Showing papers on "Voltage regulation published in 1985"

Electric power distribution system engineering

Abstract: Distribution System Planning and Automation Introduction Distribution System Planning Factors Affecting System Planning Present Distribution System Planning Techniques Distribution System Planning Models Distribution System Planning in the Future Future Nature of Distribution Planning The Central Role of the Computer in Distribution Planning Impact of Dispersed Storage and Generation Distribution System Automation Summary and Conclusions References Load Characteristics Basic Definitions The Relationship Between the Load and Loss Factors Maximum Diversified Demand Load Forecasting Load Management Rate Structure Problems References Application of Distribution Transformers Introduction Types of Distribution Transformers Regulation Transformer Efficiency Terminal or Lead Markings Transformer Polarity Distribution Transformer Loading Guides Equivalent Circuits of a Transformer Single-Phase Transformer Connections Three-Phase Connections Three-Phase Transformers The T or Scott Connection The Autotransformer The Booster Transformers Amorphous Metal Distribution Transformers Problems References Design of Subtransmission Lines and Distribution Substations Introduction Subtransmission Distribution Substations Substation Bus Schemes Substation Location The Rating of a Distribution Substation General Case: Substation Service Area with n Primary Feeders Comparison of the Four-and Six-Feeder Patterns Derivation of the K Constant Substation Application Curves Interpretation of the Percent Voltage Drop Formula Supervisory Data and Data Acquisition Advanced SCADA Concepts Advanced Developments for Integrated Substation Automation Capability of Facilities Substation Grounding Transformer Classification Problems References Design Considerations of Primary Systems Introduction Radial-Type Primary Feeder Loop-Type Primary Feeder Primary Network Primary-Feeder Voltage Levels Primary-Feeder Loading Tie Lines Distribution Feeder Exit: Rectangular-Type Development Radial-Type Development Radial Feeders with Uniformly Distributed Load Radial Feeders with Nonuniformly Distributed Load Application of the A,B,C,D General Circuit Constants to Radial Feeders The Design of Radial Primary Distribution Systems Primary System Costs Problems References Design Considerations of Secondary Systems Introduction Secondary Voltage Levels The Present Design Practice Secondary Banking The Secondary Networks Spot Networks Economic Design of Secondaries Unbalanced Load and Voltages Secondary System Costs Problems References Voltage Drop and Power Loss Calculations Three-Phase Balanced Primary Lines Nonthree-Phase Primary Lines Four-Wire Multigrounded Common Neutral Distribution System Percent Power (or Copper) Loss A Method to Analyze Distribution Costs Economic Analysis of Equipment Losses Problems References Application of Capacitors to Distribution Systems Basic Definitions Power Capacitors Effects of Series and Shunt Capacitors Power Factor Correction Application of Capacitors Economic Justification for Capacitors A Practical Procedure to Determine the Best Capacitor Location A Mathematical Procedure to Determine the Optimum Capacitor Allocation Capacitor Tank Rupture Considerations Dynamic Behavior of Distribution Systems Problems References Distribution System Voltage Regulation Basic Definitions Quality of Service and Voltage Standards Voltage Control Feeder Voltage Regulators Line-Drop Compensation Distribution Capacitor Automation Voltage Fluctuations Problems References Distribution System Protection Basic Definitions Overcurrent Protection Devices Objective of Distribution System Protection Coordination of Protective Devices Fuse-to-Fuse Coordination Recloser-to-Recloser Coordination Recloser-to-Fuse Coordination Recloser-to-Substation Transformer High-Side Fuse Coordination Fuse-to-Circuit-Breaker Coordination Recloser-to-Circuit-Breaker Coordination Fault Current Calculations Fault Current Calculations in Per Units Secondary System Fault Current Calculations High-Impedance Faults Lightning Protection Insulators Problems References Distribution System Reliability Basic Definitions National Electric Reliability Council Appropriate Levels of Distribution Reliability Basic Reliability Concepts and Mathematics Series Systems Parallel Systems Series and Parallel Combinations Markov Processes Development of the State Transition Model to Determine the Steady-State Probabilities Distribution Reliability Indices Sustained Interruption Indices Other Indices (Momentary) Load-and Energy-Based Indices Usage of Reliability Indices Benefits of Reliability Modeling in System Performance Economics of Reliability Assessment Problems References Electric Power Quality Basic Definitions Definition of Electric Power Quality Classification of Power Quality Types of Disturbances Measurements of Electric Power Quality Power in Passive Elements Harmonic Distortion Limits Effects of Harmonics Sources of Harmonics Derating Transformers Neutral Conductor Overloading Capacitor Banks and PF Correction Short-Circuit Capacity or MVA Bus Voltage Rise and Resonance Harmonic Amplification Resonance Harmonic Control Solutions Harmonic Filter Design Load Modeling In The Presence Of Harmonics Problems References Appendix A: Impedance Tables for Lines, Transformers, and Underground Cables Appendix B: Graphic Symbols Used in Distribution System Design Appendix C: Glossary for Distribution System Terminology Appendix D: The Per-Unit System Notation Answers to Selected Problems Index

