Excitation Scheme On Alternators

ABSTRACT

One of the most important elements of electric power system is synchronous generator or alternator, because it is the  source of electrical energy. In alternator, mechanical energy (usually from a turbine) is transformed into electrical energy. Energy transformation is possible only if alternator excitation exists. Excitation of alternator also defines alternator output values: voltage and reactive power. This means that generator excitation regulation is actually regulation of alternator output energy and also impacts the stability of entire electric power system. Brushless excitation systems have been largely applied in recent years for alternators and this types of excitation is discussed in this work

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

COMMON VFD TERMS

TABLE OF CONTENTS

CHAPTER ONE

INTRODUCTION

1.1      BACKGROUND OF THE PROJECT

• AIM OF THE STUDY
• ADVANTAGES OF THE STUDY
• APPLICATION OF THE STUDY
• FUNCTION OF THE STUDY

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF THE STUDY
• TYPES OF EXCITATION SYSTEM
• OVERVIEW OF AN ALTERNATOR
• HISTORICAL BACKGROUND OF AN ALTERNATOR
• PRINCIPLE OF OPERATION
• CLASSIFICATIONS OF ALTERNATOR

CHAPTER THREE

METHODOLOGY

• OPERATION OF THE ALTERNATOR
• SYSTEM BLOCK DIAGRAM
• EXCITATION SYSTEMS METHODS OF AN ALTERNATOR
• CONCLUSION
• REFERENCES

CHAPTER ONE

1.1                                                        INTRODUCTION

The system which is used for providing the necessary field current to the rotor winding of the synchronous machine, such type of system is called an excitation system. In other words, excitation system is defined as the system which is used for the production of the flux by passing current in the field winding. The main requirement of an excitation system is reliability under all conditions of service, simplicity of control, ease of maintenance, stability and fast transient response.

The amount of excitation required depends on the load current, load power factor and speed of the machine. The more excitation is needed in the system when the load current is large, the speed is less, and the power factor of the system becomes lagging.

The excitation system is the single unit in which the each alternator has its exciter in the form of generator. The centralised excitation system has two or more exciter which feeds the bus-bar. The centralised system is very cheap, but the fault in the system adversely affects the alternators in the power plant.

1.2                                                     AIM OF THE STUDY

The aim of this study is to discuses a mechanism that  is responsible to generate Magnetic field in alternator. This DC voltage can be supplied to the alternator separately or may be produced from the AC current produced by it thorough conversion. This mechanism is called excitation system.

1.3                                            ADVANTAGES OF THE STUDY

Exciters reduce the number of wearing parts. The main alternator has a rotating field as described above and a stationary armature (power generation windings). Varying the amount of current through the stationary exciter field coils varies the 3-phase output from the exciter.

1.4                                            APPLICATION OF THE STUDY

Excitation is used in alternator,  synchronous motor We can use it where ever small amount of DC supply is required.

1.5                                               FUNCTION OF THE STUDY

1. Supply DC current to field (rotor) windings.
2. Automatically adjust If to maintain Vt as output changes within continuous capability of gen
3. Control system voltage Vt/ reactive power flow
4. enhance transient stability
5. enhance dynamic stability.