Introduction

The most commonly used method of production of electricity from hydro power is by dams, which are constructed across the large rivers.The cost of hydroelectricity is relatively low, making it a competitive source of renewable electricity. The hydro station consumes only water, unlike coal or gas plants.With a dam and reservoir it is also a flexible source of electricity since the amount produced by the station can be changed up or down very quickly to adapt to changing energy demands. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of greenhouse gases than fossil fuel powered energy plants.

Principle of Working.

The water in rivers posses two types of energies: kinetic energy and potential energy. The energy of water due to its motion is called as kinetic energy. The energy of water due to its high level is called as potential energy. Depending on the type of hydraulic power plants kinetic and/or potential energy of water is used to generate electricity.The Kinetic energy possessed by water rotates dynamo shaft which in turn rotates the dynamo. By the principle of electromagnetic induction, E.M.F is induced in the dynamo. This e.m.f is responsible for generating electric current.

Thus, finally the current induced is transmitted to nearest power station , and further through power lines.

A typical hydroelectric dam has the following main parts:

• Water Reservoir: A large quantity of water is stored in a reservoir (or dam). The height or depth of the stored water determines how much electricity can be generated. As the depth increases, the generation of electricity also increases.

•  Gate: A control gate is used for releasing/blocking water from the dam. Depending upon the electricity requirements, the gate is opened.

• Penstock: The released water from the dam reaches the turbine blade through the penstock. The proper slope and diameter of the penstock is important for the efficiency of the dam.

• Turbine: The turbine consists of a number of large fan blades and a spindle. The spindle rotates when water strikes the blades. Thus the power of flowing water is converted to the rotational power of the spindle.

• Alternator: The spindle of the turbine is connected to the alternator, where rotational power of the spindle is converted into electrical power. The produced electricity is then distributed to the grid.

• River: The outflow of water from the turbine is released to a river.

Working of Hydroelectric Power Station

Now let’s roll, the process of hydropower energy in this case all starts at the dam, as i said earlier, a dam is a body of water that is not flowing, in other words it is a barrier constructed across a stream to impound water, thus, a dam can be said to be synonymous to a reservoir of water.
 Water in the dam is allowed to flow through pipes called penstock in a vertical plane , it is to be noted that there is a need for a difference in height between the dam and the other components of the plant. Each penstock has its own hitch gate at the top to stop water flow for maintenance or during emergency. i.e. to control water flow. At the end of the penstock is the scroll case , which is designed to create a consistent pressure of water entering the turbine from all sides. Inside the scroll case is a set of veins known as the wicket gate. The wicket gates are controlled by a governor system which closes and opens them in response to the condition at the national grid, this means that a higher load on the system opens the wicket gate and a lower load on the system gradually shuts the wicket gate.The turbine blades transmits the rotational motion to a shaft known as the runner which in turn transmits to the generator. The generator at this point is not the same as the domestic generator, though they both work with the same principle, the principle of electromagnetism, just that the rotational motion in the domestic generator is gotten from the piston effect which is sourced from burning fossil fuel i.e. petrol, contrarily, the rotational motion in this plant is sourced from water which drives the turbine to turn kinetic energy to mechanical energy. 

The generator then uses the principle of electromagnetic induction to turn the mechanical energy developed by the turbine to a three phase alternating current which is Electrical energy; this connects to the national grid and then subsequently gets transmitted and distributed via transmission and distribution lines respectively, and that’s how you get power at your homes and offices for both domestic and industrial uses.