Tuesday, December 6, 2011
1:20 PM | Posted by
Muslim |
TRANSMISSION LINES
Why use high-voltage transmission lines? The best answer to that question is that high-voltage transmission lines transport power over long distances much more efficiently than lower-voltage distribution lines for two main reasons. First, high-voltage transmission lines take advantage of the power equation, that is, power is equal to the voltage times current.
Therefore, increasing the voltage allows one to decrease the current for the same amount of power. Second, since transport losses are a function of the square of the current flowing in the conductors, increasing the voltage to lower the current drastically reduces transportation losses. Plus, reducing the current allows one to use smaller conductor sizes.
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Module(3)
Thursday, June 30, 2011
The photovoltaic (sometimes called “voltaic” for short) type of solar power plant converts the sun’s energy directly into electrical energy. A photovoltaic array is shown in above figure. This type of production uses various types of films or special materials that convert sunlight into direct current (DC) electrical energy systems.
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Module(2)
Wind generation has increased in popularity and the technology has improved tremendously over the last decade. In the year 2006, the total installed capacity of U.S. wind generation was about 11,000 MW. Wind turbine generators are continuing to be installed worldwide. The total installed capacity worldwide is about 74,000 MW. Above figure shows typical wind generators.
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Module(2)
Wednesday, June 29, 2011
The combined-cycle power plant consists of two means of generation: combustion turbine and steam turbine. The combustion turbine is similar to a jet engine whose high-temperature and high-pressure exhaust spins a turbine whose shaft is connected to a generator. The hot exhaust is then coupled through a heat recovery steam generator (HRSG) that is used to heat water, thus producing steam to drive a secondary steam turbine generator.
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Module(2)
Combustion turbine (CT) power plants burn fuel in a jet engine and use the exhaust gasses to spin a turbine generator. The air is compressed to a very high pressure. Fuel is then injected into the compressed air and ignited, producing high-pressure and high-temperature exhaust gasses. The exhaust is moved though turbine blades much the same way steam is moved through turbine blades in a steam power plant.
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Module(2)
Pumped storage hydro power production is a means of actually saving electricity for future use. Power is generated from water falling from a higher lake to a lower lake during peak load periods. The operation is reversed during off-peak conditions by pumping the water from the lower lake back to the upper lake. A power company can obtain high-value power during peak-load generation periods by paying the lower cost to pump the water back during off-peak periods. Basically, the machine at the lower level is reversible; hence, it operates as a hydro-generator unit or a motor– pump unit.
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Module(2)
Hydroelectric power plants capture the energy of moving water. There are multiple ways hydro energy can be extracted. Falling water such as in a penstock, flume, or waterwheel can be used to drive a hydro turbine. Hydro energy can be extracted from water flowing at the lower section of dams, where the pressure forces water to flow. Hydroelectric power generation is efficient, cost effective, and environmentally cooperative. Hydro power production is considered to be a renewable energy source because the water cycle is continuous and constantly recharged.
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Module(2)
the last technique for steam power plants is solar power plants.
Solar power plants are environmentally friendly as they produce no pollution.
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Module(2)
Geothermal power plants use hot water and/or steam located underground to produce electrical energy. The hot water and/or steam are brought to the surface where heat exchangers are used to produce clean steam in a secondary system for use with turbines. Clean steam causes no sediment growth inside pipes and other equipment, thereby minimizing maintenance.
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Module(2)
BOILING WATER REACTOR (BWR)
Above figure shows a boiling water reactor (BWR). Again, there is a reactor building or containment shell where the nuclear reactor and some of its complement equipment are located. The reactor housing of the BWR tends to be larger than the PWR and looks almost like an inverted lightbulb.
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Module(2)
there are two different types of light-water reactor designs
used, the pressurized water reactor (PWR) and the boiling water reactor (BWR). we will discuss (PWR) this lesson and (BWR) in the next lesson .
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Module(2)
In nuclear power plants such as the one shown in above figure, a controlled nuclear reaction is used to make heat to produce steam needed to drive a steam turbine generator.
the Question now is What is Nuclear Energy?
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Module(2)
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| Coal power plant |
Steam turbine power plants can use coal, oil, natural gas, or just about any combustible material as the fuel resource. However, each fuel type requires a unique set of accessory equipment to inject fuel into the boiler, control the burning process, vent and exhaust gases, capture unwanted byproducts, and so on.
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Module(2)
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| Steam turbine and electric generator |
High-pressure and high-temperature steam is created in a boiler, furnace, or heat exchanger and moved through a steam turbine generator (STG) that converts the steam’s energy into rotational energy that turns the generator shaft. The steam turbine’s rotating shaft is directly coupled to the generator rotor. The STG shaft speed is tightly controlled for it is directly related to the frequency of the electrical power being produced.
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Module(2)
Monday, June 27, 2011
Power generation plants produce the electrical energy that is ultimately delivered to consumers through transmission lines, substations, and distribution lines. Generation plants or power plants consist of three-phase generator(s), the prime mover, energy source, control room, and substation. The generator portion has been discussed already in the previous lessons. The prime movers and their associated energy sources are the focus of this lesson.
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Module(2)
There are two ways to connect three windings that have a total of six leads(the ends of the winding wires) symmetrically. The two symmetrical connection configurations of a three phase generator (or motor) are called delta and wye(some people say Star).
Above Figure shows these two connection types. Generators usually have their stator windings connected internally in either a delta or wye configuration.
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Module(2)
when we speak about the generator speed we have to speak about two important factors.first factor is Rotor poles
Rotor Poles
Increasing the number of magnetic poles on the rotor enables rotor speeds to be slower and still maintain the same electrical output frequency. Generators that require slower rotor speeds to operate properly use multiple-pole rotors.
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Module(2)
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Module(2)
We will now study how a generator works.you now know the faraday's law. Keep in mind that virtually all generators in service today have coils of wire mounted on stationary housings, called stators, where voltage is produced due to the magnetic field provided on the spinning rotor.
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Module(2)
Before we start Module(2) we need to know two important Physical laws.If you understand this two laws,you will understand how voltage is Generated in Powr stations.you also will know how Electricity is produced and consumed.
Faraday’s Law
AC voltage is generated in electric power systems by a very fundamental physical law called Faraday’s Law. Faraday’s Law represents the phenomena behind how electric motors turn and how electric generators produce electricity.
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Module(2)
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