Evaluation Of Voltage Drop And Its Effect In Electrical Distribution Network

ABSTRACT

This study presents the evaluation and effects of voltage drop in power distribution networks. The issues of voltage drop in power distribution networks has become a recurrent decimal in power distribution sector, which has avert effects on electronics appliances, which result in incessant fire out in offices and residential buildings. Bells University was investigated for a period of three months (1ST February to 30TH April, 2014). Data were obtained in that area with the help of questionnaires. Causes of various voltages drop in six power distribution injection substation sectors were obtained from both residential and industrial areas with the corresponding time (hour). Mathematical modeling was developed for voltage drop. Firstly, it was observed from Bells university power system that there were no technical reports recorded on voltage drop cases and due to lack of technical record, this aspect has witnessed a low response time from the technical sector to eradicate. It is observed that voltage drop occurrences and response time before repairs has similar exponential pattern, which justify the neglect of voltage drop. Voltage drop in both residential and industrial areas were considered.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

INTRODUCTION

1.1    BACKGROUND OF THE STUDY

• AIM OF THE STUDY
• OBJECTIVE OF THE STUDY
• PURPOSE OF THE STUDY
• SIGNIFICANCE OF THE STUDY
• LIMITATION OF THE STUDY
• APPLICATION OF THE STUDY

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF VOLTAGE DROP
• VOLTAGE DROP IN DIRECT-CURRENT CIRCUITS: RESISTANCE
• REVIEW OF ELETRIC POWER DISTRIBUTION
• HISTORICAL BACKGROUND OF ELECTRIC POWER DISTRIBUTION
• HOW TO MEASURE VOLTAGE DROP
• CAUSES OF VOLTAGE DROP IN POWER DISTRIBUTION SYSTEM
• EFFECTS OF VOLTAGE DROPS ON THE FEEDER
• PROPOSED SOLUTIONS TO MITIGATE FUTURE OCCURRENCE OF VOLTAGE DROPS

CHAPTER THREE

METHODOLOGY

• INTRODUCTION
• RESEARCH DESIGN
• INSTRUMENT
• MODELING OF VOLTAGE DROP
• ALLOWED VOLTAGE DROP INDICES
• INFLUENCE OF NETWORK IMPEDANCES ON VOLTAGE DROP
• PROBABILISTIC COMPUTATIONAL MODEL TO EVALUATE VOLTAGE DROP

CHAPTER FOUR

4.0    RESULTS ANALYSIS

• MEASUREMENT RESULTS
• EVALUATION OF VOLTAGE DROPS BY MEASUREMENT AND BY THE DISTRIBUTION NETWORK MANAGEMENT SYSTEM
• VOLTAGE DROP USING THE MONTE CARLO METHOD
• TESTING OF SYSTEM OPERATION

CHAPTER FIVE

• CONCLUSION
• REFERENCES

CHAPTER ONE

1.0                                                                              INTRODUCTION

The power sector has become one important basic facility or infrastructure needed by people around the world today. Power sector industry has become a tool, used to facilitate economic growth of any developing country. The power sectors generate and supply power at the desire voltage used to energize the electronics devices on our various home. Recent time, fire outbreaks have resulted from power supply in our university buildings due to power surge from either over voltage or under voltage. Often time, due to the damage  posted by this over voltage power supply, researchers has profound solution by deducing different electrical power rating fuse for different purposes to avoid a recurrence decimal of fire outbreak and damage to electrical appliances. In addition various power surge circuit breakers and stabilizers were design to content with this over voltage in power networks. Also, the issue of voltage drop was not properly attended to; it has become a normal scenario in power distribution sector in Nigeria. The voltage drop leads to fire outbreak from both home appliances and inductive load equipment. Voltage drop has negative effect on lighting illumination; excessive voltage drop can result in a reduction of equipment life, reliability, and performance. Line losses, resulting from undersized conductors, will result in increased utility costs, while simply over-sizing conductors to limit voltage drop will result in increased project construction costs [1,2,3].

Therefore the issues of voltage drop, voltage drop characteristic and resultant effects are considered in this research work. The Power Holding Company of Nigeria (PHCH) is serfdom with responsibility to provide service to customers at a specific voltage level, for example, 220 V or 240 V. However, due to kirchhoff’s laws, the voltage magnitude and thus the service voltage to customers will in fact vary along the length of a conductor such as a distribution feeders [4,5,6,7].

