ECE 421 - Electric Energy Systems
1 – Overview of Power Systems and
Electric Power Generation
Instructor:
Kai Sun
Fall 2014
1
Outline
•History of Electric Industry
•Introduction to Electric Power Systems:
– Energy resources, grid operation and reliability, and smart grid
technologies
•Job Markets
Sources:
– Dr. Robert B. Schainker’s presentation “Pictorial History of the Development of Electricity”
at EPRI in 2003
– Empires of Light: Edison, Tesla, Westinghouse, and the Race to Electrify the World, by Jill
Jonnes, Random House, NY, 2003
– H. Saadat, Power System Analysis (3rd Ed.), McGraw-Hill, 2010
– EPRI Power System Dynamics Tutorial, EPRI, Product ID: 1016042, 2009
– NERC.com, Wikipedia.org, and other websites
2
Some Big Names Who Developed the Field of Electricity
Big Names (Ordered by DOB)
Achievements
Benjamin Franklin (1706-1790 ), American
Lightning rod, Charge conservation
Charles A. de Coulomb (1736-1806), French
Coulomb's law
James Watt (1736-1819), Englishman
Steam engines, concept of power
Count A. Volta (1745-1827), Italian
Battery
Andre’ M. Ampere (1775-1827), Frenchman
Electromagnetism, Ampere’s law,
Hans C. Orsted (1777-1851), Danish
Electromagnetism
Carl F. Gauss (1777-1855), German
Gauss's law
George S. Ohm (1789-1854), German
Ohm's law
Michael Faraday (1791-1867), Englishman
Electromagnetic induction
Joseph Henry (1797-1878), American
Self- and mutual- inductance
James P. Joule (1818-1899), Englishman
Energy, Joule's first law
Gustav R. Kirchhoff (1824-1889), Prussian/German
Kirchhoff's circuit laws
James C. Maxwell (1831-1879), Scotsman
Electromagnetic field, Maxwell's equations
George Westinghouse (1846-1914), American
AC power system
Thomas A. Edison (1847-1931), American
Incandescent light bulb, DC power system
Nikola Tesla (1856-1943), Croatian/American
AC induction motor & transformer, AC power system
Heinrich Hertz (1857-1894), German
Electromagnetic waves
William Stanley, Jr. (1858-1916), American
New transformer design still used today, other devices
Charles P. Steinmetz (1865-1923), German/American
Mathematical theories for AC systems
3
1831: World’s 1st Electric Dynamo by Faraday
• August 29, 1831: Faraday demonstrated how to make electricity from a change in
magnetism
(Source: Wikipedia.org)
4
1876: World’s 1st R&D Lab by Edison
• Started in 1876 at Menlo park, NJ.
• The Laboratory buildings were removed
in 1929 by industrialist Henry Ford to his
Greenfield Village Museum in Dearborn,
Michigan
• Edison’s team on the front steps
of the lab building (Circa 1880).
Top row (standing), left to right: Albert Herrick,
Francis Jehl, Samuel Edison (Edison's father),
George Crosby, George Carman, Charles Mott,
John Lawson, George Hill, Ludwig Boehm.
Middle row: Charles Batchelor, Edison, Charles
Hughes, William Carman.
Bottom row: William Holzer, James Hipple.
5
1879: 1st Commercially Practical Incandescent Light by
Edison
First successful light bulb model,
used in public demonstration at
Menlo Park, December 1879
(source: Wikipedia.org)
Edison and his Menlo Park crew (taken in 1880, i.e. soon
after new lights were installed)
6
1882: 1st Commercial Power Plant for a City by Edison
• Three floors of Pearl Street Generation Station in NYC (commissioned on Sept. 4, 1882)
– It had six coal-fed steam locomotive engines powering six direct current dynamos
– Served 59 customers (all incandescent lamps at 110V through underground cables) within a
1.5km radius area. (Motor loads were added to such systems after 1884)
7
• By the time Edison was in his mid-30s,
he was said to be the best-known
American in the world
• Edison has more patents (1,093) in his
name than any other person, including:
– 389, Electric Light & Power
– 195, Phonograph
– 150, Telegraph
– 141, Storage Batteries
– 34, Telephone
– Kinetograph Motion Camera
– Kinetoscope Motion Viewer
– Magnetic Ore Separator
Thomas Edison at his desk
dictating into the
“Edison Business
Phonograph”
8
1st Home To Be Lit By Electricity
• J.P. Morgan - Financial backer of
Edison Electric Light Co., which later
became General Electric Co.
