Advanced Power Systems

1
Advanced Power Systems

• ECE 0909.402-02, 0909.504-02
• Lecture 4 Electric Generation Power Industry
• 12 February 2007
• Dr. Peter Mark Jansson PP PE
• Associate Professor Electrical and Computer
  Engineering

2
Aims of Todays Lecture

• Overview of Chapter 3 concepts
• Heat engines, steam cycles and efficiencies
• GTs, CCs, Baseload Plants and LDCs
• Polyphase synchronous generators
• Electric industry today (NUGS, IPPs, QFs)
• Regulatory impacts (PUHCA, PURPA, FERC)

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Aims of Todays Lecture (cont)

• 15 minute stretch break at 6
• Introduction to Distributed Generation
  Technologies
• Next Week Guest Lecture by Dr Krishan Bhatia on
  Fuel Cells

4
New homework

• HW 4 due next Monday
• Now posted on web
• 3.6, 3.7, 3.9, 3.10, 3.11, 4.1, 4.2, 4.3, 4.4,
  4.5, 4.6
• Plus article and queries.

5
Polyphase synchronous generators

• How did we arrive at the 3 phase standard for
  generators?
• What does synchronous mean anyway?
• First another look back.

6
History - EM Induction Generators

• 1831 Michael Faradays Electromagnetic Induction
  Experiment

switch
Soft iron ring
battery
N
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First Evolution DC Generator
Faraday 1831
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Second Evolution AC Generator
Pixii 1832
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AC Generator Output
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Lenz Law

• When an emf is generated by a change in magnetic
  flux according to Faraday's Law, the polarity of
  the induced emf is such that it produces a
  current whose magnetic field opposes the change
  which produces it. The induced magnetic field
  inside any loop of wire always acts to keep the
  magnetic flux in the loop constant. In the
  examples below, if the B field is increasing, the
  induced field acts in opposition to it. If it is
  decreasing, the induced field acts in the
  direction of the applied field to try to keep it
  constant.

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Lenz Law
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synchronous

• A fixed-speed machine (generator or motor) that
  is synchronized with the utility grid to which it
  is connected
• To generate 60Hz a two pole generator would need
  to rotate at 3600 rpm in order to provide
  synchronous output

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Multi-pole machines

• Two pole machines have 1 N and 1 S pole on their
  rotor and their stator (Fig 3.13)
• Single Phase Four pole machines have 4 poles
  (rotor 2 N and 2 S) on both rotor and stator

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Synchronous machines LM 1

• How fast would a generator that is synchronized
  with the utility grid in France need to rotate
  to
• Generate 50Hz if it had four (4) poles?

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Finally the 4-pole, 3-? Wye synchronous generator

• For balanced power input and output
• Input from the steam turbine
• Output to the electric grid/loads
• What is the number of poles per phase?
• What will be the rotation speed of this most
  common generator in the US? (Fig 3.14 p 122)

Write Your Answer as LM 2
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GTs, CCs, Baseload Plants

• To overcome Lenzs Law all of these generators
  require motive horsepower
• Gas Turbines
• Steam Turbines
• Hydro Turbines

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Steam Electric Power Plant
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Heat Rate
In the power industry the heat rate is more often
expressed in Btu/kWh
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Steam power plant schematics

• Fig 3.18, p. 128
• Fig 3.19, p. 129
• Fig 3.18, p. 131

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Typical ? and Heat Rates

• Coal Plant Older ?0.3 (HR 11,375 Bth/kWh)
• Coal Plant Newer ?0.35 (HR 9,750 Bth/kWh)
• CT (typical) ?0.3 (HR 11,375 Bth/kWh)
• CT Newer ?0.40 (HR 8,530 Bth/kWh)
• STIG ?0.45 (HR 7,580 Bth/kWh)
• CC ?0.50 (HR 6,825 Bth/kWh)
• Cogeneration ?0.85 (HR 4,015 Bth/kWh)

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Thermal Plant Impacts

• Each kWh from 33.3 coal fired plant
• 146 kg of Cooling Water raised 10o C
• 1.09 kg CO2
• 0.396 kg of Coal consumed
• Flyash and bottom ash to be disposed of

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Other power plant schematics

• Fig 3.21, p. 132
• Fig 3.22, p. 133
• Fig 3.23, p. 134
• Fig 3.24, p. 135
• Fig 3.25, p. 136

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LDCs

• What is a Load Duration Curve?
• Every load hour of the year (8760 hours of system
  load data) arranged from the highest demand to
  the lowest demand
• A key design tool in determining how to match
  generation mix with load profiles of the utility
  company

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US Industry structure - utilities

