A hydropower generating station is made up of several components, all necessary for the production of electricity. The availability of a head, meaning the difference in elevation between a point upstream of the generating station and a point downstream, is essential; otherwise, electricity cannot be produced. Therefore, the first step consists of building a water intake and penstocks to channel the water to the turbine located below. It is also always advantageous to build a dam to create a reservoir upstream of the water intake. In addition to increasing the head and, therefore the quantity of energy produced by the same volume of water, the reservoir can store water for days and seasons, which can then be used on the basis of the varying demand for electricity.

Thus, a hydropower generating station is made up of several components including a reservoir, a dam, a headrace, a water intake, a penstock and, of course, a station where the turbines and generators are installed.

Retaining Structures

The flow of a river generally varies a great deal during the year. In the sp Read More
A hydropower generating station is made up of several components, all necessary for the production of electricity. The availability of a head, meaning the difference in elevation between a point upstream of the generating station and a point downstream, is essential; otherwise, electricity cannot be produced. Therefore, the first step consists of building a water intake and penstocks to channel the water to the turbine located below. It is also always advantageous to build a dam to create a reservoir upstream of the water intake. In addition to increasing the head and, therefore the quantity of energy produced by the same volume of water, the reservoir can store water for days and seasons, which can then be used on the basis of the varying demand for electricity.

Thus, a hydropower generating station is made up of several components including a reservoir, a dam, a headrace, a water intake, a penstock and, of course, a station where the turbines and generators are installed.

Retaining Structures

The flow of a river generally varies a great deal during the year. In the spring, with the snowmelt, rivers contain much more water than in the dead of summer or the middle of winter, when water accumulates as snow. Therefore, it is very important to manage the natural flow of rivers to adjust them to the demand for electricity. This is achieved through a reservoir containing millions of cubic metres of water in order to be able to respond to the demand for electricity all year long.
Some reservoirs in Quebec are gigantic. The Manicouagan reservoir on the Côte-Nord covers an area of 4 318 square kilometres and has a storage capacity of nearly 140 billion cubic metres of water. The reservoir at the Robert-Bourassa hydropower generating station in James Bay covers an area of 2 815 square kilometres and contains 61 billion cubic metres of water. These are veritable inland seas and formidable reservoirs of energy that can mitigate changes in rainfall over several years.

Reservoir

The creation of a reservoir requires the construction of a dam and dikes capable of holding back a large quantity of water and increasing the head as much as possible. The dam, the best known component of a hydropower generating station, is built on the riverbed. Dikes, on the other hand, are often built the length of a reservoir to prevent water from leaving through secondary valleys. The Daniel-Johnson Dam located at the Manic-5 plant near Baie-Comeau is 214 metres high and 1.3 km long. It is the largest multiple arch dam in the world.
If the water level in the reservoir becomes too high, excess water is evacuated through the spillway. The most famous spillway is undoubtedly the spillway of the Robert-Bourassa Dam with its ten steps, each ten metres high. The spillway looks like a giant staircase.

Headrace
The headrace is a channel that directs water to the intake at the generating station. The length of the channel depends on the geography of the site and design of the hydropower generating station. This type of channel was built in Shawinigan at the onset of the 20th century to bring water from the Saint-Maurice River to the generating stations.

The Components of a central
A hydropower generating station is comprised of many pieces of equipment, but only one, the generator, produces electricity. To ensure production, the generator must be driven by a turbine that spins, powered by water. The electricity produced by the generator is raised to very high voltages by a transformer and then travels along power lines.

Turbine
The main section of the turbine is the scrollcase which begins to turn as water strikes the blades. The hydraulic turbine uses the energy of water in movement and under pressure to create mechanical energy. The turbine is connected directly to the generator by a metal shaft that transmits its rotational movement. The flow of water and the head determine the type of turbine to install at the generating station. In Quebec, the most commonly used turbine is the Francis turbine, best suited for average to high changes in head and large volumes of water. Propeller turbines are also used for low heads, as are variations of these turbines (Kaplan) with blades that can be adjusted according to the available flow.
1 to 15 metres: Propeller turbine

1 to 30 metres: Kaplan turbine

10 to 300 metres: Francis turbine

Generator
The generator is made up of two main parts: the rotor and the stator. As their names indicate, the rotor is the mobile section and the stator is stationary. The rotor’s outer surface is covered with electromagnets made of wire coiled around a metal core. The stator’s inner surface is made up of copper windings. When the rotor turns inside the stator, the electrons in the copper windings vibrate. Their movement generates an electric current.

Transformer
This is a device that steps up the voltage of alternating current produced by the generator. The transformer consists of two coils. Low voltage electric current enters the primary coil followed by the secondary coil, where high voltage electric current is produced and moved towards transmission lines. High voltage electricity is easy to transmit and suffers fewer losses during transmission over long distances.

There are also transformers that step down the voltage of electricity from transmission and distribution networks. In this kind of transformer, the primary coil receives high voltage electricity and the second coil reduces the voltage.