Volt/Var Control on Distribution Systems with Lateral Branches Using Shunt Capacitors and Voltage Regulators Part I: The Overall Problem

Abstract: In this paper (Part I) and two companion papers (Part II and Part III) the problem of volt/var control on general radial distribution systems is formulated, simplified and solved. The objective is to minimize the peak power and energy losses while keeping the voltage within specified limits under varying load conditions. The decision variables to be optimally determined are (i) the locations, sizes and the real-time control of the specified number of ON/OFF switched and fixed capacitors and (ii) the locations and real-time control of the minimum number of voltage regulators. It is shown in this paper (Part I) that the regulator (volt) and the capacitor (var) problem may be treated as two decoupled problems. Part II of this set of three papers, conjoined with Part 1. provides the analytical tools by which optimal solutions for both problems may be determined. Application of the theory to representative radial systems is shown in Part III whhich also illustrates the economic benefits and numerical results achievable through both regulation and compensation schemes.

Volt/Var Control on Distribution Systems with Lateral Branches Using Shunt Capacitors and Voltage Regulators Part III: The Numerical Results

Abstract: In this paper, the numerical results obtained through the application of the optimal design and control schemes of the capacitor and voltage regulator problems (which are formulated and solved on an analytical basis in the previous paper, Parts I and II) are demonstrated on a thirty-bus test system with six lateral branches. The results are discussed in order to demonstrate the applicability of the theory and the bases underlying the modeling of the overall problem.

Microcomputer controlled electronic alternator for vehicles

Abstract: A microprocessor-based electronic voltage regulation system for controlling the charging of the battery in a vehicle. The conventional voltage regulator is eliminated and the intelligence of the microprocessor already present on the vehicle for controlling engine operation is used to regulate the output of the alternator. The battery temperature signal from a temperature transducer and a battery voltage signal from a sense line connected directly to the positive terminal of the battery are supplied to the microprocessor through an analog-to-digital converter. The microprocessor is programmed to ascertain from the battery temperature signal the desired set point voltage based upon an inverse first order relationship between battery temperature and desired battery voltage with preset maximum and minimum voltage set point levels. Energization of the field windings is controlled in accordance with a comparison between the desired set point voltage and the battery voltage signal on the battery sense line and is implemented in response to a control signal from the microprocessor by a solid-state power switching circuit which interfaces with the alternator field windings. In addition, the microprocessor is provided with additional feedback information relating to various driving conditions, such as vehicle deceleration, throttle position, engine RPM, and elapsed time since ignition, and is further programmed to modify the desired voltage set point or modify engine RPM in accordance with such driving conditions. Overcurrent protection for the logic circuitry and improved diagnostic capabilities are also provided.

