0. ECE 476 POWER SYSTEM ANALYSIS
Lecture 1
Introduction
Professor Tom Overbye
Department of Electrical and Computer Engineering

1. About Me
Professional
Received BSEE, MSEE, and Ph.D. all from University of Wisconsin at Madison (83, 88, 91)
Worked for eight years as engineer for an electric utility (Madison Gas & Electric)
Have been at UI since 1991, doing teaching and doing research in the area of electric power systems
Developed commercial power system analysis package, known now as PowerWorld Simulator. This package has been sold to about 400 different corporate entities worldwide
DOE investigator for 8/14/2003 blackout

2. About Me Nonprofessional Married to Jo Have three children
Tim age 13
Hannah age 11
Amanda age 9
Live in country by Homer
Like to bike to work (at least part of the way)
Teach 2nd/3rd Grade Sunday School class at First Baptist Church

3. My Kids

4. Simple Power System Every power system has three major components
generation: source of power, ideally with a specified voltage and frequency
load: consumes power; ideally with a constant resistive value
transmission system: transmits power; ideally as a perfect conductor

5. Complications No ideal voltage sources exist Loads are seldom constant
Transmission system has resistance, inductance, capacitance and flow limitations
Simple system has no redundancy so power system will not work if any component fails

6. Notation - Power Power: Instantaneous consumption of energy
Power Units
Watts = voltage x current for dc (W)
kW – 1 x 103 Watt
MW – 1 x 106 Watt
GW – 1 x 109 Watt
Installed U.S. generation capacity is about 900 GW ( about 3 kW per person)
Maximum load of Champaign/Urbana about 300 MW

7. Notation - Energy
Energy: Integration of power over time; energy is what people really want from a power system
Energy Units
Joule = 1 Watt-second (J)
kWh – Kilowatthour (3.6 x 106 J)
Btu – J; 1 MBtu=0.292 MWh
U.S. electric energy consumption is about 3600 billion kWh (about 13,333 kWh per person, which means on average we each use 1.5 kW of power continuously)

8. Power System Examples
Electric utility: can range from quite small, such as an island, to one covering half the continent
there are four major interconnected ac power systems in North American, each operating at 60 Hz ac; 50 Hz is used in some other countries.
Airplanes and Spaceships: reduction in weight is primary consideration; frequency is 400 Hz.
Ships and submarines
Automobiles: dc with 12 volts standard
Battery operated portable systems

9. North America Interconnections

10. Electric Systems in Energy Context
Class focuses on electric power systems, but we first need to put the electric system in context of the total energy delivery system
Electricity is used primarily as a means for energy transportation
Use other sources of energy to create it, and it is usually converted into another form of energy when used
About 40% of US energy is transported in electric form
Concerns about need to reduce CO2 emissions and fossil fuel depletion are becoming main drivers for change in world energy infrastructure

11. Sources of Energy - US About 86% Fossil Fuels
CO2 Emissions (millions of metric tons, and per quad)
Petroleum: 2598, Natural Gas: 1198, 53.0 Coal: , 92.3
1 Quad = 293 billion kWh (actual)
1 Quad = 98 billion kWh (used, taking into account efficiency)
Source: EIA Energy Outlook 2007, Table 1, 2005 Data

12. Electric Energy by Sources, US
Source: EIA State Electricity Profiles, 2006

13. Electric Energy by Sources, Calif.
Oregon is
71% Hydro,
while
Washington
State is
76% Hydro
Source: EIA State Electricity Profiles, 2006

14. Electric Energy by Sources, Illinois
Source: EIA State Electricity Profiles, 2006

15. Global Warming and the Power Grid What is Known: CO2 in Air is Rising
Value was about
280 ppm in 1800,
384 in 2007
Rate of increase is about 3ppm per year
Source:

16. As is Worldwide Temperature
Baseline is 1961 to 1990 mean
Source:

17. Change in U.S Annual Average Temperature
Source:

18. But Average Temperatures are Not Increasing Everywhere Equally
Source :

19. World Population Trends
Country %
Japan
Germany
Russia
USA
China
India
World
Source: values in millions; percent change from 2005 to 2025

20. Eventual Atmospheric CO2 Stabilization Level Depends Upon CO2 Emissions
Regardless of what we do in the short-term the CO2 levels in the atmosphere will continue to increase. The eventual stabilization levels depend upon how quickly CO2 emissions are curtailed. Emissions from electricity production are currently about 40% of the total

21. Energy Economics
Electric generating technologies involve a tradeoff between fixed costs (costs to build them) and operating costs
Nuclear and solar high fixed costs, but low operating costs
Natural gas/oil have low fixed costs but high operating costs (dependent upon fuel prices)
Coal, wind, hydro are in between
Also the units capacity factor is important to determining ultimate cost of electricity
Potential carbon “tax” major uncertainty

22. Ball park Energy Costs Nuclear: $15/MWh Coal: $22/MWh Wind: $50/MWh
Hydro: varies but usually water constrained
Solar: $150 to 200/MWh
Natural Gas: 8 to 10 times fuel cost in $/MBtu
Note, to get price in cents/kWh take price in $/MWh and divide by 10.

