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PowerPower: Instantaneous consumption of energy
Power Unit: Watt (W)
Installed Saudi generation capacity is about 50 GW (about 1.8 kW per person)
Maximum load of the Eastern Province of Saudi Arabia is about 12.5 GW
Energy
Energy: Integration of power over time; energy is what people really want from a power system
Saudi annual electric energy consumption is about 212 billion kWh (about 7,862 kWh per person, which means on average we each use 0.79 kW of power continuously)
Energy UnitsJoule = 1 Watt-second (J)kWh – Kilowatthour (3.6 x 106 J)
Power System Examples
Power grid: can range from quite small, such as an island, to one covering half the continent
– there are several major “interconnected” ac power systems in Saudi Arabia, each operating at 60 Hz ac. Many other countries, such as all other GCC countries, operate at 50 Hz.
Power System Examples
Airplanes and Spaceships: reduction in weight is primary consideration; frequency is 400 Hz.
Ships and submarines Electric vehiclesBattery operated portable systems
Sources of Energy - US
Source: EIA Energy Outlook 2011
CO2 Emissions (millions of metric tons)
Petroleum: 2598 Natural Gas: 1198Coal: 2115
About 86% Fossil Fuels
In 2009, US got about 0.75%
of its energy from wind and only 0.04% from solar (PV and solar thermal)
Global Warming and the Power Grid, What is Known: CO2 in Air is Rising
Source: http://www.esrl.noaa.gov/gmd/ccgg/trends/
Value wasabout 280ppm in 1800; in 2011 it is 394 ppm
As Has Been Worldwide Temperature
Source: http://www.cru.uea.ac.uk/cru/info/warming/
Baseline is 1961 to 1990 mean
Electricity Market Models
• Vertical Monopoly: One company owns everything: generation, transmission, and distribution
• Deregulated Market: Several companies compete.
Vertical MonopoliesWithin a particular geographic market, the
electric utility had an exclusive franchise
Generation
Transmission
Distribution
Customer Service
In return for this exclusivefranchise, the utility had theobligation to serve all existing and future customersat rates determined jointlyby utility and regulators
It was a “cost plus” business
Utility Restructuring (Deregulation)Driven by significant regional variations in
electric rates (in some parts of the world, like the US and Europe)
Goal of restructuring is to reduce rates through the introduction of competition
Eventual goal is to allow consumers to choose their electricity supplier.
This is similar to the telecommunication market restructuring. Instead of a single service provider, multiple providers compete (STC, Mobily, Zain, etc.).
History
o William Gilbert, English (1544-1603)– Was the first to use the term electric
Derivation from the Greek word for amber. The word amber itself was derived from the
Arabic word عنبر.
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o Alessandro Volta, Italian (1745-1827)– Invented the first battery in 1800. – Today we use the unit Volt for the electric potential.
Historyo André-Marie Ampère, French (1775-1836)
– Understood the relation between electric currents and magnetism. Essential for motors, generators, and transformers.
– Ampere is used as a unit for electric current.
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o George Simon Ohm, German (1789-1854)– Related electric current to the electromotive force (Ohm's law). – The cornerstone for circuit analysis and designs. – Ohm is the unit for resistance.
History
o Michael Faraday, British (1791-1867)– His work set the foundations of all
electromechanical theories. – The unit of capacitance (farad) is named after
him.
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Historyo Antonio Pacinotti, Italian (1841-1912)
– invented a device that had two sets of windings wrapped around a common core.
– This was the basis for the transformers we use today. – Westinghouse further developed the transformer and
had several early models Gaulard and Gibbs transformer developed in 1883 Stanley transformer developed in 1886.
– Meanwhile, Ferranti was developing his own. This created fights over patenting!
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Historyo John Hopkins, British– Patented the three-phase system for
generation and distribution in 1882
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Thomas Edison (1847-1931)
oAmericanoHad 1000+ patents! –his first patent was granted at age 21–his last one was at age 83. –What is Edison’s average patenting rate per
month?! – 1.5 patents/month!!– The most important of which is…
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Nikola Tesla (1856-1943)
o Serbiano 800 patents… only!!o Moved from Serbia to the US in 1884. o Worked for Edison in his lab as a research
assistant.o He left Edison’s lab after a salary dispute!
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Should it be AC or DC?
o Edison system was 100V DCo In September 1882, his plant in New
York started operation– the world's first commercial electric
lighting power station.
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Problems With Low Voltage
o For the same power, the lower the voltage, the higher is the current.
P: PowerV: VoltageI: Current
IVP
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Problems With Low Voltage
o High currents require large cross section wires
– Expensive copper wires– Heavy wires that cannot be easily mounted on
transmission towers– Customers voltage is substantially reduced at heavy
loading conditions
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Wire Resistance
A
lRwire
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o To reduce the wire resistance A should be increased. However, bigger cross section wires are– more expensive– heavier and would require poles to be placed at
shorter spans.
Edison’s Options
o To have several small cross-section wires feeding areas with high demands. – Expensive solution; more wires for long miles.
o To place electrical generators at every neighborhood. – Impractical and expensive solution. – Might be the choice of the future grid, though!
o To increase the voltage– Best solution, but the technology to increase the voltage
of the dc system was not available then.
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Tesla’s Solution
IVP
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o Tesla knew the problem was related to the low voltage (100 V) Edison was using in his dc system. – For same power, increasing the supply voltage reduces the
current.– Hence the voltage drop across the wire could be reduced.
o However, adjusting the voltage of dc systems was beyond the technology at that time.
Here Comes the AC!
o Main Advantage of AC:– The voltage of AC systems can be changed by
transformers.
o How about DC?– The transformers cannot change the DC voltage.
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Power plant Transformer 1
Transmission line
Low Voltage Transformer 2
Low Voltage
High Voltage
Tesla’s Solution (AC system)