Dead beat microprocessor control of PWM inverter for sinusoidal output waveform synthesis

Abstract: A new control technique based on dead beat control theory to obtain a nearly sinusoidal PWM inverter output voltage is described. The closed loop digital feedback system measures the output and controls the inverter switches to generate the required PWM pattern to produce low total harmonic distortion (THD) sinusoidal output voltage. This scheme inherently provides very good voltage regulation, phase positioning and compensation for load disturbances and nonlinear loads. This paper presents a theoretical analysis, computer simulation and experimental results for a single-phase bridge inverter controlled by an Intel 8086 microprocessor based system.

Method of and system for controlling a photovoltaic power system

Abstract: In a method of and a system for controlling a photovoltaic power system including a solar battery and a power converter receiving the output of the solar battery, the voltage of the solar battery is kept at a voltage reference which is determined in accordance with the operating condition of the system thereby to maximize the power of the solar battery. Operating mode is switched between a first mode in which the voltage reference is periodically decreased and a second mode in which the voltage reference is periodically increased. The switching between the first and the second mode is effected in accordance with the direction of change of the power and the voltage of the solar battery. Where there is a reactance between the solar battery and the point at which the voltage or the current is detected, or a time lag element in a voltage detector or a current detector, an arrangement may be provided to compensate detection error due to the reactance or the time lag element.

Direct current power control on selectable voltage step-up and step-down

Abstract: A DC power circuit for converting an input DC voltage into a predetermined output DC voltage includes a first switching device for switching a DC input voltage, an inductance device connected to an output terminal of the first switching device, a second switching device connected to an output terminal of the inductance device for switching an output from the inductance device, a driver circuit for comparing the output DC voltage with a first reference voltage to drive the first and second switching devices in accordance with the comparison, and a control circuit for comparing the input DC voltage with a second reference voltage to enable the driver circuit to selectively drive either the first or second switching device in accordance with the comparison. The control circuit primes or enables the second switching device to thereby step up the input DC voltage to produce a resultant output voltage from the inductance device when the input DC voltage is lower than the second reference voltage, and primes or enables the first switching device to thereby step down the input DC voltage to produce the resultant output voltage from the inductance device when the input DC voltage is higher than the second reference voltage.

Power converter with duty ratio quantization

Abstract: A discrete proportional-integral-differential controller, driven from a sampling digital error amplifier, is used to penetrate a quantized duty ratio control signal to provide dynamic output voltage regulation for switching dc-to-dc power converters. The sampling frequency of the digital PID controller is equal to the switching frequency of the power converter, so the digital controller may be used at different switching frequencies without recompensation. Digital techniques are also used to provide output current limiting, soft-start, undervoltage lockout, overvoltage shutdown, and power master-clear indications.

Volt/Var Control on Distribution Systems with Lateral Branches Using Shunt Capacitors and Voltage Regulators Part II: The Solution Method

Abstract: In this paper the optimal solutions of the following two decoupled problems are given on the basis of the model presented in Part I:(i) The capacitor (var) problem: determination of the locations, sizes and the real-time control of n ON/OFF switched and fixed shunt capacitors, (ii) The regulator (volt) problem: determination of the locations and real-time control of minimum number of voltage regulators. The objective in both problems is to minimize the peak power and the energy losses and to provide smooth voltage profile along the distribution system with lateral branches. For the first time, the nonlinear costs of installation of the capacitors are incorporated into the capacitor problem.

Generator voltage regulating system

Abstract: A voltage regulator for regulating the output voltage of a diode-rectified alternating current generator that supplies the electrical loads on a motor vehicle including the storage battery. The voltage regulator has an up-down counter which is incremented when the output voltage of the generator is below a desired regulated value and is decremented when the output voltage of the generator is above the desired regulating value. The magnitude of the count in the counter is repeatedly sampled and used to determine the on time of a semiconductor switch that is connected in series with the field winding to thereby control the duty cycle of the field voltage pulses. The counter is incremented at a lower rate when the speed of the engine that drives the generator is below a predetermined speed than it is when the speed of the engine is above the predetermined speed. When the generator is not rotating, the up-count of the counter is limited to a predetermined value that provides a minimum field voltage duty cycle. The system is capable of sensing either battery voltage or rectifier output voltage and is controlled to automatically switch between battery voltage and rectifier voltage under certain operating conditions.

