The diagram illustrates how electricity is generated in hydroelectric power station.
Overall, the four step process statrs with storing the river water in high-level reservoir and ends with generate electicity. During the day time, the the water from the dam forced towards generator to produce electricity and at night, the water pumped towards the dam. The generator with turbines manage water flow during day and night time.
The process begin with storing river water in a high-level reservoir, then the dam opened in the day time, allows water to flow into the generator of the power station. In this period of time, with the flow of water, electricity is generated.
The top part of the generator associated with power lines and the bottom part connected to low-level reservoir. At day, the reversible turbines of the generator operated, which allows water into low-level reservoir. At night, it pump water back into high-level reservoir, when the dam is closed.