1.2                                                  BACKGROUND STUDY

Voltage, electrical potential difference, electric tension or electric pressure (denoted ∆V and measured in units of electric potential: volts, or joules per coulomb) is the electric potential difference between two points, or the difference in electric potential energy of a unit charge transported between two points. Voltage is equal to the work done per unit charge against a static electric field to move the charge between two points. A voltage may represent either a source of energy (electromotive force) lost, used, or stored energy (potential drop). A voltmeter can be used to measure the voltage (or potential difference) between two points in a system; usually a common reference potential such as the ground of the system is used as one of the points. Voltage can be caused by static electric fields, by electric current through a magnetic field, by time-varying magnetic fields, or some combination of these three. Voltage drop describes how the supplied energy of a voltage source is reduced as electric current moves through the passive elements (elements that do not supply voltage) of an electrical circuit. The voltage drop in an AC circuit is the product of the current and the impedance (Z) of the circuit. Electrical impedance, like resistance, is expressed in ohms. Electrical impedance is the vector sum of electrical resistance, capacitive reactance and inductive reactance [8,9,10].

Resistive loads are loads which consume electrical energy in a sinusoidal manner. This means that the current flow is in time with and directly proportional to the voltage. Resistive load contains no inductance or capacitance, just pure resistance. Therefore; when a resistive load is energized, the current rises instantly to its steady-state value without first rising to a higher value. Resistive loads include incandescent lighting etc [10,11].

An Inductive Load is a load that pulls a large amount of current (an inrush current) when first energized. After a few cycles or seconds the current “settles down” to the full-load running current. Inductive loads can cause excessive voltages to appear when switched. Examples of Inductive Loads are motors, transformers, and wound control gear.[11.12]

A Capacitive Load is an AC electrical load in which the current wave reaches its peak before the voltage. Capacitive loads are loads that capacitance exceeds inductance. The important difference between resistive and inductive loads is that resistances do not store electrical energy, so when you interrupt the voltage across them, the current falls to zero, essentially instantaneously. Inductive loads store energy in magnetic fields that is proportional to the square of the current given in the Equation 1 below

(1)

Where E is the stored energy is in joules or watt seconds, L is the inductance in henries and I is the current in amperes. A pure inductance (most inductive loads, except for super conducting ones, also have resistive losses, so are not pure inductance) there is a different relationship between voltage and current than the simple ratio that resistors have.

(2)

From Equation 2, V is the volts across the inductor, L is the inductance in henries and di/dt is the rate of change of the current through the inductor in amperes per second [13,14].

1.2                                                     AIM OF THE STUDY

The main aim of this work is to highlight voltage drop and its effect in electrical distribution network.

1.3                                              OBJECTIVES OF THE STUDY

The main objectives of this paper are as follows:

1. a) To study the opportunity of using digital instrument for the analysis of voltage drop disturbances;
2. b) To compare field measurements and results

1.4                                                   SCOPE OF THE STUDY

This paper presents a methodology for measuring, monitoring and controlling voltage drop in electrical power distribution networks. The distribution of single-phase and double-phase loads along the network and their random instant demand values can be considered as the main causes to voltage drop in distribution systems. Contrary to some other disturbances in electrical power systems, for which the performance is evident for the ordinary customer, voltage drop belongs to those disturbances in which their perceptible effects are produced in the long run.

1.4                                           SIGNIFICANCE OF THE STUDY

Since voltage drop gradually affects equipment, this disturbance should be dealt with by statistical analysis. This study helps in analyzing the effect, remedy for voltage drop in electrical distribution network.

1.5                                             LIMITATION OF THE STUDY

There are other different methods of evaluating voltage drop in a network such as using KVL and KCL or using constitutive equations, but in this study only digital voltmeter was used.

1.6                                            APPLICATION OF THE STUDY

Knowing the voltage drop of any electrical network is very important and can be useful and carried out by students, electrical technicians and engineers.

1.7                                                PURPOSE OF THE STUDY

The purpose of evaluating the voltage drop of a network is to know the level of safety of our appliances when they are used in the network.