Methods for Reduction of Voltage Unbalance in Weak Grids Connected to Wind Plants



1 INTRODUCTION
The location of wind turbines is based on wind properties. Normally, areas with good wind resources are geographical remote. The cost of the electrical power grid connecting the wind plants should be as low as possible. The voltage quality in a weak power grid may be poor, and unbalanced voltages can occur. Induction machines are attractive as wind turbine gener ....etc

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Ever since the discovery of the wheel, man has been in constant pursuit to achieve better and faster means of transportation. The FLYING TRAINS that is the MAGLEV (magnetic levitation) trains is the realization of such zestful endeavors. These ultra high-speed trains are acting as an indisposable resource to make the world smaller. Maglev is a generic term for a family of technologies in which a vehicle is suspended, guided and propelled by magnetic forces. Due to its need for an entirely new infrastructure, maglev technology has had a prolong ....etc

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Abstract
A method for estimating the phase current unbalancein a multiphase buck converter is presented. The method uses theinformation contained in the voltage drop at the input capacitor’seffective series resistance (ESR) to estimate the average current ineach phase. Although the absolute estimation of the currents dependson the value of the ESR and is therefore not absolutely accurate,the relative estimates of the currents with respect to one otherare shown to be very accurate. The method can be implementedwith a low-rate down-sam ....etc

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It is a step towards a new breed of computer chips that couple memory with information processing. Such chips retain data when computer is turned off, eliminating the time-consuming process of booting up information from hard drive to processor. If we can make semiconductor based magnetic memories when we turn on computer it would be like a TV set-all information will be there with no need for reloading the operating system. All spintronic computers eliminate the need for parallel processing. Computing could be accelerated and customized with r ....etc

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The magnetic amplifier (colloquially known as the mag amp) is an electromagnetic device for amplifying electrical signals. The magnetic amplifier was invented early in the 20th century, and was used as an alternative to vacuum tube amplifiers where robustness and high current capacity were required. World War II Germany perfected this type of amplifier, and it was used for instance in the V-2 rocket. The magnetic amplifier has now been largely superseded by the transistor-based amplifier, except in a few safety critical, high reliability or ....etc

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Introduction

Couplers, also known as isolators because they electrically isolate as well as transmit data, are widely used in industrial and factory networks, instruments, and telecommunications. Every one knows the problems with optocouplers. They take up a lot of space, are slow, optocouplers age and their temperature range is quite limited. For years, optical couplers were the only option. Over the years, most of the components used to build instrumentation circuits have become ever smaller. Optocoupler technology, however, hasn't kept ....etc

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A magnetic amplifier is a device which controls the power delivered from an a.c. source by employing a controllable non linear reactive elements or circuit generally interposed in series with the load. The power required to control the reactive element or circuit is made for less than the amount of power controlled; and hence power amplification is achieved. The non-linear reactive element is a saturable reactor. When used in a combination with a set of high-grade rectifiers, it exhibits power amplification properties in the sense that small ch ....etc

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Power frequency magnetic fields as high as 15,000,000 milligauss are commonly found internally in equipment such as power transformers, motors and generators .Although these fields are almost contained within the equipment ,some leakage will occur. This paper concentrates on magnetic fields in the range of zero to several hundred milligauss. This level of magnetic field may be experienced by the general public as a result of operation of electrical equipment, current carrying lines, house wiring, electrical appliances, lighting equipment or an ....etc

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CONTENTS

1. Acknowledgement
2. Introduction
3. Objectives
4. Components
5. Working
6. Benefits
7. Activities (present and future)
8. Magnetic materials
9. Regenerators
10. Superconducting magnets
11. Active magnetic regenerators (AMR?s)
12. A rotary AMR liquefier
13. Comparison





ACKNOWLEDGEMENT

The compilation of this seminar would not have been possible without the support and guidance of the following people and organization. With my deep sense of gratitude, I thank my respected teachers for supporting ....etc

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It is not often that scientific discoveries hold the promise of saving consumer?s money while protecting the environment and reducing the use of fossil fuels. Define the perfect fuel and it would most lightly be one that burns cleanly, poses no harm to the environment and, above all, is renewable or in limitless supply.

The researchers in the U.S Department of Energy?s Ames Laboratory under a construct with the Astronautics Corporation of America have developed a refrigerator with out a standard gas-compression cooling system. Magnetic refr ....etc

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