Showing papers on "Power module published in 1981"

Excitation System Models for Power System Stability Studies

Abstract: Excitation system models suitable for use in large scale system stability studies are presented in this paper. With these models, most of the excitation systems currently in widespread use on large, system connected generators in North America can be represented.

Control of electric power systems

Abstract: commercial and industrial type. It must withstand with reasonable security the capricious forces of nature. In an age of high energy costs it is called upon to transform the prime energy resources into electric form with an optimum overall efficiency. The control functions are obviously many and varied. Some control and decision processes, exemplified by the optimal utilization of the controlled flow of river systems involve dynamics with month-long time constants. Other phenomena, like the transients on the transmission lines following lightning strikes, run their course in a few milliseconds. The slower control processes are normally handled by computer-assisted human operators. The faster control functions are trusted to fully automatic control systems of either open or closed-loop nature. The objective of this article is first to outline briefly the basic functional features of a power system and, secondly, describe some of the more important controls required for its satisfactory operation. Finally some of the more relevant research and development areas are identified and discussed. Fig. 1 shows a one-fine diagram of a section of a larger system. The electric power is produced in the generators. transformed to an appropriate voltage level in the transformers and then via the buses sent out on the transmission fines for final distribution to the loads. Via tie-lines the system is connected to neighboring systems belonging to the same pool. Fig. 1 does not show the low-voltage distribution portion of the system, which contains the majority of the load objects. For most important system studies it is sufficient to use lumped or composite representations of the loads. The load symbols in Fig. 1 are of the latter type. The circuir breakers permit the tripping of faulty components and also sectionalizing of the system. High voltage dc (HVDC) is being used in special cases. However, the vast majority of the world's electric power is being generated, transformed, transmitted and distributed as high voltage ac (HVAC) of the threephase variety. Collectively the generators, transformers, buses, lines and loads constitute the power network or grid.

Low Voltage Bulk Power System Restoration Simulation

Abstract: Time is the crucial element in restorative state control for electric power systems. One method for reenergizing large portions of a blacked out electric power system with a minimum of switching and thus time to restoration, is described. Results of a simulated system restart utilizing actual power system facilities are compared to power flow studies. The simulation tests were performed on the Los Angeles Department of Water and Power (LADWP) system in order to verify the concept of utilizing generation operating at extremely low voltage to energize as large a part as possible of the unloaded bulk power transmission system located within the service area.

Non-interrupting power supplies for loads of less than 500 watts

Abstract: The distinguishing feature of so-called no break or non-interrupting power supplies over ordinary standby or emergency power systems is that no supply interruption (even momentary) occurs when the commercial power source fails or when commercial power again becomes available. This invention comprises a non-interrupting modular power supply system which can be configured for loads of from 15 to 100, watts or for 75 to 500 watts, respectively. The system combination supplies single or multiple regulated DC outputs meeting the requirements of the equipment being operated. A source of AC power is converted to DC for utilization by a load and for charging a back-up battery. When the source of AC power fails, the battery supplies power to the load. Means are provided to monitor the battery voltage to control its charging.

DC-to-AC inverter

Abstract: A dc-to-ac inverter employing a control low power section and a power section. The low power section comprises a square wave generator, cross-coupled NOR latches and low level transistor switches for providing switching current to the power section. The power section employs complementary FET drivers and power switches connected to a battery or other source of dc and a ferro-resonant transformer for changing dc to ac. The power section is protected by a voltage sensor. In a preferred embodiment, this voltage is proportional to the current through the respective power switches and is used to unlatch the applicable NOR latch, thereby causing shut off of the protected network of the power section. 14 The control section is also protected by normal unlatching of the NOR latches after a normal square wave voltage half cycle. A switch is also provided in the control section for permitting the square wave generator and NOR latches to be supplied with regulated voltage, while removing such voltage from the low level transistor switches. A preferred packaging arrangement for an inverter system providing power to a large system is to package the low power or control components separately and the high power for one load segment in a separate module. Subsequent high power modules are conveniently driven by the same low power or control module since the FET drivers are such high gain power drivers, they require little power and are readily connectable in parallel.