• J.P. Morgan’s home was the first
home to be lit by electricity using
Edison’s new electric light bulbs,
powered by an Edison DC dynamo in
Morgan’s home basement.
9
Nikola Tesla
•
•
•
•
•
•
•
•
Tesla’s bio in IEEE paper template
Rotating Magnetic Principle
Polyphase AC Generators,
Motors, and Grid Equipment
AC Induction Motor
Practical Wireless Communication
Tesla High Voltage Coil
Telephone Repeater
700 Other Patents
Nikola Tesla in the lab he set up in Colorado Springs
(1899) to study electric energy by generating millions of
volts (note: the photo is a double exposure.)
“Nikola Tesla” (by David Bowie) in movie The Prestige
(2006) (Source: IMDb.COM)
10
George Westinghouse: One Of The Few Who Appreciated The
Practical Importance Of Tesla’s Polyphase Patent
• An entrepreneur having the ability to
transform new ideas to commercial reality
while allowing for relatively simple
maintenance practices
– Invented railroad air brake and
signaling equipment; had many
patents on natural gas piping systems
& equipment
– Bought numerous electricity patents
from Tesla
– Commercialized AC generation &
transmission systems
– Battled Edison over AC vs. DC
– Generation & grid applications
– When Tesla needed money,
Westinghouse paid for Tesla’s room &
board at the Waldorf Astoria, NY City
11
Westinghouse-Tesla Polyphase Exhibit In The “Electricity Building”
At The Chicago World's Fair (1893)
• Westinghouse’s AC bid won over GE’s
DC bid for the fair’s power & lighting
contract.
12
1st Westinghouse Generator
• One of the 1st Westinghouse Niagara Falls
Power Company generators being built in
Pittsburgh in 1894 (Note: Westinghouse won
this contract over a GE bid.)
• This machine was a two phase, 25 Hz AC
generator (3.8MW), the largest generator in the
World, at the Time.
Most of the patents cited above were from Tesla
First Three Westinghouse Generators in Stanford
White's "Cathedral of Power" at Niagara Falls (Photo
Taken April 6, 1896)
13
The Success Story
Transforming new ideas to
commercial reality while
allowing for relatively simple
maintenance practices
Competitor (1882)
Innovator (1888)
Commercializer
(1889-)
Demonstration (1893)
Application (1893-1896)
14
Morgan and Tesla
• In 1900 Morgan invested $150,000 in inventor Nikola
Tesla's Wardenclyffe Tower, a high power transatlantic
radio transmission project.
• By 1903 Tesla had spent the initial investment without
completing the project, and with Guglielmo
Marconi already making regular transatlantic
transmissions with far less expensive equipment, Morgan
declined to fund Tesla any further.
• Tesla tried to generate more interest in Wardenclyffe by
revealing its capability of wireless electricity transmission,
but the loss of Morgan as a backer, and the later 1907
financial crisis dried up any further investment
Note: In 2007, a MIT group powered a 60W bulb WIRELESSLY
over 7 feet in the air between two coils resonating together at
9.9MHz. (for more information search for keyword “WiTricity” )
Wardenclyffe Tower (1901–1917),
also known as the Tesla Tower, was
an early wireless transmission tower
designed by Nikola Tesla in
Shoreham, New York and intended
for commercial trans-Atlantic
wireless telephony, broadcasting,
and proof-of-concept demonstrations
of wireless power transmission ( a
more powerful version of wireless
communication).
(Source: Wikipedia.org)
15
From Generator to Grid
• William Stanley, Jr, had 129 Patents,
including:
– Transformer (new design still used
today)
– Inductor Alternator
– Line Insulator
– Line Switch
– Vacuum (Thermos) Bottle
• Charles Steinmetz
– A mathematician who invented AC
system theories (e.g. on hysteresis,
steady-state analysis and transients)
for AC machine and network
performance calculations
– Recognized as one of the great
inventors and minds of the 1900’s.