23. Natural Gas Prices 1990’s to 2008

24. Course Syllabus Introduction and review of phasors & three phase
Transmission line modeling
Per unit analysis and change of base
Models for transformers, generators, and loads
Power flow analysis and control
Economic system operation/restructuring
Short circuit analysis
Transient stability
System protection

25. Brief History of Electric Power
Early 1880’s – Edison introduced Pearl Street dc system in Manhattan supplying 59 customers
1884 – Sprague produces practical dc motor
1885 – invention of transformer
Mid 1880’s – Westinghouse/Tesla introduce rival ac system
Late 1880’s – Tesla invents ac induction motor
1893 – First 3 phase transmission line operating at 2.3 kV

26. History, cont’d
1896 – ac lines deliver electricity from hydro generation at Niagara Falls to Buffalo, 20 miles away
Early 1900’s – Private utilities supply all customers in area (city); recognized as a natural monopoly; states step in to begin regulation
By 1920’s – Large interstate holding companies control most electricity systems

27. History, cont’d
1935 – Congress passes Public Utility Holding Company Act to establish national regulation, breaking up large interstate utilities (repealed 2005)
1935/6 – Rural Electrification Act brought electricity to rural areas
1930’s – Electric utilities established as vertical monopolies

28. Vertical Monopolies
Within a particular geographic market, the electric utility had an exclusive franchise
Generation
Transmission
Distribution
Customer Service
In return for this exclusive
franchise, the utility had the
obligation to serve all
existing and future customers
at rates determined jointly
by utility and regulators
It was a “cost plus” business

29. Vertical Monopolies
Within its service territory each utility was the only game in town
Neighboring utilities functioned more as colleagues than competitors
Utilities gradually interconnected their systems so by 1970 transmission lines crisscrossed North America, with voltages up to 765 kV
Economies of scale keep resulted in decreasing rates, so most every one was happy

30. Current Midwest Electric Grid

31. History, cont’d ’s
1970’s brought inflation, increased fossil-fuel prices, calls for conservation and growing environmental concerns
Increasing rates replaced decreasing ones
As a result, U.S. Congress passed Public Utilities Regulator Policies Act (PURPA) in 1978, which mandated utilities must purchase power from independent generators located in their service territory (modified 2005)
PURPA introduced some competition

32. History, cont’d – 1990’s & 2000’s
Major opening of industry to competition occurred as a result of National Energy Policy Act of 1992
This act mandated that utilities provide “nondiscriminatory” access to the high voltage transmission
Goal was to set up true competition in generation
Result over the last few years has been a dramatic restructuring of electric utility industry (for better or worse!)
Energy Bill 2005 repealed PUHCA; modified PURPA

33. Utility Restructuring
Driven by significant regional variations in electric rates
Goal of competition is to reduce rates through the introduction of competition
Eventual goal is to allow consumers to choose their electricity supplier

34. State Variation in Electric Rates

35. The Goal: Customer Choice

36. The Result for California in 2000/1
OFF

37. The California-Enron Effect
Source : RI AK
electricity
restructuring
delayed
no activity
suspended WA OR NV CA ID MT WY UT AZ CO NM TX OK KS NE SD ND MN IA WI MO IL IN OH KY TN MS LA AL GA FL SC NC W VA PA NY VT ME MI NH MA CT NJ DE MD AR HI DC

38. August 14th, 2003 Blackout

39. 2007 Illinois Electricity Crisis
Two main electric utilities in Illinois are ComEd and Ameren
Restructuring law had frozen electricity prices for ten years, with rate decreases for many.
Prices rose on January 1, 2007 as price freeze ended; price increases were especially high for electric heating customers who had previously enjoyed rates as low as 2.5 cents/kWh
Current average residential rate (in cents/kWh) is 10.4 in IL, 8.74 IN, 11.1 WI, 7.94 MO, 9.96 IA, CT, 6.09 ID, in CA, US average