Showing papers on "Voltage regulation published in 1986"

Power Systems Analysis

Abstract: 1. Background. Introduction. Electric Energy. Fossil-Fuel Plant. Nuclear Power Plant. Hydroelectric Power Plant. Other Energy Sources. Transmission and Distribution Systems. The Deregulated Electric Power Industry. 2. Basic Principles. Introduction. Phasor Representation. Complex Power Supplied to a One-Port. Conservation of Complex Power. Balanced Three-Phase. Per Phase Analysis. Balanced Three-Phase Power. Summary. 3. Transmission-Line Parameters. Introduction. Review of Magnetics. Flux Linkages of Infinite Straight Wire. Flux Linkages Many-Conductor Case. Conductor Bundling. Transposition. Impedance of Three Phase lines Including Ground Return. Review of Electric Fields. Line Capacitance. Determination of Line Parameters Using Tables. Typical Parameter Values. Summary. 4. Transmission-Line Modeling. Introduction. Derivation of Terminal V, I Relations. Waves on Transmission Lines. Transmission Matrix. Lumped-Circuit Equivalent. Simplified Models. Complex Power Transmission (Short Line). Complex Power Transmission (Radial Line). Complex Power Transmission (Long or Medium Lines). Power-Handling Capability of Lines. Summary. 5. Transformer Modeling and the Per Unit System. Introduction. Single-Phase Transformer Model. Three-Phase Transformer Connections. Per Phase Analysis. Normal Systems. Per Unit Normalization. Per Unit Three-Phase Quantities. Change of Base. Per Unit Analysis of Normal System. Regulating Transformers for Voltage and Phase Angle Control. Autotransformers. Transmission Line and Transformers. Summary 6. Generator Modeling I (Machine Viewpoint). Introduction. Classical Machine Description. Voltage Generation. Open-Circuit Voltage. Armature Reaction. Terminal Voltage. Power Delivered by Generator. Synchronizing Generator to an Infinite Bus. Synchronous Condensor. Role of Synchronous Machine Excitation in Controlling Reactive Power. Summary. 7. Generator Modeling II (Circuit Viewpoint). Introduction. Energy Conversion. Application to Synchronous Machine. The Park Transformation. Park's Voltage Equation. Park's Mechanical Equation. Circuit Model. Instantaneous Power Output. Applications. Synchronous Operation. Steady-State Model. Simplified Dynamic Model. Generator Connected to Infinite Bus (Linear Model). Summary 8. Generator Voltage Control. Introduction. Exciter System Block Diagram. Generator Models. Stability of Excitation System. Voltage Regulation. Generator Connected to Infinite Bus. Summary. 9. Network Matrices. Introduction. Bus Admittance Matrix. Network Solution. Network Reduction (Kron Reduction). YBUS Structure and Manipulation. Bus Impedance Matrix. Inverse Elements to Determine Columns of ZBUS. Summary. 10. Power Flow Analysis. Introduction. Power Flow Equations. The Power Flow Problem. Solution by Gauss Iteration. More General Iteration Scheme. Newton-Raphson Iteration. Application to Power Flow Equations. Decoupled Power Flow. Control Implications. Regulating Transformers in Power Flow Analysis, Power Flow Solutions for Large Power Systems. Summary. 11. Automatic Generation Control and the New Market Environment. Introduction. Power Control System Modeling. Application to Single Machine-Infinite Bus System. Simplified Analysis of Power Control System. Power Control, Multigenerator Case. Special Case Two Generating Units. Division of Power System Into Control Areas. Formulation of the Economic Dispatch Problem. Classical Economic Dispatch (Line Losses Neglected). Generator Limits Included. Line Losses Considered. Calculation of Penalty Factors. Economic Issues and Mechanisms in the New Market Environment. Transmission Issues and Effects in the New Market Environment. Summary. 12. Unbalanced System Operation. Introduction. Symmetrical Components. Use of Symmetrical Components for Fault Analysis. Sequence Network Connections for Different Types of Faults. More General Fault Circuit Analysis. Power From Sequence Variables. Sequence Representation of Y and ...D Connected Circuits. Generator Models for Sequence Networks. Transformer Models for Sequence Networks. Sequence Representation of Transmission Lines. Assembly of Sequence Networks. Fault Analysis for Realistic Power System Model. Matrix Methods. Summary. 13. System Protection. Introduction. Protection of Radial Systems. System with Two Sources. Impedance (Distance) Relays. Modified-Impedance Relays. Differential Protection of Generators. Differential Protection of Transformers. Differential Protection of Buses and Lines. Overlapping Zones of Protection. Sequence Filters. Computer Relaying. Summary. 14. Power System Stability. Introduction. Model. Energy Balance. Linearization of Swing Equation. Solution of Nonlinear Swing Equation. Other Applications. Extension to Two-Machine Case. Multimachine Application. Multimachine Stability Studies. Summary. Appendices. Reluctance. Force Generation in a Solenoid. Method of Lagrange Multipliers. Root-Locus Method. Negative- and Zero-Sequence Impedances of Synchronous Machines. Inversion Formula. Modification of Impedance Matrices. Conductor Characteristics. Selected Bibliography. Index.