16
Reasons for AC Winning over DC
•Voltage levels can be easily transformed in AC systems, thus
providing the flexibility for use of different voltages for
generation, transmission and consumption
•To reduce transmission power losses (RI2) and voltage drops,
voltage levels have to be high for long-distance power
transmission. HVAC was easier to implement by means of
transformers. (At present, the cross-over point for HVDC to be
competitive is around 500km for overhead lines or 50km for
underground/submarine cables.)
•AC generators and motors are much simpler than DC generators
and motors (commutators needed)
17
How Transformers Work?
V2 can be larger or smaller than V1
It only works with AC!
Source: Alstom.com
18
Why 3-phase AC?
• Generation and transmission adopt 3-phase
because:
– 3 wires for 3 loads (if balanced)
– Power is 3-phase AC is constant, not in
pulses as in 1-phase AC. Thus, more
power is delivered and 3-phase motors
run more smoothly
Why not 6 or 12? http://www.youtube.com/watch?v=HqZtptHnC2I
19
1st 100 Years of Electric Industry
• 1882: Pearl Street Station, the 1st DC system by Edison, operated in NYC
• 1886: Commercially practical transformer and AC distribution system
developed by Stanley
• 1888: Development of poly-phase AC by Tesla started AC vs. DC battle
• 1889: 1st AC transmission line in the US (1-phase, 21km at 4kV in Oregon)
• 1893: 1st 3-phase line (2.3kV, 12 km by SCE) in North America; AC vs. DC battle
ended when AC was chosen at Niagara Falls.
• 1912-1923: 1st 110kV and 220kV HVAC overhead lines
• 1950s: 345kV-400kV EHV AC lines by USA, Germany and Sweden
• 1954: 1st modern commercial HVDC transmission (96km submarine cable) in
Sweden.
• 1960s: 735-765kV EHV AC in Russia, USA and Canada
• 1972: 1st thyristor based HVDC Back-To-Back system between Quebec and New
Brunswick in Canada
20
AC/DC Hybrid: a Super Grid?
(Source: “GOBITEC and Asian Super Grid for Renewable
Energies In Northeast Asia” by Fraunhofer Institute, 2014)
(Source: presentation by A.-A. Edris in 2007 at EPRI)
(Source: www.smartplanet.com)
21
Energy Resources for Electricity Generation
From “Electricity sector of the United States” at Wikipedia.org
22
Fossil Fuel Power Plants
• Coal-fired steam turbine power plant
Rankine
Cycle
23
•Coal-fired steam turbine power
plant (Rankine Cycle)
1. Boiler burns pulverized coal to
produce high P&T steam
2. Turbines (HP, MP, and LP) convert
heat of flowing steam to mechanical
energy to spin a generator
3. Generator converts mechanical
energy to electric energy
• Concerns:
– Low efficiency (η<45%)
– Environmental concerns (major
emitters of CO2)
A coal plant in Rochester, Minnesota (source: wikipedia.org)
24
Brayton
Cycle
(Source: blogspot.com)
•Gas turbine power plant
(Brayton Cycle)
– A gas turbine is also called
combustion turbine and operates
like a jet engine
– Efficiency η→46%
– Start quickly in minutes (used for
peak load)
– Usually used in conjunction with a
heat recovery system generator
(HRSG) for a combined-cycle or cogeneration power plant.
Combustion Turbine Power Plant (source: TVA.com)
25
•Combined-cycle power plant
– Higher overall efficiency (η>60%)
Brayton
Cycle
+
Rankine
Cycle
26
Nuclear Power Plants
• Steam power plant except that the
boiler is replaced by a nuclear reactor,
e.g. BWR (boiling-water reactor) and
PWR (pressurized-water reactor)
• (η≈30%)
(Source: Wikipedia.org)
27
Hydroelectric Power Plants
• Generated electric power:
P
=
W
EP V ρ gh
=
= q ρ gh
t
t
=
Po η=
PW η q ρ=
gh 9.81qhη (kW)
η - overall efficiency
h – effective head of water (m)
q – rate of flow (m3/s)
ρ - density of water ≈1000kg/m3
g – acceleration due to gravity ≈9.81m/s2
h
q
Norris Dam: 1st major TVA project built in the mid-1930s
(source: wikipedia.org)
28
Types of Hydro Plants
•Run-of-the-river hydro plants
– Use the nature flow of rivers
– Cheap; very little environmental impact
– Power outputs may have seasonal fluctuations
•Pumped-storage hydro plants
– Typically have two reservoirs at two elevations
– Energy storage function (accounts for >99% of
bulk storage): during off-peak times, the
generator can operate as a synchronous motor
(pump) to save surplus electricity by elevating
water
– Brought to full power within a few minutes from
startup (important for grid stability in, e.g.
