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Showing papers on "Power factor published in 1974"



Patent
02 Jan 1974
TL;DR: A single phase, high frequency, transistor or gate turnoff thyristor chopper ballast circuit especially suited for mercury vapor lamps preferably operates on a unfiltered full wave rectified line voltage and electronically shapes the lamp current and therefore the line current to obtain a high power factor as discussed by the authors.
Abstract: A single phase, high frequency, transistor or gate turnoff thyristor chopper ballast circuit especially suited for mercury vapor lamps preferably operates on a unfiltered full wave rectified line voltage and electronically shapes the lamp current and therefore the line current to obtain a high power factor. The ballast circuit is lightweight with low volume due to elimination of large low frequency energy storage, filtering, and transformer components. The forced, high frequency ripple lamp current waveshape, achieved by comparison of the sensed current with an appropriate reference signal, provides for good regulation, an initially high starting current to eliminate glow-to-arc mode, automatic sweeping of the chopping frequency to avoid acoustic resonance effects, and a minimum current in the valley regions of the supply voltage for improved reignition characteristics.

103 citations


Patent
02 Jan 1974
TL;DR: In this paper, a single phase transistor or gate turn-off thyristor d-c chopper fed by rectified unfiltered line voltage with a forced load current wave-shape for high power factor and good regulation is presented.
Abstract: Solid state chopper circuits for alternating-current or directcurrent loads use only high frequency filtering and electronically shape the line current to obtain a high power factor The control circuit generates a reference signal which is shaped according to a selected control function and also determines the input power By comparing a sensed instantaneous power current with the reference signal, as by using a comparator with hysteresis, a solid state switch in the chopper circuit is operated at a high frequency chopping rate to shape the power current and therefore the line current An application is a ballast for a gaseous discharge lamp The preferred circuit is a single phase transistor or gate turn-off thyristor d-c chopper fed by rectified unfiltered line voltage with a forced load current wave-shape for high power factor and good regulation

88 citations


Journal ArticleDOI
TL;DR: In this paper, the dynamic interactions between mechanical and reactive modes of machines in a multi-machine power system are investigated in terms of machine angles, transient voltages, and coefficients which are functions of system parameters and operation conditions.
Abstract: In this paper the dynamic interactions between mechanical and reactive modes of machines in a multi-machine power system are investigated. The dynamic interactions are expressed in terms of machine angles, transient voltages, and coefficients which are functions of system parameters and operation conditions. The effect of the dynamic interaction can be examined by the electric torque loci on the A6-Aw phase plane. It is found that the interaction between the mechanical modes of machines has significant effect on stability characterized by the natural mechanical oscillation frequency and damping of individual machines.

72 citations


Journal ArticleDOI
TL;DR: In this paper, the average electric power can be measured by a system that samples voltages and currents at predetermined intervals, and the sampled signals are digitized and the result is computed by numerical integration.
Abstract: Average electric power can be measured by a system that samples voltages and currents at predetermined intervals. The sampled signals are digitized and the result is computed by numerical integration. The response of the system agrees with that of a standard electrodynamic wattmeter within 0.02 percent from dc to 1 kHz, with the possible exception of zero power factor measurements. Measurements up to 5 kHz can be made with somewhat greater uncertainties.

69 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a technique that simulates load and generation changes and outages of transmission lines and transformers using the sensitivity matrix of the basic system state, and the real and reactive power flowing in the system elements and voltages at all the system buses are then computed.
Abstract: This paper presents a technique that simulates load and generation changes and outages of transmission lines and transformers. The modification of power injected into the system buses, which would simulate the outage of a transmission element, is calculated using the sensitivity matrix of the basic system state. The real and reactive power flowing in the system elements and voltages at all the system buses are then computed. The proposed technique has been applied to the Saskatchewan Power Corporation system andto the combined SPC and Manitoba Hydro systems. The power flows and bus voltages calculatedby the proposed technique are compared with those obtained from the Newton Raphson load flows.

67 citations


Journal ArticleDOI
J.L. Willems1
TL;DR: In this paper, the authors deal with the determination of optimum parameter values of conventional load-frequency regulation of interconnected power systems and show that the control performance is rather insensitive to changes of the parameters in the vicinity of their optimum values.
Abstract: This paper deals with the determination of optimum parameter values of conventional load-frequency regulation of interconnected power systems. It is shown that the control performance is rather insensitive to changes of the parameters in the vicinity of their optimum values. On the other hand the optimum value of the bias parameter depends strongly on the weighting factors used in the penalty function, as well as on the numerical data of the power system model. The importance of such sensitivity considerations is discussed in connection with the recommendation made by Elgerd and Fosha to have a bias setting which is lower than the natural frequency characteristic of the controlled area.

