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Presents the latest developments in switchgear and DC/DC converters for DC grids, and includes substantially expanded material on MMC HVDC This newly updated edition covers all HVDC transmission technologies including Line Commutated Converter (LCC) HVDC; Voltage Source Converter (VSC) HVDC, and the latest VSC HVDC based on Modular Multilevel Converters (MMC), as well as the principles of building DC transmission grids. Featuring new material throughout, High Voltage Direct Current Transmission: Converters, Systems and DC Grids, 2nd Edition offers several new chapters/sections including one on the newest MMC converters. It also provides extended coverage of switchgear, DC grid protection and DC/DC converters following the latest developments on the market and in research projects. All three HVDC technologies are studied in a wide range of topics, including: the basic converter operating principles; calculation of losses; system modelling, including dynamic modelling; system control; HVDC protection, including AC and DC fault studies; and integration with AC systems and fundamental frequency analysis. The text includes: A chapter dedicated to hybrid and mechanical DC circuit breakers Half bridge and full bridge MMC: modelling, control, start-up and fault management A chapter dedicated to unbalanced operation and control of MMC HVDC The advancement of protection methods for DC grids Wideband and high-order modeling of DC cables Novel treatment of topics not found in similar books, including SimPowerSystems models and examples for all HVDC topologies hosted by the 1st edition companion site. High Voltage Direct Current Transmission: Converters, Systems and DC Grids, 2nd Edition serves as an ideal textbook for a graduate-level course or a professional development course.
This book describes a variety of reasons justifying the use of DC transmission as well as the basic concepts and techniques involved in the AC-DC and DC-AC conversion processes.
The direct current transmission scheme linking the island of Gotland to the main land of Sweden by means of a submarine cable under the Baltic Sea is the first commercial realisation of a modern technique for the transmission of electrical energy. It is certainly not accidental that this pioneering initiative was allotted to the Gotland scheme. Various viewpoints may be presented regarding this, but the essential factor relates to the circumstances that permitted the magnitude ofthe transmitted power to be given a value which would not have been technically or economically feasible for any other project. The power, on the one hand, was sufficiently small to justify the risk associated with such a new venture, for it fell within limits acceptable both to ASEA as the manufacturer and to the Swedish State Power Board as the customer. On the other hand, the power was large enough to demonstrate the technical and economic characteristics of the new system and to provide the opportunity of gaining invaluable experience that could be applied to future large-scale transmission systems. In 1954 a team under the direction of Dr. Uno Lamm successfully commissioned the Gotland scheme, representing the culmination of many years of intensive development work.
This book provides a comprehensive overview on Transcranial Direct Current Stimulation (tDCS) and the clinical applications of this promising technique. Separated into three parts, the book begins with basic principles, mechanisms and approaches of tDCS. This is followed by a step-by-step practicum, methodological considerations and ethics and professional conduct pertaining to this novel technique. Chapters are authored by renowned experts who also direct and plan tDCS educational events worldwide. Bridging the existing gap in instructional materials for tDCS while addressing growing interest in education in this field, professionals within a broad range of medical disciplines will find this text to be an invaluable guide.
A direct current generator, or DC generator, produces a voltage of constant polarity, which means the voltage and current do not change over time. DC generators are basically AC generators whose output voltage is switched the other way round at the proper moment, so that the direction of the voltage is always in a single direction. The AC generator uses slip rings to transfer the current to the electrical circuit, while the DC generator uses a split-ring commutator. Generators can be very small or quite huge. Commercial DC generators are commonly found in traction applications like subways and trains. Factories that do electrolysis, electroplating and those that produce aluminum, caustic soda, chlorine, and some other industrial materials need large amounts of direct current and use DC generators.An electric motor is very similar to a generator, except that power is provided to turn the rotors. They may, in fact, be described as generators "running backwards". When current is passed through the armature of a DC motor, a torque is generated by magnetic reaction, and the armature revolves. Adjustable speed is difficult to obtain with motors whose armatures are connected to fixed frequency power lines (AC motors). Here is where DC motors shine; their rotating field speed depends on the rotor speed itself. The speed of DC series motors varies with load, and torque varies inversely with speed. This makes them particularly suitable to starting high inertia loads such as railway trains. Starting a DC motor requires often an external resistor or rheostat to limit the current. The value, in Ohms, of that resistor is reduced in steps as the speed of the motor increases, until finally that resistor is removed from the circuit as the motor reaches close to its final speed.This 4-hr Quick Book provides discusses salient features of DC motors and generators in detail. The course is based entirely on Naval Education and Training Materials (NAVEDTRA 14177), Electricity and Electronic Training Series; Module-5 and covers Chapter 1 and 2 titled “Direct Current Generators and Direct Current Motors”. Learning ObjectiveAt the conclusion of this course, the reader will be able to:• State the principle by which generators convert mechanical energy to electrical energy.• State the rule to be applied when you determine the direction of induced emf in a coil.• State what component causes a generator to produce direct current rather than alternating current.• State how field strength can be varied in a dc generator.• State the three classifications of dc generators.• State the term that applies to voltage variation from no-load to full-load conditions and how it is expressed as a percentage.• State the factors that determine the direction of rotation in a dc motor.• State the right-hand rule for motors.• Describe the main differences and similarities between a dc generator and a dc motor.• List the advantages and disadvantages of the different types of dc motors.• Discuss the means of controlling the speed and direction of a dc motor.• Explain the need for a starting resistor in a dc motor.
