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Showing papers on "Voltage regulation published in 1975"


Journal ArticleDOI
R. F. Woll1
TL;DR: In this article, the authors focus on the problem of unbalanced voltage at the point of utilization of a three-phase induction motors and the effect of such voltage imbalance on the operation of the motors.
Abstract: Three-phase electric power systems generally provide voltage supply at the generating station that is well balanced in both magnitude and displacement. For varying reasons, however, some degree of voltage unbalance occurs at the point of utilization, and, depending upon the amount of unbalance, this can have an adverse effect upon the operation of polyphase induction motors. A major cause of unbalanced voltage at the point of utilization is that single-phase loads on a system are not uniformly applied to all three phases. This is particularly true for some rural electric power systems, and it can also occur in large urban power systems where heavy single-phase demands are imposed by facilities such as extensive shopping plazas. A large manufacturing plant may have well balanced incoming supply voltage, but unbalance can develop within the plant from its own single-phase power requirements if these are not uniformly spread among the three phases. Regardless of the cause, unbalanced voltage is harmful to three-phase induction motors. The paper to follow concentrates upon that aspect of unbalanced voltage.

98 citations


Patent
Alden J. Gray1
02 Apr 1975
TL;DR: In this paper, a multiple voltage electrical supply system with an alternator having electrically isolated generating windings disposed so as to insure that the magnetic flux linking each of the generators bears a substantially constant ratio to that linking the other generators.
Abstract: A multiple voltage electrical supply system continuously connected for individually charging a plurality of battery supplies continuously connected in series with one another to supply a plurality of load circuits having differing d.c. input voltage requirements and, typically, also having differing expected electrical power consumption rates. The system includes an alternator having electrically isolated generating windings disposed so as to insure that the magnetic flux linking each of the generating windings bears a substantially constant ratio to that linking the other of the generating windings. The exemplary embodiment has generating windings of different characteristic resistance per unit length such that there is an increased internal voltage drop in the winding intended to supply the lighter electrical load. The resultant voltage regulation characteristics are such that a single voltage regulator is sufficient to maintain both of the output voltages at a substantially constant predetermined ratio.

82 citations


Journal ArticleDOI
TL;DR: In this paper, the accuracy of the digital methods for protection of high voltage transmission lines under transient fault condition on a long line was explored and an improved method for future digital protection schemes.
Abstract: This paper explores the accuracy of the digital methods for protection of high voltage transmission lines under transient fault condition on a long line and describes an improved method for future digital protection schemes. With this method it is possible to calculate R and L of high voltage transmission lines so that any number of harmonics on the current and voltage waveforms can be eliminated and it is shown to be suitable for distance protection during the first cycle of fault occurrence.

73 citations


Patent
Herko Joseph M1, James Maurice Joyce1
20 Oct 1975
TL;DR: In this paper, an improved pulse width modulated (PWM) voltage regulator-converter system is presented, which can function alone as a switched voltage regulator system or in combination with a switched power converter.
Abstract: Disclosed herein is an improved pulse width modulated (PWM) voltage regulator-converter system which can function, alone, as a switched voltage regulator system or in combination with a switched power converter, synchronized therewith to form an improved voltage regulator-converter/power converter system. In the pulse width modulated voltage regulator-converter embodiment of the invention, secondary windings of a "current mode" regulator-converter interstage transformer are coupled to regulator-converter power transistors in a push-push circuit configuration. Signals generated by a system clock means and an error signal, derived from the output of an averaging filter, drive a pulse width modulated control means connected to the primary windings of the regulator-converter interstage transformer to thereby increase the maximum regulated output voltage of the voltage regulator-converter system after conditioning in the averaging filter. In the pulse width modulated voltage regulator-converter/power converter embodiment of the invention, the aforementioned output voltage of the voltage regulator-converter system is coupled directly to a switched power converter connected in a push-pull circuit configuration. In turn, additional signals generated by the system clock means switch the power converter in synchronizm with the voltage regulator-converter system.

