Control of a Wind Driven Doubly Fed Induction Generator During Grid Faults

Table of Contents

CHAPTER (1) INTRODUCTION

1-1 General

1-2 Thesis Objectives

1-3 Thesis Outlines

CHAPTER (2) LITERATURE REVIEW

2-1 Introduction

2-2 Synchronous Generators Driven by a fixed speed Turbine

2-2-1 Wound Field Synchronous Generator (WFSG) Driven by a wind turbine

2-2-2 Permanent-Magnet Synchronous Generator (PMSG) Driven by a wind turbine

2-3 Induction Generators Driven by a variable speed wind turbine

2-3-1 Squirrel Cage Induction Generator (SCIG) Driven by a wind turbine

2-3-2 Doubly Fed Induction Generator (DFIG) Driven by a wind turbine

2-4 Field oriented Control

2-4-1 Direct field oriented control of a wind driven DFIG

2-4-2 Indirect field oriented control of a wind driven DFIG

2-5 Enhancement techniques of DFIG performance during grid faults

2-5-1 Traditional techniques for protection of wind turbines during grid faults

2-5-2 Crowbar protection technique

2-5-2-1 Series antiparallel thyristors LVRT technique

CHAPTER (3) Field Orientation Control of a Wind Driven DFIG Connected to the Grid

3-1 Introduction

3-2 System description

3-3 Dynamic modeling of the DFIG

3-3-1 Turbine model

3-3-2 Induction machine model

3-4 DC Link model

3-5 Complete system model

3-6 Field oriented control of DFIG

3-7 Complete system configuration

3-8 Simulation results and discussions

CHAPTER (4) Dynamic Performance of a Wind Driven Doubly Fed Induction Generator During Grid Faults

4-1 Introduction

4-2 Dynamic Model of a DFIG System

4-3 Mathematical Model of DFIG System Under Unbalanced Grid Voltage

4-4 System Description

4-5 Simulation results and discussions

CHAPTER (5) Enhancement of Fault Ride through Capability of a Wind Driven Doubly Fed Induction Generator Connected to the Grid

5-1 Introduction

5-2 System under study and proposed FRT scheme

5-3 Control strategy of the proposed FRT scheme

5-4 Choice of size of storage inductor

5-5 Simulation results and discussions

CHAPTER (6) Conclusions and Recommendations

6-1 Conclusions

6-2 Recommendations for future work

Objectives and Research Themes

The thesis focuses on the performance and control of a Doubly Fed Induction Generator (DFIG) driven by wind turbines, specifically addressing the challenges of maintaining system stability during unbalanced grid faults. The primary objective is to develop a field orientation control method for optimal power regulation and to introduce a novel fault ride-through (FRT) scheme that utilizes stored mechanical energy to enhance grid connectivity during fault conditions.

• Mathematical modeling of DFIG-based wind energy conversion systems.
• Implementation of field-oriented control for active and reactive power regulation.
• Dynamic analysis of DFIG performance under various grid fault conditions.
• Development of a cost-effective fault ride-through (FRT) scheme to prevent generator disconnection.
• Validation through extensive MATLAB/SIMULINK simulation studies.

Excerpt from the Book

Summary of Chapters

CHAPTER (1) INTRODUCTION: Provides an overview of wind energy, the motivations for using DFIG in wind farms, and outlines the core objectives of the thesis.

CHAPTER (2) LITERATURE REVIEW: Reviews existing wind generation technologies, various generator types, and current control methods, including traditional FRT protection techniques.

CHAPTER (3) Field Orientation Control of a Wind Driven DFIG Connected to the Grid: Presents the dynamic model of the DFIG system and details the field-oriented control scheme designed for active and reactive power management.

CHAPTER (4) Dynamic Performance of a Wind Driven Doubly Fed Induction Generator During Grid Faults: Analyzes the transient behavior of the DFIG system under various unbalanced grid conditions using the method of symmetrical components.

CHAPTER (5) Enhancement of Fault Ride through Capability of a Wind Driven Doubly Fed Induction Generator Connected to the Grid: Introduces a novel FRT scheme that stores mechanical energy to improve DFIG stability during grid faults and performs extensive simulation validations.

CHAPTER (6) Conclusions and Recommendations: Summarizes the key findings regarding the proposed FRT scheme's effectiveness and provides suggestions for future research using artificial intelligence.

Keywords

Wind energy, Doubly Fed Induction Generator, DFIG, Grid faults, Field oriented control, Fault ride-through, FRT, LVRT, Renewable energy, Power electronics, MATLAB, SIMULINK, Symmetrical components, Wind turbine, Power system stability.

Frequently Asked Questions

What is the core focus of this research?

The research focuses on controlling wind-driven Doubly Fed Induction Generators (DFIG) to improve performance and maintain grid connectivity during unstable grid conditions and faults.

What are the primary themes addressed in the work?

Key themes include the dynamic modeling of DFIGs, the implementation of field-oriented control (FOC) for power management, and the design of novel fault ride-through (FRT) strategies.

What is the main research objective?

The primary goal is to enhance the fault ride-through capability of DFIGs, allowing them to stay connected to the grid during faults instead of being disconnected.

Which scientific methodology is utilized?

The study utilizes mathematical modeling, the method of symmetrical components for analyzing grid faults, and extensive computer simulations performed in MATLAB/SIMULINK.

What topics are discussed in the main body?

The main body covers the theoretical background of DFIG systems, field orientation principles, modeling of system dynamics during faults, and the design and simulation of a new FRT scheme.

How is the work characterized by keywords?

The work is characterized by terms such as DFIG, Fault ride-through, Field oriented control, Grid integration, and Wind power system stability.

How does the proposed FRT scheme differ from traditional crowbar methods?

Unlike the crowbar method, which dissipates excess energy as heat, the proposed FRT scheme stores the input mechanical energy of the wind turbine during a fault and utilizes it after fault clearance.

What is the benefit of the proposed FRT scheme according to the simulation results?

The simulation results demonstrate that the proposed scheme effectively reduces transient oscillations, prevents generator disconnection, and provides rapid reestablishment of terminal voltage following a fault.