• Traditionally given a monopoly franchise
• In exchange, subject to regulation
• State and Federal
• Most are distribution only
• Many remain vertically integrated (G, T D)
• 3200 US electric utilities
• Four types

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US Industry structure - utilities

• Investor Owned (IOU)
• 5, generate gt 2/3 of power
• Federally Owned
• TVA, BPA, US Army Corps, sell power non-profit
• Other Publicly Owned
• Munis, state, 2/3 of this type, lt9
• Coops originally set up by REA

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US Industry structure nonutilities

• Nonutility Generators (NUGs)
• Prior to 1940 20 of power
• By mid-1970s a small fraction
• Late 1980s-1990s as regulators changed rules
• Some utilities had to sell off their assets
• Growth of NUGS in some states was significant
• By 2001 NUGs were delivering over 25

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Regulatory impacts (PUHCA, PURPA, EPAct, FERC
Orders 888 2000)

• Public Utility Holding Company Act of 1935
• 1929 16 holding companies controlled 80 of US
  utilities
• Financial abuses in many large companies
• Stock Market Crash left many in bankruptcy
• PUHCA provided regulation and break-up of large
  HCs
• Public Utility Regulatory Policies Act of 1978
• 1973 oil crisis led to large rise in utility
  retail rates
• PURPA set up to encourage energy efficiency and
  renewable energy technologies

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Regulatory impacts (PUHCA, PURPA, EPAct, FERC
Orders 888 2000)

• Energy Policy Act of 1992
• Created new entity EWG
• EPAct set up to begin opening up the grid to
  allow competitive generators to compete for
  customers hopefully to drive down costs and
  prices
• FERC Orders 888 2000
• 888 Requires IOUs to publish nondiscriminatory
  tariffs that can be applied to all
  generators/competitors
• 2000 Calls for the creation of regional
  transmission organizations RTOS to control
  transmission system operation

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Industry today (NUGS, IPPs, QFs)

• NUG non-utility generator
• IPP non-PURPA-regulated NUGs
• QF meet PURPA requirements for efficiency or
  renewable energy use

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(No Transcript)
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California Meltdown

• Open market on wholesale in March 98
• First 2 years good prices (35/MWh)
• 40 of Californias generation sold
• August 2000 - 170/MWh (800/MWh)
• In 2000 customers paid 5x 1999 prices
• Due to low imports of hydro and adjacent power
• Market manipulation by Enron and 30 others

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Californias end of open markets

• Wholesale market stays high into 2001
• January 01 rolling blackouts (1500/MWh)
• By Feb customers had paid more than 99
• By May PGE declares bankruptcy
• CalPX market shutdown
• FERC intervenes with price caps (Sum 01)

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August 2003 Blackout

• MISO in charge of Ohio transmission system was a
  key player in failure to control isolated
  reactive power problem and loss of major
  transmission service in Northern Ohio.
• gt50 million people were out of service for
  extended period while the grid was restarted
• Largest widespread blackout in US history
• Nationally there is a major rethink of
  deregulation

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LM 3

• Connect each event with its year
• A) Largest US Blackout 1978
• B) PURPA 2001
• C) California Meltdown 2003
• D) FERC Order 888 1992
• E) Public Utility Holding Co Act 1999
• F) FERC Order 2000 1996
• G) Energy Policy Act 1935

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Distributed Generation

• Economies of Scale Begin a Reversal

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Typical Power Generator Output

• Large Hydropower Installation 10 GW
• Nuclear 1,100 MW
• Coal 600 MW
• CC Gas Turbine 250 MW
• Simple Cycle CT 60 - 150 MW
• Molten Carbonate Fuel Cell - 4,000 kW
• Wind Turbines 10 1500 kW
• Fuel Cell (automotive) 60 kW
• Microturbine 30 kW
• Residential PEM Fuel Cell 5 kW
• Residential PV System 3-5 kW

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Typical End Use Consumption

• Laptop Personal Computer 20 Watts
• Desktop Personal Computer 100 Watts
• Residential Household (ave.) 1-2 kW
• Commercial Customer (ave.) 10 kW
• Supermarket 100 kW
• Office Building 500 1,000 kW
• Large Factory 1 MW
• Peak Use of Largest Buildings 100 MW

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What is Distributed Generation?

