Hidroelectricity (Large Hydropower Plants)f

HIDROELECTRICITY

UNIVERSIDAD NACIONAL DE COLOMBIA

SEDE BOGOTÁFACULTAD DE INGENIERÍA

Renewable EnergyLARGE HYDROELECTRIC POWER

PLANTS

04/19/20232

CONTENT

1. Introduction.

2. Hydroelectric power plants.

3. Basics and the Bernoulli´s Equation.

4. Types of Hydroelectric Power Plants

5. The classification according to availability of water head

2. Hydropower Plants.

04/19/20232. Hydropower Plants.3

1. Introduction

The sun provides of energy the hearth.

Losses due the friction, turbulence, noise and others.

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2. Hydropower Plants


• Dam and Reservoir

• Control gate

• Power House

• Transformer

• Penstock

• Spillway

• Generator

• Turbines

04/19/20235 2. Hydropower Plants.

Gates

Spillway

Tainter


Generator

• Faraday´s Principle

• Rotor: Generates a magnetic field.

• Stator: On witch the electrical current is generated.

• Transformers: varies the voltage and the intensity.


Turbines

Water turbines are critical to the use of energy in the hydraulic central element . Mechanical energy transformed into kinetic energy (the result of motion) of a stream .

Its most important component is the rotor having a plurality of blades that the force produced by moving water are driven , rotating.


• Water turbines can be classified into two groups:

• Turbines action. Are those in which the water pressure energy is completely transformed into kinetic energy. Their main characteristic is that the high pressure water at the entrance and the exit roller .An example of this type are the Pelton turbines.

• Reaction turbines . Are turbines in which only a part of the pressure energy of the water is transformed into kinetic energy . In this type of turbine , the water has a small pressure at the outlet than at the inlet .An example of this type are the Kaplan turbines.

Turbines


Pelton turbines

• is a cross-flow turbomachine formed by a rotor with buckets on its periphery

• are designed to exploit large hydraulic jumps of low flow. has a long gallery called pressure pipe to transport fluid from great heights, sometimes more than two hundred meters. At the end of the gallery pressure water is supplied to the turbine through one or more needle valves, also called injectors, to increase the incident flow speed over spoons.


Pelton turbines

• The lance nozzle water jet directly against the series of shaped blades mounted ladle about the rim of a wheel, the double of the distance between the wheel axle and the center of the water jet diameter is called Pelton. Water acts on the spoons exchanging energy with the wheel by virtue of its change in momentum, which is almost 180 °


Kaplan turbines

• has an impeller that works similarly to the propeller of a motor boat, and are named after their inventor, the Austrian Viktor Kaplan. They are used in small height jumps and large flows. The wide blade or turbine blades are driven by high-pressure water released by a gate.


Francis turbines

• It is known as pressure turbine because the pressure varies in the zones of the roller. Francis turbines may be used in jumps of different heights over a wide flow range, but optimal performance when working in a rate between 60 and 100% of maximum flow.

• They can be installed with the axis horizontal or vertical, but in general, the most common arrangement is the vertical axis.


Turbines


Turbines

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3. Basics & the Bernoulli´s Equation


• Newton´s Second Law along a streamline

• Frictionless flow

• No compressive flow.

• It doesn´t consider the energy losses

• Heads (energy per unit of weight)

2

.2

p VH Z const

g

2 2

1 22 2

p V p VZ Z

g g

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General Equitation of Energy


2 2

1 22 2A r L

p V p VZ h h h Z

g g

ha: Energy added by a machine (pump)

hr: Energy removed by a machine (Turbine)

hL: Energy losses

Power added/removed by a machine

m mP h Qhm: Head of the Machine

2

2

2

2

f

a

L Vh f

D g

Vh K

g

Equations for lossesf: friction factor

L: length pipe

D: Diameter.

K: Constant of the accessory

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Mechanical Efficiency


A Apump

l l

O Oturbine

R R

P h Q

P P

P P

P h Q

Pl: Power given to The pump

PO: Output power of the turbine

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Mechanical Efficiency


A Apump

l l

O Oturbine

R R

P h Q

P P

P P

P h Q

Pl: Power given to The pump

PO: Output power of the turbine


Energy in a Reservoir


Types of Hydroelectric Power Plants

There are many types of hydroelectric

power plants. Their selection depends

upon the volume of water available and

the flow of water. It also depends on the

area which is available to us and the

money we want to spend. There are

very large power plants like micro hydro

plants as well as small plants


Pumped-storage Hydroelectricity

This system actually works on the demand for electricity. It uses different elevations between two reservoirs for water pumping, depending on the requirement. When the requirement for electricity is less; then the excess of generation power pumps the water into a slightly higher basin. In case of higher demand the turbines releases back water into a low reservoir through it. The pumped-storage is commercially the most important form of storage energy and it also enhances the daily capability factor of the system.


