Front Cover

Microgrid: Advanced Control Methods and Renewable Energy System Integration

Copyright

Contents

Contributors

About the Editor

Preface

Acknowledgments

Chapter 1: Microgrid Control Problems and Related Issues

1 Introduction

2 Microgrid Review

3 Microgrid Components

3.1 Microsources

3.2 Microturbines

3.3 Fuel Cells

3.4 Storage Devices

3.5 DER Interfaces

4 Microgrid Controls

4.1 Grid-Connected Operation

4.2 Islanded Operation

4.3 Inverter Controller

4.4 Microgrid Classification

4.5 Control Functions

4.6 Control Operations of Microgrids

4.7 Electronically Coupled Microgrids

4.8 Basic Control Techniques

4.9 Centralized Control

5 A Microgrid as a System of Systems

5.1 SoS Structure

5.2 SoS Framework

5.3 Control Hierarchy

5.4 Grid Synchronization in Distributed Generation Units

5.5 Overall Microgrid Modeling for Control Implementation

6 Control Methods for a Microgrid System of Systems

6.1 Hierarchical Control

6.2 Consensus Control

6.3 Decentralized Control

6.4 Networked Control

7 Future Directions

8 Conclusions

Acknowledgments

References

Chapter 2: Distributed Control Techniques in Microgrids

1 Introduction

2 Definitions of the Smart Grid and a Microgrid

3 Overview of the Control Structure

3.1 Control Requirements

3.2 Control Hierarchy

3.2.1 Primary Control

3.2.2 Secondary Control

3.2.3 Tertiary Control

3.3 Distributed Control Within Control Hierarchy

4 Overview of Distributed Techniques

4.1 Droop-Based Techniques

4.2 Distributed Model Predictive Control-Based Techniques

4.3 Consensus-Based Techniques

4.4 Agent-Based Techniques

4.5 Decomposition-Based Techniques

5 Applications in Power Systems

5.1 Application in Primary Control

5.2 Application in Voltage Coordination

5.3 Application in Economic Power Coordination

5.4 Application in Frequency Coordination

6 Conclusions and Future Trends

6.1 Challenges Ahead

6.2 High-Voltage DC

6.3 Nonmodel-Based Control

6.4 Model Predictive Control

References

Chapter 3: Hierarchical Power Sharing Control in DC Microgrids

1 Introduction

1.1 Advantages of DC Microgrids

1.2 Applications of DC Microgrids

2 Power Management Issues

2.1 Classification of Energy Units in DC Microgrids

2.2 Hierarchical Power Sharing in DC Microgrids

2.3 Hierarchical Power Sharing in Conventional Power Systems

3 Primary Control: Level I

3.1 Droop Control

3.2 Cost-Based Droop Control

4 Secondary Control: Level II

4.1 Centralized Controller

4.2 Decentralized Controller

5 Tertiary Control: Level III

5.1 Power Flow Control Between the Microgridand the Utility Grid

5.2 Power Flow Control Among a Cluster of Microgrids

5.3 Power Flow Control Among Distributed Generatorsin a DC Microgrid

6 Autonomous Operation of DC Microgrids

6.1 Autonomous Droop Approach

6.2 Control of the Converters in Autonomous DC Microgrids

7 Conclusion and Future Work

References

Chapter 4: Master/Slave Power-Based Control of Low-Voltage Microgrids

1 Introduction

2 Master-Slave Architecture

2.1 Control Principle

2.2 Control Strategy

2.2.1 Grid-Connected Operation

2.2.2 Islanded Operation

3 Power-Based Control

4 Data Collection and Preprocessing

4.1 Data Collection

4.2 Preprocessing

5 Set Point Computation

5.1 Active Power Control

5.2 Reactive Power Control

5.3 Grid-Connected Mode: Active and Reactive Power Control

6 Remarks on Voltage Control

7 Control Analysis

7.1 Power-Based Principle Analysis

7.2 System Analysis

7.3 Stability Analysis

8 Application Example

8.1 Active Power Profiles

8.2 Power Flow at the PCC

8.3 Distribution Losses

8.4 Voltage Deviations at Grid Nodes

8.5 Performance Indexes

9 Summary

References

Chapter 5: Load-Frequency Controllers for Distributed Power System Generation Units

1 Introduction

2 Autonomous Microgrid System

2.1 State-Space Model of the Autonomous Microgrid

3 Reinforcement Learning Techniques

3.1 Heuristic Dynamic Programming

3.2 Discrete-Time Bellman Equation

3.3 Value Iteration Algorithm

3.4 Actor-Critic Neural Networks

4 Online Actor-Critic Neural Network Implementation

4.1 Performance Evaluation of the Proposed Controller

5 Photovoltaic Solar Cells

6 Cooperative Control for Dynamic Games Over Graphs

6.1 Graphs

6.2 Formulation of the Cooperative Control Problem

6.3 Formulation of Dynamic Graphical Games

6.3.1 Evaluation of the Dynamic Graphical Game

6.3.2 Discrete-Time Coupled Hamiltonian Functions

6.3.3 Discrete-Time Bellman Equations

6.3.4 Coupled HJB Optimality Equations

6.3.5 Nash Solution for the Dynamic Graphical Game

7 Online Adaptive Learning Solution

8 Critic Neural Network Implementation for Online Adaptive Learning [alg5.3]Algorithm 5.3

9 Online Critic-Network Tuning in Real Time

10 Simulation Results

11 Conclusions

Acknowledgments

References

Chapter 6: An Optimization Approach to Design Robust Controller for Voltage Source Inverters

