Suryanarayanan Summer10wrkshp CSM
-
Upload
claudiu-stanciu -
Category
Documents
-
view
10 -
download
0
description
Transcript of 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]
Picture taken directly from [2]
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
How is electricity produced?
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
How is electricity produced?
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]
How is electricity produced?
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
Information on slide adapted from [4]
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
Information on slide adapted from [4]
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
Information on slide adapted from [4]
How is electricity produced?
Picture taken directly from [5]
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?
Picture taken directly from [6]
A 345000 Volts generator step-up transformer
How is electricity delivered?
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’
How is electricity delivered?
Source: Technology Review, Jul 01 [7]
The US electric grid
How is electricity delivered?
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)
How is electricity delivered?
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
How is electricity delivered?
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?
Picture taken directly from [10]
Picture taken directly from [11]
Transformers
Picture taken directly from [9]
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
How is electricity consumed?
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
How is electricity consumed?
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
Picture taken directly from [12]
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)
This slide is intentionally left blank
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 )