This book provides an in-depth introduction to all major control and stability issues related to microgrids. It is the first book to offer a comprehensive look into the methodologies and philosophies behind system modeling, coordinated control, and protection for developing reliable, robust, and efficient operation of modular uninterruptible power supply systems. For each topic, a theoretical introduction and overview are backed by concrete programming examples that enable the reader to thoroughly understand the topic and develop and conduct simulation models.
Author(s): Jinghang Lu, Baoze Wei, Xiaochao Hou, Yao Sun
Series: Power Systems
Publisher: Springer
Year: 2023
Language: English
Pages: 226
City: Cham
Preface
Acknowledgments
Contents
List of Symbols
1 Introduction
1.1 Uninterruptible Power Supply
1.1.1 Off-line UPS System
1.1.2 Line-Interactive UPS System
1.1.2.1 Traditional Line-Interactive UPS System
1.1.2.2 Flexible Microgrid Based on Line-Interactive UPS System
1.1.3 On-line UPS System
1.2 Modular UPS
1.3 Organization of This Book
Part I Front-End Rectifier Controlof the Modular UPS System
2 An RGPI Observer-Based Resonant Super-Twisting Sliding Mode Control
2.1 Modeling of The AC/DC Converter
2.2 The Output Loop RGPIO-Based DC-Link Voltage Controller Design
2.2.1 The Design of RGPIO
2.2.2 System Stability Analysis
2.2.3 Frequency Domain Analysis for the RGPIO
2.2.4 Evaluation of the System Robustness Against Parameter Variation
2.2.5 DC-Link Voltage Controller
2.3 The Inner Loop RST-SMC Based Current Tracking Design
2.3.1 Super-Twisting Control
2.3.2 Current Tracking Loop
2.4 Simulation Results
2.4.1 Operation Under Load Resistance Variation
2.4.2 Operation with Current Command Step
2.5 Experimental Results
2.5.1 Dynamic Performance Under Load Step Change
2.5.2 Dynamic Performance Under DC-Link Voltage Increase
2.5.3 Current Loop Performance with Current Reference Step Change
2.5.4 THD of the Current at the Steady State
2.6 Conclusion
References
3 An ESO for DC-Link Voltage Control of Three-Phase AC/DC Converters
3.1 ESO-Based DC-Link Voltage Control Strategy
3.1.1 DC-Link Modeling
3.1.2 Enhanced State Observer Design
3.1.3 Parameter Tuning and Stability Analysis
3.1.4 Frequency Domain Analysis for ESO
3.1.5 System Robustness Assessment
3.1.6 Controller Design
3.2 Experimental Results
3.2.1 Test 1
3.2.2 Test 2
3.3 Conclusion
References
Part II Distributed Control and Protectionof the Modular UPS System
4 Distributed Adaptive Virtual Impedance Control for Parallel-Connected Voltage Source Inverters in Modular UPS System
4.1 Basic Droop Control Strategy
4.2 Stability Analysis and Stabilization Methods
4.2.1 The Proposed DAVIC Method
4.2.2 The Design of the Control Parameters of the Adaptive Virtual Impedance Loop
4.2.3 The Selection of Virtual Impedance and the Stability Analysis
4.3 Simulations
4.3.1 Performance Verification of the Proposed Adaptive Virtual Impedance Control
4.3.1.1 Different Preset Virtual Impedance to Mimic Unbalanced Output Impedances
4.3.1.2 Different Preset Voltage References to Mimic the Offset in Different Digital Controllers
4.3.2 Dynamic Performance Test Under Different Output Impedances
4.3.2.1 Conventional Virtual Impedance Control Method
4.3.2.2 Proposed DAVIC
4.3.2.3 Verification of the Proposed Adaptive Virtual Impedance Control with Communication Delay
4.4 Experimental Results
4.4.1 The Same Preset Virtual Impedance in the Parallel Modules Using Conventional Virtual Impedance Control
4.4.2 Different Preset Virtual Impedance in the Parallel Modules Using Conventional Virtual Impedance Control
4.4.3 The Same Preset Virtual Impedance in the Parallel Modules with Adaptive Virtual Impedance
4.4.4 The Two Different Presets of Unbalanced Virtual Impedances in the Parallel Modules Using the Proposed Control
4.5 Conclusion
References
5 Distributed Average Integral Secondary Control for Modular UPS Systems-Based Microgrids
5.1 Distributed Control Framework
5.1.1 The Concept of the Conventional Distributed Secondary Control
