ECE 476 POWER SYSTEM ANALYSIS

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

2. 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

3. 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

4. My Kids

5. 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

6. 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

7. 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

8. 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 – 1055 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)

9. 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

10. North America Interconnections

11. 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

12. Sources of Energy - US About 86% Fossil Fuels CO2 Emissions (millions of metric tons, and per quad) Petroleum: 2598, 64.0 Natural Gas: 1198, 53.0Coal: 2115, 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

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

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

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

16. Global Warming and the Power Grid What is Known: CO2 in Air is Rising Valuewas about 280 ppmin 1800, 384 in 2007 Rate ofincreaseis about3ppmper year Source: http://cdiac.ornl.gov/trends/co2/sio-mlo.htm

17. As is Worldwide Temperature Baseline is 1961 to 1990 mean Source: http://www.cru.uea.ac.uk/cru/info/warming/

18. Change in U.S Annual Average Temperature Source: http://www.sws.uiuc.edu/atmos/statecli/Climate_change/ustren-temp.gif

19. But Average Temperatures are Not Increasing Everywhere Equally Source : http://www.sws.uiuc.edu/atmos/statecli/Climate_change/iltren-temp.jpg

20. World Population Trends Country 2005 2015 2025 % Japan 127.5 124.7 117.8 -7.6 Germany 82.4 81.9 80.6 -2.1 Russia 142.8 136.0 128.1 -10.3 USA 295.7 322.6 349.7 18.2 China 1306 1393 1453 11.2 India 1094 1274 1449 32.4 World 6449 7226 7959 23.4 Source: www.census.gov/ipc/www/idb/summaries.html; values inmillions; percent change from 2005 to 2025

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

22. 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

23. 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.

24. Natural Gas Prices 1990’s to 2008

25. 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

26. 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

27. 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

28. 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

29. Generation Transmission Distribution Customer Service Vertical Monopolies • Within a particular geographic market, the electric utility had an exclusive franchise 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

30. 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

31. Current Midwest Electric Grid

32. History, cont’d -- 1970’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

33. 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

34. 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

35. State Variation in Electric Rates

36. The Goal: Customer Choice

37. OFF OFF The Result for California in 2000/1

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

39. August 14th, 2003 Blackout

40. 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, 19.56 CT, 6.09 ID, 14.03 in CA, 10.76 US average