1. ECE 530 – Analysis Techniques for Large-Scale Electrical Systems
Lecture 1: Power System Overview
Prof. Hao Zhu
Dept. of Electrical and Computer Engineering
University of Illinois at Urbana-Champaign
Acknowledgement: Prof. Overbye (taught ECE 530 in Fall’13)

2. Course Overview
Course presents the fundamental analytic, simulation and computation techniques for the analysis of large-scale electrical systems.
The course stresses the importance of the structural characteristics of the systems, with an aim towards practical analysis.

3. Course Syllabus Course mechanics and topics Introduction
Analysis of nonlinear electrical systems, with detailed coverage of power flow and related issues
Data and computational issues associated with large-scale systems including sparsity and visualization
Nonlinear parameter estimation in electrical systems
Modeling for dynamic analysis including time scale separation and modal analysis
Dynamic performance analysis including solution of differential-algebraic systems

4. References
Sources of Info: Books, journals, conferences, and real-life problems
A. J. Wood, B. F. Wollenberg, and G. B. Sheble, “Power Generation, Operation, & Control,” 3rd ed., 2014
A. R. Bergen, “Power Systems Analysis,” 1986
M. Crow, “Computational Methods for Electric Power Systems,” 2002.
Y. Saad, “Iterative Methods for Sparse Linear Systems,” (Free online)

5. Other resources IEEEXplore, Google scholar Peers, networking
IEEEXplore, Google scholar
Peers, networking

6. 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

7. 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

8. 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
TW – 1 x 1012 Watt
Installed U.S. generation capacity is about 900 GW ( about 3 kW per person)
Maximum load of Champaign/Urbana about 300 MW

9. 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)
MWh – One MW for one hour
TWh – One million MWh
Btu – J; 1 MBtu=0.292 MWh
U.S. electric energy consumption is about 4000 TWh kWh (about 12,500 kWh per person, which means on average we each use 1.4 kW of power continuously)

10. Notation and Voltages
The IEEE standard is to write ac and dc in smaller case, but it is often written in upper case as AC and DC.
Three-phase is usually written with the dash, also as 3-phase.
In the US the standard household voltage is 120/240, +/- 5%. Edison actually started at 110V dc. Other countries have other standards, with the European Union recently standardizing at 230V. Japan’s voltage is just 100V.

11. 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

12. North America Interconnections

13. 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

14. Sources of Energy - US About 84% Fossil Fuels
About 40% of our energy is consumed in the form of electricity, a percentage that is gradually increasing. The vast majority of the non- fossil fuel energy is electric!
In 2012 we got about 1.4% of our energy from wind and 0.04% from solar (PV and solar thermal)
About 84% Fossil Fuels
1 Quad = 293 billion kWh (actual), 1 Quad = 98 billion kWh (used, taking into account efficiency)
Source: EIA Annual Energy Outlook 2013, Electric Power Monthly, July 2013

15. US Historical and Projected Energy Usage
Projections say we will still be 79% fossil in 2040!
Source: EIA Annual Energy Outlook 2014

16. Worldwide Energy Usage
Source: EIA International Energy Outlook, 2013

17. 1980-2011 Energy by Region million toe Former Soviet Union
North America
Latin America
Former Soviet Union
Europe
Middle East
Africa
Asia

18. Variation In Electricity Sources

19. Electric 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” seen as unlikely soon

20. Ball park Energy Costs Nuclear: $15/MWh Coal: $22/MWh Wind: $50/MWh
Hydro: varies but usually water constrained
Solar: $120 to 180/MWh
Natural Gas: 8 to 10 times fuel cost in $/Mbtu (3-12)
Note, to get price in cents/kWh take price in $/MWh and divide by 10.

21. Natural Gas Prices 1990’s to 2013
Marginal cost for natural gas fired electricity price
in $/MWh is about 7-10 times gas price

22. Key Driver for Renewables: Concerns about Global Warming
Value was about 280 ppm in 1800; in 2013 it is 396 ppm
Source:

23. Worldwide Temperature Graph
Baseline is 1961 to 1990 mean
Source:

24. Looking Back a Little Further
With lots more uncertainty!
Source:

25. Going Back Further it Was Mostly Cold!

26. Compelling Evidence?
natural forcing only
natural (solar + volcanic) forcing alone does not account for warming in the past 50 years
anthropogenic forcing only
natural + anthropogenic forcing
adding human influences (greenhouse
gases + sulfate aerosols) brings the models and observations into pretty close agreement
"With four parameters I can fit an elephant and with five I can make him wiggle his trunk." — John von Neumann
Source: Prof. Gross Fall 2013 ECE 333 Notes

27. And Where Might Temps Go?
The models show rate of increase values of between 0.18 to 0.4 C per decade. The rate from 1975 to 2005 was about 0.2 C per decade.
Source:

28. Brief History of Electric Power
Early 1880’s – Edison introduced Pearl Street dc system in Manhattan supplying 59 customers within a one mile radius
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, 12 km in Southern California

29. 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; highest voltages were 200 kV

30. 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