Water is the cheapest source of power. A hydro-electric power plant is aimed at harnessing from water flowing under pressure. In hydroelectric power plants, the energy of water are utilized to drive the turbine hydro or waterpower is important only next to the thermal power. Hydroelectric power was initiated in India in 1897 near Darjeeling. The arrangement of different components used in hydraulic power plants is discussed below.
Classification of Hydro-Electric Power Plant
Classification According To the Availability of Head
Low head power plant : The operating head of water is less than 10m that power plant is known as low head power plant. Kaplan turbine is used as prime mover in this type of power plant.
Medium head power plant : The operating head of water ranges from 10 to 50m, then the power plant is known as medium head power plant. Francis turbine is used as prime mover in this type of power plant.
High head power plant : The operating head of water exceeds 50m, the plant is known as “high head power plant”. Pelton turbine is used as prime mover in this type of power plant.
Classification According To the Nature of Load
Base load plant : This type of power plant is designed to take the load on the base portion of the load curve. The load on the plant is more or less constant throughout the operation period. Large scale hydro plants are used for this purpose.
Peak load plant : This type of power plant is designed to take the load on the peak load of the load curve. The load on the plant is more or less constant throughout the operation period. Small scale and Micro hydro plants are used for this purpose.
Classification According To the Quantity of Water Available
Run off river plant without pondage
This type of power plant has no storage pond. This type of power plant uses the water as it comes. This type of plant has no control over the river flow.
Run off river plant with pondage
This type of power plant has storage pond. This type of plant stores water during off peak hours and uses waterduring peak hours of the same day. The capacity of the pond is based on fluctuating load in 24 hours.
Storage type plants
This type of power plant stores water in the dam during rainy season and supply the same during dry season. Almost, all hydropower plants in India are of this type. This plant can be used as base load as well as peak load plant as water is available.
Classification Based On the Power Developed By the Plant
| Large- hydro | More than 100 MW and usually feeding into a large electricity grid |
| Medium-hydro | 15 – 100 MW – usually feeding a grid |
| Small-hydro | 1 – 15 MW – usually feeding into a grid |
| Mini-hydro | Above 100 kW, but below 1MW; either stand alone schemes or more often feeding into the grid |
| Micro-hydro | From 5kW up to 100 kW; usually provided power for a small community or rural industry in remote areas away from the grid. |
| Pico-hydro | From a few hundred Watts up to 5kW. |
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