• Small-scale power generation
• Typically less than 50 MW
• Located in the distribution system of a utility
• Often customer (not utility) owned
• May include use of waste heat

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Cogeneration and CHP

• Capturing and using waste heat while generating
  electricity
• CHP combined heat and power

40
HHV and LHV

• Often during combustion of a fuel, latent heat is
  generated. If we include the latent heat in our
  calculations (i.e., if our furnace or system is
  able to capture that heat and make it useful) we
  want to use the higher heating value of our fuel.
• HHV high(er) heating value, gross heat of
  combustion
• LHV low(er) heating value, net heat of combustion

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HHV and LHV tables

• GAS HHV LHV (in Btu/lb) RATIO
• Methane 23,875 21,495 90
• Propane 21,669 19,937 92
• Natural Gas 22,500 20,273 90
• Gasoline 19,637 18,434 94
• No. 4 oil 18,890 17,804 94

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Power plant efficiency

• ? output power / input fuel energy
• Large Centralized power stations
• ? is typically based upon HHV of fuel
• Distributed Generation power stations
• ? is often based upon LHV of fuel
• To convert

43
LHV / HHV example

• A small micro-power plant has a fuel input of
  12,500 Btu (LHV) per kWh of electricity it
  generates. Find its LHV and HHV efficiencies if
  we assume it runs on gasoline
• Gasoline LHV/HHV 0.9378
• Efficiency 3412 Btu/kWh / Heat Rate
• ? LHV 3412 / 12,500 27.3
• ? HHV ? LHV x LHV/HHV 27.3 x 0.9378
  25.6

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LM 4 - You try it

• A micro-power plant has a fuel input of 14,500
  Btu (HHV) per kWh of electricity it generates.
  Find its LHV and HHV efficiencies if we assume it
  runs on methane
• Methane LHV/HHV 0.9003
• Efficiency 3412 Btu/kWh / Heat Rate

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Microturbines

• Very small gas turbines (NG or waste gas)
• Typically 500 W to 300 kW
• Typical Microturbine Components
• Compressor
• Turbine
• P-M generator
• Combustion chamber
• Heat exchanger (recuperator)

Often all on one shaft
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Leading Manufacturers

• Capstone Turbine Corporation
• One moving part common shaft 96,000 rpm
• C30 - 30 kW unit
• ? LHV 26, Heat Rate 13,100 Btu/kWh
• C60 - 60 kW unit
• ? LHV 28, Heat Rate 12,200 Btu/kWh
• Elliot Microturbines
• TA100R - 105 kW unit
• ? LHV 29, Heat Rate 11,770 Btu/kWh
• 172 kW thermal potential for hot water ? TTE gt
  75

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Elliot Microturbine Application

• The Elliot TA 100A produces its full output of
  105 kW when burning 1.24 x 106 Btu/hr of natural
  gas. Its waste heat is used to supplement an
  existing boiler by raising its temperature from
  120 -140 oF. It operates for 8000 hours/year.
• A) If 47 of the fuel is transferred to boiler
  what should flow rate be?
• B) If boiler is 75 efficient and NG is 6 per
  MMBtu how much money will microturbine save in
  displaced fuel?
• C) If electric costs 8 / kWh what is annual
  savings?
• D) If OM is 1,500 per year what are net
  savings?
• E) If microturbine costs 220,000 what is Initial
  RR and SPB?

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LM 5

• A) If we can not use the waste heat is it
  economical to install a microturbine in this
  application?
• (assume you require lt 10 yr Simple Payback)
• B) What if your electric costs are 11 / kWh?
• C) What is lowest price electricity can be to
  still meet your 10 yr simple payback requirement?

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Reciprocating IC Engines

• Very small piston-driven, 4 stroke ICEs
• Typically 500 W to 6,500 kW
• Typical Operation
• Intake, Compression, Power, Exhaust
• Spark ignited (Otto cycle)
• Compression ignition (Diesel cycle)
• Multi-fuel gasoline, natural gas, kerosene,
  propane, fuel oil, alcohol, waste gas

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Advanced Reciprocating Engines

• Current design is cheapest of all DGs
• Efficiencies are good
• Today electrical ? 37-40
• Turbocharged Thermal fuel ? horsepower
• Otto cycle ? LHV 41, ? HHV 38
• Diesel cycle ? LHV 46, ? HHV 44
• ARES Targets ? ELECTRIC 50, ? CHP 80
• HRSG can increase overall ? CHP 85

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Stirling Engines

• Energy is supplied from outside the system
• External combustion, can run on any heat source
• Invented in Scotland and patented in 1816
• Used quite extensively until early 1900s
• Eliminated from market by efficient technologies
• Current efficiencies relatively low lt 30
• Size ranges from 1 25 kW
• No explosions, relatively quiet devices
• Good match with solar dishes
• Four states of Transition in Stirling Cycle

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New homework

• HW 4 due next Monday
• Now posted on web
• 3.6, 3.7, 3.9, 3.10, 3.11, 4.1, 4.2, 4.3, 4.4,
  4.5, 4.6
• Plus article and queries.