings to be installed within a common power panel enclosure. The adapter consists of a plastic base member through which multiple contact jaws extend for plugging onto the individual phase buses of a multi-phase power system. The opposite ends of the jaws include means for connecting with the line terminal of both the electric circuit breakers as well as the electric disconnect switches.

Experimental study on stabilization of model power transmission system by using four quadrant active and reactive power control by SMES

Abstract: This paper presents the experimental results of stabilization of a model power transmission system by using a Superconducting Magnet Energy Storage (SMES). The SMES, which was composed of two sets of GTO (Gate Turn Off thyristor) power converters and a superconducting coil, is capable of controlling active power (P) and reactive power (Q) simultaneously in four quadrants by changing the firing angles of power converters. The model power transmission system was designed to simulate the behavior of a real scale long distance bulk power transmission system with voltage of 500 kV, capacity of 2000 MVA and length of 280 km. In this study, we have experimented power system stabilizing control by applying P-Q simultaneous control ability of SMES. From the results of experiment it was demonstrated that stabilizing effect by means of SMES is very significant.