Transient Characteristics, Modelling and Stability Analysis of Microgird

Foreword
Preface
Acknowledgements
Contents
Abbreviations
Chapter 1: Introduction
	1.1 Trends and Development of Power Electronic System
	1.2 Features of Microgrid
	1.3 Transient Characteristics of Microgrid
	1.4 Transient Stability Problem of Microgrid
	1.5 Challenges of Transient Characteristics and Stability Analysis of Microgrid
	1.6 Structure of the Book
	References
Chapter 2: Transient Characteristics of Current Controlled IIDGs During Grid Fault
	2.1 Basic Principles and Control Structures
		2.1.1 Topology of Three-Phase Inverter
		2.1.2 Principle of Constant Current Control
		2.1.3 Principle of PQ Control
	2.2 Transient Characteristics of Constant Current Controlled IIDGs
		2.2.1 Fault Models
		2.2.2 Fault Current Calculation
	2.3 Transient Characteristics of PQ Controlled IIDGs
		2.3.1 Transient Characteristics of PQ Controlled IIDGs During Symmetrical Fault
			2.3.1.1 Fault Models
			2.3.1.2 Fault Current Calculation
		2.3.2 Transient Characteristics of PQ Controlled IIDGs During Asymmetrical Fault
			2.3.2.1 Case 1: IIDGs with Symmetrical Positive Sequence Current (SPSC) Control
				Fault Model
				Fault Current Calculation
			2.3.2.2 Case 2: IIDGs with Active Power Oscillation (APOC) Control
				Fault Analysis When Positive and Negative Sequence Currents Are Injected into the Grid-Connected System
					Fault Model
					Fault Current Calculation
				Fault Analysis When Positive and Zero Sequence Currents Are Injected into the Grid-Connected System
					Fault Model
					Fault Current Calculation
			2.3.2.3 Case 3: IIDGs with Reactive Power Oscillation (RPOC) Control
				Fault Model
				Fault Current Calculation
			2.3.2.4 Case 4: IIDGs with Active and Reactive Power Oscillation (ARPOC) Control
				Fault Model
				Fault Current Calculation
		2.3.3 Influence of Current Limiter
	2.4 Summary
	References
Chapter 3: Transient Characteristics of Voltage Controlled IIDGs During Grid Fault
	3.1 Principle and Control Structures
		3.1.1 Principle of V/f Control
		3.1.2 Principle of Droop Control
		3.1.3 Principle of Virtual Synchronous Control
	3.2 Transient Characteristics of V/f Controlled IIDG During Grid Fault
		3.2.1 Fault Models
		3.2.2 Fault Current Calculation
			3.2.2.1 Mathematical Model of Fault Current
			3.2.2.2 Fault Current Estimation
		3.2.3 Influencing Factors of Fault Current Characteristics
			3.2.3.1 Influence of Line Impedance and Fault Occurring Moment
			3.2.3.2 Influence of Fault Type
			3.2.3.3 Influence of Nonlinear Limiter
				A. Influence of Current Limiter
				B. Influence of Modulation Wave Limiter
	3.3 Transient Characteristics of Droop Controlled IIDG During Grid Fault
		3.3.1 Fault Models
		3.3.2 Fault Current Calculation
			3.3.2.1 Mathematical Model of Fault Current
			3.3.2.2 Fault Current Estimation
		3.3.3 Influencing Factors of Fault Current Characteristics
			3.3.3.1 Influence of Low-Pass Filters in Power Control Loop
			3.3.3.2 Influence of Droop Coefficients
			3.3.3.3 Influence of Nonlinear Limiter
	3.4 Transient Characteristics of VSG Controlled IIDG During Grid Fault
		3.4.1 Fault Models
		3.4.2 Fault Current Calculation
			3.4.2.1 Mathematical Model of Fault Current
			3.4.2.2 Fault Current Estimation
		3.4.3 Influencing Factors of Fault Current Characteristics
	3.5 Summary
	References
