This book is devoted to the optimum design of the DCT in a hybrid AC/DC microgrid, which takes into account not only the influence of different inductors/capacitors values, but also numerous design goals (i.e., VCG, efficiency, stability and so on). This book examines the DCT's design problem in detail. It begins by reviewing existing DCTs in, the hybrid AC/DC microgrid and their design problems. Following that, this book proposes a family of DCT optimization design approaches to ensure that the designed DCT has good power transmission and voltage regulation ability in the hybrid AC/DC microgrid, even when the actual inductors/capacitors values fluctuate with practical power and temperature. Following that, this book provides a family of multi-objective optimization design methodologies for the DCT to guarantee that it concurrently achieves the requirements of VCG, efficiency, and system stability. This book also covers how to control the DCT in a hybrid AC/DC microgrid optimally and generically.
Author(s): Xin Zhang, Fanfan Lin, Hao Ma, Bin Zhao, Jingjing Huang
Publisher: Springer
Year: 2023
Language: English
Pages: 246
City: Singapore
Preface
Contents
About the Authors
1 Introduction
1.1 Introduction to Hybrid AC/DC Microgrid
1.1.1 Concepts of Hybrid AC/DC Microgrid
1.1.2 Challenges of Hybrid AC/DC Microgrid
1.2 Background of DC Transformer
1.2.1 Functions of DC Transformer
1.2.2 Types of DC Transformer
1.3 Control Strategy for DC Transformer
1.3.1 Open-Loop Control for DC Transformer
1.3.2 Closed Loop Control for DC Transformer
1.4 Challenges in DC Transformer Design
1.4.1 Challenges in Voltage Conversion Gain
1.4.2 Challenges in Cascaded System Stability
1.4.3 Challenges in Efficiency Improvement
References
2 The Proposed Robust Circuit Parameters Design for the CLLC-Type DC Transformer in the Hybrid AC/DC Microgrid
2.1 Introduction
2.2 Review: Power Flow Scenarios of the Hybrid AC/DC Microgrid and the CLLC-DCT Control Scheme
2.2.1 Power Flow Scenarios of Hybrid AC/DC Microgrid
2.2.2 Cooperation Between the DCT and the BIC
2.2.3 Control Scheme of the CLLC-DCT in the Hybrid AC/DC Microgrid
2.3 Robust Circuit Parameters Design of the CLLC-DCT in the Hybrid AC/DC Microgrid
2.3.1 Target Designed Parameters
2.3.2 Design Requirements
2.3.3 Design Challenges and Criteria
2.3.4 Robust Circuit Design Method for the CLLC-DCT According to the Design Criteria
2.3.5 Design Example
2.4 Experimental Verification
2.4.1 Experimental Waveforms of CLLC-DCT with Bidirectional Power Flow
2.4.2 Power Transmission Ability Verification of CLLC-DCT
2.4.3 Voltage Conversion Gain (M) Verification of DCT
2.4.4 Characteristics of the CLLC-DCT Under the High-Power Condition
2.5 Conclusion
Appendix
References
3 The Proposed Simplified Resonant Parameters Design of the Asymmetrical CLLC-Type DC Transformer in the Renewable Energy System via Semi-Artificial Intelligent Optimal Scheme
3.1 Introduction
3.2 Design Challenges of the ACLLC-Type DCT
3.2.1 Parameters Need to be Designed
3.2.2 Design Challenges
3.2.3 Objective
3.3 PT and VCG Oriented Design Criteria
3.3.1 Design Criterion-I to Ensure PT
3.3.2 Design Criterion-II to Ensure VCG
3.3.3 Further Simplification of the Above Criteria
3.4 Proposed Semi-AI Circuit Parameter Design
3.4.1 Preliminary of the Proposed Semi-AI Design Method
3.4.2 Proposed Semi-AI Design Method
3.4.3 Determine the Parameters Lr1R, Lr2R, Lm1R, Lm2R, Cr1R, Cr2R
3.5 A Design Example Based on the Proposed Semi-AI Approach
3.5.1 Step-By-Step Parameter Determination
3.5.2 Transformer Design Based on the Required Parameters in Step 5
3.6 Experimental Verification
3.6.1 Bidirectional Power Flow Characteristics
3.6.2 PT and VCG Verification
3.6.3 Other Characteristics of the Proposed DCT
3.6.4 Comparison Between the Approach in [25] and the Proposed Approach
3.7 Conclusion
References
4 The Proposed Two-Stage Parameter Design Methodology of a Generalized Resonant DC Transformer in Hybrid AC/DC Microgrid with Optimum Active Power Transmission
4.1 Introduction
4.2 Problems Description
4.2.1 Problems in Resonant DCT
4.2.2 Objective
4.3 Preliminary: APTR and VCG Oriented Design Requirements
4.3.1 General Topology
4.3.2 Design Requirement Based on APTR
4.3.3 Design Requirement Based on VCG
4.4 Challenges and Design Criteria in the Presence of Parameter Variations
4.4.1 Challenges
4.4.2 Proposed Design Criteria
4.5 Proposed Two-Stage Parameter Design
4.5.1 Preliminary Designs
4.5.2 Proposed Two-Stage Parameter Design Method to Achieve the Optimum k and g
4.5.3 Determination of the Parameters Lr1R, Lr2R, Lm1R, Lm2R, Cr1R, Cr2R
4.5.4 An Illustrative Design Example
4.6 Experimental Validation
4.6.1 APTR Ability Comparison
4.6.2 VCG Ability Comparison
4.6.3 Loss Breakdown Comparison
4.6.4 Bidirectional Power Flow Characteristic of the Proposed DCT
