Electrical power engineering test (2)
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This document contains questions and answers about various topics in electrical power engineering. It discusses abbreviations like UPS, ONAN, and BDV. It also covers derating factors, synchrocheck relays, conditions for parallel transformer connections, induction motor starting methods, synchronous generator excitation systems, UPS system components, precautions when changing CT burden on energized systems, differential motor protection circuits, and a circuit to start three pumps sequentially with a 55kW motor.
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Electrical power engineering test (1)
1. The document discusses questions about electrical power engineering topics. It defines abbreviations like PMG, MCB, and RTD. It explains the differences between demand factor and load factor. It discusses the meaning of CT burden = 10 VA and the function of an AVR.
2. Drawings and explanations are provided for speed control of 3 phase induction motors by varying frequency, transformer short circuit testing, and controlling parameters like active power, reactive power and voltage in a power generator.
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Electrical power engineering test (1)
1. The document discusses questions about electrical power engineering topics. It defines abbreviations like PMG, MCB, and RTD. It explains the differences between demand factor and load factor. It discusses the meaning of CT burden = 10 VA and the function of an AVR.
2. Drawings and explanations are provided for speed control of 3 phase induction motors by varying frequency, transformer short circuit testing, and controlling parameters like active power, reactive power and voltage in a power generator.
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1. The document describes an experiment to determine the effects of VAR compensation on voltage regulation, power factor, and transmission efficiency for varying loads on a long transmission line.
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Untitled document.PDF
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BEF43303 - 201620171 W1 Power System Analysis and Protection.pdf
Here are the steps to solve this problem:
1) Choose base voltage VB1 = 20kV, VB2 = 200kV
2) Change base of generator and transformer impedances to 100MVA base
3) Determine line and load impedances in per unit
4) Draw the single line diagram showing all impedances in per unit
The solution is left as an exercise for the student.
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The document discusses the characteristics and operating principles of induction motors and Scherbius machines.
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[2] A Scherbius machine is a polyphase commutator machine with a single-phase rotor winding that produces a 3-phase voltage. Its stator is excited by the rotor current of a main induction motor.
[3] The Scherbius machine frequency is determined by an autotransformer taps ratio, which allows closed-loop control to maintain a constant speed for the main motor rotor.
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This document summarizes an experiment on AC position control. The aim was to investigate the effects of loop gain and velocity feedback changes on the dynamic characteristics. Various equipment was used including an AC motor, synchro transformers, and an oscilloscope. Observations showed that reducing the brake setting caused instability, while increasing velocity feedback and loop gain improved step and following performance. Applications include power amplifiers, servo potentiometers, and speed or position configurations.
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The document describes the modeling of an armature-controlled DC servo motor. It includes:
1. Describing the key components of a DC motor including the armature, field, rotor and stator.
2. Developing a physical model that considers the armature resistance and inductance, as well as load inertia and friction.
3. Deriving the mathematical models for motor torque, back EMF, armature circuit dynamics, and mechanical dynamics.
4. Numerically solving the models using Simulink, including the electrical, mechanical, and feedback loops between electrical and mechanical domains.
Automatic synch of gen
The document discusses automatic synchronization of generators, including:
1) Synchronization involves matching the frequency, voltage, and phase angle between two AC power sources or systems before connecting them.
2) Synchronization is achieved through automatic synchronizers that monitor these parameters and send a close signal once matching conditions are met.
3) Typical synchronization schemes involve an automatic synchronizer relay, sync-check relay, and circuit breaker that are coordinated to safely connect the generators.
EEP301: Dc modular servo motor
This document summarizes several lab experiments conducted on a DC modular servo motor system. The experiments studied the characteristics of a pre-amplifier, utilized an error signal from an operational amplifier to drive an output potentiometer via the pre-amplifier and motor, showed improvements from closing the feedback loop compared to an open loop, investigated the effects of loading on speed, assembled a reversible speed control system, and investigated the effect of gain on deadband and step response. Graphs were included showing relationships between various measured variables.
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This document provides an overview of generator basics, including:
1) Descriptions of synchronous generator types and connections to power systems such as direct connected and unit connected configurations.
2) Explanations of generator excitation and automatic voltage regulator (AVR) control systems.
3) Discussions of generator grounding methods like low impedance, high impedance, and dual grounding; and considerations for multiple generator installations.
4) Details on generator protection devices and multifunction digital relays, appropriate levels of redundancy, and potential VT connection issues.
Auto synch considerations methods
This document discusses providing security against faulty synchronization when connecting two electrical sources. It defines proper closure as having acceptable phase angle difference, slip frequency, voltage difference and magnitude. Faulty synchronization can cause damage through excessive mechanical stress and current flows. Modern automatic synchronizing relays calculate a safe advance time to close based on measured phase angle and slip frequency. Sync check relays supervise synchronization but may introduce delays. Proper synchronization is important for generator connection and tie line applications.
