The diagram below shows how electricity is generated in hydroelectric power station

   

 National geographic says,  In,1882 the world's first hydro electric power plant began operating in the united state along the fox river, Appleton.

Image by Franz W. from Pixabay

Energy conversion

    The world hydro refers too water. We all know that the static huge amount of water can have ultimate potential energy. We need to convert the potential energy into electrical energy. First of all, the potential energy in converted into kinetic energy by allow the water into the penstock. 

    The kinetic energy is then converted into mechanical energy because of water strike the turbine results in rotating the turbine. The rotating shaft is connected with alternator or generator which produce the electrical energy and then transformer is used to step down the voltage. 

    The rotation of generator defines the frequency in electrical hertz. The supply is connected to power grid of the transmission line.

Construction

image credit: Tennessee Valley Authority,distributed under a CC BY-SA 3.0 license.

    This  site is chosen by parameters which are mostly forest area having high rainfall regions. The area which is used to construct the hydroelectric power station should be easy to visit.

    The dam is built across the river to store the huge amount of water.

Water reservoir

Image by Thomas Ehrhardt from Pixabay

    Basic requirement of hydroelectric power plant is the availability of water. If the water availability is high, proportionally water reservoir is high. We can store the large amount of water depends on the height of the dam.The level of water surface in the dam is said to be head race level.

Penstock

    The dam and the rotating turbine are connected by means of penstock. The penstock is nothing but 

pipe made up of concrete or steel. Which carry water from the dam to the rotating turbine.

Regulation valve

    The value which is used to control the flow of water from the dam.

Prime mover

    image credit:U.S. Army crops of Engineers, distributed under a Public domain

   

    Water through the penstock enter into the turbine through the regulation valve. The most commonly used turbine is Pelton turbine. The potential energy of the water is converted in to kinetic energy  through penstock and then kinetic energy is converted in to mechanical energy by Pelton turbine which is rotates the shaft used to run the generator

Draft tube

    The  output of the turbine is connected to tube which release water is called draft tube. The main function of the draft tube is releasing water with partially zero energy in the river. hence, the velocity of the water is reduced.

Tail race level

    The level of water at which the water from the draft tube is tail race. The tail race level may be called  as water level of river

 Safety measures

• Spill way
• Surge tank

Spill way

Image by Daina Krumins from Pixabay

    The storage of water reservoir is limited to certain value. if the water raises above the certain value, it would leads to unstability of the dam causes massive flood damages all the residents and collapse the Environment. Which may endanger to flora and fauna. The water increases after the certain level must be discharged slowly via  spillway

Surge tank

    The sudden increases in pressure in penstock leads to damage of pipe lines. The surge tank is a tank which allows the water when it is in high pressure to reduce the pressure in the penstock.

Conclusion

     The water is a renewable source of energy and always exists in nature. On the other hand, the fuel needed for the thermal, diesel plants are exhaustible.

Comments below

What is the disadvantage of hydroelectric plant? why?