Near-Optimum Dynamic Regulation of DC-DC Converters Using Feed-Forward of Output Current and Input Voltage with Current-Mode Control

Abstract: Near-optimum dynamic regulation of a dc-dc converter is obtained by adding feed-forward of output current and input voltage to a current-mode controller. The results are a) near zero output impedance and audio susceptibility, from dc to nearly the switching frequency, b) much reduced magnitude, duration, and energy content of the output-voltage transient after a transient change of output current or input voltage, and c) smaller size and lower cost for the output filter capacitor. Feed-forward is applicable to both forward and flyback types of converters and to all types of current-mode control. The cost of feed-forward for a forward-type converter is a low-power resistor and a current sensor; a flyback-type converter needs also an analog multiplier-divider integrated circuit (IC). A description is given of the control loop, conditions to achieve extremely good transient response, calculation of the peak deviation of the output voltage for a step load change, practical methods for current feed-forward, and experimental results. The theoretical predictions are in excellent agreement with the experimental results. In the experiments, adding output-current feed-forward reduced the transient deviations of output voltage by factors of 6.7 in magnitude, 50 in duration, and 335 in energy content. The added components were a 1/4-W resistor and a 12-mm ferrite toroid with a 10-turn winding.

An Expert System Assisting Decision-Making of Reactive Power/Voltage Control

Abstract: An expert system is developed to assist in the decision-making of the reactive power/voltage control problem. The knowledge required to perform the task is identified. To alleviate a voltage problem, empirical rules are used to generate appropriate control actions when slight voltage violations occur. Controls such as shunt capacitors, transformer tap changers and generator voltages are utilized. Theoretical justification of the empirical rules is presented. When it is judged that the voltage problem is so severe that empirical judgements may not be reliable, the developed expert system can help in formulating the problem so that an available application software package can be effectively utilized. In this paper, production rules are proposed to perform the above functions. Numerical examples are also presented.

A digitally controlled AC to DC power conditioner that draws sinusoidal input current

Abstract: An ac to dc power conditioner, which draws sinusoidal input current, is described and analyzed. Two control loops are used. The inner quantized-gain current program loop uses variable hysteresis to improve noise immunity. Digital proportional-integral control provides output voltage regulation by adjusting the gain of the current program loop.

Synchronous power rectifier

Abstract: A synchronous power rectifier incorporating a bipolar power transistor operable in a switching mode to rectify the energy from a secondary winding of a power transformer. The synchronous rectifier reduces or eliminates the need of rectifier diodes, which provides power rectification without the power loss associated with the rectifier diode voltage drops. Moreover, the present invention includes further refinements of the circuit, including adjustment of the rectifier switching time to accommodate delayed turn-off times of bipolar power devices, and adjustment of the switching signal duration to provide output voltage regulation independent of the excitation of the transformer primary. The resulting embodiments of the present invention provide a modular switching power supply circuit of high efficiency, which may be operable together in combination to provide multiple output voltages.

