Design Of A Simple Protection Scheme For A 1 X 15Mva, 33/11Kv Injection Substation

ABSTRACT

This research work is aimed at designing a simple protection scheme for RSU 1 X 15MVA, 33/11kv Injection Substation. Primary data were collected from Port Harcourt Electricity Distribution Company and others were calculated which aided in the hand calculation and decision making on the verification of lightning arresters and protective margin, voltage gradients and transformers differential protection (Case 1). The table value for verification of lightning arresters and protective margin indicated that discharge current was 0.7996KA meaning that the available 5KA lightning arresters in use are adequate and protective margin of 145% is adequate as it is >20%. The table value of voltage gradients indicated that E step (tolerable) for faults of duration < 3seconds and sustained faults are 305.8V and 9.135V respectively while E touch (tolerable) for faults of duration < 3seconds and sustained faults are 308.1V and 9.03375V respectively showed that they are good as none is greater than the reference figures. The table value for transformers differential protection (Case 1) showed that a matching CT of ratio 3.280A/4.374A which is a mismatch. Case 2 of the transformer differential protection is improved protection as it showed a matching CT ratio of 4.921A/4.374A. Report from verification of relay operation, case 1 showed that T1ASR and T2ASR failed to trip their respective CBs under fault condition while case 2 relay operation report showed that T1ASR and T2ASR tripped normally. Case 2 relay operation is improved protection too.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

1.0         INTRODUCTION

1.1         BACKGROUND OF THE PROJECT

• PROBLEM STATEMENT
• AIM AND OBJECTIVE OF THE STUDY
• SIGNIFICANCE OF THE STUDY
• SCOPE OF THE STUDY
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF THE STUDY
• RELATED WORKS
• DESCRIPTION OF 33/11KV INJECTION SUBSTATIONS
• OVERVIEW OF THUNDER ARRESTER
• COMPONENTS OF THUNDER ARRESTER
• TYPES OF LIGHTNING ARRESTERS
• MODELS OF LIGHTNING ARRESTER
• THUNDER ARRESTERS IN THE PROTECTION OF POWER LINES

CHAPTER THREE

3.0      MATERIALS AND METHOD

• MATERIAL
• METHOD

CHAPTER FOUR

4.1     RESULT

CHAPTER FIVE

• CONCLUSION

REFERENCES

CHAPTER ONE

1.0                                             INTRODUCTION

1.1                                BACKGROUND OF THE STUDY

An injection substation can be viewed as a substation by which a step down of higher voltage to a lower one is perfected as transmitted in densely populated dwellings. To serve the densely populated areas, transformers whose capacities are in the MVA value are used. It constitutes a set of complex electrical devices such as circuit breakers, current transformers, voltage transformers, busbars and power transformers in a confined place. Many substations act as a connecting point of systems and/or areas that operate at different voltage levels. Such substations include power transformers to scale the voltage of one area to match the voltage of the adjacent area. In order to provide adequate reliability to the overall system, protective devices are installed to detect abnormalities and react accordingly in a coordinated way with other devices [Thompson, 2016].

Transformers generally speaking appear to be the most important component in the transmission of electricity. This they become very imperative as they change voltage level as required. Each control panel is always connected to a defined fascia annunciation compartment which will alert the operator by means of alarm. The annunciation may be classified into trip annunciation and warning annunciation [Sudipta et al, 2013].

Adequate precautions need to be taken to allow equipment operate normally at peak efficiency, eliminate damage to life and property and provides reliable uninterrupted service of quality because of high cost in investing on power system. A relay can be viewed as an electrical device that responds to its input information in a determined way and by the virtue of its contact operation, initiates a sudden change in the corresponding control circuits [Duru, 2014].

Different power apparatus must always be connected and provided with protection in the control room. equipment devices (in the switchyard) to the individual protective relays in the control house. Every protection or control function needs a distinct wire and a distinct physical termination at the required relay [Mital, 2013].

1.2                                    PROBLEM STATEMENT

It was noticed that the injection substation was overloaded, but with the deployment of mass metering, the load consumed was driven low by customer’s energy utilization awareness, as they are directly responsible for the load they use, which in turn results in energy they consume over time. With further investigation, it was also noticed that the route length of the feeders also plays a vital role in the amount of power loss as it travels along conductors to the customers. This study was carried out to solve the problems of overloading, poor reliability and high losses, which results into lots of power interruption.

1.3                        AIM AND OBJECTIVE OF THE STUDY

The aim of this research work is to conduct analysis of electric power supply from Port Harcourt main (Z2, Trans-Amadi) for improved distribution in the study case. The objectives of this research work are:

1. To collect data from the supply network to the study case for improved
2. To investigate the electric power distribution problems facing substations Environs.

• Modelling of the study network using ETAP

1.4                                SIGNIFICANCE OF THE STUDY

This study will help to improve efficiency and allow future demand. This study will be of great benefit to all electrical engineers by exposing them on how to protect a substation by installing different types of security devices to the station.

1.5                                       SCOPE OF THE STUDY

The research work is considered a load flow studies which to investigate the activities of 1x11kV distribution feeders in distribution network. Electrical power sector has been operating for many years. However, due to poor maintenance culture, the electric power network suffers overloading, poor reliability and high losses, which results into lots of power interruption.

1.6                                     PURPOSE OF THE STUDY

Hence this project intends to:

1. Improve electric power distribution network for Trans-Amadi, Port Harcourt by modelling it and identifying possible problems.
2. Recommend ways to reduce the rate at which electricity interruption occurs daily in Trans-Amadi, Port Harcourt

• Prescribe solutions to minimize overloading and losses along the distribution

1.7                                     PROJECT ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work,   chapter two presents the literature review of the study,  chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.