Power source device for a load with a stand-by power supply system

Abstract: A power source device according to this invention comprises a voltage and phase detector for detecting the voltage and phase of a power supply system, a first controller for controlling an inverter so that an output of the inverter may agree with either a reference voltage and a reference phase or with the voltage and the phase of the power supply system, a second controller for switching the inputs of the first controller from the reference voltage and phase to the power supply system voltage and phase, or vice versa, when the phases of a reference oscillator and the power supply system have agreed, and a third controller for switching the power to a load from the inverter to the power supply system, or vice versa, when the synchronism between the inverter output and the power supply system has been detected.

Self-oscillating high frequency power converter

Abstract: A self-oscillating power converter utilizes a MOSFET power transistor switch with its output electrode coupled to a tuned network that operatively limits the voltage waveform across the power switch to periodic unipolar pulses. The transistor switch may be operated at a high radio frequency so that its drain to gate interelectrode capacitance is sufficient to comprise the sole oscillatory sustaining feedback path of the converter. A reactive network which is inductive at the operating frequency couples the gate to source electrodes of the transistor switch and includes a variable capacitance as a means of adjusting the overall reactance, and hence the converter's switching frequency in order to provide voltage regulation. A resonant rectifier includes a tuned circuit to shape the voltage waveform across the rectifying diodes as a time inverse of the power switch waveform.

Control of Reactive Power in Distribution Systems with an End-Load and Varying Load Condition

Abstract: The flow of the reactive power in utility systems produces losses which utility engineers attempt to keep at a minimum level by the installation of capacitor banks. Previous work focussed on obtaining the optimal conditions for a fixed load level. The present paper deals with the conditions of fixed load, growth in the load and the presence of end-load in the feeder. A mathematical analysis of shunt capacitor application for the reductions of peak power loss and energy loss for a uniform feeder with an end-load condition is presented. Generalized equations for calculating the reductions of peak power and energy losses in a feeder are derived. The optimum location and the rating of the capacitor banks on feeders with uniformly distributed loads and end-load injection are developed. A method to assess the economical effectiveness of whether or not to install capacitor banks in a condition of load growth is also given. The method is applied to a test case of a practical system.

Power supply system and a control method thereof

Abstract: A power supply system including an inverter, a reserved power source and changeover switches for outputting one of outputs of the inverter and reserved power source to supply a load current to a load. The system further includes a control circuit for controlling a phase, a frequency and a voltage of the output of the inverter to coincide with a phase, a frequency of the output of the reserved power source and a specified voltage, respectively. The specified voltage is determined to be a predetermined reference voltage when the load current is below a detection level and to be a reduction voltage decided between zero volt and the voltage of the reserved power source when the load current is equal to or more than the detection level. A method for controlling a power supply system described above is also disclosed.

High voltage supply circuit for an x-ray tube

Abstract: A high voltage supply circuit for an x-ray tube includes a high voltage transformer having a primary side driven by voltage pulses generated by a drive circuit. The drive circuit includes sub-circuits for controlling the pulse repetition frequency, which is selected as equal to a parallel resonant frequency of a high voltage generator connected to the secondary side of the transformer, for the purpose of saving energy. The drive circuit also includes a sub-circuit for controlling the pulse duration, with the filament voltage in the x-ray tube being regulated by this pulse duration.

Voltage Dependence Of Composite Loads In Power Systems

Abstract: This paper concerns the voltage dependence of composite loads in power systems. Based upon continuous field measurements by automatic monitoring devices, dynamic responses of typical system loads to sudden voltage changes have been obtained. The parameters of a load model have been evaluated from the field data, and their changes in a day and in a year have been presented for typical system loads. A constructive approach to synthesize load characteristics from load components has been discussed by comparing the synthesized load parameters with the measured ones.

