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Hydraulic ( Power Plants )

Hydraulic Power Plants


Hydraulic Power is the power obtained from the energy of falling water where as Hydraulic Power Plant is the Power Plant utilising the potential energy of water at high level for genenration of Electrical energy. 

Hydraulic Power Plants, however, cannot be located everywhere, firstly there must be an ample quantity of water at sufficient head and secondly a suitable site must be available. 

The amount of power that can be developed depends on the quantity of water available, the rate at which it is available, the head etc.


Hydraulic Power Plant
Hydraulic Power Plant

The Electrical power , P developed is given by the Equation.

P = wQHη× 9.81 × 10-³ kw

Where w is the specific weight of water in kg/m³, Q is the rate of flow of water in m³/s, 
H is the height of fall of head in m and  η is the generation Efficiency.

In a hydraulic power Station, water head is created by constructing a dam across a river or lake.

The pressure head of water or kinetic energy of water is utilized to drive the water turbines coupled to alternators and, therefore, genenration of Electrical power.

India is blessed with immense amount of Hydroelectric potential and ranks fifth in terms of exploitable hydro potential on global scenario.

According to the accesment made by CEA, India is endowed with economically exploitable hydropower potential to the tune of 148,700 MW of installed capacity.


Merits and Demerits


Merits :- Such plant are neat and clean, robust, highly reliable, cheapest in operation and maintenance and have got longer life. Such plants do not need any fuel, can be run up and synchronised in few minutes, and have no standby losses.

Very acute governing is possible with water turbines resulting in constant frequency and Efficiency of such plants does not fall with the age.

Demerits :- It need long area, enormously high Construction cost, long time for erection and long Transmission lines.

Reservoir of such a plant submerges huge areas, uproots large population and creates social and other problems.

Long dry season may affect the power supply.


Selection of Site 


While selecting a suitable site for a Hydroelectric power plant, if a good system of natural storage lakes at high altitudes and with large catchment areas can be located, the plant will be comparatively economical.

Anyhow the essential characteristics of a good site are large catchment area, high average rainfall and a favourable place for constructing the storage of reservoir.

The land should be cheap in cost and Rocky in order to withstand the weight of large building and heavy machinery.

There should be possibility of providing adequate transportation facilities so that the necessary equipment and machinery could be easily transported.


Hydrology


Hydrology is a science which deals with the depletion and replenishment of water resources.

Hydrograph indicates the power available from stream at different times of a day, week of year.

Precipitation includes all the water that falls from atmosphere to the Earth.

Run - off can also be named as discharge of stream flow. It may be defined as the part of the precipitation which is available as stream flow.

Flow duration curve is the plot of flow available during a period versus the fraction of time.

Mass curve is the graph of comulative values of water quantity ( run - off ) against time.

Storage is provided to make more water available during deficient flow times and thus increase the firm capacity of the power plant and also Increases the energy generated.

Pondage is required near the power plant, in case Power plant is away from storage reservoir, in order to meet the hourly changes in Power demand.

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