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History of Power Systems (c) M. A. El-Sharkawi, university of Washington 1 Road to Power Systems • Greek philosopher Thales of Miletus (around 600 BC) – When rubbing fur on amber, electric charge is built up on the amber. – The charge attracts light objects such as hair. (c) M. A. El-Sharkawi, university of Washington 2 Road to Power Systems • English physician William Gilbert (1544-1603) – Was the first to use the term electric • Derivation from the Greek word for amber (ηλεκτρον). • The word amber itself was derived from the Arabic word Anbar. (c) M. A. El-Sharkawi, university of Washington 3 Road to Power Systems • Italian scientist Alessandro Guiseppe Antonio Anastasio Volta (1745-1827) – Galvanism occurred whenever moist is placed between two different metals. – The first battery was invented in 1800. – Today we use the unit Volt for the electric potential in honor of this great Italian inventor. (c) M. A. El-Sharkawi, university of Washington 4 (c) M. A. El-Sharkawi, university of Washington 5 Road to Power Systems • French mathematician and physicist André-Marie Ampère (1775-1836). – Explain the link between magnetism and electric currents. • The basis of electromagnetic devices: motors, generators, transformers, etc. – Today we use Ampere as a unit for electric current in honor of this French scientist. (c) M. A. El-Sharkawi, university of Washington 6 Road to Power Systems • German scientist George Simon Ohm (1789-1854) – Related electric current to the electromotive force. – His work is known as Ohm's law. – The theory opened the door wide for circuit anaysis and designs. – We now use Ohm as the unit for resistance (or impedance) in his honor. (c) M. A. El-Sharkawi, university of Washington 7 Road to Power Systems • English chemist and physicist Michael Faraday (1791-1867). – Developed the foundations of all electromechanical theories. – In his memory, the unit of capacitance (farad) is name after him. (c) M. A. El-Sharkawi, university of Washington 8 Road to Power Systems • French instrument maker Hippolyte Pixii (1808-1835) – Not widely known inventor – Built the first generator (or dynamo). – His machine, named magnetoelectric, was later developed into the electrical generators. (c) M. A. El-Sharkawi, university of Washington 9 Pixii’s Generator (c) M. A. El-Sharkawi, university of Washington 10 Road to Power Systems • Italian Antonio Pacinotti (18411912) – 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. (c) M. A. El-Sharkawi, university of Washington 11 Stanley’s Transformer (c) M. A. El-Sharkawi, university of Washington 12 Road to Power Systems • English Electrical Engineer and Physicist John Ambrose Fleming (1849-1945) • invented the first electronic device – two electrodes inside a vacuum tube. One electrode was a heated filament (called Cathode) that emitted electrons and the other (called Anode) collected them – This was the first vacuum tube diode • Lee DeForest (American) later wrapped a thin grid of wires around the cathode. – By applying a small negative voltage to the grid he managed to control the amount of electrons reaching the Anode. – This was the first vacuum tube amplifier (c) M. A. El-Sharkawi, university of Washington 13 Vacuum Tube (c) M. A. El-Sharkawi, university of Washington 14 Road to Power Systems • The Ukranian Julius Edgar Lilienfeld (1881-1963) • Professor of Physics at the University of Leipzig in Germany • In 1926, he discovered the field effect principals of the solid state material • In 1947, Bell Laboratories physicists Walter Houser Brattain (1902-1987), John Bardeen (1908-1991), and William Bradford Shockley (1910-1989) developed the first practical bipolar transistor based on Lilienfeld discovery • These discoveries led the way to the power electronics revolution (c) M. A. El-Sharkawi, university of Washington 15 Thomas Edison and Nicholai Tesla (c) M. A. El-Sharkawi, university of Washington 16 Thomas Edison • Born on February 11, 1847, in Milan, Ohio, and died on 1931 at age 84. • Had 1093 patents. – his first patent was granted at age 21 – his last one was at age 83. – an average of about 1.5 patent per month. (c) M. A. El-Sharkawi, university of Washington 17 Thomas Edison • In 1874 at age 27, Edison opened his first research and development laboratory in Newark, New Jersey. • In 1876, he moved the facilities to Menlo Park, NJ – The finest research and development laboratories in the world at that time. (c) M. A. El-Sharkawi, university of Washington 18 Thomas Edison • The electric light bulb is one of Edison’s most important inventions (1878). (c) M. A. El-Sharkawi, university of Washington 19 Thomas Edison • Edison received the U.S. congressional gold medal for career achievements in 1928. • When Edison died on 1931, people world wide dimmed their lights in honor of his man’s achievements. (c) M. A. El-Sharkawi, university of Washington 20 Nikola Tesla • Nikola Tesla was born in Smiljan, Croatia on July 9, 1856. • During his career, Tesla had over 800 patents. • Tesla moved from Europe to the United States in 1884. • He worked for Thomas Edison in his lab as a research assistant. (c) M. A. El-Sharkawi, university of Washington 21 Tesla’s ac motor (c) M. A. El-Sharkawi, university of Washington 22 Nikola Tesla • Tesla received the IEEE Edison Medal in 1917, the most coveted electrical prize in the United States. • Tesla was inducted into the Inventor's Hall of Fame in 1975. • In 1956, the term "tesla" was adopted as the unit of magnetic flux density in the MKSA system in his honor. • In 1975, the IEEE Power Engineering Society established the Nikola Tesla Award in his honor. • Tesla died on January 7, 1943. (c) M. A. El-Sharkawi, university of Washington 23 The Battle of ac versus dc Voltage or Current Voltage or Current Time Time (c) M. A. El-Sharkawi, university of Washington 24 The Battle of DC versus AC • Edison system was 100V Direct Current • In September 1882, his Pearl Street plant in lower Manhattan starts operation – the world's first commercial electric lighting power station. – City of Brockton, Massachusetts is the first city to be electrified (1883). (c) M. A. El-Sharkawi, university of Washington 25 Problems With Low Voltage • For the same power, the lower the voltage, the higher is the current. P V I P: Power V: Voltage I: Current (c) M. A. El-Sharkawi, university of Washington 26 Problems With Low Voltage • 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 (c) M. A. El-Sharkawi, university of Washington 27 Line Voltage Drop Rwire Source I Vload VS R Load Vload VS I Rwire Vload VS I R R R Rwire (c) M. A. El-Sharkawi, university of Washington 28 Rwire Wire Resistance : Resistivity of wire l A:cross section of wire A l: length of wire • To reduce the wire resistance, A should increase. However, bigger cross section wires are – more expensive – heavier and would require poles to be placed at shorter spans. (c) M. A. El-Sharkawi, university of Washington 29 Edison’s Options • To have several small cross-section wires feeding areas with high demands. – • To place electrical generators at every neighborhood. – • Expensive solution; more wires for long miles. Impractical and expensive solution. To increase the voltage – Best solution, but the technology to increase the voltage of the dc system was not available then. (c) M. A. El-Sharkawi, university of Washington 30 Tesla’s Solution P V I • 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. • However, adjusting the voltage of dc systems was beyond the technology at that time. (c) M. A. El-Sharkawi, university of Washington 31 Tesla’s Solution • Tesla was aware of the transformer invented by Pacinotti • The transformer can adjust the ac voltage, not the dc • Tesla proposed to rebuild the power system based on ac technology (c) M. A. El-Sharkawi, university of Washington 32 Here Comes the AC! • Main Advantage of AC: – The voltage of AC systems can be changed by transformers. • How about DC? – The transformers cannot change the DC voltage. (c) M. A. El-Sharkawi, university of Washington 33 Tesla’s Solution (AC system) Low Voltage High Voltage Transformer 2 Transmission line Power plant Transformer 1 Low Voltage (c) M. A. El-Sharkawi, university of Washington 34 Tesla’s Solution (ac system) Rwire Source I VS V1 Vload V2 Transformer 1 (c) M. A. El-Sharkawi, university of Washington Transformer 2 R Load 35 Example VS = 100 V, R = 1 , Rwire = 0.5 Compute the following: 1. The voltage at the load side 2. The percentage of the load voltage with respect to the source voltage 3. The energy consumed by the load during a 10 hour period 4. The maximum load (minimum resistance) if the load voltage cannot be reduced by less than 10% of the source voltage. 5. The energy consumed by the new load during a 10 hour period. (c) M. A. El-Sharkawi, university of Washington 36 Solution Vload Vs 100 66.67 V Rwire 0.5 1 1 1 R Vload 66.67 % Vs 2 Vload 66.67 2 EPt t 10 44.444 kWh R 1 (c) M. A. El-Sharkawi, university of Washington 37 Solution Vload Vs 1 Rwire 1 R 1 0 .9 0 .5 1 R EPt 2 load V R 0.9* 100 t 2 4.5 (c) M. A. El-Sharkawi, university of Washington 10 18.0 kWh 38 Edison’s Reaction to Tesla’s Idea • Edison was not impressed by Tesla’s AC system because of its unsafe high voltage wires that would pass through residential areas. • Most historians believe that Edison’s rejection to the AC system was because he had too much money invested in the DC infrastructure. (c) M. A. El-Sharkawi, university of Washington 39 Edison’s Reaction to Tesla’s Idea • Edison used unconventional methods to convince the public that Tesla’s high voltage ac system was too dangerous. – Live demonstrations where he deliberately electrocuted animals such as puppies, cats, horses and even elephants. – Edison went so far as to convince the state of New York to use an electric chair powered by high voltage ac system to execute condemned inmates on the death row. Most historians believe that his real motive was to further tarnish the safety of the ac system. (c) M. A. El-Sharkawi, university of Washington 40 Edison high voltage test (c) M. A. El-Sharkawi, university of Washington 41 And the Winner is (c) M. A. El-Sharkawi, university of Washington 42 World at Night (c) M. A. El-Sharkawi, university of Washington 43 World Electric Energy Capacity 20,000 19,000 TWh=109 kWh TWh 18,000 17,000 16,000 15,000 14,000 13,000 12,000 1994 1996 1998 2000 2002 2004 2006 Year (c) M. A. El-Sharkawi, university of Washington 44