54 citations


Patent
03 Feb 1975
TL;DR: In this paper, a voltage regulator in series with the current return path is employed to control the output voltage level of a laser or gas discharge lamp, and a duty cycle modulator is used to reduce the voltage level.
Abstract: A regulated power supply for a laser or gas discharge lamp employs a variable duty cycle oscillator to control the output voltage level. Output current to the laser or lamp load is maintained at a constant value by a feedback loop that controls the oscillator duty cycle. The output current is sensed by a novel circuit which employs a voltage regulator in series with the current return path. A change in output current causes a concomitant change in voltage across a resistor divider that shunts the voltage regulator. The voltage from this divider is a feedback signal that is supplied to a duty cycle modulator which controls the oscillator duty cycle. Another feedback signal is derived in delayed response to voltage output in excess of a certain high value. This feedback signal, which occurs, e.g., when the laser or lamp load does not ignite within a certain time period, also modifies the oscillator duty cycle so as to reduce the output voltage to a level that can be maintained continuously without damage or overheating of any circuit component.

30 citations


Patent
16 May 1975
TL;DR: In this article, two voltage inverter circuits are connected in series across a common load and controlled electronic power switches are provided to short-circuit the output of the respective inverter circuit during the time period when it is not producing output energy.
Abstract: Circuit arrangement for producing an alternating output voltage from a d.c. input voltage employing two d.c. to a.c. voltage converters, i.e., inverter circuits, which are controlled by high frequency pulse width modulated signals so that one of the inverter circuits produces the positive half waves of the alternating output voltage and the other inverter circuit produces the negative half waves of the alternating output voltage. The outputs of the two voltage inverter circuits are connected in series across a common load and controlled electronic power switches are provided to short-circuit the output of the respective inverter circuit during the time period when it is not producing output energy.

27 citations


Patent
05 May 1975
TL;DR: In this article, the switching frequency of a single-ended converter is stabilized by adjusting the charging threshold of a timer circuit controlling the conducting interval of the switching devices in response to a voltage regulation error signal.
Abstract: In a typical self-oscillating, single-ended converter that is pulse width modulated to regulate the output signal, duty cycle changes to stabilize the output signal cause the switching frequency of the converter to vary. The switching frequency of the single-ended converter disclosed herein is stabilized by controlling the on and off durations of the switching device in an inverse proportional relationship to each other. The relation is controlled by adjusting the charging threshold of a timer circuit controlling the conducting interval of the switching devices in response to a voltage regulation error signal which controls the nonconducting interval thus limiting the total period of the switching device to a fixed interval.

24 citations


Patent
Victor Rodek1, Thomas B. Michaels1
07 Feb 1975
TL;DR: In this article, a constant power regulator for a xerographic fuser is proposed, where power control is achieved by taking the sum of the load voltage and current, and the output of this summing circuit is detected by a photodetector that electrically isolates the power regulator from a voltage regulator which has an output for controlling the power supply to the fuser through, for example, a triac, controlled as a function of the signal and the detected voltage generated by the power regulating circuit.
Abstract: A constant power regulator for a xerographic fuser in which power control is achieved by taking the sum of the load voltage and current. The regulator includes an operational amplifier connected as a voltage adding circuit. The operational circuit amplifier of the power regulator adds the voltage drop across the fuser and a reference resistor connected in series with the fuser and the voltage drop across the fixed reference resistance which represents the current flow through the fuser. The output of this summing circuit is detected by a photodetector that electrically isolates the power regulator from a voltage regulator which has an output for controlling the power supply to the fuser through, for example, a triac, controlled as a function of the power supply signal and the detected voltage generated by the power regulating circuit.

23 citations


Journal ArticleDOI
P.L. Noferi1, L. Paris
TL;DR: In this paper, a method for the reliability evaluation of a power generation and transmission system, when considering, together with the constraints on the active power capability of elements, the voltage constraint in network nodes, is presented.
Abstract: The paper deals with a method for the reliability evaluation of a power generation and transmission system, when considering, together with the constraints on the active power capability of elements, the voltage constraint in network nodes. The approach suggested is an extension of a previous method for the reliability evaluation when considering only the active power capability constraints. The method is based on the approximate evaluation, by means of linear computation methods, of the reactive power flows and of the consequent voltage values in network nodes. This evaluation is performed starting from the approximate evaluation of the active power flow derived with the classic method of d.c. load-flow computation. The system performance, as a consequence of voltage constraints, is quantitatively evaluated by means of two indices: the first being the power disconnected in the nodes as a consequence of unacceptable voltage values or lack of reactive generation, the second being the irregularity of the voltage Service.