Secondary equipment

1- Draft Tube
Located under the turbine, it evacuates water while diminishing its flow towards the tailrace.

2- Turbine Shaft
This piece of equipment connects the turbine to the generator.  The shaft transmits the mechanical energy of the turbine to the generator’s rotor.  Set in motion by the turbine scrollcase, the shaft causes the rotor to spin.  

3-Thrust Bearing
Its role is to support the weight of the turbine wheel, shaft and rotor of the alternator.

4- Cruise
Its function is to maintain the turbine at a constant speed by a deposit for production. In case of variation of the rotation of the turbine, the controller back to its regular speed by controlling the degree of opening or closing of guidelines that determine the quantity of water directed onto the wheel.

5-Exciter
Piece of equipment located at the top of the generator. The exciter is made up of a rotor and a stator. Its function consists of producing a direct current to feed the rotor’s electromagnets. 

What we find more specifically in Figure ONE are:

1- Dam
Structure generally made of concrete built on a riverbed to retain and accumulate water to be used to produce electricity.

2- Reservoir
Area where water retained by the dam is stored to produce electricity.

3- Water Intake
This is a structure that directs water from the reservoir or river to the penstocks. Debris traps prevent the entry of debris.

4- Valve
Bulkhead and mobile which controls the entry of water into the dam.

5- Penstock
This is a huge metal pipe, concrete channel or channel carved in rock that directs water from the intake to the turbine scrollcase.

6- Turbine
Piece of equipment made of steel and equipped with a metal scrollcase.  The power of water causes the scrollcase to turn. The turbine transforms the energy of water into mechanical energy, causing a shaft to rotate and power the generator. 

7- Generator
This piece of equipment is the only component to produce electricity at the generating station. The generator is made up of a rotor and a stator. Rotating the rotor causes electrons in the copper windings in the stator to vibrate, creating an electric current.  

8-Tailrace
Structure that redirects water flowing through the turbine to the natural course of the river.

What we find in the image TWO:

Generator

1- Rotor
Mobile section of the generator covered with electromagnets fed by an exciter. The rotor turns inside the stator, thanks to the rotation of the turbine shaft set in motion by the force of the turbine.

2- Stator
Stationary section of the generator, made up of copper windings.

3- Copper Windings
Windings facing the rotor’s electromagnets. Cooper is a good electrical conductor.

What we find in the image THREE:

Turbine

1- Wicket Gate
Helical-shaped conduit around the scrollcase that ensures consistent water distribution. The wicket gate directs water from the penstock to the turbine’s scrollcase.

2- Scrollcase
Mobile component of the turbine mounted horizontally on the turbine shaft. The scrollcase is powered by the flow of water.  It causes the shaft to spin and rotate the generator.

3- Dawn wheel
Each rigid surfaces, like pallets or fins, placed at an angle around the wheel.

4- Turbine Shaft
Exhibit which forms the vertical axis of the turbine and generator. The shaft transmits power from the turbine wheel (rotation) to the rotor of the alternator.

5- Vacuum
Duct beneath the wheel, which serves to remove water turbines, is to say, having pushed the paddle wheel.

6- Cover Turbine
Removable parts surrounding the turbine.

© 2010, Cité de l'Énergie. All Rights Reserved.

Illustration of a hydropower generating station

Illustration prepared by the Cité de l'énergie. It represents a generating station and its different components: dam, turbine, generator, water intake, tailrace, headrace, wicket gate. The numbers correspond to the definitions provided in the presentation text.

Illustration - Hamon-Bienvenue.ca

© 2010, Cité de l'Énergie. All Rights Reserved.


Illustration of a turbine.

Illustration prepared by the Cité de l'énergie. It represents a turbine and its different components: wicket gate, scrollcase and shaft. The numbers correspond to the definitions provided in the presentation text.

illustration - Hamon-bienvenue.ca

© 2010, Cité de l'Énergie. All Rights Reserved.


Illustration of a generator.

Illustration prepared by the Cité de l'énergie. It represents a generator and its different components: rotor, stator and copper windings. The numbers correspond to the definitions provided in the presentation text.

Illustration - Hamon-Bienvenue.ca

© 2010, Cité de l'Énergie. All Rights Reserved.


Learning Objectives

In all six modules, the objectives are related to skill levels of science, technology and history adapted to Cycle One in the public school system.

Skill levels include:

Finding answers and solutions to scientific and technological problems;
Building on personal scientific and technological knowledge;
Communicating in language used in science and technology.

Questioning social realities from a historical perspective;
Interpreting social realities using the historical method;
Building citizenship awareness through history.

Learning about the world of technology heightens student awareness of technology as an integral part of the world around us. The study of engineering concepts serves to provide the student with tools to design and create a technical prototype. By studying mechanisms from the standpoint of forces, movement and the transformation of energy, the student will understand how certain technology systems work.  

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