suryanarayanan summer10wrkshp csm

Electric Power Concepts

Prof. Sid Suryanarayanan Div. of Engg., Colorado School of Mines

[email protected] http://www.mines.edu/~ssuryana

Outline of presentation   How is electricity produced?

  Or – How does a power plant work?

  How is electricity delivered?   Or – What is the electric grid?

  How is electricity used?   Or – How different are electric loads?

  Each topic will be a 15 presentation   Handouts and web links will be provided

Introduction  Raising student interest in electric

power is important   Almost 50% of the power industry

workforce will be eligible to retire in less than 5 years

  Electric power engineering relies strongly on concepts of mathematics and science   Pre-college students have to be motivated

in Math and Sci. to maintain US competitiveness

Introduction

 Studies indicate many students lose interest in Math & Sci. in high school and middle school years

  To capture the interest of K-12 students, we must present electric power concepts in eye-catching modes   Simulations, applets, interactive

modules, etc.

Electric power systems - a brief history

  1879: Edison perfects work on electric light

  1882: Edison opens Pearl St. Station, NYC   DC generators (“dynamos”)   30 kW load of 110 V incandescent

lighting   59 customers spread over 1 sq. mile

Picture taken directly from [3]


Electric power systems - a brief history

  1885: Stanley develops transformer and installs AC distribution system in MA   More attractive option than DC

  1888: Tesla invents 2φ induction and sync motors   Patents purchased by Westinghouse

All pictures taken directly from [2]

  1889: first operational AC transmission line in US   1φ 4 kV 21 km (13 miles) b/w Portland and Oregon City

  1893: First 3 φ line in US   12 km (7.5 miles) at 2.3 kV

  20th century   US NAE names ‘electrification’ most important engineering achievement of 20th C

Electric power systems – 21st C

  2005: Energy Policy Act   Distributed Generation

  2007: Energy Independence and Security Act   Smart Grid Initiative

  2009: American Recovery and Reinvestment Act   $$ for Smart Grid projects

  Abundant opportunities for education, jobs, & careers for power engineers of future

  Catch them young, watch them grow !

How is electricity produced?

  Electricity is produced from other sources   coal, natural gas, wind, nuclear, hydro…

  Typically, electricity is generated in a power plant   Depending on type of fuel used, power

plants operate differently   We will look at the operation of a

thermal power plant


  Thermal power plant uses steam as the main driver to produce electricity

 Coal, nuclear, geothermal are all thermal power plants

  Let us see how a coal-fired thermal power plant works


 Coal-fired thermal power plant uses coal as the fuel   Sulfur content in coal determines its

cleanness (lower Sulfur cleaner coal)  Coal is brought to the power plant from

the mines via trains and stored in silos  When required, coal is crushed into a

fine powder in coal mills   This helps the coal burn efficiently

Information on slide adapted from [4]


  Finely crushed coal is then brought to a boiler where it is fired at 3000o F

  The high energy from burning this coal is used to convert water to superheated steam   Water circulates in pipes within the boiler

and becomes steam   The steam, which has high energy, is

now brought to a turbine


How is electricity produced?   As the steam passes through the turbine, it

moves the blades on the turbine   This happens at high speeds

  As this happens, steam cools off and needs to be reconverted to water for use again   The cooled steam in the pipe is then passed

through cold water   The steam in the pipes cool further to become

water   The cold water outside the pipe becomes steam

and is let off through smoke stacks


How is electricity produced?   The blades of the turbine are connected to

a shaft that spins an electric generator   This is where mechanical energy of the shaft is

converted to electricity   Generator has a moving part (rotor) and a

stationary part (stator) – essentially an electromagnet

  As the rotor moves within the stator, an electric current is produced

  Thus, electricity is produced and awaits delivery


How is electricity delivered?   Electricity produced by generators are at lower

voltages   Typically, power plants are located far from load

centers (cities, etc.)   Power needs to travel long distances over

transmission lines to reach cities   To do so, the voltage of electricity must be raised

  Imagine voltage as an equivalent of pressure; electricity as water; and transmission lines as pipes

  Higher pressure is needed to push water through pipes over long distances

  An electrical device called transformer performs the task of raising the voltage of electricity at the power plant

How is electricity delivered?


A 345000 Volts generator step-up transformer


  Through the ‘power grid’ (aka network)   3 large interconnections of transmission

lines and other components crisscrossing North America

  The power grid has been called the ‘most complex man made machine’


Source: Technology Review, Jul 01 [7]

The US electric grid


WECC

Source: DoE Distributed Energy Program [8]

WHY INTERCONNECT?

How is electricity delivered?   Advantages of interconnection

  Ability to supply loads from a combination of generators across the nation

  Since electricity travels almost at the speed of light, we can get electrical power produced by a generator in NYC delivered to Golden CO (a distance of ~1800 miles) in 100th of 1 second!

