Working of hydroelectric power plant

In this article we are going to learn how Hydroelectric Power Plant works, what are the requirements of hydroelectric power plant for the selection of site, etc.

ThreeGorgesDam hydroelectric power plant

Hydroelectric Power Plant

In hydropower plant potential and kinetic energy of the water is used to rotate the turbine and hence generator to generate electricity.

Classification of Hydroelectric Plants:

  1. Conventional and pumped storage plants: in the conventional type, water is collected in the dam and its head is used for the rotation of turbine. In lean demand period, water is pumped back using water pump in the storage tank and used in peak demand period for the generation of electricity.
  2. Base and peak load plants: Hydel power plant is used as base load plant in lean demand period where as it can be used as peak load plant when there is shortage of water. Example of base load plant is conventional one and example of peak load plant is pumped storage plants.
  3. Base and head discharge: in hydel power plant potential energy of the water is converted into kinetic energy which is then converted in to mechanical energy and finally to electrical energy. All these energy conversions depend upon two main factors i.e. level of water in tank (head of water) and second is flow of water through the turbine.

Layout of Hydroelectric Power Plant (Hydro Station):

Following figure shows the basic layout diagram of the hydroelectric power plant.

Hydroelectric Power Plant Layout
Layout of Hydro Electric Power Plant

Construction & Working of Hydroelectric Power Plant:

Following are some of the main components of the hydroelectric power plant.

  1. Reservoir: water harvested from the catchment area is stored in the reservoir which is then used to generate the electricity.
  2. Dam: it is made in the path of the river to make the reservoir to hold the rain water.
  3. Spillways: Spillways are made to make the dam safe. When level of water is exceeds some defined point, it will discharge through these spillways.
  4. Forebay: when there is sudden change in the turbine load, in such cases there is need of temporary storage of water. This temporary storage of water near turbine is called as forebay.
  5. Surge tank: surge tank is build in between dam and the valve house. It is used to take care of the system load fluctuations.
  6. Penstock: it is water pipeline carrying water from dam to turbine.
  7. Prime mover or turbine: it is the main part of the power station. It is coupled with the generator. Turbine is rotated by the flow of water. As it is coupled with the generator, generator also rotates which produces electricity.
  8. Powerhouse: it consists of turbine, alternator and electrical equipment.
  9. Tail races: outlet water of the turbine is discharged to the river trough tail races.
  10. Selection of site:

Following are some of the factors that should be considered for Hydropower Power Plant while selecting a site.

  • Availability of water
  • Location of the dam
  • Head of water
  • Storage of water
  • Transport facilities
  • Distance from the load centre

Youtube video to understand working of hydroelectric power plant:

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