Hydroelectric Power Plant – Parts, Working, Advantages & Disadvantages

ElectronElectronics & ElectricalDigital Electronics

A hydroelectric power plant is a generating station which converts the potential energy of water at high level into electrical energy.

Generally, the hydroelectric power plants are installed in hilly areas where dams can be built and large water reservoirs can be obtained. In a hydroelectric power plant, the water head is created by constructing a dam across a river. From the dam, water is led to a water turbine. The water turbine converts the hydraulic energy of the falling water into mechanical energy. The turbine drives the alternator, which converts the mechanical energy of the turbine into electrical energy.

Schematic Diagram and Working of Hydroelectric Power Plant

A hydroelectric power plant simply involves the conversion of hydraulic energy of falling water into electrical energy. For the proper and efficient working, the hydroelectric power plant has many arrangements. A schematic diagram of a typical hydroelectric power plant is shown in the figure.

  • In a hydroelectric power plant, the dam is constructed across a river or lake. Water from the catchment area collects at the back of the dam to form a reservoir.

  • A pressure tunnel is formed between the reservoir and the valve house and water is brought to the valve house at the start of the penstock (a penstock is huge steel pipe which carries water from valve house to the turbine).

  • The valve house contains main sluice valves which control the water flow to the power house and automatic isolating valves which cut off supply of water when the penstock bursts.

  • Water from the valve house is taken to the water turbine through the penstock. Now, the water turbine converts the hydraulic energy of falling water into mechanical energy. The turbine drives an alternator which converts the mechanical energy of the turbine into electrical energy.

  • In a hydroelectric power plant, a surge tank, which is open from the top, is also built just before the valve house. The surge tank protects the penstock from bursting in case the turbine gates suddenly close due to electrical load being thrown off. When the turbine gates close, there is a sudden stopping of water at the lower end of the penstock which can burst the penstock. The surge tank absorbs these pressure swings (i.e. water surges) by increasing its water level.

Site Selection for Hydroelectric Power Plant

The following factors should be considered while selecting the site for a hydroelectric power plant −

  • Availability of Water – Since water is the main requirement for a hydroelectric power plant. Hence, the hydroelectric power plant should be built at a place a huge amount of water is available at a good head.

  • Storage of Water – The site selected for the hydroelectric power plant should provide adequate facilities for constructing a dam and storage of water to ensure the generation of power throughout the year.

  • Type and Cost of Land – The bearing capacity of the land should be adequate so that heavy equipment can be installed. Also, the land for the construction of the hydroelectric power plant should be available at reasonable price.

  • Transportation Facilities – A hydroelectric power plant requires transportation of equipment and machinery. Therefore, the site selected for the power plant should be well connected to other parts of the country by rail, road, etc.

Advantages of Hydroelectric Power Plant

The following are the primary advantages of a hydroelectric power plant −

  • Water is used for the generation of electrical energy. Therefore, it requires no fuel.

  • No smoke and ash is produces, hence it is quite neat and clean.

  • As water is the source of energy which is available free of cost. Thus, the hydroelectric power plant requires very small running cost.

  • Hydroelectric power plant is simple in construction and requires less maintenance.

  • Hydroelectric power plant is robust and has a longer life.

  • The hydroelectric power plants can be put into service instantly, i.e. it does not require a long starting time.

  • Apart from the generation of electrical energy, the hydroelectric power plants also help in irrigation and controlling floods.

Disadvantages of Hydroelectric Power Plant

The disadvantages of the hydroelectric power plants are listed below −

  • The capital cost of the hydroelectric power plants is high because it involves the construction of dam.

  • There is uncertainty about the availability of water because it depends upon the weather conditions.

  • In case of hydroelectric power plant, the cost of transmission lines is high because the power plant is located in hilly area which are quite away from the load centres.

  • For the construction of hydroelectric power plants, skilled and experienced personals are required.

raja
Updated on 08-Feb-2022 12:21:36

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