Ultra-Capacitors in Power Conversion Systems E-Book

Petar J. Grbovic

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: Wiley - IEEE
• Sprache: Englisch

Seitenzahl: 407

Veröffentlichungsjahr: 2013

Beschreibung

Ultra-capacitors, used as short-term energy storage devices, are growing in popularity especially in the transportation and renewable energy sectors. This text provides an up-to-date and comprehensive analysis of ultra-capacitor theory, modeling and module design from an application perspective, focusing on the practical aspects of power conversion and ultra-capacitor integration with power electronics systems. Key features: * clearly explains the theoretical and practical aspects of ultra-capacitor, analysis, modelling and design * describes different power conversion applications such as variable speed drives, renewable energy systems, traction, power quality, diesel electric hybrid applications * provides detailed guidelines for the design and selection of ultra-capacitor modules and interface dc-dc converters * includes end-of-chapter exercises and design examples This is an essential reference for power electronics engineers and professionals wanting to expand their knowledge of advanced ultra-capacitor energy storage devices and their application in power conversion. It is also a valuable resource for industrial design engineers as well as academics and advanced students in power electronics who want to develop their understanding about this highly topical subject.

Leseprobe

Table of Contents

Title Page

Copyright

Preface

What this Book is About

What is Inside the Book

Who Should Read this Book (and Why)

Acknowledgments

Chapter 1: Energy Storage Technologies and Devices

1.1 Introduction

1.2 Direct Electrical Energy Storage Devices

1.3 Indirect Electrical Energy Storage Technologies and Devices

1.4 Applications and Comparison

References

Chapter 2: Ultra-Capacitor Energy Storage Devices

2.1 Background of Ultra-Capacitors

2.2 Electric Double-Layer Capacitors – EDLC

2.3 The Ultra-Capacitor Macro (Electric Circuit) Model

2.4 The Ultra-Capacitor's Energy and Power

2.5 The Ultra-Capacitor's Charge/Discharge Methods

2.6 Frequency Related Losses

2.7 The Ultra-Capacitor's Thermal Aspects

2.8 Ultra-Capacitor High Power Modules

2.9 Ultra-Capacitor Trends and Future Development

2.10 Summary

References

Chapter 3: Power Conversion and Energy Storage Applications

3.1 Fundamentals of Static Power Converters

3.2 Interest in Power Conversion with Energy Storage

3.3 Controlled Electric Drive Applications

3.4 Renewable Energy Source Applications

3.5 Autonomous Power Generators and Applications

3.6 Energy Transmission and Distribution Applications

3.7 Uninterruptible Power Supply (UPS) Applications

3.8 Electric Traction Applications

3.9 Summary

References

Chapter 4: Ultra-Capacitor Module Selection and Design

4.1 Introduction

4.2 The Module Voltage Rating and Voltage Level Selection

4.3 The Capacitance Determination

4.4 Ultra-Capacitor Module Design

4.5 The Module's Thermal Management

4.6 Ultra-Capacitor Module Testing

4.7 Summary

References

Chapter 5: Interface DC–DC Converters

5.1 Introduction

5.2 Background and Classification of Interface DC–DC Converters

5.3 State-of-the-Art Interface DC–DC Converters

5.4 The Ultra-Capacitor's Current and Voltage Definition

5.5 Multi-Cell Interleaved DC–DC Converters

5.6 Design of a Two-Level N-Cell Interleaved DC–DC Converter

5.7 Conversion Power Losses: A General Case Analysis

5.8 Power Converter Thermal Management: A General Case Analysis

5.9 Summary

References

Index

This edition first published 2014

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Library of Congress Cataloging-in-Publication Data

Grbovi Petar J.

Ultra-capacitors in power conversion systems : applications, analysis, and design from theory to practice / Petar J. Grbovi.

pages cm

Includes bibliographical references and index.

ISBN 978-1-118-35626-5 (hardback)

1. Electric current converters– Equipment and supplies. 2. Supercapacitors. 3. Electric machinery– Equipment and supplies. I. Title.

TK7872.C8G695 2014

621.31′5– dc23

2013018944

A catalogue record for this book is available from the British Library.

ISBN: 9781118356265

Preface

What this Book is About

This book is about ultra-capacitors and their application in power conversion systems. It is particularly focused on the analysis, modeling, and design of ultra-capacitor modules and interface dc–dc power converters.

Power conversion systems and power electronics play a significant role in our everyday life. It would be difficult to imagine a power conversion application, such as industrial controlled electric drives, renewable sources, power generation and transmission devices, home appliances, mobile diesel electric gen-sets, earth moving machines and equipment, transportation, and so on, without power electronics and static power converters. In most of these applications, we are facing growing demands for a device that is able to store and re-store certain amounts of energy during a short period. Controlled electric drives may require energy storage to save energy during braking or provide energy in case of power supply interruption. Wind renewable “generators” may need energy storage to smooth power fluctuations caused by wind fluctuation. Power transmission devices such as static synchronous compensators (STATCOMs) need energy storage to support the power system with active power during faults and unstable operation. Mobile diesel electric gen-sets need energy storage to reduce fuel consumption and CO2 pollution. There is a strong requirement for energy storage in transportation systems in order to improve the system's efficiency and reliability.

