Ece 530 analysis techniques for large scale electrical systems
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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).

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Ece 530 analysis techniques for large scale electrical systems

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)

Course overview
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.

Course syllabus
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


  • 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,” 1996. (Free online)

Other resources
Other resources

  • IEEEXplore, Google scholar

  • Peers, networking

Simple power system
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


  • 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

Notation power
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

Notation energy
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 – 1055 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)

Notation and voltages
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.

Power system examples
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

Electric systems in energy context
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

Sources of energy us
Sources of Energy - US

About 40% of our energy is consumed in the formof electricity, a percentagethat 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 andsolar 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

Us historical and projected energy usage
US Historical and Projected Energy Usage

Projections say we will still be 79% fossil in 2040!

Source: EIA Annual Energy Outlook 2014

Worldwide energy usage
Worldwide Energy Usage

Source: EIA International Energy Outlook, 2013

1980 2011 energy by region
1980-2011 Energy by Region

million toe

Latin America

North America

Former Soviet Union


Middle East



Electric energy economics
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

Ball park energy costs
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.

Natural gas prices 1990 s to 2013
Natural Gas Prices 1990’s to 2013

Marginal cost for natural gas fired electricity price

in $/MWh is about 7-10 times gas price

Key driver for renewables concerns about global warming
Key Driver for Renewables: Concerns about Global Warming

Value wasabout 280ppm in 1800; in 2013 it is 396 ppm


Worldwide temperature graph
Worldwide Temperature Graph

Baseline is 1961 to 1990 mean


Looking back a little further
Looking Back a Little Further

With lots more uncertainty!


Going back further it was mostly cold
Going Back Further it Was Mostly Cold!

Compelling evidence

natural forcing only

anthropogenic forcing only

natural +anthropogenic forcing

Compelling Evidence?

natural (solar + volcanic) forcing alone does not account for warming in the past50 years

  • "With four parameters I can fit an elephant and with five I can make him wiggle his trunk." — John von Neumann

adding human influences (greenhouse

gases + sulfate aerosols) brings the models and observations into pretty close agreement

Source: Prof. Gross Fall 2013 ECE 333 Notes

And where might temps go
And Where Might Temps Go?

The modelsshow rate of increase valuesof between0.18 to 0.4 C per decade.The rate from1975 to 2005was about 0.2 C per decade.


Brief history of electric power
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

History cont d
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

History cont d1
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