51 citations


Patent
23 Dec 1974
TL;DR: In this article, a static VAR generator circuit has a control system adapted to utilize the values of three phase load currents to generate time delayed firing angles for thyristor controlled inductors which are utilized with parallel capacitors to provide unity power factor and balanced electrical currents to the AC source.
Abstract: A static VAR generator circuit having a control system adapted to utilize the values of three phase load currents to generate time delayed firing angles for thyristor controlled inductors which are utilized with parallel capacitors to provide unity power factor and balanced electrical currents to the AC source. The time delayed firing angles are calculated from integrating furnace load currents over prescribed intervals during real time to thus maintain balanced load current at specified phase angles, usually zero, in the three phase system.

46 citations


Patent
Edward D Barton1, James M. Donohue1
10 Jun 1974
TL;DR: In this article, a digital power control utilizing zero voltage switching of silicon controlled rectifiers and achieving full isolation of the load from the control circuitry is presented, where a thermistor is employed to determine the temperature of the loads and a voltage step generator is utilized in conjunction with the thermistor to effect a control of the number of cycles of power to apply to the load.
Abstract: A digital power control utilizing zero voltage switching of silicon controlled rectifiers and achieving full isolation of the load from the control circuitry. A thermistor is employed to determine the temperature of the load and a voltage step generator is utilized in conjunction with the thermistor to effect a control of the number of cycles of power to apply to the load.

40 citations


Journal ArticleDOI
TL;DR: In this paper, an analytical method for the study of orthogonal-flux systems and parallel-fluctuated systems is presented, which is applied to study and compare controllable inductors.
Abstract: Analytical methods for the study of orthogonal-flux systems and parallel-flux systems are presented. The analyses are applied to study and compare orthogonal-flux and parallel-flux controllable inductors. It is found that the two systems have a great qualitative similarity but differ in the magnitudes of similar effects. This paper lays the ground work to be used in the study of parametric power converters or parametric voltage regulators to be presented in subsequent papers.

37 citations



Patent
28 Jan 1974
TL;DR: In this article, power lines within a building or other user location are connected through a fuse and a filter to an external power grid that supplies power at the usual 50 Hz or 60 Hz.
Abstract: Power lines within a building or other user location are connected through a fuse and a filter to an external power grid that supplies power at the usual 50 Hz or 60 Hz. Communications apparatus such as a central computer and a number of typewriters is connected to the power lines within the building at at least two locations and transmits communications signals over the power lines. The communications signals have a frequency different from the frequency of the electrical power supplied by the external power grid and preferably in the audio range. The filter is tuned to pass the electrical power but substantially to block passage of the communications signals. Two important advantages are that the power lines within the building double as communications lines and that the building presents a purely resistive load to the external power grid, so that the grid has an improved power factor.

Patent
21 Aug 1974
TL;DR: In this paper, a power line data transmission system is disclosed in which data is transmitted over a line carrying alternating current power by varying or modulating the power factor of the line or the phase angle of the power on the line in accordance with a signal to be transmitted.
Abstract: A power line data transmission system is disclosed in which data is transmitted over a line carrying alternating current power by varying or modulating the power factor of the line or the phase angle of the power on the line in accordance with a signal to be transmitted. A series connected reactance and switch are connected across the line. The switch is turned on and off in response to the data signal to be transmitted over the line. The phase angle of the voltage and current on the line is detected at the receiving location. The phase relation between the voltage and the current is detected or compared to produce a binary digital signal corresponding to the data sent over the line. The detection of the voltage and current being out of phase by a predetermined amount may be used to generate a signal indicating a digital one. The detection of the voltage and current being in phase may be used to generate a signal corresponding to a digital zero.


Patent
08 May 1974
TL;DR: In this paper, the spring-mass system of the compressor which is forced into vibration by the motor is arranged to have a selectively variable resonant frequency generally centered on the power line frequency.
Abstract: A compressor of the resonant type driven by an electrodynamic linear motor incorporates means to control the stroke and to improve the power factor. The spring-mass system of the compressor which is forced into vibration by the motor is arranged to have a selectively variable resonant frequency generally centered on the power line frequency. Means responsive to any overstroking are operative to vary the natural frequency of the spring-mass system, for example by varying the stiffness of the spring means, so as to oppose further overstroking and maintain a high power factor.

