A hydropower plant is a power plant that converts the potential energy of water into mechanical energy or electrical energy. This makes water and electricity available to people. These can be power plants by turbines on rivers or reservoirs or current and tidal power plants on the sea.
In most hydroelectric power plants, the water is retained by dams in higher reservoirs. The kinetic energy of the drainage is transferred to the water turbine or water wheel, and the water turbine or water wheel drives the generator directly or via a gearbox to convert the mechanical energy into electrical energy.
Many hydroelectric power plants also have a substation to feed electricity into the medium-voltage or high-voltage grid. There is a fundamental difference between a run-of-river power plant and a storage power plant.