Integral cycle control of stand-alone generators

Abstract: Reducing the cost of small-scale stand-alone generators (up to 100kW), particularly in micro-hydro applications, is of increasing interest. Methods proposed recently include the use of electronic load governors to regulate the generated frequency, and the use of induction generators in place of the more conventional synchronous generator. The use of a load governor results in constant-flow operation of the turbine, and thus eliminates any hydraulic stability problems. Many load governors switch increments of load on a cycle-by-cycle basis. Voltage regulation of induction generators may similarly be achieved by switching steps of capacitance each cycle. This paper analyses the stability of such integral cycle methods for controlling both synchronous and induction generators. The results, along with actual system responses, illustrate the viability of these techniques provided the stability requirements discussed are met.

Current-sensing scheme for switched reluctance motor drives

Abstract: By using the on-state forward voltage drops of the power switches to measure phase currents, and by using diode logic to sense the voltage drops, it is possible for a single voltage comparator to perform the current regulation function for an entire power converter. Current regulation is obtained in drives using either overlapping or nonoverlapping current conduction for excitation of the motor phases. A thermistor compensates for offsets and for temperature sensitivity of the power switch voltage drops.

Power supplies with magnetic amplifier voltage regulation

Abstract: A power supply including a saturable reactor voltage regulator using a core formed of relatively inexpensive magnetically soft material with a B-H loop which is poor in squareness. The reset point of the saturable reactor core is established by a clamping circuit, including a transistor switch and diode in series, which effectively clamps a short circuit across the reactor winding when the core reaches a desired reset point on its B-H loop. The proper time of actuation of the clamping circuit is selected by a control circuit which includes a comparator for generating a control signal for actuating the switch whenever an error voltage derived from the output voltage exceeds the voltage level of a triangular wave developed by integrating a replica of the input pulsations to the magnetic amplifier structure. The saturable reactor is driven to saturation at a time during positive pulsations related to the position of the reset point. In one embodiment, the clamping circuit is connected directly across the reactor winding, while in a second embodiment, the clamping circuit is connected across a secondary reactor winding. A bias winding for the reactor may be provided to shift the B-H loop of the core to the right to increase the range of adjustment.

Method for optimum matching of the voltage from a solar generator to a parallel-connected battery

Abstract: A method for optimum matching of the voltage from a solar generator to a parallel-connected battery in different operating conditions. A DC/DC voltage converter (chopper) which produces the optimum matching is arranged between the solar generator and the battery. In order to reduce the power losses caused by the DC/DC voltage converter and in order to avoid such losses at the time of year when it is cold and when the battery voltage is low, the voltage of the solar generator is matched precisely to the battery at low temperature and hence at the maximum voltage produced by the solar generator and when the battery is partially discharged and the battery voltage is in consequence relatively low. The DC/DC voltage converter is used only to increase the voltage of the solar generator and is switched on only when, as a result of the prevailing operating conditions, an increase in the voltage provided by the solar generator is necessary for optimum matching.

Inductive transmission of power and data

Abstract: The application relates to the inductive transmission of power and data, in which a supply voltage after rectification (1) is transmitted via an inverter (2) and a transformer (U) for supporting a battery (8) and switching signals in both directions. This transmission device is preferably intended for pipelines composed of pipe sections. For further simplification of known transmission devices each pipe head is designed as a transformer into which a coil (26) is sunk, and the pipe (21) serves as the transformer core. The transmitted alternating voltage is rectified in a power supply unit (5, 6) on the secondary side of the transformer and is converted to the battery voltage.

Inverter type X-ray apparatus

Abstract: Disclosed is an inverter type X-ray apparatus comprising a DC-DC converter for converting a DC voltage into a different DC voltage, an inverter for inverting an output voltage of the DC-DC converter into an AC voltage, a high voltage transformer for transforming an output voltage of the inverter into a higher voltage, a rectifier for converting an AC output voltage of the transformer into a DC voltage, and an X-ray tube to which an output voltage of the rectifier is applied. In the apparatus, the DC-DC converter includes a reactor, a switching element and a capacitor which are interconnected so that the DC-DC converter can generate an output voltage higher or lower than an input voltage.