Chapter 4: Fault Ride Through Control Methods of VSG Controlled IIDGs
	4.1 Typical Topology of VSG Controlled IIDGs
	4.2 Problem Description of VSG Controlled IIDGs During Fault
		4.2.1 Instantaneous Inrush Current of VSG Controlled IIDGs
		4.2.2 Analysis for Maximum Withstanding Time of VSG Controlled IIDGs During Fault
		4.2.3 Difficulties in Restraining Instantaneous Inrush Current of VSG Controlled IIDGs
	4.3 Fault Ride Through Control Methods of VSG Controlled IIDGs
		4.3.1 Current Limiting Control Method Based on Virtual Impedance
			4.3.1.1 Control Principle
			4.3.1.2 Experiment Results
				A. Hardware Implementation of Fault Detection
				B. Experiment Verification of the Current Limiting Method Based on Virtual Impedance
		4.3.2 Fast Inrush Current Restraining Method Based on Control Mode Switching
			4.3.2.1 Control Principle
			4.3.2.2 Instantaneous Inrush Current Restraining
			4.3.2.3 Smooth re-Switching Control
			4.3.2.4 Experiment Results
	4.4 Summary
	References
Chapter 5: Full-Order Modeling and Dynamic Stability Analysis of Microgrid
	5.1 Full-Order Modeling of Microgrid
		5.1.1 Coordination Transformation for DERs
		5.1.2 Modeling of Inverters with Different Control Strategies
			5.1.2.1 Modeling of Droop Controlled Inverter
			5.1.2.2 Modeling of VSG
			5.1.2.3 Modeling of Current Controlled Inverter
		5.1.3 Modeling of Network
		5.1.4 Modeling of Different Kinds of Loads
			5.1.4.1 Modeling of ZIP Load
			5.1.4.2 Modeling of Induction Motor Load
		5.1.5 Full-Order Modeling of Microgrid
	5.2 Model Verification
	5.3 Parameter Stability-Region of Microgrid
		5.3.1 Bifurcation Theory
		5.3.2 Parameter Stability-Region Analysis
			5.3.2.1 Case 1: Numerical Bifurcation Analysis on mp-mq Plane
			5.3.2.2 Case 2: Numerical Bifurcation Analysis on P-V Plane
		5.3.3 Verification of Bifurcation Instability
	5.4 Summary
	References
Chapter 6: Time-Scale Model Reduction of Microgrid Based on Singular Perturbation Theory
	6.1 Multi-Time Scale Property of Microgrid
	6.2 Wide Frequency Range Stability Problem Classification
	6.3 Time-Scale Model Reduction of Microgrid
		6.3.1 Singular Perturbation Theory
		6.3.2 Singular Perturbation Reduction of Microgrid
		6.3.3 Verification of Reduced Order Model
	6.4 Comparative Study of Different Reduced Models
		6.4.1 Eigenvalue Comparative Analysis
		6.4.2 Numerical Comparative Simulation
	6.5 Summary
	References
Chapter 7: Spatial-Scale Model Reduction of Multi-Microgrid Based on Dynamic Equivalent Theory
	7.1 The Concept of Dynamic Equivalent Modeling for Multi-Microgrid
	7.2 Dynamic Equivalent Model of External Microgrid
		7.2.1 The Division of External Microgrid
		7.2.2 Simplification of Network
		7.2.3 Aggregation of Buses
		7.2.4 Aggregation of DERs
			7.2.4.1 Aggregation of Droop-Controlled DER
			7.2.4.2 Aggregation of PQ-Controlled DER
	7.3 Verification of the Dynamic Equivalent Model
		7.3.1 Evaluation for the Studied System
		7.3.2 Evaluation of Testing Multi-Microgrid with 15 Buses
	7.4 Summary
	References
Chapter 8: Modeling and Stability Analysis of Asymmetrical Microgrid Based on Dynamic Phasor Theory
	8.1 Concept of Dynamic Phasor Method
	8.2 Dynamic Phasor Modeling of Asymmetrical Microgrid
		8.2.1 Dynamic Phasor Model of VSG
			8.2.1.1 DC Side of VSG
			8.2.1.2 Control Part of VSG
			8.2.1.3 LC Filter and Coupling Inductor
		8.2.2 Dynamic Phasor Model of Single-Phase PV
		8.2.3 Aggregation of DG Model
