The purpose of hydroelectric power plants is to use, through an existing jump in a water course, the potential energy contained in the mass of water, to convert it into electrical energy.
Among the various types of hydroelectric facilities, one can distinguish large hydroelectric plants and small power plants.
Small hydroelectric plants do not require large regulating reservoirs and, therefore, have a low environmental impact. Finding a place to place them depends on the rainfall levels in the area, and also on its topographic characteristics. It will be, then, these parameters that will indicate the hydraulic resources that can be used through this type of plant.
Broadly speaking, the use of hydraulic energy is carried out by capturing (with or without a reservoir) the flow of the river, which is conducted towards the power plant (forced pipe) where, using the height difference to acquire kinetic energy, it moves a turbine and, finally, it is returned to the river through a channel.
Components of a mini-hydro power plant
Capture of flow (dam or reservoir)
Through the construction of a dam in the upper part of the river, a water catchment is carried out that diverts a certain flow to be taken to the power station.
Mini hydroelectric plants are normally run-of-river (no water is stored); therefore, the turbined flow and the power produced is variable, depending on the water that passes through the river at any given time. Other plants that have reservoirs can regulate the turbined flow at the necessary moment.
Channel
Starting from the dam, a channel is made to transport the water from it, to the point that has the desired difference in level with the original bed of the river.
Charging chamber
It is the water regulation tank, between the point of arrival of the channel and the point of exit of the pressure tube.
Pressure pipe or penstock
It is the conduction of water, from the loading chamber to the turbine.
Machine building
It is the building where the turbine, generator, automation and other auxiliary elements have been installed.
Gauging channel
It is the conduction that returns the flow of water to the river, once it has passed through the turbine.
The turbine
The turbine transforms the energy of the water into mechanical energy. There are several types, and the use depends on the flow rate and the expected head.
For small differences in level (from 2 to 10 m), propeller-type turbines are used, which basically consist of an inlet chamber, a distributor, a suction tube and an impeller with 4 or 5 propeller-type blades.
The Francis turbine is used for medium heads (from 5 to 100 m) and is characterized by the fact that its impeller is made up of a crown of fixed blades, which constitute a series of channels that receive the water radially and direct it towards the exit of the impeller. axial shape.
When we find higher jumps (from 50 to 400 m), the Pelton turbine is used. This turbine has an impeller that, on the periphery, has double-spoon-shaped blades mounted on which a jet of water falls, directed by one or more injectors.
The injectors are in charge of regulating the flow and, consequently, the power of the turbine.
Electric generator
The generator is in charge of transforming the mechanical energy of rotation of the turbine into electrical energy. It works on the principle of electromagnetic induction.
