Tuesday, 8 May 2018

How To Generate Electricity In Hydro Power Plant??

How To Generate Electricity In Hydro Power Plant?? 



Full Process Of To Produce The Power In The Hydro Power Station Using The Water And Full Description About The Hydro Power Station Differents Parts Which A Helping To Generate Electricity!! 



A Generating Station which utilises the potential energy of water at a high level for the generation of electrical energy is known as a Hydro Electric Power Station.






Hydro-Electric Power Stations are generally located in hilly areas where dams can be built conveniently and large water reservoirs can be obtained.

In a hydro-electric power station, water head is created by constructing a dam across a river or lake. From the dam, water is led to a water turbine. 






The water turbine captures the energy in the falling water and changes the Hydraulic Energy (i.e., product of head and flow of water) into mechanical energy at the turbine shaft.


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The turbine drives The Alternator which converts mechanical energy into electrical energy.





Hydro-electric power stations are becoming very popular because the reserves of fuels (i.e., coal and oil) are depleting day by day.

They have the added importance for flood control, storage of water for irrigation and water for Drinking Purposes.




Schematic Arrangement of Hydro-electric Power Station


a hydro-electric power station simply involves the conversion of hydraulic energy into electrical energy, yet it embraces many arrangements for proper working and efficiency.


The schematic arrangement of a Modern hydro-electric Plant is shown in Figer.





The dam is constructed across a river or lake and water from the catchment area collects at the back of the dam to form a reservoir.


A Pressure Tunnel is taken off from the reservoir and water brought to the valve house at the start of the penstock.

The valve house contains main sluice valves and automatic isolating valves. The former controls the water flow to the power house and the latter cuts off supply of water when the penstock bursts.


From the valve house, water is taken to water turbine through a Huge Steel Pipe known as penstock.





The water turbine converts hydraulic energy into mechanical energy.

The turbine drives the alternator which converts mechanical energy into electrical energy.


The constituents of a hydro-electric plant are


  • (1) hydraulic structures
  • (2) water turbines and
  • (3) electrical equipment.


We shall discuss these items in turn.


1. Hydraulic structures: 

Hydraulic structures in a hydro-electric power station include dam, spillways, headworks, surge tank, penstock and accessory works.


Dam:

A dam is a barrier which stores water and creates water head.


Dams are built of concrete or stone masonary, earth or rock fill.

The type and arrangement depends upon the topography of the site. A Masonary Dam may be built in a narrow canyon. An earth dam may be best suited for a wide valley.

The type of dam also depends upon the foundation conditions, local materials and transportation available, occurrence of earthquakes and other hazards.

At most of sites, more than one type of dam may be suitable and the one which is most economical is chosen.



Spillways:

There are times when the river flow exceeds the Storage Capacity of the reservoir.

Such a situation arises during heavy rainfall in the catchment area. In order to discharge the surplus water from the storage reservoir into the river on the down-stream side of the dam, spillways are used.


Spillways are constructed of concrete piers on the top of the dam. Gates are provided between these piers and surplus water is discharged over the crest of the dam by opening these gates.



Headworks:

The headworks consists of the diversion structures at the head of an intake.

They generally include booms and racks for diverting floating debris, sluices for by-passing debris and sediments and valves for controlling the flow of water to the turbine.

The flow of water into and through headworks should be as smooth as possible to avoid head loss and cavitation.

For this purpose, it is necessary to avoid sharp corners and abrupt contractions or enlargements.



Surge tank:

Open conduits leading water to the turbine require no protection.

However, when closed conduits are used, protection becomes necessary to limit the abnormal pressure in the conduit. For this reason, closed conduits are always provided with a surge tank.

A surge tank is a small reservoir or tank (open at the top) in which water level rises or falls to reduce the pressure swings in the conduit.



Penstocks:

Penstocks are open or closed conduits which carry water to the turbines. They are generally made of reinforced concrete or steel.

Concrete penstocks are suitable for low heads (< 30 m) as greater pressure causes rapid deterioration of concrete.


The steel penstocks can be designed for any head; the thickness of the penstock increases with the head or working pressure.



2. Water turbines: 

Water turbines are used to convert the energy of falling water into mechanical energy. The principal types of water turbines are:

(i) Impulse turbines 
(ii) Reaction turbines




Impulse turbines:

 Such turbines are used for high heads. In an impulse turbine, the entire pressure of water is converted into kinetic energy in a nozzle and the velocity of the jet drives the wheel.



Reaction turbines:

 Reaction turbines are used for low and medium heads.


In a reaction turbine, water enters the runner partly with pressure energy and partly with velocity head.

The important types of reaction turbines are :
(a) Francis turbines
(b) Kaplan turbines



3.Electrical equipment:

The electrical equipment of a hydro-electric power station includes alternators, transformers, circuit breakers and other switching and protective devices.



Question Part:


1)What is hydro power plant???
Ans: A generating station which utilises the potential energy of water at a high level for the generation of electrical energy is known as a hydro-electric power station.

2) What is turbine???
Ans : The turbine drives the alternator which converts mechanical energy into electrical energy.

3)What is function of dam in hydro power plant??
Ans : A dam is a barrier which stores water and creates water head. Dams are built of concrete or stone masonary, earth or rock fill. The type and arrangement depends upon the topography of the site. A masonary dam may be built in a narrow canyon. An earth dam may be best suited for a wide valley. The type of dam also depends upon the foundation conditions, local materials and transportation available, occurrence of earthquakes and other hazards. At most of sites, more than one type of dam may be suitable and the one which is most economical is chosen.

4)What is spillways in hydro power plant???
Ans : There are times when the river flow exceeds the storage capacity of the reservoir. Such a situation arises during heavy rainfall in the catchment area. In order to discharge the surplus water from the storage reservoir into the river on the down-stream side of the dam, spillways are used. Spillways are constructed of concrete piers on the top of the dam. Gates are provided between these piers and surplus water is discharged over the crest of the dam by opening these gates.

5)What is the function of surge tank??
Ans : Open conduits leading water to the turbine require no protection. However, when closed conduits are used, protection becomes necessary to limit the abnormal pressure in the conduit. For this reason, closed conduits are always provided with a surge tank. A surge tank is a small reservoir or tank (open at the top) in which water level rises or falls to reduce the pressure swings in the conduit.

6) What is function of penstok???
Ans : Penstocks are open or closed conduits which carry water to the turbines. They are generally made of reinforced concrete or steel. Concrete penstocks are suitable for low heads (< 30 m) as greater pressure causes rapid deterioration of concrete. The steel penstocks can be designed for any head; the thickness of the penstock increases with the head or working pressure.

7)What is impulse turbine And where is use its in hydro power plant??
Ans :  Such turbines are used for high heads. In an impulse turbine, the entire pressure of water is converted into kinetic energy in a nozzle and the velocity of the jet drives the wheel.

8)Give the types of reaction turbine???
Ans : The important types of reaction turbines are :
(a) Francis turbines
(b) Kaplan turbines

9)Which type of electric equipment are used in hydro power plant???
Ans : The electrical equipment of a hydro-electric power station includes alternators, transformers, circuit breakers and other switching and protective devices



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