In this two part article series let us see the various components of hydroelectric power plants and the working of hydroelectric power plants. The most important part of the hydroelectric power plant is the dam, which acts as the water reservoir.
The penstock is the long pipe or the shaft that carries the water flowing from the reservoir towards the power generation unit that comprises of the turbines and generator. The water in penstock possesses kinetic energy due to its motion and potential energy due to its height.
The total amount of power generated in the hydroelectric power plant depends on the height of the water reservoir and the amount of water flowing through the penstock. The amount of water flowing through the penstock is controlled by the control gates.
The water flowing from the penstock is allowed to enter the power generation unit that comprises of the turbines and generator. When water falls on the blades of the turbine the kinetic and potential energy of water is converted into the rotational motion of the blades of the turbine. Due to rotation of blades the shaft of the turbine also rotates. The turbine shaft is enclosed inside the generator. In most of the hydroelectric power plants there are more than one power generation units comprising of the turbine and generator.
There is large difference in height between the level of turbine and level of water in the water reservoir. This difference in height, also called as head of water, decides the total amount of power that can be generated in the hydroelectric power plant.
There are various types of water turbines such as Kaplan turbine, Francis turbine, Pelton wheels etc. The type of turbine used in the hydroelectric power plant depends on the height of the reservoir, quantity of water and the total power generation capacity.
It is in the generator where the electricity is produced. The shaft of the water turbine rotates in the generator, which produces alternating current in the coils of the generator. It is the rotation of the shaft inside the generator that produces magnetic field which is converted into electricity by electromagnetic field induction. Hence the rotation of the shaft of the turbine is crucial for the production of electricity and this is achieved by the kinetic and potential energy of water. Thus in hydroelectricity power plants potential energy of water is converted into electricity.