backing up wind/solar power generation)
Pumped storage Plant in Rönkhausen, Germany
(source: wikipedia.org)
29
Solar Power
• Photovoltaic (PV)
– Photoelectric effect: Light->electricity
(efficiency ~ 15%)
• Concentrated solar power (CSP)
– Light->heat->electricity
• Parabolic Troughs,
• Parabolic dish concentrators (Dish
Stirling, efficiency~30%)
• Solar Tower
Stirling Engine
30
31
32
Wind Power Plants
•Generated electric power:
EK mv 2 Aρ vt ⋅ v 2
=
= =
P
W
t
2t
2t
Aρ v3 π D 2 ρ v3
= =
2
8
π D 2 ρ v3
=
PO η=
CP PW η CP
(W)
8
v (m/s)
A (m2)
CP – power coefficient ≈0.4
< 16/27 or 0.59 (Betz Limit)
η – overall efficiency
ρ – air density ≈1.2kg/m3 at 70oF
33
34
Types
• Onshore
– Closer to existing electrical grids
– More noise and visual pollution
– Limited land sites
• Offshore
– Higher investment and maintenance
costs
– Less noise
– Huge resources; higher and more
stable wind speed
Offshore wind farm (5MW turbines, Belgium)
35
Wind Turbines
• Doubly-Fed Induction Generators (DFIG)
– Most commonly used
– “Double fed”: energy is delivered to the grid from both the stator and the rotor
– The power electronic converters enable DFIG to operate at the optimal rotor speed
and to maximize power generation by controlling the active and reactive power
injected into the grid at a constant voltage frequency.
Can short-circuit the rotor
during an external fault to ridethrough the voltage dip
36
Global Wind Energy (by 2013)
** Provisional Figure
(Source: "Global Wind Statistics 2013“, Global Wind Energy Council. Feb 2014)
37
Reliability Concerns in Integration of Wind Generation
Supply-demand mismatch
Legend:
•
Wind
•
People
Increased congestion risk
Inaccuracy in short-term wind forecast
38
Other Clean Energy
Resources
• Geothermal Power Plants
– Utilize heat within the earth, usually in the form
of underground steam or hot water
– 3GW installed in USA by 2009
• Biomass Power (Biopower) Plants
– Combustion of plants, agricultural residues and
other wastes to generate electricity
– Causes zero net increase in CO2
– 2.2GW installed in USA by 2010
• Tidal Power Plants
– Capturing potential/kinetic energy of tides
caused by the gravitational pull from the moon
(twice a day)
• Fuel Cell
– Convert chemical energy into electricity
Read Saadat’s Ch1.9-Ch1.12
39
(Source: www.conserve-energy-future.com)
Question
•Which of these generation resources utilize steam turbines in
generating electric power?
– Coal-fired power plant
– Combined-cycle power plant
– Parabolic Trough
– Solar Tower
– Pressurized water reactor
– Geothermal power plant
40
Structure of an AC Power System
• Generation
– Low voltages <25kV due
to insulation
requirements
• Transmission system
– Backbone system
interconnecting major
power plants (11~35kV)
and load center areas
– 161kV, 230kV, 345kV,
500kV, 765kV, etc.
• Sub-transmission system
– Transmitting power to
distribution systems
– Typically, 35/69kV138kV
• Distribution system
– Typically, 4kV-34.5kV
Source: Green Transmission Efficiency Initiative: A Series of Workshops. EPRI PID 1019531, 2009.
41
42
Bulk Electric System or Bulk Power System
• NERC definition
– The bulk electric system is a term commonly applied to the portion of an electric
utility system that integrates “the electrical generation resources, transmission
lines, interconnections with neighboring systems, and associated equipment,
generally operated at voltages of 100 kV or higher.”
