Lecture 1: Introduction to Power Generation, Transmission, and Distribution PDF

PPT14 Principle of Power Generation, Transmission and Distribution Lecture 1 Introduction Prepared by: ENGR. LARA ANDREA D. VILLASANTA, REE, RME In order to understand this...  Outline...

PPT14 Principle of Power Generation, Transmission and Distribution Lecture 1 Introduction Prepared by: ENGR. LARA ANDREA D. VILLASANTA, REE, RME In order to understand this...  Outline History E&M Principles Types of Power Plants Power System Components  Brief History of Electric Power Early 1880’s – Edison introduced Pearl Street dc system in Manhattan supplying 59 customers. 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. 4  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” (cheapest for one firm to produce everything because of “economies of scale”); states step in to begin regulation. By 1920’s – Large interstate holding companies control most electricity systems. 5  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passes Public Utility Holding Company Act to establish national regulation, breaking up large interstate utilities (repealed 2005). 1935/6 – Rural Electrification Act brought electricity to rural areas. 1930’s – Electric utilities established as vertical monopolies. 6  History, cont’d -- 1970’s 1970’s brought inflation, stagnation of demand growth, increased fossil-fuel prices, calls for conservation and growing environmental concerns. Increasing prices replaced decreasing ones. In that context, U.S. Congress passed Public Utilities Regulatory Policies Act (PURPA) in 1978, which mandated utilities must purchase power from independent generators located in their service territory (modified 2005). PURPA introduced some competition. 7  History, cont’d – 1990’s & 2000’s 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. Texas followed suit in 1996 and 1999. Result over the last few years has been a dramatic restructuring of electric utility industry (for better or worse!) Energy Bill 2005 repealed PUHCA; modified PURPA. 8  Principles energy = “the ability to do work” measured in Joules power = rate of energy generation or use measured in Watts = Joules / sec current = rate of charge flow Water pipes analogy measured in Amps voltage = “pressure” pushing current measured in Volts  Moving Electrons Create Magnetic Fields electromagnets DEMO: electromagnet & compass on overhead  Magnetic Fields Push on Moving Electrons or moving magnetic fields push on stationary electrons generators speakers DEMO: force on current apparatus DEMO: make current with magnet & coil  The Purpose of a Power Plant is to Turn a Loop of Wire in a Magnetic Field Why do we need “mechanical means”? It takes a force to push a conductor through a magnetic field — inertia won’t due. Car alternator... DEMO: copper tube DEMO: Genecons DEMO: Al plate and mag Powerhouse @ Hoover Dam  Types of Power Plants Classification by the “mechanical means” used to turn the generator... Thermal (water steam by burning Coal, Oil, NG) Nuclear (water steam by Uranium or Plutonium fission) Geothermal Hydroelectric (falling water) Wind Solar... Thermal Power Plant Nuclear Power Plant Hydroelectric Power Plant Hoover Itaipu  Power Plant Components ELECTRICAL MECHANICAL Generators & Turbines Conveyors Transformers Silos Switches Boilers Busses Scrubbers & Stacks Circuit Breakers Pumps Capacitor Banks Cooling Towers  At the front end Conveyors Boilers Scrubbers and Stacks Pumps Cooling Towers  Generators The whole point of the power plant is to turn the generators to produce electrical energy.  Turbines Difficult to replace A spare is often kept  Busses uninsulated electrical conductors large cross-section = low resistance must be far from ground and other components to avoid arcing flirthermography.com Switches & Switchyards http://www.learnz.org.nz/trips06/images/big/b-switchyard.jpg Transformers PURPOSE: to change the voltage – increase = “step-up” – decrease = “step-down” Often run hot, must be cooled, prone to explode. – oil inside – cooling fins and fans – blast walls DEMO: pass around small transformer DEMO: two coils, one with meter, other with battery  Circuit Breakers PURPOSE: stop the flow of current if too much flows (due to short circuit or excess demand) DEMO: blow room breaker 230 kV breaker  Capacitor Banks Purpose: to smooth out spikes or “glitches” in the line voltage. DEMO:charge/discharge a cap DEMO:Lenz’s Law Transmission Lines and the “grid”  Why are High Voltages Used? Transmission lines typically carry And why is that so? Transformers voltages of 110 kV, 230 kV, or cannot add energy, so if the even higher. The wires are not voltage is increased, the current insulated, so they are kept high (in amps) must decrease. The off the ground and well separated charges flowing through the wires from each other, to prevent constantly collide with the atoms, arcing (sparks) and injury or losing energy and heating the people or animals. wire. We call this resistance. Recall that the power (energy per Why use such high voltages? time) lost to that heating is given Using very high voltages on the by the equation P=I2R. If the transmission lines reduces the current is reduced, the power amount of energy wasted heating used in heating the wire is up the wires. reduced. Transformer Sub-Station Purpose: to reduce the very high voltages from the transmission lines (>100kV) to intermediate voltages used to serve an individual TTR Substations, Inc. town or section of a city (typically 66 kV or 33 kV) To your house... smaller transformers (on power line poles or green boxes on the ground) reduce the voltage further to the 240V delivered to individual homes  Simple Power System Every large-scale power system has three major components: – generation: source of power, ideally with a specified voltage and frequency – load or demand: consumes power; ideally with a constant resistive value – transmission system: transmits power; ideally as a perfect conductor Additional components include: – distribution system: local reticulation of power (may be in place of transmission system in case of microgrid), – control equipment: coordinate supply with load. 35  Complications No ideal voltage sources exist. Loads are seldom constant and are typically not entirely resistive. Transmission system has resistance, inductance, capacitance and flow limitations. Simple system has no redundancy so power system will not work if any component fails. 36  Power Power: – Instantaneous rate of consumption of energy, – How hard you work! Power = voltage x current for dc Power Units: Watts = amps times volts (W) kW – 1 x 103 Watt MW – 1 x 106 Watt GW – 1 x 109 Watt Installed U.S. generation capacity is about 1000 GW ( about 3 kW per person) Maximum load of Austin about 2500 MW. Maximum load of UT campus about 50 MW. 37  Energy Energy: – Integration of power over time, – Energy is what people really want from a power system, – How much work you accomplish over time. Energy Units: Joule = 1 watt-second (J) kWh – kilowatthour (3.6 x 106 J) Btu – 1055 J; 1 MBtu=0.292 MWh U.S. annual electric energy consumption is about 3600 billion kWh (about 13,333 kWh per person, which means 38  Power System Examples Interconnection: 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 America (five, if you count Alaska), 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 and higher voltages used in electric vehicles. Battery operated portable systems. 39  Goals of Power System Operation Supply load (users) with electricity at – specified voltage (120 ac volts common for residential), – specified frequency, – at minimum cost consistent with operating constraints, safety, etc. 40