1 Introduction

2 System Modeling

2.1 Preliminaries

2.2 Derivation of the Mathematical Model of the System

3 The Proposed Control Design Method

3.1 Controller for Robust Stabilization

3.1.1 Robust Stabilization

3.2 Integral Control for Set Point Tracking

3.3 Controller Optimization

3.4 Controller Implementation

4 Results and Analysis

4.1 Controller Design

4.2 Robustness Test

4.3 Disturbance Test

4.4 Tracking Performance Test

5 Conclusion

Acknowledgments

References

Chapter 7: Demand Side Management in Microgrid Control Systems

1 Introduction

2 Demand-Side Management

2.1 Definition

2.2 History

2.3 Advantages

3 Related Historical Event: The California Electricity Crisis

3.1 Description of Events

3.2 Analysis of the Reasons

3.3 Remarks

4 Demand Response

4.1 Definition

4.2 Services Category

4.2.1 Peak Clipping

4.2.2 Valley Filling

4.2.3 Load Shifting

4.2.4 Strategic Conservation

4.2.5 Strategic Load Growth

4.3 Customers Category

4.3.1 Residential Sector

4.3.2 Industrial Sector

4.3.3 Commercial Sector

4.3.4 Summary

4.4 Loads Category

4.4.1 Deferrable Loads and Nondeferrable Loads

4.4.2 Adjustable Loads and Nonadjustable Loads

4.5 Approaches Category

4.5.1 Incentive-Based Demand Response

4.5.2 Time-Based Demand Response

5 Demand-Side Management Methods

5.1 Multiobjective Optimization Method

5.2 Linear Matrix Inequality Approach

6 Conclusions

Acknowledgments

References

Chapter 8: Towards a Concept of Cooperating Power Network for Energy Management and Control of Microgrids

1 Introduction

2 Toward the Concept of a Network of Smart Microgrids

3 The Network Model and Architecture

3.1 Microgrid Architecture

3.2 Wind Power Generation Modeling

3.3 Solar Photovoltaic Generator Modeling

3.4 Energy Storage System Dynamics

3.5 Loads

3.6 Energy Management Unit

3.7 Demand-Side Management and Demand Response

3.8 Price-Based Demand Response Programs

3.9 Control Strategies for MGs

3.10 Hierarchical Control of MGs

4 Power Control Strategy for the Network of MGs

4.1 Problem Formulation

4.2 Necessary Conditions for Global Optimality

4.3 State Variable Constraints

4.4 The Optimal Control Strategy of the Network of MGs

4.5 Example

5 LQG-Based Optimal Control of Power Flows in a Smart Network of MGs

5.1 Problem Formulation

5.2 LQG Optimal Control Strategy

5.3 Example

6 Model Predictive Control-Based Power Scheduling in a Network of MGs

6.1 Model Predictive Control-Based Power Scheduling

6.2 Optimization Problem Formulation

6.3 Example

7 Conclusions

References

Chapter 9: Power Electronics for Microgrids: Concepts and Future Trends

1 State of the Art in DC Microgrid Technology

2 DC MG Applications

2.1 Battery-Based DC Architectures

2.2 Flexible DC MG Architecture

3 DC MG Control

3.1 Hierarchical Layers

3.2 Distributed Control Principles

4 Converters in DC MGs

5 Protection Systems for DC MGs

5.1 Protection Devices

5.2 Design of Protection Systems

5.3 Conclusions and Future Trends

References

Chapter 10: Power Electronic Converters in Microgrid Applications

1 Introduction

2 Power Semiconductor Switches

3 Classification of Power Converters

4 Conventional Two-Level Converter

4.1 Pulse Width Modulation

4.2 Carrier-Based Pulse Width Modulation

4.3 Zero Sequence Injection

4.4 Space Vector Modulation

4.5 Modeling

5 Three-Level Neutral Point-Clamped Inverters

6 Different Modes of Operation of Power Converters

7 Power Converter Topologies for Renewable and Distributed Energy Systems

7.1 PV Systems

7.2 Wind Energy Conversion Systems (WECS)

7.3 Storage System Converters

8 Conclusion

References

Chapter 11: Power Talk: Communication in a DC Microgrid Through Modulation of the Power Electronics Components

1 Introduction

2 Control in DC Microgrids

2.1 Primary Control

2.2 Upper Control Layers: Secondary and Tertiary Control

2.3 Communications for Microgrid Control

3 Power Talk for DC Microgrids: The Foundations

3.1 Model of a Low-Voltage DC Microgrid

3.2 The General Power Talk Multiple-Access Channel

4 Communication With Detection Spaces

4.1 Time Division Multiple Access for Single-Bus and Multibus Systems

4.2 Full Duplex for Single-Bus Systems

4.2.1 Full-Duplex Systems

4.3 The Main Communication Impairment: Dealing With Load Variations

5 Constraints: Signaling Space

6 Conclusion

References

Chapter 12: Pilot-Scale Implementation of Coordinated Control for Autonomous Microgrids

1 Electronically Coupled Distributed Generation Units

1.1 System Layout

1.2 Mathematical Model

2 Laboratory-Scale Experiment I

2.1 Voltage Tracking Properties of Distributed Generation Unit 1

2.2 Voltage Tracking Properties of Distributed Generation Unit 2

2.3 Effect of Load Perturbations

2.3.1 The First Case

2.3.2 The Second Case

2.3.3 The Third Case

3 Laboratory-Scale Experiment II

3.1 Microgrid Setup

3.2 Implementation

4 Laboratory-Scale Experiment III

4.1 Microgrid-Battery Energy Storage System Architecture

4.2 Microgrid-Battery Energy Storage System Operation: First Scheme

4.3 Microgrid-Battery Energy Storage System Operation: Second Scheme

5 Conclusions

Acknowledgments

References

Index

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