High frequency generator to be used in induction heating, laser, plasma and the alike

Abstract: A high frequency generator is coupled to a resonant load. An inverter is swept through a range of frequencies at reduced power. The phase difference between the load current and voltage is measured. When the phase difference is at or near zero, the resonant frequency of the load is detected and the inverter provides full power to the load. The phase difference between the load current and voltage is monitored during operation so that the operating frequency of the inverter can be changed as the resonant frequency of the load changes.

Single regulation power supply with load compensation of an auxiliary voltage output

Abstract: A single regulation power supply providing load compensation of an auxiliary voltage output, wherein power is transferred from the primary winding of a transformer to a first and a second secondary windings each coupled to a rectifying and filter network respectively providing a main and an auxiliary voltage output, wherein a control loop senses the algebraic sum of the main output voltage and the voltage drop developed in a resistor by current drawn by a load on the auxiliary voltage output and controls current pulses applied to the primary winding so as to keep constant such sum, thereby rendering the auxiliary voltage insensitive to load changes at the auxiliary output, to any desired extent determined by the value of such resistor, with the trade off of a limited degradation in the control of the main voltage output.

Capacitor-plate bias generator for CMOS DRAM memories

Abstract: A capacitor-plate bias generator produces a voltage on the capacitor plate node which consists of a constant voltage plus the sense-level voltage. Consequently, the capacitor-plate node tracks any variations in the sense-level voltage. The constant voltage is 3VBG, or 3 times the bandgap voltage of silicon. The circuit includes a reference-voltage source which produces the sum of the sense-level voltage and VBG, and a feedback control circuit for enabling either a charge pump or a charge bleeder to regulate the capacitor-plate voltage at a level above the circuit supply voltage.

Charge pump voltage regulator

Abstract: A voltage regulator (11) provides a pulse width modulated voltage regulator output (40) to a drive circuit (37) to provide field coil excitation for a voltage generator (15-17) providing a charging signal for a battery (14). The voltage regulator output determines on/off states of an FET power switching device (28) coupled in series with a field coil (17) across a maximum power source voltage potential VBAT corresponding to battery voltage. The drive circuit includes a charge pump (26, 35, 36) with a low capacitance capacitor (26) coupled and decoupled across a source of voltage potential at a rate determined by a high frequency signal (41), provided by the regulator, having a frequency substantially in excess of the frequency of the voltage regulator output. The drive circuit includes a pair of switches (21, 35) which alternately couple one terminal of the capacitor to either battery voltage or ground potential in accordance with the voltage regulator output. The above configuration provides a control voltage (44) at the gate of the FET substantially in excess of battery voltage and this insures maximum field current when the FET is on. This is achieved with a minimum capacitance for the capacitor, thus reducing circuit size and cost. Battery current drain of the drive circuit is minimized by disconnecting the one terminal of the capacitor from battery voltage when the FET is off.

Adaptive Harmonic Control in PWM Inverters with Fluctuating Input Voltage

Abstract: New techniques of harmonic reduction and voltage regulation in PWM inverters with fluctuating input voltage are described. A novel selective harmonic reduction technique is also developed for three-phase full-bridge inverters to reduce the number of switchings per output cycle. For keeping the fundamental load voltage at the present value and suppressing the generation of low-order harmonics when the input voltage fluctuates, the conventional sinusoidal reference of the triangulation method is replaced by a quasi-sinewave whose magnitude varies inversely with the input voltage to keep the product of the reference voltage and the input voltage sinusoidal. Harmonic analysis of the W-type modulation and M-type modulation is given to show that the load voltage spectra of the output waveforms generated with the proposed methods are insensitive to the source voltage fluctuation and load variation. Experimental results confirm the theoretical analysis.

Circuit arrangement for operating a high-pressure discharge lamp

Abstract: A circuit for operating a discharge lamp (1) by means of a direct voltage. The circuit comprises direct voltage terminals (A,B) for connection of a direct voltage source, alternating voltage output terminals (K,L) for connection to the discharge lamp, a direct voltage/alternating voltage sine converter (3), and a current limiter (5) for limiting the current through the lamp in its operating condition. A controllable direct voltage converter (2) is coupled between the sine converter and the direct voltage input terminals.