– Radial transmission facilities serving only load with one transmission source are
generally not included in this definition
• For short, a bulk electric system is the part of the transmission/subtransmission system connecting
– power plants,
– major substations, and
– HV transmission lines
• Most of power system reliability concerns are about bulk electric systems
43
US Electric Industry Structure
• 3,195 utilities in the US in 1996. Fewer than 1000 engaged in power generation
Categories
Examples
Investor-owned utilities
240+, 66.1% of electricity
AEP, American Transmission Co., ConEd, Dominion Power, Duke
Energy, Entergy, Exelon, First Energy, HECO, MidAmerican,
National Grid, Northeast Utilities, Oklahoma Gas & Electric,
Oncor, Pacific Gas & Electric, SCE, Tampa Electric Co., We
Energies, Xcel,
Publicly owned utilities
2000+, 10.7%
Nonprofit state and local government agencies, including
Municipals, Public Power Districts, and Irrigation Districts, e.g.
NYPA, LIPA,
Federally owned utilities
~10, 8.2%
Tennessee Valley Authority (TVA), Bonneville Power
Administration (BPA), Western Area Power Administration
(WAPA), etc.
Cooperatively owned utilities
~1000, 3.1%
Owned by rural farmers and communities
Non-utilities, 11.9%
Generating power for own use and/or for sale in whole-sale
power markets, e.g. Independent Power Providers (IPPs)
44
De-regulation: Competitive US Power Market Structure
• Regulation: the government sets down laws and rules that put limits on and define
how a particular industry or company can operate.
• De-regulation:
Why?
– Infrastructure was built
– Monopolies are inefficient: high operation costs,
no penalty for mistakes, not customer-focused
– Well-developed generation technologies.
Generation
Owner
Generation
Owner
…
Generation
Owner
Transmission
How?
– Market-driven, complying with reliability
standards
– Typically, bid-based, security-constrained,
economic dispatch with nodal prices: The price
in the day-ahead market is determined by
matching offers from generators to bids from
consumers at each node to develop a supplydemand equilibrium price, usually on an hourly
interval, and is calculated separately for subregions in which the system operator's powerflow model indicates that constraints will bind
transmission imports.
Distribution
Distribution
Distribution
…
Service
Service
Service
45
California was the 1st
state to implement full
deregulation
46
Power Blackouts of in North America
Date
Area
Impacts
Nov 9, 1965
North America (NE)
20,000+MW, 30M people
13 hrs
Jul 13, 1977
North America (NY)
6,000MW,
26 hrs
Dec 22, 1982
North America (W)
12, 350 MW, 5M people
Jul 2-3, 1996
North America (W)
11,850 MW, 2M people
13 hrs
Aug 10, 1996
North America (W)
28,000+MW, 7.5M people
9 hrs
Jun 25, 1998
North America (N-C)
950 MW,
19 hrs
Aug 14, 2003
North America (N-E)
61,800MW, 50M people
2+ days
Sep 8, 2011
US & Mexico (S-W)
4,300MW, 5M people
12hrs
9M people
0.15MK people
Duration
47
NERC (North American Electric Reliability Corporation)
• As a non-government organization, formed by the electric utility industry in
1968 to promote the reliability of bulk power systems in North America.
• Initially membership was voluntary and member systems followed the
reliability criteria for planning and operating bulk power systems to prevent
major system disturbances following severe contingencies
• As of June 2007, FERC (U.S. Federal Energy Regulatory Commission) granted
NERC the legal authority to enforce reliability criteria with all users, owners,
and operators of the bulk power systems in the U.S.
• NERC Membership is now mandatory and member systems comply with
NERC’s Reliability Standards (approved by FERC) to both promote reliable
operations and to avoid costly monetary penalties if caught non-compliant.
Every system operator should read, understand and follow NERC’s Reliability
Standards. (Visit http://www.nerc.com for more information on NERC.)
