Hydel power stations on the Basis of Hydraulic considerations
The hydro power stations are classified in to following types on the basis of hydraulic considerations, namely.
1. Run-off River plants without pondage.
2. Run-off River plants with pondage.
3. Storage plants.
4. Pumped storage plants.
1. Run-off River plants without pondage:
This type of plants does not store the water and uses the water as it comes. This plant has no control over the river flow. Hence, the water is wasted during low load conditions and high flood conditions.
During try seasons, the capacity of plants goes down due to low flow rates of the water. The utility of these plants is very less compared to other plants.
The power house constructed along the main flow of the river. Because of non uniformity of supply and lack of assurance for continuous power generation these plants are used very less.
Ex: Niagra falls plant is good example for Run-off river plant and it is show in below
2. Run-off River plants with pondage:
The usefulness of the run-off river plants is increased by using pondage in the plant. Pondage is nothing but collection of water and behind a dam near the plant. This is mainly useful to store water during off peak hours and uses the same water during peak hours of the same day. Pondage plants will work satisfactorily as base load stations.
Pondage increases the stream capacity for short period, hours or week depending upon the capacity of the pond. When a lot of flow of water is available in the river this plants are operated as “Base loads plants” and if stream flow is less – then these plants as a “peak load plants”.
3. Storage plants:
If the rain fall occurs a short period of the year and remaining period of the year is dry, it becomes essential to store water during the rainy season and supply the same during dry season.
A storage type plant is one with a
reservoir of sufficiency large size to permit carry-Over storage from the wet
reason to the dry reason and thus to supply firm flow substantially more than
the minimum natural flow. This plant can be used as a base load plant as well
as peak load plant as water is available will control.
In India majority of hydro-electric plants are of this type
4. Pumped Storage plants:
This type of plants are mainly used for supplying the sudden peak loads for shot duration. These plants will works in two modes, namely
i) Pumping phase: In this mode of operation, the water
is pumped from tail race side to higher level of the reservoir. In this mode the generator
will work as a motor.
ii) Generating phase: In this mode of operation, the water
flows from higher level to tail race for generation of electric power.
In Andhra Pradesh this type of power plant is available at srisailam left bank which is of the capacity 6 x 150 = 900 MW. Shows the pumped storage plants
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