The 2nd edition of this book incorporates the tremendous clinical advances that have occurred in the field of transcranial direct current stimulation (tDCS) over the past 5 years. Since the 1st edition was published, the clinical use of tDCS has moved from its infancy, and is now in a thrilling new phase with numerous possibilities as well as challenges. tDCS is a technique that excels in terms of safety and tolerability, and within a few years, novel technological developments will allow its use at home. At the same time, large, phase III trials have been exploring the clinical efficacy of tDCS, the results of which have been published in leading journals such as the New England Journal of Medicine and JAMA Psychiatry. This 2nd edition summarizes the state of the art of the field. Written by leading experts in the field, the book is divided into 5 parts: Introduction and Mechanisms of Action; Research Methods; tDCS in the life cycle; Applications of tDCS in neuropsychiatric disorders (further divided into Psychiatry and Neurology); and The clinical use of tDCS. It also includes several new chapters, covering topics such as precision stimulation of tDCS; combination of tDCS with different neuroimaging modalities; and use of tDCS in new clinical conditions. Moreover, all chapters have been rewritten and updated. This book will be of significant interest to psychiatrists, neurologists and neuroscientists new to the field as well as those with a background in tDCS who want to increase their understanding of particular psychiatric conditions.
The aim of this book is to provide a comprehensive review of the use of Transcranial Direct Current Stimulation (tDCS) in different psychiatric conditions. Here we review tDCS clinical studies employing different types of design (from single-session tDCS studies to randomized clinical trials) as well as studies evaluating the impact of tDCS in neurophysiological, behavioral and brain imaging outcomes. Although the understanding about physiological foundations and effectiveness of clinical therapies of psychiatric diseases has been considerably increased during the last decades, our knowledge is still limited, and consequently psychiatric diseases are still a major burden to the individual patient and society. Recently, interest in pathological alterations of neuroplasticity in psychiatric diseases as a critical condition for development, and amelioration of clinical symptoms increased, caused by the fact that new tools, such as functional imaging, and brain stimulation techniques do allow to monitor, and modulate these phenomena in humans. Especially non-invasive brain stimulation techniques evolved as an attractive potential new therapeutic tool. The interest in non-invasive brain stimulation has grown exponentially in the past 25 years, with the development of non-pharmacological, neuromodulatory techniques such as tDCS and repetitive transcranial magnetic stimulation (rTMS). TDCS, although even newer than rTMS, has attracted considerable attention in both basic and clinical research scenarios. In the context of clinical research, tDCS is being increasingly investigated as a novel treatment tool for several psychiatric disorders, such as major depression, schizophrenia and neurocognitive and substance abuse disorders. Transcranial Direct Current Stimulation in Neuropsychiatric Disorders – Clinical Principles and Management intends to serve as a practical guide on the field, attracting the interest of psychiatrists, neurologists and neuroscientists with little or no experience with tDCS, as well as those with a background on tDCS who want to increase their knowledge in any particular psychiatric condition.
Medium Voltage Direct Current Grid is the first comprehensive reference to provide advanced methods and best practices with case studies to Medium Voltage Direct Current Grid (MVDC) for Resilience Operation, Protection and Control. It also provides technical details to tackle emerging challenges, and discuss knowledge and best practices about Modeling and Operation, Energy management of MVDC grid, MVDC Grid Protection, Power quality management of MVDC grid, Power quality analysis and control methods, AC/DC, DC/DC modular power converter, Renewable energy applications and Energy storage technologies. In addition, includes support to end users to integrate their systems to smart grid. - Covers advanced methods and global case studies for reference - Provides technical details and best practices for the individual modeling and operation of MVDC systems - Includes guidance to tackle emerging challenges and support users in integrating their systems to smart grids