  Drawback of interconnection   Because the system is fully interconnected, any bad

event in one part of the system has the potential to show up across the system (cascade)


 Applet developed by Univ. of Illinois for introducing ‘power grid’ to K-12 students

  Interactive module with real time simulation screens

 Accompanying lessons and games available for teachers on the web site

http://tcip.mste.illinois.edu/lessons/ThePowerGrid.pdf


  http://tcip.mste.illinois.edu/applet2.php

  Educational objectives met by applet [1]:   Students learn how energy is transferred from

generators to loads via the power grid through transmission lines, substations, and transformers

  Benefits and drawback of interconnections   Power and energy is conserved at all places   Fuel type affects power ratings, controllability

and environmental impact   Lines can carry only up to their rated values;

When excess power is forced through lines, they disconnect

How is electricity consumed?   The power grid transfers electricity from far away

generators using a high voltage network of components

  This electricity is still at high voltage that is not readily usable by homes and buildings   Distribution systems

  High voltage electricity must be converted to lower voltage electricity

  Again, a transformer will do the job of stepping-down voltage too!

  Voltage is stepped-down in several stages   Loads such as TVs, Nintendo Wii™ consume electricity

that is delivered

How is electricity consumed?



Transformers


How is electricity consumed?   Different loads in different places have

different characteristics   Let us look at some electrical loads and see

how they behave   Before that, we must understand how we are

billed by the utility for the electricity we consume   Cost of 1 unit of electric energy ($/kWh) x Σ{Power

rating of device (kW) x time of use (h)}   Electricity used is measured using a energy

meter or kilowatthour meter


 Applet developed by Univ. of Illinois for introducing ‘power and energy use at home’ to K-12 students

  Interactive module with real time simulation screens

 Accompanying lessons and games available for teachers on the web site

http://tcip.mste.illinois.edu/lessons/PowerandEnergy.pdf


  http://tcip.mste.illinois.edu/applet1.php

  Educational objectives met by applet [1]:   Students learn that energy is delivered from

distribution network to the various home loads   Electrical loads vary in power demand   Energy is power used over time   Energy is metered and priced over time in units

of kWh   Energy and money can be saved by using more

efficient loads (like E-star)

The Smart Grid Initiative


Acknowledgements

  Prof. Thomas Overbye, UIUC   Prof. Zeb Tate, Univ. of Toronto  Ms. Jana Sebastik, UIUC

References 1)  J. E. Tate, T. J. Overbye, J. Sebestik, G. C. Reese, “Interactive Lessons for Pre-University Power Education,”

IEEE. Trans Pwr Sys, vol. 23, no. 3, pp. 824-830, Aug 2008 2)  C. L. Sulzberger, “Triumph of AC: from pearl street to Niagara,” IEEE Power & Energy Magazine, v. 1, no. 3,

pp. 64-67, May 2003 3)  Smithsonian Institution. “Powering a generation: Views of Pearl street station” [Online] {Available}

http://americanhistory.si.edu/powering/past/pearl.htm (Accessed Jun 09) 4)  Xcel Energy. “Welcome to Energy Classroom” [Online] {Available} http://www.energyclassroom.com/

(Accessed Jun 09) 5)  Tenn Valley Authority. [Online] {Available} http://www.tva.gov/power/images/coalart.gif (Accessed Jun 09) 6)  Mitsubishi Electric Power Products Inc. [Online] {Available}

http://www.meppi.com/Products/Transformers/PublishingImages/M7039%20OPPD%20NCPS%20345%20kV.JPG (Accessed Jun 09)

7)  Technology Review. “A smarter power grid.” [Online] {Available} http://www.technologyreview.com/energy/12474/ (Accessed Jun 2009)

8)  US Dept. of Energy. “Distributed energy program: US power grids.” [Online] {Available} http://www.eere.energy.gov/de/us_power_grids.html (Accessed Jun 2009)

9)  How Stuff Works. “How power grids work” [Online] {Available} http://science.howstuffworks.com/power5.htm (Accessed Jun 2009)

10)  Pauwels Transformers Inc. “Three phase pad mount distribution transformer” [Online] {Available} http://pauwels.us/images/ThreePhasePadMountDistribution.png (Accessed Jun 2009)

11)  Big Rivers Group – Jackson Energy Purchase Corp. [Online] {Available} http://jpenergy.apogee.net/foe/graphics/tdsd.jpg (Accessed Jun 2009)

12)  US Dept. of Energy. Office of Electricity Delivery and Energy Reliability [Online] {Available} http://www.oe.energy.gov/DocumentsandMedia/smartgrid_diagram.pdf (Accessed Jun 2009)

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Handouts

  IEEE transactions paper by Zeb Tate and Tom Overbye

  Lessons on power grid and home energy use from applets

 Accompanying TCIP slides for information (http://tcip.mste.uiuc.edu/TCIP-Education-NSFReview2009-Zeb.ppt )