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Sunday, April 16, 2023

Hydropower Plant - Learn all major component

Hydropower is a renewable energy resource. Hydropower plant is generally located in hilly areas where dams can be built conveniently and large water reservoirs can be obtained. This type of power station can be used to produce large amounts of electrical energy. Mostly these power plants are used as peak load power stations because they can be started and stopped easily and fast. Also fossils, fuels ( coal, oil, and gas) are limited in the world and these fuels are expensive. Hence hydroelectric power plant may be a good alternative electrical source.

 What is Hydropower Plant ?

In hydroelectric power plant, water is stored in a dam which is located upper level from the ground. Water head is created by construction the different type of dam as required across any river or lake. This type of water head store huge potential energy of water.  The water fall from its headrace through penstock into water turbine and the potential energy of water at headrace is converted into kinetic energy and this kinetic energy is converted into mechanical energy at the turbine shaft as turbine shaft is rotated by water. A generator or alternator is coupled with turbine shaft to convert mechanical energy into electrical energy to generate electricity.
Hydropower Plant - Learn all major component

Major components of hydropower plants are:-

  • Dam/Reservoir/weir

This is used to store water from river/stream and also to control the flow of water i.e. diverting the water from its natural way to store it and use to generate electricity. Depending on location, flow duration curve, budget etc., its structure is different as requirement. Depending on its, hydropower plant can be classified as ROR, PROR, storage type. Similarly, the weir is a structure across the river to divert the portion of water flow of river through intake.

  • Intake
It is an conveyance system to draw the flow from river by using dam or weir. Also, it is provided with trash rack to prevent the entry of floating debris and coarse into the water conveyance system in different condition.
  • Water cannel/tunnel

It is used to run water from dam. As depending on its location and budget, cannel or tunnel can be chosen and delivering flow to the forebay or surge tank.

  • Spillway

This is used to remove surplus water from reservoir, forebay etc. so that excess amount of water won't damage the structure in power plant in all conditions.

  • Settling basin

This is the structure that is used to settle small slit particle so that will not damage penstock, turbine. The flow from intake or gravel trap is sent to settling basin where suspended sediment particles will settle down and these will be discharge back into the river in some time interval by using flushing gate or valve.

  • Surge tank/Forebay

This is small tank that can store water for emergency i.e. when load suddenly increase, Governor will open the valve more so required more water to rotate turbine faster. At that time, more required water is passes from surge tank/forebay. Similarly, at sudden decrease load, surplus water is stored in surge tank. A spillway is provided in it to pass excess water flow. Forebay serves as a secondary settling basin as it settle small slit particles and there is features of flush for it.

  • Penstock

From surge tank/Forebay, water is running through penstock to turbine to rotate turbine. Flow of water is controlled at the end of penstock. It is a convey system connected to the power house or turbine where water or flow is in high pressure with minimum head loss. Generally, head of the power plant is measured from top parts of penstock to the base part of penstock or turbine. There are a lot of anchor blocks and supports which are used to stabilized it in different conditions.

  • Turbine

This is a electro-mechanical equipment used in hydropower plant which is connected after penstock i.e. water flow from penstock will hit the turbine. There are different types of turbine that will convert kinetic energy into mechanical energy. Depending on net water head, water flow etc., we need to select good turbine for hydropower plant. For high head and low flow, generally pelton turbine is preferred and in other hand for low head and high flow or discharge, Francis turbine is more preferred.

  • Generator

Generally, turbine shaft is coupled to generator shaft so when turbine rotates, generator also rotates and it will generate electricity by converting mechanical energy into electrical energy. Generated electricity will be connected to interconnected system by using step up power transformer. Generally, generated voltage is not feasible to use or transfer without converting it into usable value voltage or transmissible voltage. After that it can be transferred and step down that voltage in usable form so that can be used easily in residential, commercial area and many more.

  • Power house

This is the house which contains turbines, generators and its accessories. Generate electricity is converted into transmission voltage at there and transmitted to substation.

  • Tailrace

Outlet water from turbine is passes to tailrace. The water head is measured from tailrace to headrace. Sometimes draft tube is added at tailrace to increase pressure and increase height.

Advantages of Hydropower Plant

1. Renewable and Clean: Hydropower is a renewable and clean energy source that produces no greenhouse gases or other harmful pollutants.

2. Reliable: Hydropower plants can provide a reliable source of energy, as long as there is a sufficient water supply.

3. Flexible: Hydropower plants can be turned on and off quickly, making them ideal for meeting peak demand for electricity.

4. Multi-Purpose: Hydropower plants can be used for other purposes, such as irrigation, flood control, and water supply.

Disadvantages of Hydropower Plant

1. Environmental Impact: The construction of dams and reservoirs can have a significant impact on the environment, including the loss of habitat for fish and other aquatic species.

2. Upfront Costs: The construction of a hydropower plant can be expensive, and the initial investment may take years to recoup.

3. Limited Sites: Hydropower plants require a sufficient flow of water and a suitable location, which may limit the number of potential sites for construction.

4. Weather Dependent: Hydropower plants rely on a sufficient supply of water, which may be affected by droughts or other weather events.

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