power system-I Introduction

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Instructor : Dr. Engr. A. K. M. Baki Room # 4A08

Ahsanullah University of Science and Technology Fall 2014

COURSE: POWER SYSTEM I (EEE 3205)

LECTURE 1: INTRODUCTION

OBJECTIVES OF THE COURSE

Give students a solid foundation of the principles of power system.

Help students develop an understanding of the concepts of power

transmission and distribution.

Teach fundamental parameters related to power transmission and

distribution system.

Give a basic idea of Flexible AC Transmission System (FACTS).

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ASSESSMENT POLICY

Class tests 15 % (3 class tests will be taken, each

of weighting 5%)

No class test will be repeated if you fail to

attend.

Assignments with Viva 5 %

Class Attendance and

class performance 10 %

Final Examination 70 %

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DONT DEPEND ONLY ON POWER POINT SLIDES.

You need to follow all the four components mentioned below: 1. Power point presentation; 2. Writing on board; 3. Oral explanations; 4. References from books (most important);

The occasional presence of blank slides in PP presentation indicates that the instructor filled in those slides during lecture.

HOW TO PREPARE FOR THE EXAMS

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REFERENCE BOOKS AND NOTES Power System Analysis

John J. Grainger, W. D. Stevenson, Jr.

Power System Analysis and Design, 4th and 5th Edition

J. Duncan Glover, Mulukutla S. Sarma, Thomas J. Overbye

A Textbook of Power System Engineering, 1st Edition, Laxmi Publications (P) Ltd.

R. K. Rajput

Principles of Power System

V. K. Mehta, Rohit Mehta

Modern Power System Analysis, 4th Edition, McGraw Hill Education (P) Ltd.

D P Kothari I J Nagrath

A Textbook on Power System Engineering, 2nd Edition, Dhanpat Rai & Co.

A. Chakrabarti, M. L. Soni, P. V. Gupta, U.S. Bhatnagar

e-book: Electrical Distribution ( www.wiley.com)

Electric Power Distribution, 6th Edition, McGraw Hill Education (P) Ltd.

S. Pabla

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MAJOR TOPICS Parameters of Power System:

Inductance and capacitance of power transmission line; Line resistance;

Representation of Line:

Equivalent circuit of short, medium and long lines, transmission line as a two ports network ,

travelling waves on transmission lines; skin effect; Ferranti effect; Corona effect;

Power Factor and Voltage Control (Reactive Power Control):

Methods of voltage control: tap changing transformer; phase shifting; booster and regulating

transformer, series/shunt capacitor, static var compensation (SVC);

Mechanical characteristic of overhead transmission line:

Sag and tension analysis; effect of temperature, wind and ice loading, supports of different levels,

dampers, insulators of overhead lines;

Transmission Lines Cables:

Potential distribution of over suspension insulator string, Underground cables: insulating resistance,

capacitance, dielectric stress, grading of cables, capacitance of three phase cables, heating of cables,

most economic conductor size.

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MAJOR TOPICS (CONTINUED) Principles of Power System Operation:

Supervisory Control And Data Acquisition (SCADA)

High voltage DC Transmission

Distribution of Power:

Basic distribution systems and distribution voltage levels , distributor calculation of radial feeders,

Distribution substation and feeder, distribution automation, types and factors affecting distribution

losses, different American and European distribution networks.

Power System Stability:

Improving dynamic stability by Flexible AC Transmission System (FACTS).

Smart Grid:

Basic concept of Smart Grid and its benefits.

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GENERATION TRANSMISSION DISTRIBUTION

MAJOR COMPONENTS OF POWER SYSTEM

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SERIES IMPEDANCE OF TRANSMISSION LINES

An electric transmission line has four parameters (Figure 1): Series resistance Series inductance Shunt capacitance Shunt conductance

Figure 1. Transmission Line Model

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Figure 2. Magnetic and electric fields associated with a two-wire line.

DISTRIBUTION OF ELECTRIC AND MAGNETIC FLUX IN A SINGLE PHASE CIRCUIT

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OVERHEAD TRANSMISSION LINE

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Main Components of Overhead Lines

Conductors (Carry electric power)

Supports ( Poles or Towers)

Insulators (Insulate the conductors from the ground)

Cross arms (Provide support to insulator)

Miscellaneous items ( danger plates, lightning arrestors, anti-climbing wires, spacer, damper etc.)

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Main Components of Overhead Lines

source: www.nationalgrid.com/uk

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Properties of Conductor Materials

High electric conductivity;

High tensile strength in order to withstand mechanical strength;

Low cost so that it could be used for long distances;

Low specific gravity so that weight per unit volume is small;

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Types of Conductor The transmission line is required to have good conductivity and high strength to prevent snapping under normal and abnormal conditions. Though copper has high conductivity it is not used for transmission purposes primarily due to its higher cost and being heavier than aluminum.

Aluminum replaces copper, for same resistance, because: Larger diameter Lower voltage gradient at the surface of the conductor Less tendency to develop corona Lower cost Lighter than copper

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Types of Conductor The following types of conductors are mainly used for transmission purposes: All Aluminum Conductors (AAC) All Aluminum Alloy Conductors (AAAC) Aluminum Conductor Steel Reinforced (ACSR) Aluminum Conductor Alloy Reinforced (ACAR)

Alternate layer of strands are laid in spiraled form in opposite directions to prevent unwinding and make the outer radius of one layer coincide with the inner radius of the next (Figure 3).

Figure 3. Alternate layer of strands spiraled in opposite directions.

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ACSR ACSR has a steel central core of few strands and surrounded by

aluminum strands in one or more layers; The steel core provides the strength; Surrounded aluminum conductors carry the current; ACSR satisfies the requirement of a good transmission line, i.e.

it has both good conductivity and sufficient strength; More tensile strength in ACSR results in less sagging so greater

span length between towers; The total number of strands in concentrically stranded cables

is 7, 19, 37, 61, 91, or more. Used in high voltage transmission lines;

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ACSR

Figure 4. Cross section of ACSR.

Galvanized Steel

Aluminum

Ratio of diameter is generally 1:6 but can

be made 1:4 to get more tensile strength

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A type of conductor known as expanded ACSR has a filler such as paper separating the inner steel strands from the outer aluminum strands. The paper gives a larger diameter (and hence, lower corona) for a given conductivity and tensile strength. Expanded ACSR is used for some extra-high-voltage (EHV) lines.

ACSR

Some voltage classifications are as follows: HV: 115 kV, 138 kV, 230 kV EHV: 345 kV, 500 kV, 765 kV UHV: 1000 kV, 1500 kV

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QUESTIONS ?