Stability studies of multimachine power systems with the effects of automatic voltage regulators

Abstract: The stability of power systems including the effects of automatic voltage regulators is studied via Lyapunov's direct method. The multivariable Popov criterion developed by Moore and Anderson is employed in constructing a Lure-type function for a power system consisting of synchronous machines interconnected by a lossless transmission system. The Lyapunov function constructed for the system with only flux decay is regarded as a special case of the result obtained in this paper. The effect of an automatic voltage regulator on power system stability is illustrated by numerical examples, showing some shifts of equipotential curves which are due to changes of voltage regulator gain.

A Single Phase Induction Motor Voltage Controller with Improved Performance

Abstract: Induction motors inherently operate with nearly constant airgap flux and therefore almost constant iron losses. When the load does not require full flux, conventional voltage controllers utilize thyristors in series with the motor to reduce airgap flux by decreasing the applied voltage. Thereby, iron losses decrease and the overall efficiency increases. However, thyristor voltage controllers tend to introduce harmonics into the current waveform which not only reduces motor efficiency but also causes harmonic pollution of the power lines. An improved voltage controller and control strategy for efficiency improvement of single phase induction motors is presented. In particular, thyristor voltage control by dynamic switching of the winding configuration is presented. Laboratory data for a voltage controller, thus enhanced, demonstrates a significant decrease in input motor current distortion and increase in efficiency below one-quarter load.

Localized response performance of the decoupled Q -V network

Abstract: In this paper the assumption of a localized voltage response due to reactive power disturbances is analyzed. Conditions on transmission line parameters, given its normal operating point, are stated which explicitly define directions of voltage changes so that the line is subject to the localized voltage response. We show that it is not possible to give an exclusive answer to the question of the localized response (tier-wise) in the decoupled Q - V network. The answer is network and operating point dependent. The operating regions in which this property is satisfied even under large changes in reactive power injections are derived on the SE graph based decoupled Q- V network. We first define a no-gain operating mode of this network and then claim that the power no-gain operating mode always implies a localized voltage response. These results cannot be used to demonstrate a voltage gain. We develop algebraic type statements to show that a system may have response which is system wide. More definite answers on the localized response are established for the echelon structure of a given network.

High voltage power supply system including inverter controller

Abstract: A high voltage power supply system includes a DC-to-DC converter for producing a DC low voltage, a DC-to-AC inverter connected to a step-up transformer for producing an AC high voltage by transforming an AC low voltage obtained from the DC low voltage, and an inverter controller for controlling an operation time period of the DC-to-AC inverter longer than that of the DC-to-DC converter. Since a residual charge stored in a capacitor of the DC-to-DC converter is rapidly discharged by lengthening the operation time period of the DC-to-AC inverter, an unwanted AC high voltage is induced at a secondary winding of the step-up transformer.

Voltage-insensitive and temperature-compensated delay circuit for a monolithic integrated circuit

Abstract: A delay circuit which is insensitive to variations in power supply voltage, which is temperature-compensated, and which is suitable for fabrication in a monolithic integrated circuit includes circuitry for charging a capacitive element through a resistive element from GND toward the power supply voltage. The voltage across the capacitive element is compared to a reference voltage by a voltage comparator, and the voltage comparator generates an output signal when the voltage on the capacitor becomes greater than the reference voltage. The reference voltage for the comparator is generated by a resistor divider connected between GND and the power supply voltage. Inasmuch as the reference voltage varies with changes in the power supply voltage in such a manner as to be maintained at a substantially fixed percentage of the power supply voltage, the time delay provided by the delay circuit is essentially independent of variations in power supply voltage. By utilizing resistors in the resistor divider that have differing temperature coefficients of resistance, the reference voltage for the comparator can be increased and decreased in a predetermined manner in response to increases and decreases in ambient temperature, allowing the time delay of the delay circuit to be adjusted in a predetermined manner as a function of temperature.