Patent
03 Jun 1974
TL;DR: In this paper, a silicon-controlled rectifier power supply for producing the direct current power for a television receiver is described, where the power supply is regulated by a shunt regulator, and the firing of the silicon controlled rectifiers is controlled by a diac and timing capacitor coupled with the output of the shunt.
Abstract: A regulated silicon-controlled rectifier power supply for producing the direct current power for a television receiver is disclosed. The power supply is regulated by a shunt regulator, and the firing of the silicon-controlled rectifiers is controlled by a diac and timing capacitor coupled with the output of the shunt regulator. Spurious operation of the diac is prevented by a trigger clamp circuit which is reset at the beginning of each half-cycle of the input alternating current waveform to permit the diac to fire once during each half-cycle to initiate conduction of the appropriate silicon-controlled rectifier. In addition, a provision is made for insuring initial start-up of the operation of the power supply by use of an auxiliary power supply effective when the alternating current input signal first is applied to the system. Finally, a protective circuit is provided to shut down the power supply circuit in the event of an overvoltage condition.

Patent
Loderer Peter Dipl-Ing1
02 Jul 1974
TL;DR: In this article, the authors proposed a circuit for supplying a D.C. load from an uncontrolled rectifier with a control element arranged between the output of the rectifier and the D.D. source to keep the power factor at a predetermined value.
Abstract: An improvement A.C. a circuit for supplying a D.C. load from an A.C. source through an uncontrolled rectifier with a control element arranged between the output of the rectifier and D.C. load using a control unit synchronized with the A.D. source to keep the power factor at a predetermined value and the circuit including a capacitor associated with the DC control element and a by-pass diode bridged across the DC load in which, in order to suppress harmonics to the greatest degree possible, the DC load is bridged by two by-pass diodes connected in series in the same direction and the capacitor associated with the DC control element is connected between one input terminal and the center connection point of the two by-pass diodes. In a second variation, the same result is achieved with the capacitor and a first decoupling diode connected in series between the input terminals of the DC control element with one electrode of the capacitor connected with one input terminal of the DC control element and the other electrode of the capacitor through a second decoupling diode to an output terminal of the DC control element.

Journal ArticleDOI
TL;DR: In this article, the performance characteristics of the bridge-core circuit which is designed are completely agreed with that of the Paraformer, and a novel characteristic of the paraformer is generated by the bridge circuit.
Abstract: Recently, a new type of a parametrically excited power converter which is made by two C-cores rotated at 90° was proposed and called as Paraformer [1]. The novel characteristic of this device has been remarked as one of the important phenomena which permit to expand the new region of nonlinear magnetics [2], although the operation principles are not yet clearly understood. It is concluded from the present work that the performance characteristics of the bridge-core circuit which we designed are completely agreed with that of the Paraformer, and a novel characteristic of the Paraformer is generated by the bridge circuit. By using the symmetrical or the asymmetrical bridge-core circuit, it is possible to make not only a practical high efficient and high sensitive voltage regulator but also a power converter which can change the output frequency. Furthermore, a large capacity power converter can be achieved by constructing a bridge circuit with 3-5 separate reactors.

Patent
13 Mar 1974
TL;DR: In this article, a mains transformer has a primary winding and a secondary winding, with the secondary winding being connected to a load circuit including a full wave rectifier, smoothing devices, and at least one positively quenchable, or positive cut-off, controlled semi-conductor rectifier associated with a respective control device.
Abstract: The arrangement includes a mains transformer having a primary winding and a secondary winding, with the secondary winding being connected to a load circuit including a full wave rectifier, smoothing devices, and at least one positively quenchable, or positive cut-off, controlled semi-conductor rectifier associated with a respective control device. The smoothing devices consist of at least one condenser, at least one choke and at least one filter tuned to double the frequency of the AC voltage mains. The magnitude of the alternating or direct current, available on the secondary side of the mains transformer in the form of current or voltage, is controlled by one or more positively quenchable controlled semi-conductor rectifiers, and the control device controls the controlled rectifier or rectifiers by pulse width modulation thereof to maintain the time slope of the power in the load circuit substantially in phase with the slope of the power, fluctuating with twice the mains frequency about the constantper-unit-of-time mean load power, of the load alternating current which is in phase with the mains AC voltage. In one embodiment, the current flowing from the AC voltage mains through a full wave rectifier into the DC load circuit is maintained constant and an AC voltage, of twice the mains frequency, is superposed on the DC voltage. In another embodiment, the DC voltage of the DC load is maintained constant and alternating current of twice the mains frequency is superposed on the direct current.