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This lab report summarizes experiments performed on a synchro positioning system. The objectives were to measure the transmitter and transformer outputs and determine their electrical zeros. Key findings include:
- The transmitter output showed a 180 degree phase shift at each zero crossing. Its electrical zero was determined to be between 210-240 degrees.
- The transformer output electrical zeros were determined to be at 60 and 240 degrees, where minimum points were observed.
- In direct drive tests, the STR150R dial rested at an angle of 160 degrees when moved 5 degrees, and returned to its starting position when moved 10 degrees. A dead band of about 35 degrees was observed between the transmitter and receiver dials.
(6) finite
1. The document discusses the behavior of a generator when loaded onto a finite bus system, as opposed to an infinite bus. It describes how the governor and automatic voltage regulator (AVR) control the generator's output to maintain stable frequency and voltage.
2. Governors have a droop characteristic to automatically adjust the generator's output based on frequency changes. The AVR keeps terminal voltage constant despite load variations.
3. Safety is important when operating a generator without an AVR, as load changes can cause overexcitation, increasing voltage beyond safe levels and potentially damaging equipment. Proper excitation adjustment is required if the AVR fails.
EEP301: Analog control of DC motor
The document summarizes an experiment analyzing the effect of different speed control methods on a DC motor. Integral control reduces steady-state error but slows the system down. Proportional control is fast but leaves some steady-state error. PID control combines these methods. The experiment applies integral, proportional-integral, and proportional-integral-derivative control to a DC motor and records the response. Integral control alone resulted in an under-damped response. Adding proportional control reduced oscillations and settling time. The proportional-integral controller became unstable at high gains, but adding derivative control stabilized the system and reduced oscillations further.
Speed control of dc motor using matlab
This document discusses speed control of a DC motor using a power electronic converter in MATLAB. It introduces MOSFETs, choppers, and separately excited DC motors. It presents the block diagram and MATLAB simulations that show the transient and steady-state periods of speed control. The results demonstrate successful speed control of the DC motor using a chopper converter and PID controller. Hardware implementation is proposed using a MOSFET as the switching device to vary the motor's armature voltage and control its speed. Future work may include building the hardware and extending the technique to other motor types.
5
This document provides an overview of DC to AC converters known as inverters. It discusses various types of inverters including voltage source inverters and current source inverters. It covers topics such as commutation types, single phase and three phase inverter circuit configurations, quantitative analysis of output voltages, and methods for controlling output voltages. The document also discusses connecting multiple inverters in series to generate higher voltage output waveforms and the use of multi-level inverters to reduce harmonic distortion.
Motor bus transfer
Motor bus transfer (MBT) schemes are used to transfer large motor loads between power sources to maintain process continuity. Larger motors may require comprehensive transfer strategies to avoid mechanical damage during improper transfers. An MBT system's mission is to maintain continuity while avoiding damage. Transfers can occur for various reasons like faults, interruptions, or maintenance. MBT can be open or closed transition, with open transition using methods like fast, in-phase, or residual voltage transfer. Motor, load, and system characteristics affect the transfer. Standards provide guidelines for acceptable voltage and frequency parameters.
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The document discusses speed control of DC motors using pulse width modulation (PWM). PWM controls motor speed by varying the duty cycle, or ratio of on/off time, of a pulsed voltage signal provided to the motor. A higher duty cycle results in a higher average voltage and faster motor speed. Specific applications discussed include conveyor systems and examples of calculating duty cycle and pulse frequency needed to control motor current within limits.
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analysis of induction motor drive using slip power recovery scheme
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This document provides an introduction to classic control components including relays, circuit breakers, contactors, overloads, timers, and counters. It describes the basic components of a classic control system including the control panel. It explains what each component is, including its structure and principles of operation. Methods for selecting, connecting, testing and addressing damages to these components are also covered. The document is an introductory overview of classic control targeted towards technical education students.
Improvement In Pre-Regulation For Power Factor Using CUK Converter
Cuk converters, operating in Discontinuous Capacitor Voltage Mode can achieve unity power factor when used as rectifiers with no need of duty-cycle modulation. This operating mode causes high voltage stresses across the semiconductors, calling for high-voltage switches like IGBT's. However, zero-voltage turn-off is achieved, resulting in limited power loss even at high frequency. Both current- and voltage-fed approaches as well as constant- and variable-frequency control are analyzed in the paper. Simulation and experimental results are Explained, which demonstrate actual converter performance. Most of the power factor regulator topologies in continuous conduction mode result in bulky magnetic, and in discontinuous conduction mode result in high harmonic content. To solve these problems a Cuk topology is presented in discontinuous conduction mode with coupled inductors for power factor regulation, the unique feature exhibited by the converter that makes the converter better than the other converter in operation for power factor regulation. Inductive coupling is used to transfer the ripple from the input to the output side thereby reducing the switching harmonics in the line current. Experimental results obtained on a some Watt prototype are also presented.
