Medium Voltage DC System Architectures

Length: 300 pages
Edition: 1
Language: English
Publisher: The Institution of Engineering and Technology
Publication Date: 2022-01-26
ISBN-10: 178561844X
ISBN-13: 9781785618444
Sales Rank: #4770759 (See Top 100 Books)

Direct Current (DC) transmission and distribution technologies have evolved in recent years. They offer superior efficiency, current carrying capacity, and response times as compared to conventional AC systems. Further, substantial advantages are their natural interface with many types of renewable energy resources, such as photovoltaic systems and battery energy storage systems at relatively high voltage, and compliance with consumer electronics at lower voltages, say, within a household environment. One of the core building blocks of DC-based technologies, especially at medium voltage levels, is power electronic systems technology. This cannot be emphasized enough as these units process, convert, and regulate all DC power and provide intelligence and sensing as electric power grids evolve.

These advantages have led to a rise in the utilization and applications of DC in modern power systems. This includes high voltage DC transmission systems, DC distribution grids, DC microgrids, electric vehicle charging infrastructure, and the maritime industry. However, there are still substantial challenges to the operation of these systems. Examples include a lack of standards for DC based power infrastructure and DC system protection.

This book presents the state of the art in medium voltage DC systems research and development, covering grid architecture, power converter design, transformers, control and protection for both traditional and mobile DC applications such as all-electric ships. This text, the first of its kind, provides essential information for researchers and research-oriented engineers working for academia, a manufacturer or utility, who wish to broaden or update their knowledge of medium voltage DC systems and associated equipment.

