What are the basic components and functions of a hydroelectric power station?

1. Basic Components and Functions of a Hydropower Station

Dam (River Barrier)

Function: The dam is a crucial component of a hydropower station. Its main function is to block the river and form a reservoir. By raising the water level, it stores a large amount of water, thus increasing the potential energy of the water. The dam can control the amount of water upstream and regulate the water level and the discharge flow of the reservoir according to the power generation requirements as well as the comprehensive needs of water use and flood control downstream. 

Intake and Diversion System

Function: The intake is located near the bottom of the dam in the reservoir. Its role is to introduce the water from the reservoir into the power generation system. The intake usually has gates and trash racks. The gates can control the inflow of water, and the trash racks can prevent floating objects in the water (such as branches, garbage, etc.) from entering the diversion system to avoid damage to equipment such as turbines. The diversion system includes pressure tunnels, penstocks, etc. It transports the water from the intake to the turbine and, during this process, utilizes the drop to make the water have sufficient pressure and velocity. For example, in some small hydropower stations in high mountain valleys, water is led from the reservoir to the power generation plant located downstream through long-distance pressure tunnels.

Turbine

Function: The turbine is the core equipment that converts the energy of the water flow into mechanical energy. When the water with a certain pressure and velocity impacts the runner of the turbine, the runner starts to rotate. Depending on the type of turbine (such as Francis turbine, Kaplan turbine, tubular turbine, etc.), the structure of the runner and the way the water acts on it are different, but the basic principle is to use the kinetic and potential energy of the water to drive the runner to rotate. For example, the Francis turbine is suitable for medium to high head hydropower stations. Its runner can efficiently convert the energy of the water into mechanical energy under the action of the water flow, driving the generator to generate electricity.

Generator

Function: The generator is directly connected to the turbine, and its function is to convert the mechanical energy output by the turbine into electrical energy. The working principle of the generator is based on the law of electromagnetic induction. When the turbine drives the rotor of the generator to rotate in the magnetic field, an electromotive force will be induced in the stator windings, thus generating alternating current. For example, in large hydropower stations, the single-unit capacity of the generator can reach several hundred thousand kilowatts, efficiently converting the mechanical energy of the turbine into high-voltage, large-capacity electrical energy for long-distance power transmission.

Tailrace and Outfall

Function: The tailrace is the channel through which the water discharged from the turbine flows out. It guides the water to the downstream river channel. The outfall is the connection point between the tailrace and the downstream river channel. Through the outfall, the water is drained back to the river. During this process, it is necessary to ensure that the drainage does not cause adverse effects such as scouring on the downstream river channel, and the ecological environment requirements should also be considered to maintain the ecological flow of the river. For example, some hydropower stations will set up energy dissipation facilities, such as stilling basins, at the outfall to slow down the water velocity and avoid damage to the downstream riverbed and riverbanks.

Itaipu Hydropower Station (Brazil and Paraguay)

The Itaipu Hydropower Station is located on the Paraná River and is a large hydropower station jointly built by Brazil and Paraguay. The dam is a concrete hollow gravity dam with a height of 196 meters and a total storage capacity of 290 billion cubic meters. The Itaipu Hydropower Station has 18 hydroelectric generating units with a single-unit capacity of 700,000 kilowatts, and its total installed capacity is 1,260,000 kilowatts. It provides a large amount of electricity for Brazil and Paraguay, playing an important role in the energy supply of South America and also promoting the local economic development and infrastructure construction.

Aswan Hydropower Station (Egypt)

The Aswan Hydropower Station is built on the Nile River and is an important energy infrastructure of Egypt. The dam is a clay-core rockfill dam with a height of 111 meters and a reservoir storage capacity of 1,689 billion cubic meters. The Aswan Hydropower Station has an installed capacity of 2,100,000 kilowatts. Its construction has far-reaching significance for Egypt's power supply, agricultural irrigation, and flood control. By controlling the amount of water in the Nile River, the Aswan Hydropower Station ensures the agricultural irrigation water for Egypt and also provides stable electricity for Egypt's industry and residents' lives.