In hydroelectric power plants the potential energy of water due to its
high location is converted into electrical energy. The total power generation
capacity of the hydroelectric power plants depends on the head of water and
volume of water flowing towards the water turbine
power plant, also called as dam or hydro power plant, is used for generation of
electricity from water on large scale basis. The dam is built across the
large river that has sufficient quantity of water throughout the river. In
certain cases where the river is very large, more than one dam can built across
the river at different locations.
Working Principle of Hydroelectric Power plant
The water flowing in the
river possesses two type of energy:
(1)the kinetic energy due to
flow of water and
(2)potential energy due to
the height of water.
In hydroelectric power and
potential energy of water is utilized to generate electricity.
The formula for total power that
can be generated from water in hydroelectric power plant due to its height is
P=r h g
where “p” is the power
produced in "watt" "r" is the
rate of flow of water which in cubic meter/second"J “h”= height of water
which is measured in "meter" It’s also head of water . The difference
between source of water (from where water is taken) and the water’s
outflow (where the water is used to generate electricity, it is the place near
the turbines). “g” is the gravity
constant 9.81 m/second square
The formula clearly shows that
the total power that can be generated from the hydroelectric power plants
depends on two major factors The
flow rate of water or volume of flow of water and
Height or head of water. More the volume of water and
More the head of water more is
the power produced in the hydroelectric power plant.
To obtain the high head of water
the reservoir of water should as high as possible and power generation unit
should be as low as possible. See Also:-Hydro Turbine Operation The maximum height of reservoir
of water is fixed by natural factors like the height of river bed, the
amount of water and other environmental factors.
The location of the power
generation unit can be adjusted as per the total amount of power that is
to be generated.
Usually the power generation
unit is constructed at levels lower than ground level so as to get the
maximum head of water.
The total flow rate of water can
be adjusted through the pen stock as per the requirements. If more power is to
be generated more water can be allowed to flow through it.
Calculation of Hydro
are concern with river or stream flow and available head through which
water falss to generate the electric
water in motion
posseses three form of energy
Kinetic enegry :-
Due to its velocity
potential enegry :-
due to its height
Kinetic enegry := v
square /2 Nm per kg of water
Pressure energy :-
p/P Nm per kg of water
Potential energy :-
gH Nm per kg of water
V = velocity of flow
p = density of watr
P = Pressure in N/M2
H= height of level
of the water above som datum level .
available from water is = WQH watss
Q= Water flow in
H = net head
available in m = Total head - the friction loss
If the efficiency of
turbine is "nt"
The Power at turbine
shaft = WQH.nt
if the efficiency of
electric generator is "ng"
The effective power
at swicth baord is := WQH nt.ng
In the above
calculation , the follwoing relation can be used to calculate the dischage
1 cusecs = 1.3 sq
mile ft per year
that is one foot
water over an area of 1.2 sq mile will give a discharge of one cusses throughout
the year. assuming the run off as 100%