48
Interconnections in North America
• Eight Regional Reliability Entities
(RREs) assisting NERC
– FRCC (Florida Reliability Coordinating
Council)
– MRO (Midwest Reliability
Organization)
– NPCC (Northeast Power Coordinating
Council)
– RFC (Reliability First Corporation)
– SERC (Southeastern Electric Reliability
Council)
– SPP (Southwest Power Pool)
– WECC (Western Electricity
Coordinating Council)
– TRE (Texas Reliability Entity)
35GW
180GW
650GW
70GW
From EPRI tutorial (Peak loads are based
on data in 2009)
49
NERC Balancing Authority
• A Balancing Authority (BA) is a part of an interconnected power system that is
responsible for meeting its own load.
• Each BA operates an Automatic Generation Control (AGC) system to balance
its generation resources to its load requirements. The generation resources
may be internal or purchased from other BAs and transferred over tie-lines
between BAs.
• Similarly, load requirements may include internal customer load, losses, or
scheduled sales to other BAs.
50
NERC Balancing Authorities
• EI has about 90 BAs, which
range in load size up to
130GW peaks
• WI (WECC) has about 30
BAs.
• ERCOT and Hydro Quebec
each operate as single BAs.
51
52
NERC Functional Model Diagram
53
Reliability of Bulk Power Systems
•Power systems should be built and operated to ACHIEVE A
RELIABLE ELECTRIC POWER SUPPLY AT THE MOST
ECONOMICAL COST
•Reliability is defined using two terms:
– Adequacy (planning): The ability of the electric systems to
supply the aggregate electrical demand and energy
requirements of their customers at all times, taking into
account scheduled and reasonably expected unscheduled
outages of system elements.
– Security (operation): The ability of the electric systems to
withstand sudden disturbances such as electric short circuits
or unanticipated loss of system elements
54
Reliability of Bulk Power Systems (cont’d)
•Important requirements of a reliable electric
power service
– Voltage and frequency must be held within close
tolerances
– Synchronous generators must be kept running in parallel
with adequate capacity to meet the load demand
– Maintain the “integrity” of the bulk power network
(avoid cascading outages)
– Others
55
NERC’s Reliability Standards:
Performance under Normal and Emergency Conditions
56
System Control Centers
Duke Energy Control Center
(source: Patrick Schneider Photo.Com)
TVA Control Center
(Source: bayjournal.com)
(source: TVA.com
57
Smart Grid
• May be defined as a broad range of solutions that optimize the energy value chain. It brings the
power of networked, interactive technologies into an electricity system to improve reliability,
security and efficiency of the electric system.
• Some features: Digitalized, Interactive, Sustainable, Resilient, Robust, Autonomous and Efficient.
Variable distributed
energy resources
Smart residential buildings
Smart commercial buildings
Smart industry buildings
(Source: http://smartgrid.epri.com/Demo.aspx)
58
EPRI Smart Grid Demonstration Initiative
(Source: Smart Grid Demonstration 5-Year Update, EPRI 08/10/13) http://smartgrid.epri.com/Demo.aspx
59
Example 1: FirstEnergy
(Source: Smart Grid Demonstration 5-Year Update, EPRI 08/10/13)
http://smartgrid.epri.com/Demo.aspx
60
Example 2: Public Service of New Mexico (PNM)
61
Electric Vehicles
Smart Modal Area Recharge Terminal
(SMART) station developed by TVA and
EPRI (sources: TVA.com and EPRI.com)
62
A future smart home
Source: news.cnet.com
63
Hiring Companies
•Power utilities, e.g.
–
TVA, TVA distributors (e.g. KUB,
LCUB, etc.), Southern Company
(Georgia Power, Alabama Power,
Gulf Power and Mississippi Power),
Duke Energy, etc.
•Independent System Operators
(ISO) / Regional Transmission
Operators (RTO)
–
PJM, SPP, ISO New England, NYISO,
Midwest ISO, CAISO and ERCOT
Positions: planning/operation engineers
64
Hiring Companies (cont’d)
•Manufacturers and service providers
– GE, ABB, Siemens, Alstom, etc.
Positions: R&D, engineers, consultants, etc.
65
Hiring Companies (cont’d)
•Government and Non-profit
organizations
–
–
–
FERC (Federal Energy Regulation
Commission)
National Laboratories (ORNL, PNNL, ANL,
NREL, etc.)
EPRI (Electric Power Research Institute)
Positions: scientists, engineers, analysts, etc.
66