23 citations


Patent
10 Mar 1975
TL;DR: In this article, the authors proposed a parallel master-slave regulator with a load current sensor and a secondary differential amplifier for controlling the normal reference voltage supplied to the primary, voltage regulating differential amplifier, where one supply will assume constant current operation at a predetermined load current while the other supply will operate at constant voltage and carry the remainder of the actual load current.
Abstract: In order to achieve the capability to operate a plurality of identical power supplies in parallel, whereby the drawbacks of the conventional master-slave regulator relationship are avoided, the regulator of each power supply is provided with a load current sensor and a secondary differential amplifier circuit responsive to a predetermined load current for controlling the normal reference voltage supplied to the primary, voltage regulating differential amplifier. As a result of the inevitable, within-tolerance differences in the characteristics of two paralleled regulators, one supply will assume constant current operation at the predetermined load current while the other supply will operate at constant voltage and will carry the remainder of the actual load current. As many identical power supplies as necessary for a given application may be operated in parallel, and a single one will automatically operate in the constant voltage mode while the rest operate in the constant current mode.

19 citations


Patent
04 Dec 1975
TL;DR: An improved power supply apparatus for providing a stabilized low voltage d.c. output from the mains, comprises two distinct chopper stages, each having its regulation control loop which operates by duty cycle control as discussed by the authors.
Abstract: An improved power supply apparatus for providing a stabilized low voltage d.c. output from the a.c. mains, comprises two distinct chopper stages, each having its regulation control loop which operates by duty cycle control. The first loop includes a current limiter and provides a rough regulation of the output voltage as a function of the mains variations, whereas the second loop provides a fine regulation of the output voltage as a function of the load variations, and isolation with respect to the load.

Patent
24 Jun 1975
Abstract: A method for charging storage cells or storage batteries by automatically switching a charger off or over to trickle charge when full charge is reached, comprising the steps of automatically determining the shape of the charging voltage curve as a function of time after the gassing voltage of the storage cell or storage battery to be charged has been reached, and switching the charging current off or over to trickle charge as soon as the increase of the charging voltage approaches zero in the course of time. The method further includes the steps of providing an auxiliary voltage by charging a capacitor with a charge current, automatically varying the charge current within pre-set limits and automatically simulating the shape of the charging voltage curve of the storage device as a function of time by means of the auxiliary voltage, after reaching the gassing voltage, such that the auxiliary voltage is a certain extent smaller than the charging voltage as long a difference quotient of the charging voltage exceeds the difference quotient of the capacitor voltage defined by a predetermined lower limit of the charge current of the capacitor after the same time. The charger is automatically cut off if the charging voltage equals or is lower than the capacitor voltage.

Patent
23 Apr 1975
TL;DR: In this article, an error amplifier consisting of a field effect transistor (FET) having a triode characteristic, a constant current circuit as a load in the drain circuit and a variable resistor in the source circuit to provide a variable reference voltage is presented.
Abstract: In series in a load current path between an input terminal and an output terminal is connected a variable resistance element having a control terminal to constitute a series-type direct current voltage regulating circuitry. An error amplifier includes a field effect transistor (FET) having a triode characteristic, a constant current circuit as a load in the drain circuit and a variable resistor in the source circuit to provide a variable reference voltage. The voltage at the output terminal is divided by a resistor network and applied to the gate of FET. The drain voltage of the FET is applied to the control terminal of the variable resistance element. Such a configuration provides a simple circuit arrangement and an excellent voltage regulation.

Journal ArticleDOI
TL;DR: In this article, the effects of static excitation systems with and without reverse current capability on synchronous generators connected to high voltage transmission lines were examined in the context of load rejection conditions.
Abstract: The effects of static excitation systems with and without reverse current capability are examined in the context of load rejection conditions on synchronous generators connected to high voltage transmission lines.

