This document describes a patent application from 1957 relating to regulating systems for synchronous generators. It aims to provide an improved system that can automatically prevent reduction of generator excitation below the stability limit. The system includes an automatic voltage regulator and overriding control means that prevent excitation from falling below a value determined by the magnitude of the generator load current. The overriding control means respond to electrical quantities relating to excitation and load current, and can boost excitation if needed to maintain stability.
Development of a Microcontroller Based 12/24 Volts Push-Pull Inverter Systemiosrjce
Conventional power inverter systems are normally specified to work with a single nominal battery
voltage. This is somewhat restrictive and causes downtimes when d.c power sources of specified voltages are not available.
In this work, a push-pull inverter circuit that generates its rated output voltage from either a 12Volts or 24 Volts d.c source
was developed. The circuit, based on a PIC 16F877A microcontroller, determines the battery voltage and generates the
required MOSFET gate drive signals required to generate a 240 volts r.m.s modified square wave output waveform. The
developed circuit and the associated microcontroller firmware were designed and modelled using proteus® software and
MicroC software respectively. The circuit was constructed, programmed and then tested. The circuit generated 240 volts
r.m.s output waveforms when it was powered from either a 12 volts or a 24 volts d.c voltage sources.
Harmonics Reduction of Multilevel Inverter Drive Using Sine Carrier Pulse Wid...IJERA Editor
The main objective of this paper is to control the speed of an induction motor by using seven level diode clamped multilevel inverter and improve the high quality sinusoidal output voltage with reduced harmonics. The presented scheme for diode clamped multilevel inverter is sine carrier Pulse Width Modulation control. An open loop speed control can be achieved by using V/ƒ method. This method can be implemented by changing the supply voltage and frequency applied to the three phase induction motor at constant ratio. The presented system is an effective replacement for the conventional method which has high switching losses, its result ends in a poor drive performance. The simulation result portrays the effective control in the motor speed and an enhanced drive performance through reduction in total harmonic distortion (THD). The effectiveness of the system is verified through simulation using PSIM6.1 Simulink package
Sensorless Control of a Fault-tolerant Multi-level PMSM DriveTELKOMNIKA JOURNAL
This paper presents a new technique to track the saliency position in a permanent magnet synchronous motor (PMSM) post a single phase open-circuit fault. The PMSM is driven by a fault-tolerant multi-level inverter that is utilized to implement a fault-tolerant control strategy to minimize system performance degradation post the fault.The fault-tolerant multi-level inverter is consisting of a number of insulated-gate bipolar transistors (IGBTs). The dynamic current reponses of the PMSM motor due to the switching actions of these IGBTs are used extract the saliency position. This process is not introducing any modification to the operation of the fault-tolerant multil-level inverter as it uses only the fundamental pulse width modulation (PWM) waveform. Moreover,it considers the modifications introduced to the PMSM motor and the multi-level inverter post the fault.Simulation results are provided to verify the effectiveness of the proposed strategy of saliency tracking of a PMSM motor driven by a fault-tolerant four-leg multi-level inverter over a wide range of speeds in the case of a single-phase open circuit fault.
International Journal of Engineering Inventions (IJEI) provides a multidisciplinary passage for researchers, managers, professionals, practitioners and students around the globe to publish high quality, peer-reviewed articles on all theoretical and empirical aspects of Engineering and Science.
Development of a Microcontroller Based 12/24 Volts Push-Pull Inverter Systemiosrjce
Conventional power inverter systems are normally specified to work with a single nominal battery
voltage. This is somewhat restrictive and causes downtimes when d.c power sources of specified voltages are not available.
In this work, a push-pull inverter circuit that generates its rated output voltage from either a 12Volts or 24 Volts d.c source
was developed. The circuit, based on a PIC 16F877A microcontroller, determines the battery voltage and generates the
required MOSFET gate drive signals required to generate a 240 volts r.m.s modified square wave output waveform. The
developed circuit and the associated microcontroller firmware were designed and modelled using proteus® software and
MicroC software respectively. The circuit was constructed, programmed and then tested. The circuit generated 240 volts
r.m.s output waveforms when it was powered from either a 12 volts or a 24 volts d.c voltage sources.