Electronic ballast with high power factor

Abstract: A source of 120 Volt/60 Hz power line voltage is full-wave-rectified and yields an unfiltered DC voltage pulsed at 120 Hz rate. This pulsed DC voltage is applied to an inverter of a type that must be triggered into oscillation. At the beginning of each of the DC voltage pulses, the inverter is triggered into oscillation; and at the end of each of the DC voltage pulses, the inverter ceases to oscillate frm lack of adequate voltage to sustain oscillation. The output of the inverter is a 30 kHz squarewave voltage amplitude modulated at the 120 Hz rate. Across the inverter output is connected a high-Q series L-C circuit resonant at about 30 kHz. A fluorescent lamp is connected in parallel with the tank capacitor of the L-C circuit. With is high-Q resonant L-C circuit series-excited and parallel-loaded, the instantaneous magnitude of the current drawn by the inverter is substantially proportional to the instantaneous magnitude of the DC voltage provided; which implies that power is drawn from the power line with a relatively high power factor.

Semiconductor device having an arrangement for preventing operational errors

Abstract: This invention relates to a semiconductor device formed on a semiconductor chip which is provided with at least a voltage transformation arrangement for transforming an external power supply voltage into an internal power supply voltage. At least a portion of circuits formed in the chip operate by using the internal power supply voltage rather than the external power supply voltage. Semiconductor devices, in particular DRAMs (dynamic random access memories), in which said internal power supply voltage is supplied are controlled so that the starting time of the internal power supply voltage at the moment of the switch-on of the external power supply is later than the starting time of the external power supply voltage, and/or the time necessary for the internal power supply voltage to increase to a predetermined operational level at said moment is longer than that required for said external power supply voltage to increase to a predetermined operational level.

Transmission of electric power at ultra-high voltages: Current status and future prospects

Abstract: The ability to transmit larger amounts of electric power over longer distances increases with the transmission voltage. Historically, this relationship--in conjunction with its associated economies of scale--provided the basic impetus for the technological drive to utilize increasingly higher voltages for the transmission of electric power: from "high voltage" (HV) transmission at 100, 138, 161, and 230 kV to "extra-high voltage" (EHV) transmission at 345, 400, 500, and 765 kV. For the past several years, research has been under way--in this country and abroad--to bring about transmission of electric power at "ultra-high voltage" (UHV), i.e., voltage in the range of 1000 to 1600 kV. This paper reviews the present status of UHV transmission research and development and discusses current prospects for the introduction of UHV technology in the commercial transmission of electric power.

ECL to TTL voltage level translator

Abstract: A voltage level translator circuit is provided that translates an input voltage referenced to an ECL supply voltage V CC to a voltage referenced to a TTL supply voltage V EE independent of power supply voltage variations. A first and a second embodiment have reference circuits coupled to receive a data input signal for providing a single signal referenced to a first supply voltage terminal to a current mirror. An output circuit is coupled to the current mirror for providing an output signal referenced to the second supply voltage terminal. A third embodiment has a reference circuit coupled to receive a data input signal for referencing a voltage on a first supply voltage terminal to a voltage on a second supply voltage terminal. A voltage setting circuit is coupled to the reference circuit for setting a voltage within the reference circuit. An output circuit is coupled to the voltage setting circuit for providing an output voltage referenced to a voltage on the second voltage terminal and independent of variations in supply voltages.

Electronic equipment with solar cell

Abstract: An output voltage of a solar cell is supplied to a voltage converter. The voltage converter converts the input voltage into a predetermined voltage, and supplies it to a capacitor. The capacitor is charged by the output current of the voltage converter. The capacitor has a relatively large capacitance. A second voltage converter converts an input voltage from the capacitor into a voltage which is lower than the charged voltage of the capacitor and higher than a minimum operating voltage of a load. The load performs a predetermined operation using the output voltage of the second voltage converter.