4.7 Conclusion
Appendix
References
5 Design of Symmetrical CLLC Resonant DC Transformer Considering Voltage Transfer Ratio and Cascaded System Stability
5.1 Introduction
5.2 Preliminaries Regarding Parameter Design for the CLLC Resonant DCT
5.2.1 Basic Design for Circuit Parameters of CLLC Resonant DCT
5.2.2 Analysis on the VTR Design Objective for the CLLC Resonant DCT
5.2.3 Analysis on the System Stability Design Objective for the CLLC Resonant DCT
5.3 Problems in Parameter Design for the CLLC Resonant DCT Considering Parameter Fluctuations
5.3.1 Fluctuations of Values of Inductance and Capacitance
5.3.2 Problem Regarding VTR Design Objective Resulting from Parameter Fluctuations
5.3.3 Problem Regarding System Stability Design Objective Resulting from Parameter Fluctuations
5.4 The Proposed Parameter Design Approach for CLLC Resonant DCT with Assistance of PSO
5.4.1 The Proposed Parameter Design for CLLC Resonant DCT with Assistance of PSO
5.4.2 RODDPSO Adopted to Consider Parameter Fluctuations
5.4.3 Design Case of the Proposed Design Approach
5.5 Experimental Results
5.5.1 Experiments of Operation at Rated Conditions
5.5.2 Experiments of VTR Verification
5.5.3 Experiments of System Stability Verification
5.6 Conclusion
References
6 Parameter Design for Symmetrical CLLC-Type DC Transformer Considering Cascaded System Stability and Power Efficiency
6.1 Introduction
6.2 Impacts of Parameter Design for the CLLC-Type DCT on Cascaded System Stability and Power Efficiency
6.2.1 Preliminaries: Basic Parameter Design for the CLLC-Type DCT
6.2.2 Impacts of Parameter Design for the CLLC-Type DCT on Cascaded System Stability
6.2.3 Impacts of Parameter Design for the CLLC-Type DCT on Power Efficiency
6.3 Challenges of Parameter Design for CLLC-Type DCT Considering Cascaded System Stability and Power Efficiency
6.3.1 Fluctuating Values of Inductors and Capacitors
6.3.2 Challenges in Parameter Design for the CLLC-Type DCT Regarding Cascaded System Stability and Power Efficiency
6.4 The Proposed Four-Stage PSO-Aided Parameter Design Approach for the CLLC-Type DCT Considering Cascaded System Stability and Power Efficiency
6.4.1 The Proposed Four-Stage PSO-Aided Parameter Design Approach for the CLLC-Type DCT
6.4.2 RODD-PSO [23] Adopted in the Parameter Design for the CLLC-Type DCT
6.4.3 Design Example
6.5 Experimental Verification
6.5.1 Experimental Operating Waveforms of the Designed CLLC-Type DCT Under Rated Conditions
6.5.2 Cascaded System Stability Verification for the Designed CLLC-Type DCT
6.5.3 Efficiency Verification for the Designed CLLC-Type DCT
6.6 Conclusion
References
7 Design Methodology for Symmetric CLLC Resonant DC Transformer Considering Voltage Conversion Ratio, System Stability and Efficiency
7.1 Introduction
7.2 Effects of Parameters on Performance of CLLC-DCT
7.2.1 Basic Design of CLLC-DCT
7.2.2 Effects of Parameters on VCR Performance
7.2.3 Effects of Parameters on System Stability Performance
7.2.4 Effects of Parameters on Efficiency Performance
7.3 Challenges in Designing CLLC-DCT Brought by Parameter Fluctuations
7.3.1 Fluctuations of Inductor and Capacitor Values
7.3.2 Challenges in Designing CLLC-DCT for Robust VCR
7.3.3 Challenges in Designing CLLC-DCT for System Stability and Satisfactory Efficiency
7.4 The Proposed Five-Stage Design Methodology for CLLC-DCT
7.4.1 The Proposed Five-Stage Design Methodology for CLLC-DCT
7.4.2 RODD-PSO [31] Used in the Proposed Design Methodology for CLLC-DCT
7.4.3 Design Example of CLLC-DCT with the Proposed Design Methodology
7.5 Experimental Verification
7.5.1 Operating Waveforms of the Designed CLLC-DCT
7.5.2 Hardware Validation of the Designed CLLC-DCT from VCR Point of View
7.5.3 Hardware Validation of the Designed CLLC-DCT from System Stability Point of View
7.5.4 Hardware Validation of the Designed CLLC-DCT from Power Efficiency Point of View
7.6 Conclusion
References
8 Multi-time Scale Frequency Regulation of a General Resonant DC Transformer in Hybrid AC/DC Microgrid
8.1 Introduction
8.2 Functions and Problems Description of the Resonant DCT in Hybrid AC/DC Microgrids
8.2.1 Functions of Resonant DCT in Hybrid AC/DC Microgrid
8.2.2 Problems Description
8.2.3 Motivation
8.3 Preliminary: General Model and Resonant Frequency of DCT
8.3.1 General Model of Resonant DCT
8.3.2 Relationship Between fr and PB
8.4 Proposed Multi-time Scale Frequency Regulation of the GCLLC-DCT
8.4.1 Cooperation Between System-Level and Local Control
8.4.2 Power Trigger Mechanism
8.4.3 Long-Time Scale Frequency Control
8.4.4 Short-Time Scale Frequency Control
8.5 Experimental Verification
8.5.1 Steady-State Characteristics of the Proposed Approach
8.5.2 Transient-State Characteristics of the Proposed Approach
8.5.3 Characteristics Comparison
8.6 Conclusion
References
Index
