Hydro Electric Power Generation :
Water-reservoir at higher altitudes is a pre-requisite for this purpose. Power-house is located
at a lower level. The difference in these two levels is known as “Head.”
Based on the “Heads”, the Hydroelectric stations are categorized below:
1. Low head up to 60 metres.
2. Medium head between 60 and 300 metres.
3. High heads above 300 metres
In this method of generation, water from higher height is passed through penstock as controlled
in the valve-house, into the water turbine. Thus, potential energy of water stored at higher altitudes is
first converted into Kinetic energy. As the water reaches the turbine, it gains speed after losing the
Potential energy. Kinetic energy of this speedy water drives the water turbine, which converts this
into mechanical output. It drives the coupled generator, which gives Electrical energy output.
A schematic diagram of such a system is shown in fig.
The valve house has a controlling valve (=main sluice valve) and a protecting valve (= an
automatic, isolating, “butterfly” type valve). As is obvious, power control is done by the main sluice
valve, while “butterfly” valve comes into action if water flows in opposite direction as a result of a
sudden drop in load on the generator. Otherwise, the penstock is subjected to extreme strains and it
has a tendency to burst due to pressure of water as a result of sudden load reduction.
Note: Variation of Head (low-, medium-, or high-head) will affect the block-schematic
After doing the work (of imparting its energy to the water turbine), the water is allowed to pass
into the tail-race reservoir.
The water turbines are essentially low-speed prime movers. In that, the best operating speed is
dependent on the head. Alternators coupled to water turbines thus have large number of poles (since
P= 120 f/N). Such alternators have the Salient-Pole type rotor.
There are different types of water turbines suitable for different cases (i.e. Heads, Power
rating, Load-variation curve, etc). Since, this is only an elementary treatment, these aspects will not
be discussed here.
If You have Any Doubts Feel Free To Comment below
Water-reservoir at higher altitudes is a pre-requisite for this purpose. Power-house is located
at a lower level. The difference in these two levels is known as “Head.”
Based on the “Heads”, the Hydroelectric stations are categorized below:
1. Low head up to 60 metres.
2. Medium head between 60 and 300 metres.
3. High heads above 300 metres
 |
| showing simple hydro plant |
in the valve-house, into the water turbine. Thus, potential energy of water stored at higher altitudes is
first converted into Kinetic energy. As the water reaches the turbine, it gains speed after losing the
Potential energy. Kinetic energy of this speedy water drives the water turbine, which converts this
into mechanical output. It drives the coupled generator, which gives Electrical energy output.
A schematic diagram of such a system is shown in fig.
The valve house has a controlling valve (=main sluice valve) and a protecting valve (= an
automatic, isolating, “butterfly” type valve). As is obvious, power control is done by the main sluice
valve, while “butterfly” valve comes into action if water flows in opposite direction as a result of a
sudden drop in load on the generator. Otherwise, the penstock is subjected to extreme strains and it
has a tendency to burst due to pressure of water as a result of sudden load reduction.
Note: Variation of Head (low-, medium-, or high-head) will affect the block-schematic
After doing the work (of imparting its energy to the water turbine), the water is allowed to pass
into the tail-race reservoir.
The water turbines are essentially low-speed prime movers. In that, the best operating speed is
dependent on the head. Alternators coupled to water turbines thus have large number of poles (since
P= 120 f/N). Such alternators have the Salient-Pole type rotor.
There are different types of water turbines suitable for different cases (i.e. Heads, Power
rating, Load-variation curve, etc). Since, this is only an elementary treatment, these aspects will not
be discussed here.
If You have Any Doubts Feel Free To Comment below
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