Patent
19 Nov 1975
TL;DR: In this paper, the collector currents of a pair of transistors are adjusted by the ratios of their load resistances to produce a temperature coefficient equal and opposite to the temperature coefficient of third transistor.
Abstract: A shunt regulator circuit having a reference voltage generator in which the collector currents of a pair of transistors are adjusted by the ratios of their load resistances to produce a temperature coefficient equal and opposite to the temperature coefficient of third transistor; a proportional sample of the output voltage is compared to the temperature stable reference voltage to adjust the shunt current to maintain the output voltage constant.

Patent
12 Mar 1975
TL;DR: A NOR or a NAND gate of integrated circuit type, having a fanout of at least three and with a propagation time in the order of 1 nanosecond for a power consumption of a fraction of a milliwatt, is provided in this paper.
Abstract: A NOR or a NAND gate of integrated circuit type, having a fan-out of at least three and with a propagation time in the order of 1 nanosecond for a power consumption of a fraction of a milliwatt, is provided. The gate comprises an inverter stage supplied by a saturable load, and an amplifier stage injecting into a diode and into a saturable load connected in such a fashion as to effect a voltage shift. At the input, there are field-effect transistors of low threshold voltage (-0.2 volts), drawing two microamps at zero gate voltage. For the remainder of the circuit, field-effect transistors having a higher absolute threshold voltage (-0.6 volts) are used, these being designed to draw a very low current at a supply voltage of 1.5 volt.

Journal ArticleDOI
TL;DR: The application of superconductors in the field windings of large steam-turbine generators appears to offer a number of significant economic and operational advantages, most of which are a consequence of the relatively low per-unit synchronous reactance that is characteristic of these machines.
Abstract: The application of superconductors in the field windings of large steam-turbine generators appears to offer a number of significant economic and operational advantages. The principal advantage offered by such machines appears to be a potentially large reduction in size, weight, and cost for a given power rating. In addition, superconducting alternators also appear to have a number of unique and potentially advantageous operational characteristics, most of which are a consequence of the relatively low per-unit synchronous reactance that is characteristic of these machines. This paper reviews the reasons for the low synchronous reactance attributable to the use of superconducting field winding, and compares the expected performance characteristics of a superconducting alternator in the 1000 MVA range with those of a conventional power system generator of comparable rating. Among the specific topics discussed are performance with regard to dynamic stability, transient stability, voltage regulation, and excitation control. The principal operational advantages of a superconducting alternator appear to be 1) the absence of a dynamic stability limit within its MVA capability, 2) significantly greater transient stability when operating at leading power factors, 3) superior voltage regulation, and 4) no degradation of dynamic stability due to automatic voltage regulator action. Consequently, superconducting alternators appear to be ideally matched to modern power system applications that require operation of generators at leading power factors.

Patent
14 Nov 1975
TL;DR: In this article, a circuit for providing high voltage DC power from commercially available 60 hertz AC utility power is described, which includes means for sensing line faults to provide circuit protection.
Abstract: Circuitry for providing high voltage DC power from commercially available 60 hertz AC utility power. The incoming 60 hertz AC voltage is rectified to a DC voltage. This DC voltage is then converted to a high frequency AC voltage by means of a sine wave inverter. This high frequency sine wave voltage is then converted to a different voltage and rectified by a voltage doubler. The inversion and rectification are under the control of logic circuitry which includes means for sensing line faults to provide circuit protection.

Patent
03 Jan 1975
TL;DR: In this article, a method and means for measuring the electric properties of capacitors, inductor and resistor elements is described, where the element to be measured and a reference element are connected in series, and standard A.C. voltage is applied to one end of the series circuit whereas a variable voltage was applied to the other end of said circuit.
Abstract: A method and means for measuring the electric properties of capacitor, inductor and resistor elements is described. The element to be measured and a reference element are connected in series, and standard A.C. voltage is applied to one end of the series circuit whereas a variable voltage is applied to the other end of said circuit. The variable voltage is controlled in order to zero the voltage or the current at the common junction of both the element to be measured and the reference element. Said standard voltage and said variable voltage are rectified, and the generated D.C. signals are used for charging integrator capacitors. These capacitors are then discharged and the ratio of charging and discharging time is a measure of the resistance, capacitance and inductance, respectively, of the unknown element. Dielectric and magnetic dissipation factors may be measured in a similar manner.