5.1.2 The Performance Verification and Problem Expression of the Traditional Distributed Secondary Control
5.1.3 The Proposed Distributed Averaging Integral Secondary Control (DAISC)
5.2 Stability Analysis
5.2.1 Stability Analysis of Voltage Considering the Secondary Control
5.2.2 Stability Analysis of Frequency Considering the Secondary Control
5.2.3 Circulating Current Analysis Regarding the Power Sharing Performance
5.3 Simulation Results
5.4 Experimental Results
5.4.1 Operation of CAN Bus Communication
5.4.2 Plug and play Performance Test
5.4.3 Load-Step Changes Dynamic Test
5.4.4 Capacitive and Inductive Loads Tests
5.5 Conclusion
References
6 Regeneration Protection in Uninterruptible Power Supply
6.1 Issue of the Regeneration in the Modular UPS System
6.2 Regeneration Protection Strategy in the Modular UPS System
6.2.1 Proposed DC-Link Voltage Protection Strategy
6.2.2 Proposed Power Sharing Strategy for UPS System
6.2.3 Small-Signal Modeling and Analysis of the Virtual Resistance
6.3 Experimental Results
6.3.1 Parallel UPS Transient Response in Plug-and-Play Test
6.3.2 Active Power Back-Feeding Without DC-Link Voltage Protection Strategy
6.3.3 Active Power Back-feeding with DC-Link Voltage Protection Strategy
6.3.4 Active Power Sharing Control Strategy
6.4 Conclusion
References
7 DC-Link Protection and Control in Modular Uninterruptible Power Supply
7.1 Analysis of DC-Link Voltage Regeneration
7.2 Proposed DC-Link Voltage Protection Method
7.2.1 Proposed Method for DCVP
7.2.2 Proposed Method for Current Sharing
7.2.3 Anti-Windup Dynamic Consensus Algorithm
7.3 Experimental Results
7.3.1 Parallel UPS Transient Response in Plug-and-Play Process
7.3.2 Power Feeding Without DC-Link Voltage Protection
7.3.3 Active Power Feeding with DC-Link Voltage Protection
7.3.4 Fundamental Current Sharing
7.3.5 Harmonic Current Sharing
7.3.6 Transient Performance for the Frequency and Voltage Amplitude Restoration Under Load Change
7.4 Conclusion
References
8 Overload and Short-Circuit Protection Strategy for Voltage-Source Inverter-Based UPS
8.1 Preliminaries and Notations
8.1.1 Primary Hardware Protection
8.1.2 Driver-Circuit-Based Hardware Protection
8.1.3 Main Power-Circuit-Based Hardware Protection or Combined with Modified Algorithm Control Method
8.1.4 Based Overload or Short-Circuit Protection Method
8.2 The System Model of the UPS System Under Droop Control
8.3 Short-Circuit Protection Strategy
8.4 Case Study for the Short-Circuit Protection
8.5 Conclusions
References
Part III Renewable Modular UPS System
9 Multi-mode Operation for On-line Uninterruptible Power Supply System
9.1 IMC-Based DC-Link Voltage Control Strategy
9.1.1 DC-Link Modeling
9.1.2 Two-Degree-of-Freedom (2-DOF) IMC-Based DC-Link Voltage Controller Design
9.1.3 Stability Analysis
9.1.4 Two-Port IMC-Based DC-Link Voltage Controller Design
9.1.5 Inner Loop Current Controller Design
9.2 Control Strategies for Multi-mode Operation in the On-line UPS System
9.2.1 PV-Aided Normal Mode of Operation
9.2.2 Enhanced Eco-mode and Seamless Transition
9.2.3 Burn-in Test Mode and Seamless Transition
9.2.4 Small-Signal Modeling and Analysis
9.3 Experimental Results
9.3.1 DC-Link Voltage Control Strategy
9.3.2 Multi-mode Operation of the On-line UPS System
9.4 Conclusion
References
10 AC Microgrid Seamless Transition
10.1 Different Control Modes for the UPS System
10.1.1 Physical and Control Structure of AC Microgrid
10.1.2 Control Targets Under Different Modes
10.2 Proposed Distributed Hierarchical Control
10.2.1 Primary Droop Control for Inverter-Based DGs
10.2.2 Secondary Distributed Leader–Follower Control
10.2.3 Tertiary Mode-Supervisory Control
10.3 Stability Analysis
10.3.1 Power Angle Stability Analysis
10.3.2 Voltage Stability Analysis
10.4 Simulation Results
10.4.1 Case 1: Seamless Transition from GC Mode to IS Mode
10.4.2 Case 2: Active Synchronization from IS Mode to GC Mode
10.4.3 Case 3: Communication-Link-Failure Resiliency in Active Synchronization Mode
10.4.4 Case 4: Plug-and-Play Capability in GC Mode
10.5 Conclusions
References
Index