Harmonics Reduction of Multilevel Inverter Drive Using Sine Carrier Pulse Wid...IJERA Editor
The main objective of this paper is to control the speed of an induction motor by using seven level diode clamped multilevel inverter and improve the high quality sinusoidal output voltage with reduced harmonics. The presented scheme for diode clamped multilevel inverter is sine carrier Pulse Width Modulation control. An open loop speed control can be achieved by using V/ƒ method. This method can be implemented by changing the supply voltage and frequency applied to the three phase induction motor at constant ratio. The presented system is an effective replacement for the conventional method which has high switching losses, its result ends in a poor drive performance. The simulation result portrays the effective control in the motor speed and an enhanced drive performance through reduction in total harmonic distortion (THD). The effectiveness of the system is verified through simulation using PSIM6.1 Simulink package
Sensorless Control of a Fault-tolerant Multi-level PMSM DriveTELKOMNIKA JOURNAL
This paper presents a new technique to track the saliency position in a permanent magnet synchronous motor (PMSM) post a single phase open-circuit fault. The PMSM is driven by a fault-tolerant multi-level inverter that is utilized to implement a fault-tolerant control strategy to minimize system performance degradation post the fault.The fault-tolerant multi-level inverter is consisting of a number of insulated-gate bipolar transistors (IGBTs). The dynamic current reponses of the PMSM motor due to the switching actions of these IGBTs are used extract the saliency position. This process is not introducing any modification to the operation of the fault-tolerant multil-level inverter as it uses only the fundamental pulse width modulation (PWM) waveform. Moreover,it considers the modifications introduced to the PMSM motor and the multi-level inverter post the fault.Simulation results are provided to verify the effectiveness of the proposed strategy of saliency tracking of a PMSM motor driven by a fault-tolerant four-leg multi-level inverter over a wide range of speeds in the case of a single-phase open circuit fault.
International Journal of Engineering Inventions (IJEI) provides a multidisciplinary passage for researchers, managers, professionals, practitioners and students around the globe to publish high quality, peer-reviewed articles on all theoretical and empirical aspects of Engineering and Science.
Static Excitation System of Generator in Hydropower Stationijtsrd
Excitation system is one of the most important parts of the synchronous generators. Excitation system of the generator comprises from machines, devices and appliances that are intended to provide direct current to the generator field winding and this current regulation. For a constant frequency supply, the output voltage of the machine depends on the excitation current. In this paper, static excitation system of 10 MW synchronous generator in hydropower station is described and analyzed how the excitation current can be controlled to be stable terminal voltage and reactive power of generator. Thida Win | Hnin Yu Lwin | Zin Wah Aung "Static Excitation System of Generator in Hydropower Station" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26742.pdf Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/26742/static-excitation-system-of-generator-in-hydropower-station/thida-win
Synchronous generators are the majority source of commercial electrical energy. They are commonly used to convert the mechanical power output of steam turbines, gas turbines, reciprocating engines and hydro turbines into electrical power for the grid.
Simulation of 3-phase matrix converter using space vector modulationIJECEIAES
This paper illustrates the simulation of 3-phase matrix converter using Space Vector Modulation (SVM). Variable AC output voltage engendered using matrix converter with bidirectional power switches controlled by appropriate switching pulse. The conventional PWM converter engenders switching common mode voltage across the load system terminals, which cause to common mode current and its leads to bearing failure in load drive. These problems can be rectified using SVM and which minimize the effect on the harmonic fluctuation in AC output voltage and stress on the power switch is reduced using bidirectional switch for proposed 3-phase matrix converter. The simulation results have been presented to validate the proposed system using matlab / simulink.