Method and device for the optimum use of at least one variable and hard to master power source

Abstract: A method and an installation are described for the optimum use of at least one variable power source which is difficult to control. In known power systems with a power source which is difficult to control, it is normal to couple to it one or more synchronous A.C. generators which can be connected with a rectifier and an inverter to an autonomous A.C. network. In this arrangement, the A.C. network is connected to a second synchronous A.C. generator which is mechanically connected, such that it can be disconnected therefrom, to a controllable auxiliary machine, such as e.g. a diesel generating set. To keep the frequency of the network constant if too much power is offered or, above all, if the power offered drops, such an amount of power is supplied from the autonomous A.C. network (5) to an additional usable load (2) that the frequency of the network (5) remains constant. The excess power to be diverted can be used, for example, for the preparation of hot water or for the electrolysis of water, combined with the use of fuel cells, or for battery charging or for pumping water to increased heights.

Auxiliary power supply switching set

Abstract: A control circuit and auxiliary power supply and a switching means for connecting the load selectively to the auxiliary power supply and the main power supply. The main power supply may be a public utility power line, and the auxiliary power supply is a windmill, a motor and generator all connected together on a common shaft. A control means senses the output voltage of the generator or output frequency and controls the switch to either connect the load to the power line or the auxiliary power supply. A battery is supplied for storing excess windmill power and for driving the motor and generator during periods of low wind.

Turn-Off Characteristics of Power Transistors Using Emitter-Open Turn-Off

Abstract: As compared with conventional reverse-biased turn-off, emitteropen turn-off provides superior transistor turn-off characteristics. Not only are the storage time and the fall time of the power transsistors much reduced, but also the device reverse-biased second breakdown phenomenon, commonly associated with turn-off of inductive load, is eliminated. Furthermore the storage time tolerance due to device variation and temperature change is minimized.

Power supply for corona discharge treatment system

Abstract: A power supply system generates a.c. power which is applied through a high voltage transformer to the electrodes of a treater. It includes a converter circuit which transforms a.c. electric power to d.c. power and an inverter which transforms the d.c. power to a.c. power. A feedback circuit senses the power delivered to the treater and separate control of both inverter frequency and output voltage is employed to prevent arc-over during the treatment process. The power supply system is particularly responsive to sudden changes in the operating conditions, and this enables treatment of relatively thin materials on a bare metal roller.

The Solar Power Satellite as a Source of Base Load Electrical Power

Abstract: This paper presents the history and current status of the Solar Power Satellite (SPS) concept with emphasis upon the latest developments in the application of the technology of microwave power transmission to the SPS. The characteristics and features of the SPS as viewed at its interface with the earth's electric power system are presented. Its environmental impact is discussed. A comparison of the SPS with other approaches to base load electrical power is presented.

Power saving device for electronic flash

Abstract: A power saving device for use in a power supply circuit has an electronic switching element which is turned on when a pushbutton normally open type switch is closed to actuate a DC-DC converter and a fully electronic control system which forces the electronic switching element into the non-conduction state after a predetermined time interval, to interrupt the connection of a low-voltage power source to the DC-DC converter.

Power Conditioning Unit for Photovoltaic Power Systems

Abstract: This paper describes a Power Conditioning Unit (PCU) for solar photovoltaic energy collection system. The PCU rated 50/62,5 kVA, 50/60 Hz, 3-phase, 4-wire has the capability to operate in a stand-alone mode or paralleled with a commercial 3-phase utility power line. The quality of power is compatible with that of the electric utilities.

Resonant power inverter and method of operation thereof

Abstract: The module includes a resonant power circuit (10) for coupling to a load. First and second switching elements (CR1, CR2) are coupled to the resonant circuit for alternately supplying a flow of current. Trigger generator means (46) provided for supplying trigger signals to enable alternately the first and second switching elements. Control means (10) is coupled to the trigger generator for operating the power module both in a first mode in which the resonant circuit current is controlled by varying the repetition rate of the trigger signals, and in a second mode in which the trigger signal repetition rate is fixed and the resonant circuit current is controlled by varying the on/off duty cycle of the module.

Mircoprocessor control of power sharing and solar array peak power tracking for high power (2.5 kW) switching power converters

Abstract: A prototype system of twin power converters for solar array supplement of spacecraft power buses is described. Analog circuits are used for inner control loops and a microprocessor directs power sharing and peak power tracking.

Power supply device for electrical devices which are allocated to underground machines operated by a hydraulic system

Abstract: In underground working, electronic control devices, the power supply of which is effected by means of a power pack fed by alternating voltage, are used for the most varied machines, such as, for example, support shields. The energy for these control devices and also for the face lighting is supplied via a special power cable with appropriate plug connector installation. According to the invention, the cable with plug connector installation is avoided by a turbine being provided as a power supply, which turbine is operated by the hydraulic system and drives a generator used for the power supply of electronic devices and face lights.