The energy storage device should be able to quickly store and re-store energy at very high power rates. The charge and discharge time should be a few seconds up to a few tens of seconds, while charging specific power is in the order of 5–10 kW/kg. Today, two energy storage technologies fit such requirements well: (i) flywheel energy storage and (ii) electrochemical double-layer capacitorss (EDLCs), best known as ultra-capacitors. In this book, ultra-capacitors are addressed alone.

What is Inside the Book

This book starts from a background of energy storage technologies and devices. Then, the detailed theory of ultra-capacitors follows. The fundamentals of power conversion systems and applications are also addressed. An important part of the book is the process of selection and design of ultra-capacitor modules. Finally, the book ends with a detailed analysis of interface dc–dc converters. In total, the book has five chapters.

The fundamentals of energy storage technologies and devices are given in the first chapter. All energy storage systems are classified into two categories: direct and indirect energy storage systems. Direct energy storage devices store electrical energy directly without conversion into another type of energy. Inductors and capacitors are direct energy storage devices. Particular devices with high energy density are super magnet energy storage devices (SMES) and ultra-capacitors. Indirect energy storage systems and devices convert electrical energy into another type of energy that is easier to handle and store. Typical systems are electromechanical energy storage systems, such as fly-wheel, hydro pumped, and compressed air energy storage systems. Electrochemical energy storage systems, such as electrochemical batteries and hydrogen fuel cells, are other well known energy storage systems.

The background theory of ultra-capacitors is presented in the second chapter. The ultra-capacitor model is given with particular attention to the application oriented model. The ultra-capacitor's energy and power are then defined and discussed. Different charging/discharging methods, such as voltage-resistance, current, and power control modes are analyzed. The ultra-capacitor's voltage and current characteristics are derived for different charge/discharge methods. Analysis and calculation of the ultra-capacitor's current stress and power losses under different conditions are discussed. An explanation is given of how ultra-capacitor losses depend on the charge/discharge frequency and how such losses are determined when the charge/discharge current frequency is in the range of megahertz (very low frequency) as well as in the range of a couple of hertz (low frequency). Some application examples, such as variable speed drives with braking and ride through capability, are given.

The fundamentals of power conversion are presented in the first part of the third chapter. Requirements for the use of a short-term energy storage device in power conversion systems are addressed and discussed. The structure of a typical power conversion system with ultra-capacitor energy storage is presented. The process of selection of an energy storage device for a particular application requirement is briefly described. Two main energy storage devices are compared: electrochemical batteries and ultra-capacitors. In the second part of the chapter we discuss different power conversion applications, such as controlled electric drives, renewable energy sources (wind, PV, and marine currents for example), autonomous diesel and natural liquid gas (NLG) gen-sets, STATCOM with short-term active power capability, UPS, and traction.

The selection of an ultra-capacitor module is intensively discussed in the fourth chapter. Design of an ultra-capacitor module is based on three main parameters, namely the module voltage, capacitance, and internal resistance. The module voltage is in fact a set of different operating voltages and the module rated voltage. The operating and rated voltages, the module capacitance and internal resistance are defined according to application requirements, such as energy storage capability, operation life span, efficiency, and so on. Ultra-capacitor losses and efficiency versus size and cost are discussed in the second part of the chapter. Some aspects of ultra-capacitor module design are presented. Series connection of elementary ultra-capacitor cells and voltage balancing issues are also discussed and the module's thermal design is considered too. The theoretical analysis is supported by several examples from some real power conversion applications.

Interface dc–dc converters are discussed in the fifth chapter. First, the background of bi-directional dc–dc power converters is given. The converters are classified in different categories, such as full power versus fractional power rated converters, isolated versus non-isolated converters, two-level versus multi-level and single-cell versus multi-cell interleaved converters. State-of-the-art topologies are compared according to the application's requirements. A detailed analysis of a multi-cell interleaved bi-directional dc–dc converter is given in the second part of the chapter where design guidelines are given too. The theoretical analysis is supported by a set of numerical examples from real applications, such as high power UPS and controlled electric drive applications.

Who Should Read this Book (and Why)

This book is mainly aimed at power electronics engineers and professionals who want to improve their knowledge and understanding of advanced ultra-capacitor energy storage devices and their application in power conversion, in the present as well as in the near future. The book could also be background material for graduate and PhD students who want to learn more about ultra-capacitors and power conversion application in general. The reader is expected to have basic knowledge in math, theory of electric circuits and systems, electromagnetics, and power electronics.