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discusses about the reduction of commutation torque ripple in BLDC motor and various convention methods and the proposed method for 2 level inverter and 3 level inverter
USE OF ARNO CONVERTER AND MOTOR-GENERATOR SET TO CONVERT A SINGLE-PHASE AC SU...IAEME Publication
This method is used to control the speed of a three-phase induction motor by using a three-phase to three-phase cycloconverter from a single-phase supply and to compare the use of ARNO converter and motor-generator set to convert a single-phase supply to a three-phase supply. ARNO converter is a rotating device which convert single-phase AC to three-phase AC. The three-phase supply needed for the three-phase induction motors which used in blowers, exhausters an oil pumps. A motor-generator set is a device for converting electrical power to another form. They are used to convert frequency, voltage or phase of power. Thus, both ARNO converter and motor-generator set have been used here one at a time to convert a single-phase AC supply to three-phase AC. Both have their own advantages and disadvantages
Analysis Approach for Five Phase Two-Level Voltage Source Inverter with PWM T...ijsrd.com
this paper gives idea of comparison of five phase two-level voltage inverter (FPTLVSI) without filter circuit and control scheme and FPTLVSI with filter circuit and PWM control scheme for induction motor drive. The paper demonstrates using mat lab simulations about comparison in term of harmonics analysis for different firing angles and find best angle suitable for output with minimum harmonics for FPTLVSI without filter circuit and control scheme and harmonics analysis of FPTLVSI with filter and PWM control scheme. This paper suggests simulation of comparison of harmonics point of view five phase two-level voltage inverter (FPTLVSI) without filter circuit and control scheme and with filter circuit and PWM control scheme for induction motor drive.
Performance of PWM Rectifier with Different Types of Loadijsrd.com
The paper presents the decoupled vector control of the PWM rectifier with the nonlinear DC-link voltage regulation and the load compensating feed forward. The concept of the proposed control system is based on Voltage Oriented Control with Space-Vector Pulse Width Modulation (SV-PWM). For the high-performance operation of the PWM rectifier and the satisfactory current tracing the decoupled current control has been introduced. The performance of the linear PI controller of the DC-link voltage is strictly dependent on its settings and it may introduce a disadvantageous voltage overshoot under a heavy load impact. In order to improve the transient response of the DC-link voltage control loop a load compensation has been proposed. The different approach to the control of the DC-link voltage based on the regulation of the square power of the DC voltage has been introduced.
Сытник В. С. Основы расчета и анализа точности геодезических измерений в стро...Иван Иванов
В книге изложены вопросы теории и практики расчета, бценки
и анализа точности геодезических измерений, выполняемых при
возведении промышленных, жилых и общественных зданий й\цн-
женериых сооружений. На основе существующих в теории вероят^~—-
ностей
математической статистики и ошибок измерений рассмат
риваются методы расчета необходимой и достаточной точности гео
дезических измерений
применительно к определенным стадиям
строительно-монтажных работ и конструктивным решениям зданий
и сооружений. Значительное внимание уделено анализу точности
результатов геодезических измерений
Заковряшин А. И. Конструирование РЭА с учетом особенностей эксплуатацииИван Иванов
Показана роль конструкторского проектирования в обеспечении эффективности технического обслуживания РЭА по фактическому состоянию. В книге
взаимосвязанно решаются вопросы обеспечения ремонто- и контролепригодности
при конструировании РЭА. Ремонтопригодность рассматривается лак решающи”
фактор обеспечения эффективности применения аппаратуры. Область значений
конструктивных показателей РЭА определяется как результат решения задачи
оптимизации заданного качества функционирования.
1. * GB780009 (A)
Description: GB780009 (A) ? 1957-07-31
Improvements relating to regulating systems for dynamo-electric machines
Description of GB780009 (A)
PATENT SPECIFICATION
Inventor: NiORIMIAN HOARRY 1SHAW Date of filing Complete
Specification: June 10, 1955.
Application Date: June 16, 1954.
No. 17726/54.
1 --Complete Specification Published: July 31, 1957.
Index at acceptance:-Class 38(4), R(4: 21A1A).