Patent
22 May 1974
TL;DR: In this paper, a phase-locked loop was used to control the phase and frequency of the power delivered by the supply to the load, and the phase-locking loop was applied to a power supply for delivering radio frequency power to a resonant load utilizing a phase locked loop.
Abstract: Power supply for delivering radio frequency power to a resonant load utilizing a phase locked loop to control the phase and frequency of the power delivered by the supply to the load.

Patent
Akamatsu Masahiko1
11 Dec 1974
TL;DR: In this article, the authors defined a turn-on AC output power control system comprising turn-off, which is defined as controlling at least three or three groups of switches operationally connected between a power source and a load in predetermined order.
Abstract: An AC output power control system comprising turn-on means controlling at least three or three groups of switches operationally connected between a power source and a load in predetermined order, means for feeding power including at least an AC component from the power source to the load or regenerating it from the load to the power source, and means for selecting two or two groups of the switches among the switches in a predetermined order and for alternatively turning them on and off.

Journal ArticleDOI
Sun Luin Kuo1
TL;DR: In this paper, a half bridge transistor inverter is proposed for dc to dc or dc to ac power conversion, which serves the same purpose of dc power conversion but eliminates the power transformer saturation problem.
Abstract: In the design of push-pull type or bridge type inverters for dc to dc or dc to ac power conversion, one serious problem arises as a result of the difference in saturation voltages and unsymmetrical switching times of the power transistors. A slight difference in one of these parameters will put different volt-seconds on the power transformer primary in the two half cycles and drive the transformer into saturation. This can result in excessive saturation current in the power transistors and can eventually cause circuit failure [5]. This paper describes a half bridge transistor inverter which serves the same purpose of dc power conversion but eliminates the power transformer saturation problem. The analysis of this inverter circuit is discussed in detail. Several proposed designs for the control and protection circuits are also included.

Journal ArticleDOI
TL;DR: In this article, the authors discussed some of the limiting factors associated with the asynchronous operation of synchronous generators and derived various quantities required for the theoretical analysis on the basis of an idealized model of a generator which is connected to an infinite bus.
Abstract: The paper discusses some of the limiting factors associated with the asynchronous operation of synchronous generators. Expressions of the various quantities required for the theoretical analysis are derived on the basis of an idealized model of a generator which is connected to an infinite bus. The generator is assumed to be operating at a constant slip. The results obtained from the experimental investigations which have been conducted on a 5 kVA salient-pole synchronous generator under asynchronous operation, are presented. These experimental results are used to verify the validity of the model used for the theoretical analysis. The theoretical analysis is then applied to study the behaviour of a 45 MVA hydro-generator and of an 82.5 MVA turbo-generator when operating asynchronously with different modes of the field winding connections. Comments are made on the nature of the variations of asynchronous power, armature current, pulsating power, reactive power demand, field current and field voltage as functions of slip.

Patent
19 Dec 1974
TL;DR: In this article, a solid state power supply circuit for a corona generator type device where two alternately fired load commutated SCR (Silicon Controlled Rectifier) means conduct in opposite directions through the primary winding of a power transformer is described.
Abstract: A solid state power supply circuit for a corona generator type device wherein two alternately fired load commutated SCR (Silicon Controlled Rectifier) means conduct in opposite directions through the primary winding of a power transformer. Each SCR means is series connected to a separate DC power source and isolated from the other SCR means by means of diodes. A corona generator is connected to the secondary of the power transformer and receives symmetrical, bipolar power pulses from the power supply circuit.

Journal ArticleDOI
TL;DR: In this article, a new approach to the problem of improvement of transient stability of a power system by means of optimal control of transients is presented, which is in continuation of the work reported in a previous paper.
Abstract: This paper presents a new approach to the problem of improvement of transient stability of a power system by means of optimal control of transients and is in continuation of the work reported in a previous paper.1 Essentially the system state is transferred from that at the beginning of the transient to a post-transient steady state in a nonoscillatory manner by means of a bang-bang control, thereby contributing significantly to the improvement of transient stability. A power system model with two interconnecting tie-lines is considered. It is shown that the control process may be implemented with two intermittent duty series capacitors or a capacitor and a reactor. Results of the synthesis of the optimal controllers and evaluation of realistic indices of performance are presented along with practical considerations.