Patent
Atsumi Watanabe1
08 Apr 1975
TL;DR: In this article, a control voltage for making the gate pulses is corrected by the use of the lowest one of the phase voltages or line voltages of the A.C. system and whose interval is constant for respective arms of the inverter.
Abstract: An inverter in the D.C. power transmission is controlled by gate pulses which are synchronized with voltages of an A.C. system and whose interval is constant for respective arms of the inverter. Simultaneously therewith, in order to prevent the inverter from causing a commutation failure due to a fault in the A.C. system, a control voltage for making the gate pulses is corrected by the use of the lowest one of the phase voltages or line voltages of the A.C. system. The control voltage becomes greater as the phase voltage or the line voltage lowers more from a rated voltage. When the control voltage increases, the gate pulses are provided at a timing of a larger advanced control angle so as to maintain the extinction angle constant.

Patent
12 Nov 1975
TL;DR: In this article, the authors proposed a regulated high voltage d.c. supply having an output voltage in the range of from 50 to 150 kilovolts such as is required for medical X-ray apparatus.
Abstract: The present invention relates to a regulated high voltage d.c. supply having an output voltage in the range of from 50 to 150 kilovolts such as is required for medical X-ray apparatus. The high voltage d.c. supply is constituted of a plurality of lower voltage d.c. to d.c. converter modules, whose output voltages are summed to produce the high voltage output. The converters are of a type which permits rapid activation and inactivation or "modulation". The modules are subjected to dynamic control to eliminate a.c. ripple, to regulate the high voltage output against supply line and load variations, and to turn the high voltage on and off in accurately timed intervals.

Journal ArticleDOI
01 Aug 1975
TL;DR: The ϵ-coupling method has been applied to the solution of the load-flow problem in power systems in connection with the weak coupling between the subsystems for active and reactive power flows, and confirms the theoretical expectation of being considerably more efficient than the Newton-Raphson algorithm.
Abstract: The ϵ-coupling method has been applied to the solution of the load-flow problem in power systems in connection with the weak coupling between the subsystems for active and reactive power flows. The load-flow algorithm, based on this method, confirms the theoretical expectation of being considerably more efficient than the Newton-Raphson algorithm, as far as computing time and memory requirements are concerned, which are on the level of those required by the decoupled algorithms. The algorithm may be adapted to problems demanding efficient load-flow computations, such as security monitoring and optimal load-low problems.

Patent
21 Feb 1975
TL;DR: In this article, a cathode ray tube linear beam deflection system capable of operation over a wide range of beam-deflection rates providing automatic power supply voltage switching to maintain linear operation and provide minimum power dissipation.
Abstract: A cathode ray tube linear beam deflection system capable of operation over a wide range of beam deflection rates providing automatic power supply voltage switching to maintain linear operation and provide minimum power dissipation. Information for the automatic switching is obtained by continuously monitoring the yoke voltage, the power supply voltage being switched to a voltage of higher magnitude when the yoke voltage exceeds a predetermined level and returned to the power supply voltage of lower magnitude when the higher magnitude voltage is no longer required.

Patent
Yukio Koyanagi1
03 Jul 1975
TL;DR: In this article, a voltage generating system comprising generators for producing a plurality of reference voltages, switching devices provided in the reference voltage generators such that any of a given one or given ones of the source voltages may be selectively taken out, an integrator to smooth a selected reference voltage to obtain an output voltage, a switching pulse generator to produce a switching pulses signal for switching the switching devices and a circuit to vary the duty ratio of the switching pulse signal so as to varying the magnitude of the output voltage.
Abstract: A voltage generating system comprising generators for producing a plurality of reference voltages, switching devices provided in the reference voltage generators such that any of a given one or given ones of the reference voltages may be selectively taken out, an integrator to smooth a selected reference voltage to obtain an output voltage, a switching pulse generator to produce a switching pulse signal for switching the switching devices and a circuit to vary the duty ratio of the switching pulse signal so as to vary the magnitude of the output voltage. This voltage generating system may be used for generating a channel selection voltage for electronic tuners (varactor tuners), for digital-to-analog converter circuits etc.

