What is Hydro Electric Plant?
Hydroelectric plants are Special types of power plants that convert the kinetic and potential energy of water into electrical energy. In hydroelectric plants turbines run due to the falling of water and when turbines run, it moves the alternator coupled with it and thus electrical energy is generated by the alternator. Since hydroelectric plant uses the kinetic energy of water then it is free from the requirement of other fuels. There are many types of hydroelectric power plants. Classification of Hydroelectric plants is based on many factors. here we will see the classification of plants on different factors.
Classification of Hydro Electric Plant on basis of Water Flow Regulation
According to water flow regulation, hydroelectric plants are classified into three categories and these are
- Reservoir Plants
- Runoff River Plants Without Pondage
- Run off River Plants ith Pondage
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Runoff River Plants Without Pondage
When water is supplied to a hydroelectric plant without Pondage or storage then this type of plant is known as Runoff River Plants Without Pondage.In this plant water is supplied without previous storage hence there is no control over the flow of water. During the high flow of water, most water gets wasted, and also during a low load period, most water is wasted. During the lean flow period of water plant capacity is very low. this type of plant has very low firm capacity. As such these plants have very low firm capacity. In this type of site, the water is used mainly for irrigation only. As the power output of these plants is very low in the same way the capital cost of these plants is also very low. The Sole purpose of these plants is to generate whatever amount of kinetic energy is available in the water.
Run off River Plants With Pondage
Pondage means storage of water near to plant to take care of hour to hour variation in load on the station. Storage of water or Pondage increases the total firm capacity of the station, provided the floods do not raise the tailrace water level thus reducing the effective water head and plant output. According to streamflow, such plants can serve as either baseload or peak load plant i.e these plants work baseload plants when plenty of water is available. When streamflow decreases these plants work as peak load plants. When these types of plants work in conjunction with coal plants, provide a maximum saving of coal.
Reservoir Plants
In these types of plants, a large amount of water is stored in a big reservoir behind a dam, by using a dam it is possible to control the flow of water and used it effectively whenever required. Storing of water increase the total firm capacity of the plant. According to the water stored in the reservoir, these plants can be used as either baseload plants or peak load plants. Most of the hydroelectric plants across the globe belong to this category.
Classification of Hydroelectric Plant According to Load
According to load hydroelectric plants are divided into the following categories
- Base load Plant
- Peak Load Plant
- Pumped Storage Plant
What is Base load Plant?
These plants feed the base load of the system. these Plants operate on a high power factor. Since these plants operate on baseload hence they supply almost constant throughout. Runoff river plants without Pondage and Reservoir plants are used as Baseload plants. The Firm capacity of Baseload Plants is high and also the unit cost of energy generation is low.
What are Peak load Plants?
Those hydroelectric plants that supply the peak load of the system are known as Peak load Plant. During the lean period Run off the river plants operates with Pondage and Supply the peak load .Sometimes reservoir plants are also used as peak load plants. Peak load plants have large seasonal storage because they store water during the off period of the plant and use this water during the peak load period. Peak Load Plants always operate on low power factors.
Classification of Hydroelectric Plant According to Head
Availability of water at a height from surface level is known as head. According to the head, hydroelectric Plants are classified into three categories.
- Low Head Plants
- Medium Head Plants
- High Head Plants
What are Low Head Plants?
if Water Head is less than thirty-meter (30 m) then this plant is known as Low Head Plants. A dam is or other types of barriers are used across the river to create the required head. For low head plants, there is no need for surge tanks because these plants are installed near the dam.
What are Medium Head Plants?
If the water head lies between 30 m and 100 m then these types of plants are known as medium head Plants. An open channel is used to bring the water from the reservoir to the forebay from where penstocks carry water to the turbine.
What are High Head Plants?
The hydroelectric plants that operate at a head above 100 m are generally known as High Head Plants. More Civil works are required to create dams, reservoirs, tunnels, surge tanks, and penstock. Francis turbines are used for heads below 200m and Pelton turbines for the higher head.