Acknowledgments

I started this story about ultra-capacitors some years ago, when I was with Schneider Electric, R&D of Schneider Toshiba Inverter (STI), in Pacy sur Eure, France. I would like to express my thanks to Dr. Philippe Baudesson and Dr. Fabrice Jadot for the support I received at that time when I first started thinking about the application of ultra-capacitors in controlled electric drives.

I would like to express my deep gratitude to Professor Philippe Delarue and Professor Philippe Le Moigne from Laboratoire d'Electrotechnique et d'Electronique de Puissance (L2EP), Lille, France, for all the creative and fruitful discussions we had and all his comments and suggestions.

I would like to express my sincere thanks to Peter Mitchell, publisher; Richard Davies, project editor; Laura Bell, assistant editor; Genna Manaog, senior production editor; Radhika Sivalingam, project manager; and Caroline McPherson, copy editor. It has been real pleasure to work with all of them.

Last but not least, I offer my deepest gratitude to my family, my wife Jelena, son Pavle, and mother Stojka, for their love and support and for their confidence in me.

Finally, let me express my deepest gratitude to God for His blessing.

Dr Petar J. GrboviIsmaning, Germany

Chapter 1

Energy Storage Technologies and Devices

1.1 Introduction

1.1.1 Energy

By definition, energy is that property of a body by virtue of which work can be done. Energy cannot be created nor destroyed; it can only be transformed from one form into another. Energy can exist in many forms, such as electromagnetic field, gravity, chemical energy, nuclear energy, and so on [1, 2]. One form of energy that we use in everyday life is so-called electrical energy. In this chapter we will discuss electrical energy storage technologies and devices.

1.1.2 Electrical Energy and its Role in Everyday Life

Electrical energy can be defined as the ability to do work by means of electric devices. Electrical energy has been used in segments of everyday life since end of 1800s, the age of Tesla and Edison. Today, electrical energy is the dominant form of energy. Approximately 60% of primary energy is converted into electrical energy and then used in diverse applications such as industry, transportation, lighting, home appliances, telecommunication, computing, entertainment, and so on.

Figure 1.1 shows a simplified block diagram of electrical energy production–transmission–consumption flow. Electrical energy is usually “generated” by electro-mechanical generators. The generators are driven by steam turbines, NLG (natural liquid gas) turbines, hydro turbines, wind-turbines, and internal combustion diesel engines. Additionally, electrical energy can be “produced” by static generators, such as photovoltaic panels and hydrogen fuel cells.

Figure 1.1 Electrical energy production–transmission–consumption process

Transmission of electrical energy from the “production” to the “consumption” location is also convenient. The “production” point can be a centralized, dislocated power station far away from the “consumption” point, for example, a big city. The electrical energy is transferred and distributed via a high voltage transmission line and a medium/low voltage distribution network. Electrical energy is “consumed” by the end customer. In fact, electrical energy is converted to another form of energy, such as heat, light, chemical energy, linear or rotational movement, and so on.

In small-scale systems, such as diesel electric locomotives, hybrid tracks, earth moving equipment (excavators), and RTG (rubber tyred gantry) cranes, for example, electrical energy is produced by an on-board diesel–electric generator and transmitted to the on-board dislocate loads (electric motors).

It is very convenient to “produce” electrical energy from another form of energy such as mechanical or chemical. However, electrical energy cannot be easily stored. Hence, electrical energy must be “consumed” at same time that it is “produced.” An imbalance between total production and consumption leads to problems of power quality, instability, and collapse of the electrical system. This makes it difficult to use electrical energy in systems with dynamic, fluctuating “production” and/or “consumption.” An energy storage device is required to store or restore electrical energy and make the dynamic balance between “production” and “consumption.” In this chapter we will briefly describe the major types of electrical energy storage technologies and devices.

1.1.3 Energy Storage

An energy storage device is a multi-physic device with the ability to store energy in different forms. Energy in electrical systems, so-called “electrical energy,” can be stored directly or indirectly, depending on the means of the storage medium. Figure 1.2 illustrates direct and indirect energy storage processes and devices.

Figure 1.2 Energy storage technologies and devices

Devices that store the electrical energy, without conversion from electrical to another form, are called direct electrical energy storage devices. The energy storage medium is the electromagnetic field. The storage devices are electric capacitors and inductors. Devices that convert and store the electrical energy in another form of energy are called indirect electrical energy storage devices. There are several forms of energy that can be converted from/to electrical energy. Some of the most appropriate forms of energy are mechanical and chemical. Mechanical energy can exist in two forms: energy of position, known best as potential energy and energy of motion, known as kinetic energy. The storage devices are flywheels, compressed air energy storage (CAES), and hydro pumped energy storage (HPES). Devices that use chemical energy as the form of energy to be stored are electrochemical batteries and fuel cells.