January 19, 2016
ECE 498HZ: Power Distribution
System Analysis
Lecture 1: Overview
Hao Zhu
Dept. of Electrical & Computer Engineering
University of Illinois, Urbana-Champaign
haozhu@illinois.edu
Acknowledgements: Ian Dobson (ISU) and Johanna Mathieu (Umich)
Anatomy of a distribution system
 Most importantly, be safe!
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The big picture
[Kersting’s, Fig. 1.1]
 Typically characterized by the distribution substation, its
voltage level and topology
– Transmission: > 110kV (138kV, 345kV, 765kV)
– Sub-transmission: 33-110kV (69kV, 34.5kV)
– Distribution: <33kV (23.9kV, 14.4kV, 13.2kV, 4.16kV)
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A closer look
 Substation
 Regional power plants,
renewable generation
 Radial feeders,
transformers
 Note this illustrates an
European grid
 Why studying it now?
[Wiki Creative Commons MBizon]
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What will be covered?
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Modeling and analysis of distribution system components
Power flow for unbalanced distribution systems
Solving the basic version of unbalanced power flow problem
Emerging areas in distribution systems
How to approach technical papers
 Syllabus
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Characteristics (North America)
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Frequency: 60 Hz
Voltage: <50kV
Power: <100 MW(usually)
Scale: <20 miles (usually)
Lines: overhead and/or underground
Usually operated radially (exception at some cities)
Dominated by loads, not generation (but the landscape is changing)
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Who owns/operates them?
 Investor-owned utilities (Ameren Illinois and Comed)
 Municipal utilities (City Water, Light & Power at Springfield, IL)
 Public utility districts
– Like CWLP except without the taxing authority of a city, usually receiving
“federal power”, e.g., Bonneville Power Administration (BPA), and
Tennessee Valley Authority (TVA)
 Rural co-operatives (Association of Illinois Electric Coops)
 Regulated by state commissions (Illinois Commerce Commission)
– Profits (how do them make money?)
– Technical requirements (frequency, voltage, reliability metrics, ect.)
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Early electricity delivery
 Early 1880’s – Edison introduced Pearl Street dc system in
Manhattan supplying 59 customers within a one mile radius
 1893 – First 3-phase transmission line operating at 2.3 kV, 12 km
in Southern California
 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);
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
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Early electric loads
 Three main types of loads:
– Consumer (residential): lights,
irons, kitchen appliances
– Traction (street cars)
– Industrial (motors)
 Utilities would advertise the
benefits of electricity
– Sometimes they’d even give
away appliances
Metropolitan Theater, now the
Metropolitan Opera, Program p.32,
1918. [UW Digital Libraries, Courtesy
of Kevin Schneider (PNNL)]
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Electrification Trends
 Electric street cars
– Major revenue source of utilities in early 1900s
– Declining, due to automobiles, in 1930s
 Industrial plants (most manufacturing factories)
– <5% electrified in 1900
– >75% electrified in 1930
 Rural electrification
– 1930s: 90% of people in cities, 10% of people in rural areas had electricity
– 1935: Rural Electrification Administration (part of the New Deal) develops
rural electric coops that have powered farming
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Load growth
 More population
 Higher per-capita consumption
– Appliances
– Air conditioning
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Commercial loads: more stores and commercial buildings
Industrial loads: post-WWII boom
Farms/Agriculture (Water pumping!)
Or even for water delivery systems in this sense
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Growth of electricity generation
 Growth of fuels used to produce electricity in US reflects growth of
loads from 1950 to 2015 (units: Billion Kilowatthours)
– Footnote a: Conventional hydroelectric power, wood, waste,
geothermal, solar/PV, and wind
[Source: EIA, Monthly Energy Review, Dec. 2015, Fig. 7.2]
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The start of competition
 1970’s brought inflation, increased fossil-fuel prices, calls for
conservation and growing environmental concerns
 Increasing rates
 As a result, U.S. Congress passed Public Utilities Regulator
Policies Act (PURPA) in 1978, which mandated utilities must
purchase power from independent non-utility producers located in
their service territory (modified 2005)
– Enabled co-generation from large commercial/industrial customers, or
even renewable generation
 PURPA introduced some competition
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Deregulation
 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!)
 Several areas within the country developed competitive energy
markets
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Utility Restructuring
 Driven by significant regional variations in electric rates through
the introduction of competition
 Eventual goal is to allow consumers to choose their electricity
supplier
 Two events affected the process of deregulation
– California electricity crisis 2000-01(Enron Crisis Timeline by FERC)
– Northeast blackout of 2003 (Final report)
https://www.ferc.gov/industries/electric/indus-act/wec/chron/chronology.pdf
http://energy.gov/sites/prod/files/oeprod/DocumentsandMedia/BlackoutFinal-Web.pdf
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2003 Northeast blackout
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Grid operators
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NERC reliability regions
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New changes in policy
 Energy Policy Act of 2005
– Utilities must provide net metering to customers who request it
– The fluids used for Hydraulic fracturing “fracking” were exempt from the
Clean Air Act, the Clean Water Act, the Safe Drinking Water Act, and the
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980.
 Energy Independence and Security Act of 2007
– Incentives for electric vehicles, and hybrids
– Increased efficiencies for light bulbs (effectively banning incandescents)
– New efficiency standards for appliances, motors, buildings, etc.
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More recently
 American Recovery and Reinvestment Act of 2009 (“The Simulus”)
– Energy infrastructure investment
• Smart meters
• Transmission upgrades
• Technology demonstration projects
– Research funding
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Illinois utility companies
 Ameren Illinois
– Serving central and south Illinois
– Part of the Mid-continent Independent System Operator (MISO)
 Comed
– Serving Chicago and Northern Illinois
– Part of PJM Interconnection (since May 2004), interconnected with
American Electric Power (AEP) at Ohio
 Also municipal and co-ops
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Illinois electricity profile
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