Construction And Simulation Of Automatic Voltage Regulator For Generator

This work automatic voltage control system for synchronous generator operation. The topic of this paper involves the design and construction of excitation control (or) Automatic Voltage Regulator (AVR) for the synchronous generator.

It is necessary to develop the electronic control system for a synchronous generator. The Automatic Voltage Regulator (AVR) is widely used in electrical power field to obtain the stability and good regulation of the electric system. The characteristics of alternator output required are constant voltage and constant current. To get the constant output, alternator field excitation is controlled by Automatic Voltage Regulator (AVR). The Automatic Voltage Regulator maintains the constant voltage up to certain level of load current independently of generator speed and load. This work deals with the design and construction of excitation control for synchronous generator and introduces the electronic control technology. The main objective of this paper is to modify the AVR with SCR device technology.

On completion of this work, the constructed circuit will be simulated using MATLAB and will improve the overall effectiveness of the synchronous generator. This includes a more accurate measurement of voltage and current, as well as improving the response time and system stability.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• PROBLEM STATEMENT
• AIM/OBJECTIVE OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• PURPOSE OF THE PROJECT
• SCOPE OF THE PROJECT
• METHODOLOGY
• DEFINITION OF TERMS
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• INTRODUCTION
• OVERVIEW OF POWER SYSTEM CONTROL
• AUTOMATIC VOLTAGE REGULATOR IN GENERATOR
• AUTOMATIC VOLTAGE REGULATION CONCEPT
• PRINCIPLES OF SYNCHRONOUS GENERATOR
• OVERVIEW OF AUTOMATIC CONTROL OF SYSTEM

CHAPTER THREE

METHODOLOGY

• INTRODUCTION
• SYSTEM SIMULATION
• CONCEPT OF AUTOMATIC VOLTAGE REGULATOR (AVR)
• MODELLING OF THE AVR SYSTEM
• SIMULINK MODEL OF AVR
• AIMS OF AN AUTOMATIC VOLTAGE REGULATING SYSTEM FOR GENERATOR
• GENERAL DEFINITION OF AUTOMATIC VOLTAGE REGULATOR
• REQUIREMENTS FOR AUTOMATIC VOLTAGE REGULATOR
• DESIGN SPECIFICATION OF AUTOMATIC VOLTAGE REGULATOR
• CIRCUIT DESCRIPTION OF THE AVR FOR THE SYNCHRONOUS GENERATOR
• SYSTEM CIRCUIT DIAGRAM
• SYSTEM DESIGNED PICTURED
• TRANSFORMER DESIGN ANALYSIS
• TRANSFORMER WINDING

CHAPTER FOUR

• SIMULATION RESULTS AND DISCUSSION
• CONSTRUCTION TESTS AND RESULTS

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION
• REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                         BACKGROUND OF THE PROJECT

According to history, electricity was discovered by Michael Faraday in his early experimental works that span through 1800-1860 [Hall (1988), Sigvard (1979)]. In the wake of the discovery of electricity, the challenges faced by engineers have been that of generating, transmitting and distributing regulated electric power for the dare need of electrical equipment and appliances.

Every generator is required to produce constant voltage or regulated voltage at the output. The constant voltage at the generator terminals is essential for satisfactory main power supply. The terminal voltage can be affected by various disturbing factors (speed, load, power factor, and temperature rise), so that special regulating equipment is required to keep the voltage constant, even when affected by these disturbing factors.

Power system operation considered so far was under condition of steady load. However, both active and reactive power demands are never steady and they continually change with the rising or falling trend. Therefore, steam input to turbo generators (or water input to hydro-generators) must be continuously regulated to match the active power demand, failing which the machine speed will vary with consequent change in frequency which may be highly undesirable. Also the excitation of generators must be continuously regulated to match the reactive power demand with reactive generation, otherwise the voltages of various system buses may go beyond the prescribed limits.

The automatic voltage regulator (AVR) is widely used in electric power systems and industrial applications to obtain the stability and good regulation of different apparatus. It may be use as an electromechanical mechanism, passive or active electronic components. Depending on the design, it may be use to regulate AC or DC voltage [1]. Thus, maintaining constant voltage at the output terminal of a generator is essential for satisfactory mains power supply. The essence of regulating this machine is that the terminal voltage can be affected by disturbances, such, as change in load, temperature, speed e.t.c, such that voltage regulating equipment is required to keep the voltage constant and maintain continuous supply within acceptable quality. To achieve this, automatic voltage regulator (AVR) system is used in power generation site to ensure voltage stability at the generator terminal. However, AVR system without any controller will provide slow responses and may cause instability. Thus, need to provide proper control of generator by AVR system to ensure generators operated at safe and stable conditions for normal operations and fast response under different type of disturbance is very essential.