Cover
Title
Copyright
Contents
About the editors
Preface
1 Medium voltage DC technologies—key enabler for a flexible, multi-terminal underlay distribution grid
    1.1 Towards a CO2 neutral energy supply
    1.2 Transition towards flexible medium voltage distribution grids
    1.3 Cellular MVDC distribution grids for a CO2 neutral energy supply
    1.4 Conclusions
    Acknowledgement
    References
2 Power electronic converters impacts on MVDC system architectures
    2.1 Changing power distribution system paradigms
        2.1.1 The opportunity of shipboard and aircraft electrification
        2.1.2 High renewable penetration threat to MVAC grids
        2.1.3 MVDC system solutions and attributes
    2.2 Power electronic converter considerations
    2.3 Emerging MVDC applications
        2.3.1 MVDC system value proposition versus technical readiness
        2.3.2 Utility interfacing applications
        2.3.3 Aircraft electrification
        2.3.4 MVDC commercial shipboard electric propulsion systems
        2.3.5 Navy shipboard MVDC electrical distribution systems
    2.4 Technical requirements and challenges on MVDC power converters
        2.4.1 Input and output requirements
        2.4.2 Switching devices
        2.4.3 System requirements
    2.5 Conclusions
    References
3 Restructuring the existing medium voltage distribution grids using DC systems
    3.1 Introduction
        3.1.1 Emerging challenges
        3.1.2 AC distribution network expansion
        3.1.3 DC technology based solutions
    3.2 Refurbishing AC infrastructure for DC operation
        3.2.1 Capacity enhancement with DC operation
        3.2.2 Operational considerations
        3.2.3 Converter station design considerations
        3.2.4 Link conductor considerations
    3.3 Parallel AC–DC link operation
    3.4 Reconfigurable AC–DC link architecture
    3.5 Hybrid AC–DC distribution systems
        3.5.1 DC interlinks in radial networks
        3.5.2 Protection, restoration and availability
    References
4 Bidirectional isolated DC–DC converters—enabling technology for MVDC networks with distributed generation
    4.1 Introduction
    4.2 Dual-active bridge DC–DC converter
        4.2.1 Fundamental operation principle
        4.2.2 Advanced modulation schemes
        4.2.3 Advanced control techniques
        4.2.4 Three-phase, three-level dual-active bridge converters
    Acknowledgements
    References
5 Multiport DC power converters for MVDC applications
    5.1 Introduction
    5.2 Overview of MVDC systems
        5.2.1 MVDC voltage levels
    5.3 Overview of DC–DC conversion for MVDC systems
        5.3.1 Modular multilevel converter technology
        5.3.2 Conventional two-port DC–DC converters
        5.3.3 Concept of multiport DC converters
    5.4 Multiport converter technology for MVDC interconnects
        5.4.1 Desired features and functionality
        5.4.2 Multiport dual active bridge
        5.4.3 MP autotransformer
        5.4.4 MP DC-MMC
        5.4.5 Comparison of prominent multiport DC topologies for MVDC
    5.5 Multiport DC converter case studies
        5.5.1 Case study 1: 20/40/60 kV, square design
        5.5.2 Case study 2: 25/30/50 kV, square design
        5.5.3 Case study 3: 20/40/60 kV, triangular design
    5.6 Summary
    References
6 Modern control and mode visualization of bidirectional DC/DC converters
    6.1 Model reference controller design for bidirectional DC/DC converters
        6.1.1 System description
        6.1.2 Stability assessments using model reference control theory
        6.1.3 Model reference control definitions and assumptions [8]
        6.1.4 Parameter selection
        6.1.5 Basic verification
    6.2 Fault tolerant, single input, multiple output, bidirectional converter modeling and design
        6.2.1 Circuit analysis
        6.2.2 State variable computation
        6.2.3 Visualizing multiport, bidirectional DC/DC converter power modes
        6.2.4 Mutual inductor effects on converter performance
    Further Reading
    References
7 Medium frequency and medium voltage transformer technology for DC–DC converter applications
    7.1 Magnetic domain analog to electric circuit
        7.1.1 Magnetic flux behavior at material interfaces
    7.2 Magnetic coupling in multi-winding components
    7.3 Realization of non-ideal magnetic components
        7.3.1 Medium frequency resistance
        7.3.2 Magnetic core loss
        7.3.3 Leakage flux and the likely permeance path approximation
        7.3.4 Parasitic capacitance and the iso-potential surface approximation
    7.4 Material and magnetic component characterization
        7.4.1 Large signal: hysteresis loop analysis
        7.4.2 Small signal: parasitic analysis
        7.4.3 Power flow: series loss analysis
    7.5 Special considerations for laminated magnetic materials
    7.6 Winding orientations
    7.7 Closing remarks
    References
8 MVDC stability: modeling, analysis, and enhancement approaches
    8.1 System modeling and small-signal stability analysis
        8.1.1 State-space model-based stability analysis
        8.1.2 Impedance-based stability analysis
    8.2 Small-signal impedance measurement
    8.3 Large-signal model and stability analysis
        8.3.1 Large-signal model of MVDC systems
        8.3.2 Large-signal stability analysis techniques
    8.4 Methods of improving system stability
        8.4.1 Small-signal stability enhancement
        8.4.2 Large-signal stability enhancement
    8.5 Summary
    Acknowledgments
    References
9 Overview of protection technologies in MVDC system
    9.1 Introduction
        9.1.1 Challenges of protection in MVDC system
        9.1.2 Classification of MVDC circuit breakers
    9.2 Mechanical circuit breaker
        9.2.1 Introduction to mechanical circuit breaker
        9.2.2 Passive resonant DC mechanical circuit breaker
        9.2.3 Active resonant DC mechanical circuit breaker
    9.3 Solid state circuit breaker
        9.3.1 Introduction to solid state circuit breaker
        9.3.2 Classification of solid state circuit breakers
        9.3.3 Unidirectional solid state circuit breakers
        9.3.4 Bidirectional solid state circuit breakers
        9.3.5 Thyristor-based solid state circuit breakers
    9.4 Hybrid circuit breaker
        9.4.1 Introduction to hybrid circuit breaker
        9.4.2 Classification of hybrid circuit breakers
        9.4.3 Arc voltage commutated hybrid circuit breaker
        9.4.4 Current commutation unit in parallel with mechanical switch
        9.4.5 Current commutation unit in series with mechanical switch
    9.5 Conclusion
    References
10 DC marine vessel electric system design with case studies
    10.1 Marine electric systems
    10.2 DC marine system concepts
        10.2.1 A generalized DC network configuration
        10.2.2 LVDC system concept and Onboard DC Grid™
        10.2.3 MVDC system concept
    10.3 Benefits and advantages
    10.4 Protection and safety
        10.4.1 Protection of Onboard DC Grid™
        10.4.2 DCCB-based protection
    10.5 Stability assessment and control
        10.5.1 Stability issues by integration of motor drives
        10.5.2 Impedance-based stability analysis
        10.5.3 Impedance of generator-thyristor system
        10.5.4 System stability assessment
        10.5.5 Stability control and simulation verification
    10.6 Integration of energy storage
        10.6.1 Functions and benefits
        10.6.2 Planning optimization of energy storage for ferries
        10.6.3 Voltage control of energy storage for drilling vessels
    10.7 Vessel control system
    10.8 Summary and lessons from field operation
    References
11 Conclusions
    11.1 MVDC architectures
    11.2 DC architecture utilization
    11.3 Dual active bridge designs
    11.4 Multiport designs
    11.5 Control and mode visualization of bidirectional converters
    11.6 Magnetic design
    11.7 Architecture stability
    11.8 Solid state breakers
    11.9 DC-based ships
Index