Run of the River Hydroelectricity

This type doesn’t have the storage or reserving capacity. The water flows and passes through the turbines. It is continuously moving and should not remain static. So the water coming from upstream should be used at the moment or it should go around the dam.


Tide Power HydroelectricityThe tidal waves produced in the oceans which rise and fall due to the attraction of the moon to earth, can be used for the generation of electricity. These systems are predictable as we know when the moon raises tides so the system can be built accordingly. And if such a system is built then it has advantages like dispatchable generation which means that the generation of electricity can be stopped on the basis of requirement. Waterwheels are used instead of a dam which convert kinetic energy rather than potential is less common systems.


Underground Hydroelectricity

This system works on the basis of large natural height difference which can be generated by the use of two waterways which can be waterfall or a mountain lake. The underground tunnel is built for the flow of water from the higher sink to the generation site and a horizontal tailrace which takes the water to the lower sink.

1:1600 scale manapuri N.Z.


The classification according to availability of water head

(i) Low-Head • (less than 30 meters)• capacity of less than about 25

MW (1 MW = 1,000,000 Watts• referred to as "small hydro



(ii) Medum-head(30 meters – 300m) • These plants consist of a large dam

in a mountainous area which creates a huge reservoir

• These dams are true engineering marvels

• Dams are also used for flood control, irrigation, recreation, and often are the main source of potable water for many communities



High-head hydro electric plants• the most common and generally

utilize a dam to store water at an increased elevation

• provides the capability of storing water during rainy periods and releasing it during dry periods

• Heads for this type of power plant may be greater than 1000 m

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Studies for the construction of a hydroelectric.

the construction of a hydroelectric plant must perform a series of studies to identify potential water uses and select the most viable. the more important studies are:

• demand study: is used to identify which is the demand of potential customers, measure the energy consumption of oil, gas, coal and other

• Socioeconomic study: is where the economic evaluation of the project is done, the organization and development , the social impact this would have on the community as land acquisition relocation of entire communities etc, this study includes the development and construction of Central maintenance, management and operation of this.



Studies for the construction of a hydroelectric

• Rainfall and hydrological study: is in charge of water supply and study is what determines the design flow of the plant, bring a statistical fluctuation of the water for several years to get an idea of the behavior of this. or is used to measure the rainfall precipitation in the region where the hydropower plant will be to study the flow of the watershed that feeds the river.

• Cartographic and topographic study: topographical studies to obtain the data necessary for the fall or head of water and thus to determine the hydropower potential of the source.

.


• Geotechnical study: stability of the land and possible faults that this contains is for the design and construction of the plant as it allows designers to get an idea that geological hazards should take into account when designing studies the center.

• Environmental impact study: the works to be built and plant operation involving a large environmental impact, because depending on the reservoir area remain a large tract of land, generating losses of agricultural land, forests and wildlife, the end this will study the feasibility of the project or not.

Studies for the construction of a hydroelectric


perspectives

Hydropower will play an important role in future electricity supply worldwide,through innovative technical solutions to power and perfect this type of energy,and the optimizing and modernizing existing facilities implementing ecological criteria harmonizing with the environment.


• border projects between countries which join energy resources, such as the Electric Interconnection System for Central American Countries (SIEPAC).

• use very long lines transmicion hydroelectric power for use in remote areas


• There is an exchange project between Germany and Norway consisting of the laying of a submarine electric current carrying wire between the two countries, because Norway covers about 98% of national power consumption with hydroelectric power.


References:Robert, W Fox. Alan T. McDodonald. Philip J. (2004). Pritchard. Introduction to fluid Mechanics. United States of America. Editorial: John Wiley & Sons.

Robert L Mott. (1994). Mecanica de Fluidos Aplicada. Editorial: Prentice Hall.

Centrales Hidroeléctricas. Documento Pdf. Recuperable en www.uca.edu.sv/facultad/clases/ing/m200018/doc1.pdf

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Hidroelectricity (Large Hydropower Plants)f