1.2                                              PROBLEM STATEMENT

Unregulated output in a synchronous generator can result either over voltage or under voltage, and transmitting electricity on this state will expose consumers’ appliances to danger which might end up destroying their appliances. In other to prevent this problem an automatic voltage regulator is used to keep the generator output voltage to normal which is 220vac. An automatic voltage regulator regulates the synchronous generator output voltage and keeps from lower or higher to normal. It protects any electric or electronic devices connected to it from damaged.

1.3                       AIM / OBJECTIVE OF THE PROJECT

The main aim of this work is to present construction and simulation of excitation control (or) Automatic Voltage Regulator (AVR) for the synchronous generator. The construction of an Automatic Voltage Regulator for synchronous generator introduces the electronic control technology which main objective is to modify the AVR with SCR device technology. Other objectives are expressed briefly. They are:

1. to study the advanced features of excitation control system,
2. To study and modify the control techniques used in control system,

• To improve the industrial consumer products with SCR.

1.4                          SIGNIFICANCE OF THE PROJECT

The Automatic Voltage Regulator (AVR) is widely used in electrical power field to obtain the stability and good regulation of the electric system. The characteristics of alternator output required are constant voltage and constant current. To get the constant output, alternator field excitation is controlled by Automatic Voltage Regulator (AVR). The Automatic Voltage Regulator maintains the constant voltage up to certain level of load current independently of generator speed and load. In this paper, the automatic voltage regulator is designed with electronic control circuit technology using SCR. Other advantages are:

• to have better system voltage regulation,
• to improve stability and
• to reduce over-voltage on loss of

1.5                                               PURPOSE OF THEPROJECT

The main purpose of this work is to maintain constant voltage and power line conditioning to the equipment load under a wide variety of conditions, even when the utility input voltage, frequency or system load vary widely.

1.6                                                 SCOPE OF THE PROJECT

The Automatic Voltage Regulator (AVR) is a close-loop electronic Regulator circuitry that interfaces the stator and exciter windings of especially brushless generators. It regulates the terminal output voltage of the Generator to a specified rated output level, inspite of varying load conditions and varying inherent conditions and losses of the alternator [Say (1976), Lawrence (1921), http://www.cmspower.com]. This unit automatically constrains the output voltage to about 100% regulation of the rated terminal voltage of the Generator [Franklin et al (2005)].

The need for a viable and affordable close-loop electronic control interface to control and stabilize the terminal voltage of the Generator, devoid of Transient and Flicker phenomenon eminent in varying load conditions and alternator constituents varying condition is the thrust of this Research.

1.7                                                     DEFINITION TERMS

HV: High Voltage. This is when any electricity supply in excess of 650volts. Primarily used for the transmission of electricity over long distances.

Kva: Kilo volt amps. A measurement of the electrical ‘pressure’ and ‘quantity’ to a building.

Loads: This is an equipment that is using the electricity supplied to a building.

LV: Low Voltage. This is an Electricity supply from 110volts to 650 volts.

Power cut: this is a failure of the mains electricity by factors outside of your premises.

Single phase power: This is the electricity produced from one phase of a three phase winding or from a dedicated singles phase winding.

Winding: This is the copper wire that produces electricity when it passes through a magnetic field.

Watts: this is the total energy supplied by a circuit.

Surge: Overvoltage supply of electricity causing damage in sensitive equipment (opposite of Brown out).

Surge Suppression: in Electronic equipment, Surge Suppression is designed to restrain surges such as lightning strikes.

AVRs. Automatic voltage regulators. The electronic device which controls the output voltage of an alternator.

Base load rating. The rating given to a generator when it is used for continuous supply of electricity at a given load 24/7.

Black out. A national or wide area power failure, causing major disruption. For example.

Brown out. A drop in the mains voltage (not a total failure) that can cause degradation of lighting and electronic equipment.

1.8                                                         METHODOLOGY

To achieve the aim and objectives of this work, the following are the steps involved:

1. Study of the previous work on the project so as to improve it efficiency.
2. Draw a block diagram.

• Test for continuity of components and devices,

1. Design and calculation for the device was carried out.
2. Studying of various component used in circuit.
3. Simulation of the circuit was carried out.

• Construction of the circuit was carried out.
• Finally, the whole device was cased and final test was carried out.

1.9                                     PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this works is on the introduction to an automatic voltage regulator. In this chapter, the background, significance, objective, aim, scope, limitation and problem, definition of terms of an automatic voltage regulator were discussed.

Chapter two is on literature review of an automatic voltage regulator. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, discussion, recommendation and reference