Input voltage compensated, microprocessor controlled, power regulator

Abstract: A regulating A.C. power controller regulates the selected levels of power to be applied to a plurality of loads by producing a digital signal directly from the A.C. voltage with a pulse duration representative of load power which can be applied as an input to the microprocessor without the need for prior analogue to digital conversion. The load power level is displayed in terms of percentage of power source. Remote control units, such as a computer, can be connected with the power controller to program it for power level settings and warm up time.

CMOS reference voltage generator employing separate reference circuits for each output transistor

Abstract: An internal power supply voltage generator for generating an internal power supply voltage for a semiconductor integrated device includes first and second reference voltage generators which produce first and second reference voltages having respective values a predetermined amount above and below an optimal value of the internal power supply voltage. The first and second reference voltage generators are constructed of a pair of serially connected NMOS and PMOS transistors, respectively, which transistors are connected between an external voltage supply and ground. The first and second reference voltages are applied to a CMOS output stage constructed of a NMOS and PMOS transistor serially connected between the external voltage supply and ground, the gates of the transistors being coupled to the first and second reference voltages, so as to provide said internal power supply voltage at a common node between the transistors. This voltage generator exhibits a lowered power dissipation and a lowered output impedance, as a result of providing a CMOS output stage.

Principles and Output Characteristics of Super High-Speed Reluctance Generator System

Abstract: In order to obtain a compact lightweight electric power source for ground vehicles, ships, and airplanes which cannot be fed from external power sources, a super high-speed reluctance generator system is proposed. The system consists of a reluctance machine, a voltage source inverter, and control circuits. The output characteristics are calculated using an equivalent circuit of the reluctance generator. The experimental results obtained at 24 000 r/min show that an efficiency of more than 85 percent and an output of more than 1.5 kW were achieved. The excellent agreement of the measured and calculated values verified the correctness of the analysis method and parameter measurements.

Voltage regulator for alternator of vehicle

Abstract: A voltage regulator maintains an output voltage of an alternator of a vehicle to a voltage in the vicinity of a preset voltage. The voltage regulator has a microcomputer for setting the OFF duty ratio, a switching circuit for switching on or off an electric current flowing through a rotor coil of the alternator and a load sensor for detecting the operation of the intermittent load. The microcomputer sets the OFF duty ratio to a value directly proportional to the difference between the output voltage and the preset voltage before the operation of the intermittent load is started. And the microcomputer gradually decreases the OFF duty ratio set by said duty ratio setting means at the initial operation time of the intermittent load, and memorizes the OFF duty ratio when the output voltage reaches its upper limit value exceeding the preset voltage. The microcomputer changes the OFF duty ratio to an average value of the OFF duty ratio set by the duty ratio setting means and the OFF duty ratio memorized by the memory means when the reoperation of the intermittent load is detected within a prescribed time after the initial operation of the intermittent load.

Dual voltage motor vehicle electrical system

Abstract: A dual voltage motor vehicle electrical system wherein batteries are series connected across the direct voltage output terminals of a generator. The system has a DC to DC converter that operates in a first mode as an equalizer to maintain the batteries in a substantially equal state of charge. When an electric starting motor is energized to crank the engine of the vehicle the converter is switched to a second mode of operation wherein it provides a substantially constant output voltage that is applied to certain electrical loads on the vehicle that require a stable voltage. The converter responds to a first reference voltage that is provided by a voltage divider connected across the batteries when operating in the first mode and responds to a second reference voltage provided by a constant voltage device when operating in the second mode. The system switches between the reference voltages, depending upon the mode of operation that is being used.

AC voltage regulator with split primary switching

Abstract: An apparatus for AC line voltage regulation has an input port for connection to an AC source, an output port for connection to a load, and a transformer assembly connected between the input and output ports The transformer assembly comprises a buck/boost winding and a primary winding wound about a common transformer core, and a switch arrangement for controlling the connection of the primary winding in circuit with the buck/boost winding The switch arrangement is controlled by switch actuators responsive to a voltage sensor assembly to connect the primary winding in either of two possible conditions when the voltage is outside predetermined limits The transformer assembly comprises either a step down transformer for reducing or bucking the output voltage or a step up transformer for boosting the output voltage according to the condition of the switch arrangement The primary may comprise separate windings controlled by the switching assembly for connection in different configurations

Design of Switching Regulator with Combined FM and On-Off Control

Abstract: The design and implementation of a switching regulator incorporating a high-frequency series-resonant converter and a combined FM and on-off feedback control is presented. The combined FM and on-off control results in a better conversion efficiency and a wider range of operational input voltage and output current. A 22.5 V, 50 W experimental regulator has been built to demonstrate the practicality of the circuit and its high efficiency, typically 92 to 96 percent, depending on the input and loading conditions.