		8.2.4 Dynamic Phasor Model of Load and Network
		8.2.5 Dynamic Phasor Model of Asymmetrical Microgrid
	8.3 Eigenvalue Analysis of Asymmetrical Microgrid
		8.3.1 Case Study 1: Load Disturbance Test
		8.3.2 Case Study 2: Asymmetrical Short-Circuit Fault Test
	8.4 Improved Voltage Unbalance Compensation Strategies for Asymmetrical Microgrid
		8.4.1 Small-Signal Analysis of the Voltage Unbalance Compensation Control
		8.4.2 Compensation Method to Improve the Dynamic Behavior
	8.5 Summary
	References
Chapter 9: Transient Angle Stability of Grid-Connected VSG
	9.1 Mathematical Model
		9.1.1 Full-Order Model of a VSG
		9.1.2 Model Reduction of a VSG
	9.2 Transient Angle Stability Mechanism
		9.2.1 Transient Angle Stability of VSG
			9.2.1.1 Case 1 Existence of Equilibrium Points
			9.2.1.2 Case 2 None Existence of Equilibrium Points
		9.2.2 Deteriorative Effect of Q-V Droop on Transient Angle Stability
		9.2.3 Simulation and Experiment Results
	9.3 Stability Region Estimation
		9.3.1 Derivative of Lyapunov Function
			9.3.1.1 Positive Definite of Derived Lyapunov Function
			9.3.1.2 Semi-Negative Definite of dV/dt
		9.3.2 Proposed Lyapunov Method Considering the Influence of Reactive Power Loop
		9.3.3 Influence of Different Parameters
			9.3.3.1 Influence of Reactive Power Control Loop
			9.3.3.2 Influence of Reference Active Power P*
			9.3.3.3 Influence of Damping Coefficient D
			9.3.3.4 Influence of Line Impedance Z
			9.3.3.5 Influence of Q-V Droop Coefficient Dq
	9.4 Summary
	References
Chapter 10: Transient Angle Stability of Islanded Microgrid with Paralleled SGs and VSGs
	10.1 Mathematical Model
		10.1.1 Model of Paralleled VSGs
		10.1.2 Model of Paralleled SGs and VSGs
	10.2 Transient Angle Stability Mechanism
		10.2.1 Transient Angle Stability of Paralleled VSGs
		10.2.2 Transient Angle Stability of Paralleled SGs and VSGs
		10.2.3 Differences Between Paralleled VSGs and Paralleled SGs and VSGs
			10.2.3.1 Influence of Different Speed Governors
			10.2.3.2 Influence of Different Damping Links
			10.2.3.3 Influence of Different Speed Governors and Damping Links
		10.2.4 Stability Improvement of Paralleled SGs and VSGs
		10.2.5 Experiment Results
	10.3 Stability Region Estimation
		10.3.1 Lyapunov Function of Paralleled SGs and VSGs
			10.3.1.1 Lyapunov Function Based on TS Fuzzy Model
			10.3.1.2 Lyapunov Function of Paralleled SGs and VSGs Without Improvement Measure
			10.3.1.3 Lyapunov Function of Paralleled SGs and VSGs with Improvement Measure
		10.3.2 Influence of Different Parameters
			10.3.2.1 Influence of Time-Delay Constant τi
			10.3.2.2 Influence of Proportional Controller Parameter Kp and Ks2
	10.4 Summary
	References
Chapter 11: Re-synchronization Phenomenon of Microgrid
	11.1 Re-synchronization Phenomenon of VSG
		11.1.1 Mechanism of Re-synchronization
		11.1.2 Influence of Different Parameters on Re-synchronization
			11.1.2.1 Case I: δc  δu
			11.1.2.2 Case II: δc  δu
		11.1.3 Simulation Results
	11.2 Re-synchronization Phenomenon of Paralleled Systems
		11.2.1 Re-synchronization of Paralleled VSGs
		11.2.2 Re-synchronization of Paralleled SGs and VSGs
	11.3 Summary
	References
Correction to: Transient Characteristics, Modelling and Stability Analysis of Microgrid
	Correction to: Z. Shuai, Transient Characteristics, Modelling and Stability Analysis of Microgrid, https://doi.org/10.1007/978...