Design and Development of Power Electronic Controller for Grid-connected PV A...
Design and simulation of a simple power electronic interface for grid-connected PV array has been proposed using boost converter and line-commutated inverter with maximum power point tracking (MPPT) controller. The output of PV array varies with irradiation, and hence the duty cycle of the PI controller is adjusted automatically to supply a constant DC voltage to the inverter circuit, the output of which is directly connected to the grid. The MPPT controller extracts maximum power from the solar array and feeds it to the single-phase utility grid. The proposed scheme has been modeled in the MATLAB 7.1 software and the complete system has been simulated for open loop and closed loop configurations. The active power fed to the grid is taken for different firing angles in open loop mode and the firing angle for maximum power has been determined. This is compared with the firing angle obtained from the closed loop mode and found that both results agree with each other.
Bidirectional full bridge dc-dc converter with flyback snubber for photovolta...
This document describes a bidirectional full-bridge DC-DC converter with a flyback snubber circuit for photovoltaic applications. The converter allows for stepped-up voltage from a solar cell to charge a battery. It uses a current-fed full-bridge on the low voltage side and a voltage-fed bridge on the high voltage side, with an isolation transformer in between. A flyback snubber is used to clamp voltage spikes caused by current differences, reducing stress on the active switches. Simulation results show the converter successfully steps up 6V solar output to over 15V for battery charging. The flyback snubber regulates voltages while improving reliability.
INDUSTRIAL TRAINING REPORT.pptx
This document provides an introduction and overview of the NTPC Barh power plant located in Bihar, India. It discusses the key components and systems of the plant including the generators, excitation systems, DC systems, switchyard equipment, and electric distribution. The plant has a total installed capacity of 3,980 MW across 5 units, with 3 units of 660 MW each made by Technopromexport and 2 additional units of 660 MW each made by BHEL. The document describes the technical specifications and workings of the generators, brushless excitation systems, DC systems including batteries, and the switchyard layout and equipment such as transformers, circuit breakers, and isolators.
Study of the impact on the protection plan of a pv production integrated to t...
This document summarizes a study on the impact of integrating a 5 MW photovoltaic production system on the protection scheme of a medium voltage grid. Simulations were performed for different fault scenarios on the grid with and without the PV system. The results showed that the PV system integration can cause unjustified operation of protections and disconnect the PV system unnecessarily. This is due to the bidirectional power flow and dynamics introduced by distributed generation. The protection scheme may need adjustment according to the penetration level of distributed PV resources to coordinate properly.
EEE Interview Question
The document contains questions and answers related to electrical engineering topics. Some key points:
- Electric traction uses electric power for railways, trams, and trolleys, now using magnetic traction for bullet trains. DC motors are commonly used.
- Electronic chokes can be used to start 40W tube lights with 230V AC/DC without other components like coils.
- "Pu" stands for per unit and is used in power system diagrams to represent components of different ratings on a common scale using base values.
- Thermal power stations obtain steam from boiling water to run turbines coupled to generators to produce electricity.
- Links are used at neutral points to withstand high amps, while
Optimum Amplitude Venturini ModulationBased Matrix Converter Fed Induction Mo...
IOSR Journal of Electrical and Electronics Engineering(IOSR-JEEE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of electrical and electronics engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electrical and electronics engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
J010627885
This document discusses the modeling and simulation of a matrix converter fed induction motor drive system. A matrix converter is a single-stage power converter that can directly convert AC power from a voltage source to an adjustable frequency output without an intermediate DC link. It has advantages over traditional variable frequency drive topologies like eliminating the DC link capacitor and allowing regeneration. The document presents the modeling of the matrix converter using optimum amplitude Venturini modulation to generate switching pulses. It also describes the modeling of a three-phase squirrel cage induction motor in MATLAB/Simulink based on a d-q stationary reference frame model. The simulation results show the performance of the proposed matrix converter topology for driving an induction motor.
ECNG 3015 - PU system and 3Phase Fault calculation
This document discusses the per unit system used for analyzing power systems. It provides three key advantages of the per unit system: 1) calculations are simplified, 2) it allows equipment to be rated, and 3) it provides a reference for voltages. The document then provides examples of converting values to the per unit system and using the per unit system to calculate fault currents at different points in a power system.
Parameter estimation of three-phase linear induction motor by a DSP-based el...