Thermal Buffering of Receivers for Parabolic Dish Solar Thermal Power Plants

Abstract: A parabolic dish solar thermal power plant comprises a field of parabolic dish power modules where each module is composed of a two-axis tracking parabolic dish concentrator which reflects sunlight (insolation) into the aperture of a cavity receiver at the focal point of the dish. The heat generated by the solar flux entering the receiver is removed by a heat transfer fluid. In the dish power module, this heat is used to drive a small heat engine/generator assembly which is directly connected to the cavity receiver at the focal point. A computer analysis is performed to assess the thermal buffering characteristics of receivers containing sensible and latent heat thermal energy storage. Parametric variations of the thermal inertia of the integrated receiver-buffer storage systems coupled with different fluid flow rate control strategies are carried out to delineate the effect of buffer storage, the transient response of the receiver-storage systems and corresponding fluid outlet temperature. It is concluded that addition of phase change buffer storage will substantially improve system operational characteristics during periods of rapidly fluctuating insolation due to cloud passage.

The Aladdin Frequency Accelerating System Power Amplifier: 140 KW at Considerably Less than a Dollar a Watt

Abstract: Modern gridded power tubes offer enormous power gain and thus make possible very economical high power radio frequency systems provided that the often troublesome problems of stability can be solved. We have developed a grounded cathode 50 Mhz, 140 KW power amplifier that achieves a power gain of over 30 db to provide radio frequency power for the electron storage ring Aladdin. Because of the low drive power requirements and the simplicity of the mechanical and electrical design, the cost of this power amplifier, including development, was less than $100,000.

Control system development for a 1 MW/e/ solar thermal power plant

Abstract: The point-focusing distributed receiver power plant considered consists of a number of power modules delivering power to a central collection point Each power module contains a parabolic dish concentrator with a closed-cycle receiver/turbine/alternator assembly Currently, a single-module prototype plant is under construction The major control system tasks required are related to concentrator pointing control, receiver temperature control, and turbine speed control Attention is given to operational control details, control hardware and software, and aspects of CRT output display

A high voltage, high power pulsed TWT power supply for space application

Abstract: The power supply presented is used to operate a pulsed TWT in a microwave experiment, which will be flown during the first Spacelab (Spaceshuttle) mission. Various high voltages up to 10 KV at a pulsed power of 9 KW are provided by the supply. The design features of power conversion, high voltage insulation, pulse generation and protection circuitry are described and test results are presented.

High current power controller

Abstract: : This report documents the design, development, and test of High Current Power Controllers (HCPCs) by Rockwell International. HCPCs are a combination of solid state and electromechanical technologies, combined for reduction of high power dissipation/voltage drop experienced in present Solid State Power Controllers (SSPCs) in the high current (10 ampere to 400 ampere) area. In addition, solid state advantages over the conventional electromechanical configuration, such as EMI reduction, longer life, etc., are retained. This report includes results of tests conducted during the study.

High Voltage/High Power for Airborne Applications

Abstract: The Air Force has requirements for large amounts of electrical power at high voltage (up to hundreds of kilovolts) for certain airborne applications. Because of the severe weight and volume constraints, these systems cannot be realized using conventional technology. The Air Force, therefore, has been heavily involved in the development of lightweight power generation and conditioning equipment. Programs have been undertaken to reduce the weight of rotating machines, transformers, switches, inverters, and capacitors. The advances made in these areas are described, and some aspects of the use of these components in the design of lightweight systems are discussed.

Programmable power processor (p/sup 3/)

Abstract: The Programmable Power Processor (P/sup 3/) is an autonomous, 18-kW power processor, for use in large high-power spacecraft power systems. An overview of the P/sup 3/ system hardware and software is presented. A full-scale breadboard of the P/sup 3/ hardware and software has been used to verify the P/sup 3/ software and hardware.

POWER SHARING AND SOLAR ARRAY PEAK POWER TRACKING FOR HIGH POWER (2. 5 kW) SWITCHING POWER CONVERTERS

Abstract: A prototype system of twin power converters for solar array supplement of spacecraft power buses is described. Analog circuits are used for inner control loops and a microprocessor directs power sharing and peak power tracking.