International Classification:-G05f.
- COM1PLETE SPECOIFlICATION Improvements relating to Regulating
Systems for DynamoElectric Machines We, THE ENGLISH ELECTRIC COMPANY
LIMITED, of Queens House, 2!8 Kingsway, London, W.C.2, a British
Company, do hereby declare the invention, for which we pray that a
patent may be granted to us,.and the method by which it is to be
performed, to be particularly described in and by 'the following
statement:This invention, relates to regulating systems for
synchronous generators of the kind including an automatic voltage
regulator arranged to control the excitation of the generator
automatically so, as to maintain the output voltage of the generator
substantially constant.
It is well known that in such systems the synchronising torque of the
generator may, under certain conditions, fall below that necessary to
maintain the generator in synchronism with the system to which it is
connected., This loss of synchronising torque may be due, for example,
to the action of the automatic voltage regulator which, in attempting
to maintain the generator output voltage constant with sudden loss of
load, reduces the generator excitation belbw the stability limit.
One object of the present invention is to provide an improved
regulating system which incorporates means for automatically
preventing reduction of the generator excitation below the stability
limit.
2. According to the invention, in a regulating system for a synchronous
generator of the kind including an automatic voltage regulator
arranged to control the generator excitation automatically in, a sense
to maintain a generator output voltage substantially constant,
overriding automatic control means are 'arranged' to prevent reduction
of generator excitation below.a value determined solely by the
magnitude of the generator load current, which value increases with
the magnitude of the generator load current and' vice versa.
According to a preferred feature of the invention the overriding
control means are arranged to respond to electrical quantities varying
with generator excitation and the [Price 3s. 6fCiet' 4sCo magnitude of
the generator load current respectively, and to boost the generator
excitation automatically if the excitation should fall below a value
determined by the actual magnitude of the generator load current or if
the magnitude of the generator load current should exceed a value
determined by the actual value of generator excitation.
According to 'a further preferred feature of the invention the
overriding control means are arranged to boost the excitation of the
generator by applying an overriding control quantity to the automatic
voltage regulator in, a sense to cause the regulator to increase the
generator excitation.
{According to yet another preferred feature of the invention the
automatic voltage regulator comprises a magnetic amplifier having an
output winding connected in circuit with excitation varying means for
the generator and a control winding connected in a comparison circuit
consisting of a substantially constant electrical reference source and
an electric control source varying with generator output voltage, so
as to be energised in 'a corrective sense in accordance with variation
of generator output voltage from a predetermined value, said
overriding control means being arranged to boost the generator
excitation by injecting an electrical quantity into said comparision
circuit.
Other preferred features of the invention will appear from. the
follovwing description with reference to the drawing accompanying the
Provisional Specification which shows the simplified circuit diagram
of a regulating system for a turbo generator embodying the invention
in preferred form., Referring now to the drawing the generator G
supplies the three phase system busbars S through a step-up
transformer T1, the field winding Gf of the generator being supplied,
from an exciter E having a self-excited field winding Esf and a
control field winding arranged in two mutually opposing sections Ecf.1
and cf'2.. The self-excited field winding Esf is connected in circuit
with a motor 780,009 operated rheostat MR which is remotely controlled
through means, not shown, to provide alternative hand control of the
3. generator output voltage, whilst the two sections Ecfl, Ecf2 of the
control field winding 'are supplied from a magnetic amplifier MA1
having a control winding MA.lc.
The control winding of the magnetic amplifier MA1i is connected across
the output terminals OT of a comparison circuit which is arranged to
compare a voltage dependent on the average of the generator line
voltages with a voltage drop due to a constant reference current
flowing through resistors. The circuit comprises, in series
relationship, a constant current reference source IR, the star
connected secondary winding of a transformer T2, dry plate rectifiers
DR1, loading resistors R1 and R2, and a variable resistor VR1. The
delta-connected primary winding of the transformer T2 is supplied from
the generator G through a transformer T3 having a star-connected
primary winding and a delta-connected secondary winding. The rectified
output voltage of the transformer T2 is thus dependent on the average
of the generator line voltages.
