Hydropower plants are one of the most important sources of renewable energy in the world providing a reliable and sustainable source of electricity for millions of people. These plants use the power of falling water to turn turbines and generate electricity making them an essential part of our energy infrastructure. In this article, we’ll explore the different components of a hydropower plant and how they work together to produce clean energy. We’ll examine each part of the plant in detail to help you better understand how this incredible technology works.
Components of a Hydropower Plant
Typical components of hydropower plant are:
1. Dam
It is a barrier that prevents water from flowing downstream, thus creating a lake behind the dam. The potential energy of the water behind the dam is directly proportional to the volume and height of the lake. The construction of a dam may not be feasible or its provision may not be justified economically due, perhaps, to the open nature of the country at the reservoir mouth, in which case there is the simple arrangement of a natural reservoir from which the power station draws water at a lower level.
In the design of any dam, certain forces have to be taken into account. Firstly, some are a function of fluid pressures and weight density of materials, and, secondly, there are those due to earthquakes, silt deposits, ice, uplift pressures and effects of floods. Those in the first category are amenable to calculation, but coping with the remainder depends largely on experience. When there are fishing interests, provisions may also be made for the passage of fish both into and out of, the reservoir.
2. Reservoir
The dam creates a lake behind its structure called a reservoir and often covers a wide area of land. The Grand Coulee dam created the Franklin D. Roosevelt artificial lake which is about 250 km long and has over 800 km of shoreline. Its surface area is about 320 km2 and the depth of the lake ranges from 5 to 120 m.
3. Penstock
It is a large pipeline that channels water from the reservoir to the turbine. The water flow in the penstock is controlled by a valve called a governor. There are several factors to consider when deciding which material to use in the building of the penstock. They are surface roughness, design pressure, method of jointing, weight, ease of installation, accessibility of the site, terrain, soil type, design life and maintenance, weather conditions, availability, relative cost and the likelihood of structural damage. When considering soil type, you have to choose a material that will not be degraded or eroded by the surrounding soil. Economically speaking, the penstock can account for up to 40% of the total cost of the plant. This is why efficient planning is critical.
4. Turbine
A turbine is an advanced water wheel. The high-pressure water coming from the penstocks pushes against the blades of the turbine causing the turbine shaft to rotate. The electrical generator is mounted directly on the same shaft of the turbine, thus the generator rotates at the speed of the turbine. There are mainly two types of turbines: impulse and reaction.
For these two types, there are three fundamental designs used in most hydroelectric power plants: Pelton (impulse), Francis (reaction) and Kaplan (reaction). Pelton turbines are designed for high water heads (50–1300 m) and relatively low flows. The Francis turbines are suitable for low to medium heads (10–350 m). The Kaplan turbines (which are also known as propeller turbines) are suitable for low heads (less than 40 m) and high flow rates.
5. Generator
It is an electromechanical converter that converts the mechanical energy of the spinning turbine into electrical energy. The generators used in all power plants are of the synchronous machine type. The generator is equipped with various control mechanisms such as excitation control and various stabilizers to maintain the voltage constant and to ensure that the generator’s operation is stable.
There are four major components to the generator; they are the shaft, exciter, rotor and stator. The water turns the turbine, which turns the shaft and causes the exciter to send an electrical current to the rotor. The rotor is comprised of a series of large electromagnets that spin inside the stator which is a tightly wound coil of copper wire. This process creates a magnetic field, which creates an alternating current, AC, by the moving of electrons.
6. Governor
It is the valve that regulates the flow of water in the penstock. When it is fully open the kinetic energy of the water is at its maximum. If the system is to shut down, the valve is closed fully.
In conclusion, hydropower plants are a crucial component of our energy infrastructure, providing reliable and sustainable sources of electricity to millions of people worldwide. By harnessing the power of falling water, hydropower plants produce clean energy with minimal environmental impact. The six key components of a typical impoundment hydroelectric power system, including the dam, reservoir, penstock, turbine, generator and governor, all work together to efficiently convert the potential energy of water into electrical energy. Understanding the intricacies of each component is crucial for efficient planning and effective operation of hydropower plants, ensuring a steady supply of clean energy for years to come.