This work describes a method to characterize a three-phase linear induction motor in order to determine the various parameters used in its per-phase equivalent circuit by a DSP-based electric-drives system. In LIM (Linear Induction Motor), the air gap is very large compared with the RIMs (Rotary Induction Motors). Further, the secondary part normally does not have slotted structure. It is just made of aluminum and steel plates. Therefore, the effective air gap is larger than the physical air gap. High air gap makes a larger leakage inductance. It leads to lower efficiency and lower power factor. DC resistance test will be done to determine the value of Rs. The primary Inductance Ls will be calculated by running the LIM at synchronous speed. The secondary parameters i.e. Llr and Rr′ will be calculated by blocked-mover test. The experiment for no load test is shown and include a DC motor coupled to the LIM under test. Two methods to calculate the secondary parameters are described.
SPEED CONTROL OF SEPARATELY EXCITED DC MOTOR USING POWER ELECTRONIC CONVERTER
In a modern technology the use of power electronic devices in the control strategies of
electrical drives is increasing. The speed of a DC motor can be varied by controlling the field
flux, the armature resistance or the terminal voltage applied to the armature circuit. The three
most common speed control methods are field resistance control, armature voltage control,
and armature resistance control. But here a technique of drive has been used for DC motor’s
speed control is chopper and some power electronics devices. It has been shown here the use
of chopper and power electronics devices which paves the way of controlling also torque and
speed characteristics of DC motor. Now the simulation of model is done and analysed in
MATLAB (Simulink) under varying speed and torque condition
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BEF43303 - 201620171 W1 Power System Analysis and Protection.pdf
BEF43303 - 201620171 W1 Power System Analysis and Protection.pdf
International Journal of Engineering Research and Development (IJERD)
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Improvement In Pre-Regulation For Power Factor Using CUK Converter
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Design and Development of Power Electronic Controller for Grid-connected PV A...
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Study of the impact on the protection plan of a pv production integrated to t...
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Optimum Amplitude Venturini ModulationBased Matrix Converter Fed Induction Mo...
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ECNG 3015 - PU system and 3Phase Fault calculation
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SPEED CONTROL OF SEPARATELY EXCITED DC MOTOR USING POWER ELECTRONIC CONVERTER
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学校原版美国波士顿大学毕业证学历学位证书原版一模一样
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Recycled Concrete Aggregate in Construction Part II
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DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODEL
As digital technology becomes more deeply embedded in power systems, protecting the communication
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our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
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Iron and Steel Technology Roadmap - Towards more sustainable steelmaking.pdf
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The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
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Electrical power engineering test (2)
- 1. Electrical power engineering test (2( Elect.Eng/ Mohamed Safwat
- 2. Q1) 1a-What are abbreviations referring to? 1- UPS 2- ONAN 3- BDV 1-UPS: Uninterruptible Power Supply Is used in very important loads. 2-ONAN: Oil Natural Air Natural is a type of cooling used in oil transformers up to (30 MVA(. 3-BDV: Break Down Voltage Break down voltage of any isolation material like [ oil , pvc , ……,etc[ This value the voltage of any system can’t be over it , may be [33 KV or 66 KV[
- 3. Q2) What is meant by derating factor = 0.65 This mean that if we have cable withstand 100 A in normal condition so if we take derating factor 0.65 the maximum withstanding current will be 65 A so we lost 35A
- 4. Q3) what is the function of Synchrocheck relay? Is used in case of parallel connection between two generators to feed large load to adapt the synchronization
- 5. Q4)What are the conditions of parallel connection between transformers? 1-The voltage ratio must be the same. 2-The per-unit impedence must be the same. 3-The polarity connection must be the same I order to avoid circulating current.
- 6. Q5) what are the suitable method to start induction motor , explain with drawings? 1-Rotor resistance method (only for wound rotor). 2-Stator resistor or reactance. 3-Auto transformer method. 4-Star-Delta Switch. 5-Soft starting method. The best method is: 1-Soft starting method. 2-Star delta switch.
- 9. Q6) what are the excitation system types for synchronous generators , explain with drawings? 1-Dc excitation system using amplidyne
- 10. 2-Ac excitation system a- using rectifier
- 12. 3-using static excitation method
- 13. Q7) draw the schematic drawing for ups system and identify each component of it ups
- 14. Q8)what are the precaution required to change the CT burden during energized system? Never open circuit a current transformer secondary while the primary is energized
- 15. Q9) draw the differential protection circuit install on motor and identify its parameters and draw C/C curve of it?
- 16. Q10)Three pumps working sequentially after delayed for some time in start one after one with motor rated power = 55 KW and rated voltage = 400V and rated power factor = 0.85 lag please draw the power and control circuit for it and determine all circuit components parameters that you use it