In operation, the variable resistor VR1 is set so that, at the desired
generator output voltage, the total voltage drop across the resistors
R1, R2 and VR1 is substantially equal in magnitude and opposite in
polarity to the voltage output derived from the rectifiers DR1. Under
these conditions no potential difference will appear across the output
terminals OT of the comparison circuit, and, the control winding MAlc
of the magnetic amplifier MA1i will not be energized.
If now the generator output voltage should rise, then since the
current in the comparison circuit, and thus the voltage drop across
the three resistors therein, is maintained constant, a potential
difference will be developed across the output terminals OT which will
result in the energization of the control winding MAlc of the magnetic
amplifier MA&.
The magnetic amplifier is arranged so that when its control winding is
energized in this way the amplifier develops an output which is
applied to the section Ecfl of the control winding on the exciter so
as to buck the selfexcited winding Esf. The excitation of the
generator G, and thus its output voltage, will accordingly be reduced
until a balanced condition is restored at which just sufficient
potential difference is maintained across the output terminals OT of
the comparison, circuit to provide sufficient energization of the
section Ecfl of the control winding on the exciter E.
On the other hand, if the generator line volts should fall, a
potential difference of opposite polarity will be developed across the
output terminals OT of the comparison circuit with a consequent
energization in the opposite sense of the control winding MAlc of the
magnetic amplifier MAl. Under these conditions the magnetic amplifier
energizes the section Ecf2 of the control winding on the exciter E in
4. a sense to boost the self-excited winding Esf and thereby increase the
generator output volts until a balanced condition 70 is once more
restored.
In order to prevent loss of synchronism a voltage is applied
automatically across the resistor R2 in a sense to cause the generator
voltage to rise suddenly if the stability limit 75 is approached. This
voltage is derived from a magnetic amplifier MIA2 and is applied to
the resistor R2 through a rectifier DR2.
The magnetic amplifier has three control windings MA2a, MA2b and MA2c
respectively. Winding MA2a is energized from the comparison circuit in
accordance with the rectified output from the transformer T2, i.e. in
accordance with the average of the generator line voltages, a variable
resistor VR2 being 85 included in circuit with this winding. Winding
MA2b is energized through a rectifier bridge RB from a current
transformer IT in one line of the generator load circuit, i.e.
in accordance with generator load current. 90 Smoothing circuits may
be provided for smoothing the D.C. output of the rectifier.
Winding MA2c is connected in series with a variable resistor VR3
across a resistor R3 in the excitation circuit of the generator G so
as 95 to be energized in accordance with generator excitation.
Windings MA2a and MA2c, as shown by the small arrows, act in the same
direction whilst winding MA2b opposes these two windings. 100 The
variable resistors VR2 and VR3 are preset so that, provided the
generator load current does not exceed a limit value which varies with
the generator excitation, increasing with increase thereof, the
winding MA2b 105 will be overcome by the combined effect of the
windings MA2a and MA2c and the magnetic amplifier MA2 will be biased
back to minimum output. Under these conditions the rectifier DR2 will
prevent the flow of reverse 110 current which would otherwise occur as
a result of the normal voltage drop across the resistor R2 due to the
constant circulating current being greater than the output current
from the magnetic amplifier MA2. The magnetic amplifier therefore has
no effect on the operation of the comparison circuit.
If, however, the generator load current should exceed such a value
that the winding MA2b overcomes the combined effect of the 120
windings MA2a and MA2c, the magnetic amplifier will develop a
comparatively large voltage, causing a current to flow in the forward
direction through the rectifier DR2 which will increase the voltage
across the resistor R2. A potential difference will therefore be
developed across the output terminals OT of the comparison circuit
which will cause the magnetic amplifier MA1 to energize the boost
winding Ecf2 of the exciter E. The excitation 130 q780,009 sense to
cause the regulator to increase the generator excitation.
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