Patent
13 Nov 1974
TL;DR: In this paper, a method and apparatus for regulation of the power factor of a 3-phase network fed with power from another 3phase network via a short high-voltage direct current transmission link interconnecting the two networks is presented.
Abstract: A method and apparatus for regulation of the power factor of a 3-phase network fed with power from another 3-phase network via a short high-voltage direct current transmission link interconnecting the two networks. The d.c. transmission link includes rectifier and inverter stations connected at opposite ends of the link and the inverter station is controlled in such manner as to supply power to the fed network at a variable leading power factor in dependence upon the actual power factor of the fed network.

Patent
23 Jan 1974
TL;DR: In this paper, the power source voltage is detected beforehand through a filter and phase shifter, and when the voltage reaches the reference voltage through comparison of the detected voltage and the reference voltages, the conduction phase is controlled by turning a phase-controlled rectifier connected in series with the Power Source circuit, and the amount of the current is controlled with respect to time to compensate the effective primary terminal voltage of the Power source transformer.
Abstract: The power source voltage is detected beforehand through a filter and phase shifter. When the detected voltage reaches the reference voltage through comparison of the detected voltage and the reference voltage, the conduction phase is controlled by turning a phase-controlled rectifier connected in series with the power source circuit, and the amount of the power source current is controlled with respect to time to compensate the effective primary terminal voltage of the power source transformer. When the power source voltage is high, current flows for a short. And when it is low, current flows for a longer period of time.

Patent
James E Staats1
21 Nov 1974
TL;DR: In this article, a countertop microwave oven comprises an upstanding box-like metal wall structure defining a heating cavity, a microwave generator including a voltage quadrupler power supply, and transmission means including a probe antenna for radiating the microwaves into the heating cavity.
Abstract: A counter-top microwave oven comprises an upstanding box-like metal wall structure defining a heating cavity, a microwave generator including a voltage quadrupler power supply, and transmission means including a probe antenna for radiating the microwaves into the heating cavity, the cavity being so dimensioned and the antenna being so positioned as to excite in said cavity preferred electromagnetic field modes for establishing preferred field patterns to achieve uniform heating of a variety of foods. The power supply includes capacitive and inductive means, having values designed to optimize the power factor, and switching means for selectively switching between low and high power modes. The heating cavity is dimensioned to produce two complementary modes of which establish an undistorted field pattern providing uniform heating over a distance greater than a wavelength of the source microwave energy, tuning means being provided to tune undesired modes off resonance.

Journal ArticleDOI
TL;DR: In this paper, the wave factor WF is defined as the ratio of actual current drawn, to that which would be drawn by a resistive load with the same power consumption, and is derived for peak, rms and average input currents to full-wave rectifiers with capacitor input filters.
Abstract: Conventional, capacitor-input-filtered, full-wave rectifier power supplies draw much higher peak and rms line currents than the supply power drains would imply if the loads were resistive. Effective multiplication factors?termed wave factors?range from 5 to 15 for peak, and from 2 to 3 for rms, while remaining between 0.7 and 1 for average. Experimental data verify theoretical calculations for the wave factors involved. Ordinary clip-on and other conventional ammeters, measuring average but calibrated to read in rms for an equivalent sine wave, are thus unable to account for the difficulties sometimes encountered in the field. These include apparently undersized fuses, breakers and lines, plus severe clipping of the line voltage wave at the load. Solutions include use of auxiliary line inductors, plus wider recognition of the need for true rms metering with adequate crest factor capability in making all line current measurements. Implicacations for UPS (Uninterruptible Power Supply) manufacturers and users are also discussed. Wave factor WF is defined as the ratio of actual current drawn, to that which would be drawn by a resistive load with the same power consumption. Wave factors are derived for peak, rms and average input currents to full-wave rectifiers with capacitor input filters.

Patent
03 Jan 1974
TL;DR: In this article, an improved method and apparatus for generating reactive power in an installation which includes a capacitor bank and two controlled converters connected to an A-C system of at least one phase was presented.
Abstract: An improved method and apparatus for generating reactive power in an installation which includes a capacitor bank and two controlled converters connected to an A-C system of at least one phase in which the two controlled converters are coupled to each other on their DC sides through a smoothing choke with the converters controlled in a control range with a differing control angles. In the present invention, the control angles of both converters are controlled in such a manner that their sum is always smaller by a predetermined amount than a 180* thereby permitting simpler control and a reduced size of smoothing coil to be used.