Anticipatory power failure detection apparatus and method

Abstract: An anticipatory power failure detection apparatus and method, for use in connection with power supplies providing a regulated voltage signal to an electronic load such as a computer, employing circuitry for determining whether a control signal, within the regulated power supply circuit, is in a saturation state. Upon detecting a saturation state for the control signal, circuitry signals that an input power failure is occurring. The regulated power supply system can be a switching-type voltage regulation control system, wherein a pulse-width modulated switching system controls the periodic input of energy to an energy-storage network which generates the regulated voltage output signal. A derivative of the error signal is periodically sampled for determining whether it is in the saturation state. The regulated power supply control signal will be in the saturation state when the unregulated input voltage supply is insufficient to maintain the regulated voltage signal at the specified optimum operating point.

Control circuit for tap-switching power supplies and multi-tap transformers

Abstract: A tap-switching circuit for automatically controlling the output voltage of a multi-tap transformer in response to a varying input line voltage and/or system load current demand, includes voltage sensing circuitry in parallel with both the transformer voltage outputs and a voltage comparator for sensing changes in the system load demand requirements. A voltage reference is provided for automatically generating a pre-selected voltage reference level signal for the line and/or system load requirements. Voltage comparison circuitry is operatively connected with the voltage sensing circuitry for generating an enable signal whenever the input line voltage and/or system load current demand requirements sensed by the voltage sensing circuitry falls below the pre-selected voltage reference level signal. A switching circuit is operatively connected to the voltage comparison circuitry, a linear regulator and to at least two taps of the multi-tap transformer for connecting the higher voltage tap to supply a pre-regulator voltage to the linear regulator whenever the enable signal is present, and for disconnecting the higher voltage tap from supplying its pre-regulator output voltage whenever the enable signal is absent.

Semiconductor device having a voltage limiter

Abstract: A semiconductor device comprising a plurality of circuits driven by at least one external power source, and at least one voltage converter transforming the voltage of the external power source into another voltage. At least a part of the plurality of circuits are driven by the output voltage of the at least one voltage converter, which is provided with a controller for controlling its load driving power, corresponding to the operation of the part of the plurality of circuits. The voltage converter includes a voltage limiter which is used exclusively for each of the different natures of the loads, and its operation and load driving power are controlled, depending on the operations of each of the loads.

Regulator circuit for converting alternating input to a constant direct output

Abstract: A high efficiency integrated power converter adapted for direct connection to line voltage and having on chip protection from overcurrent may be implemented utilizing a GTO-SCR as the switch element in a switching power converter such that the converter requires no external transformer or inductor based voltage reducing circuitry. The input voltage may vary over a wide dynamic range without deterioration in circuit performance due to the extremely high anode to cathode breakdown voltage of the switching element and further due to the on chip protection from excess current flow through the switching element.

Voltage regulator for generator used in automobile

Abstract: In a generator charging a battery on an automobile with output voltage thereof, a voltage regulator has a constant voltage source (20); first and second voltage dividers (91, 92 and 94, 95) dividing the voltage of the constant voltage source (20); a series circuit consisting of a thermo-sensitive element (101-103) and a resistor (93) and being connected to the middle point of the first voltage divider (91, 92); a first diode (104) having an anode connected to the middle point of the first voltage divider; a second diode (105) having an anode connected to the middle point of the second voltage divider (94, 95); and a third diode (106) having a cathode connected to both the cathodes of the first and the second diode (104 and 105) and supplying a reference voltage (V Ref ), wherein the output voltage of the generator is compared with the reference voltage (V Ref ), thereby, the output voltage of the generator is regulated to the reference voltage (V Ref ).