Journal ArticleDOI
TL;DR: In this paper, a method for obtaining dynamic solutions for the electrical and mechanical transients that accompany balanced or unbalanced faults on an isolated synchronous generator is described, illustrated with a system containing a prime mover plus governor, synchronous generators, manual or automatic voltage regulation, and reclosing feeder circuit breaker.
Abstract: A method is described for obtaining dynamic solutions for the electrical and mechanical transients that accompany balanced or unbalanced faults on an isolated synchronous generator. The method is illustrated with a system containing a prime mover plus governor, synchronous generator, manual or automatic voltage regulation, and reclosing feeder circuit breaker. A combination of abc and Odq variables is employed in the interest of simplicity and economy in computation.

Patent
19 Feb 1975
TL;DR: In this article, the output of the secondary winding is rectified and filtered to provide the converter output, and voltage regulation is accomplished by controlling the one-shot multivibrator.
Abstract: Various types of static DC to DC converters are known. Some of these have output rectifiers including phase controlled SCRs. The present invention eliminates the need for controlled output SCRs by pulse width modulation of switching elements in a control circuit controlling the converter circuitry itself. This results in the elimination of some switching devices, higher reliability and higher-efficiency, A unijunction oscillator drives a one-shot multivibrator and a flip flop. The unijunction oscillator, one-shot multivibrator and flip flop feed two AND gates which are alternately enabled to allow pulses of current to flow from a DC source through opposite halves of a primary winding of a transformer. The output of the secondary winding is rectified and filtered to provide the converter output. Voltage regulation is accomplished by controlling the one-shot multivibrator. In one embodiment, paralleling of a number of converters is enabled by providing for frequency and pulse width synchronization.

Patent
08 Dec 1975
TL;DR: In this paper, the voltage dividing DC circuit breaker comprises serially connected high voltage and low voltage switches to carry load current, and a crossed field switching device is connected in parallel to the low voltage switch.
Abstract: The voltage dividing DC circuit breaker comprises serially connected high voltage and low voltage switches to carry load current. Serial capacitors are connected in parallel thereto and a crossed field switching device is connected in parallel to the low voltage switch. When the low voltage and high voltage switches are opened, current is forced through the crossed field switching device. When the crossed field switching device is turned off, the arcing high voltage switch is forced below its chopping current. The open circuit voltage is divided across the capacitors.

Patent
14 Apr 1975
TL;DR: In this paper, a switching control network has been used for each of the triodes and an oscillator for voltage regulation, for control of the switching phase of the diodes via the latter network.
Abstract: The control system has a switching control network which supplies the control signals for each of the triodes and an oscillator for voltage regulation, for control of the switching phase of the diodes via the latter network. The output voltage of the converter is supplied to a voltage monitor with a current monitor for the output current from the converter, and a phase monitor detects the phase difference between the output voltage signal for controlling the frequency of the voltage regulating oscillator in conjunction with a signal denoting the required power factor.

Patent
02 May 1975
TL;DR: In this article, a solid state control system for controlling a high voltage primary power pplied to a plurality of power supplies by means of a TTL voltage level is presented, where circuit means are provided to sense the power supply whose DC voltage goes to zero volts due to circuit anomalies, or other reasons.
Abstract: A solid state control system for controlling a high voltage primary power pplied to a plurality of power supplies by means of a TTL voltage level. Circuit means are provided to sense the power supply whose DC voltage goes to zero volts due to circuit anomalies, or other reasons. Upon sensing the anomaly the indicator means indicate via a storage device which power supply has failed, before interrupting the primary power.

Patent
22 Dec 1975
TL;DR: In this paper, a clamping circuit is connected in parallel with the chopper and smoothing reactor and provides a current path between the load and the direct current source when load voltage attempts to exceed source voltage as a result of commutation transients in the voltage-turn-off chopper.
Abstract: Apparatus for limiting the peak magnitude of voltage applied to a chopper excited load to the magnitude of the source voltage. In a system including a chopper, a smoothing reactor and a load serially connected to a direct current power source, a clamping circuit is connected in parallel with the chopper and smoothing reactor and provides a current path between the load and the direct current source when load voltage attempts to exceed source voltage as a result of commutation transients in the voltage-turn-off chopper. Where the load is a direct current motor, the clamping circuit in combination with a freewheeling diode provides a suppression circuit for power source transients.