Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni...

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Hydrology for HYDROPOWER PLANTS MODULE Bruno Majone (a.a. 2014/15, 40 hours) Bruno Majone Department of Civil, Environmental and Mechanical Engineering University of Trento e-mail: [email protected] (room 401, DICAM) tel.: 0461 28 2637

Transcript of Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni...

Page 1: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Hydrology for

HYDROPOWER PLANTS

MODULE

Bruno Majone

(a.a. 2014/15, 40 hours)

Bruno MajoneDepartment of Civil, Environmental and Mechanical

Engineering

University of Trento

e-mail: [email protected]

(room 401, DICAM)

tel.: 0461 28 2637

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Objectives: from the syllabus“By the end of the course, students should be able to: perform the main

hydrological analyses needed for the design of hydropower systems and the

simulation of its productivity…...........”

Contents: from the syllabus

Introduction: Functioning of a hydropower system; classification and main components

Reservoir hydrological design: hydrodinamic curves; flow duration curves volume design. OperationReservoir hydrological design: hydrodinamic curves; flow duration curves volume design. Operation

simulation in hydropower planning.

Streamflow measurements: weirs, velocity-area method, dilution gauging, rating curves,

measurement errors and their influence on rating curves.

Catchment-scale hydrological models: modules composing a hydrological model; snow

accumulation and melting; models of evapotranspiration, interception by vegetation and water

infiltration; continuous hydrological models; construction of a catchment-scale hydrological model;

model calibration and validation; flood models: Instantaneous Unit Hydrograph.

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Lectures Slides (part of them with courtesy of Alberto

Bellin, University of Trento, and Gianluca Botter,

University of Padova).

Book:

S. L. Dingman, Physical Hydrology, Prentice Hall, New

Jersey, 1994.

Bibliography

Jersey, 1994.

The examination consists of two elements: final oral

discussion, presentation of the homework.

Exam

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Hydro-Electric Power Plant

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Hydropower energy is ultimately derived from the sun, which

drives the water cycle. In the water cycle, rivers are recharged

in a continuous cycle. Because of the force of gravity, water

flows from high points to low points. There is kinetic energy embodied in the flow of water.

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How a Hydroelectric Power System Works - Part 1

Flowing water is directed at

a turbine (remember

turbines are just advanced

waterwheels). The flowing

water causes the turbine towater causes the turbine to

rotate, converting the water’s

kinetic energy into

mechanical energy.

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How a Hydroelectric Power System Works – Part 2

The mechanical energy produced by the turbine is converted into

electric energy using a turbine generator. Inside the generator,

the shaft of the turbine spins a magnet inside coils of copper wire.

It is a fact of nature that moving a magnet near a conductor

causes an electric current.

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How much electricity can be generated by a hydroelectric power plant?

The amount of electricity that can be generated by a

hydropower plant depends on two factors:

• flow rate - the quantity of water flowing in a given time; and

• head - the height from which the water falls.

The greater the flow and head, the more electricity produced.

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When more water flows through a turbine, more electricity

can be produced. The flow rate depends on the size of the

river and the amount of water flowing in it. Power production

is considered to be directly proportional to river flow. That

is, twice as much water flowing will produce twice as much

electricity.

Flow Rate = the quantity of water flowing

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The farther the water falls, the more power it has. Thus Power

production is directly proportional to head. That is, water

falling twice as far will produce twice as much electricity.

Head = the height from which water falls

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Principles of a hydropower system

[m3/s]

Line of the gross head Hydraulic losses

Total head Piezometric line

ηρ HQP 81.9=

[m3/s][m]

P =QH

102η

[l/s] [m]

penstock

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Example of a complex hydropower system

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Hydropower plants

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Hydropower plant layout

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Essential features of Hydro-Electric Power Plant

The essential features of a water power plant are:

1. Catchment area.

2. Reservoir.

3. Dam and intake house.

4. Water way.4. Water way.

5. Power house.

6. Tail race or outlet water way.

1. Catchment Area.

The catchment area of a hydro plant is the whole area

behind the dam, draining into a stream or river across which

the dam has been built at a suitable place.

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2- Water reservoir:� In a reservoir the water collected

from the catchment area is stored

behind a dam.

� Catchment area gets its water from

rain and streams.

� The level of water surface in the

reservoir is called Head water level.

Note: Continuous availability of water

is a basic necessity for a hydro-

electric power plant.

3- Dam :� The purpose of the dam is to store

the water and to regulate the out

going flow of water.

� The dam helps to store all the

incoming water. It also helps to

increase the head of the water. In

order to generate a required quantity

of power it is necessary that a

sufficient head is available.16

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• Dam are classified based on following factors:

a) Function

b) Shape

c) Construction material

d) Design

a) Based on function the dam may be called as storage dam, diversion dam or detention dam.

b) Based on the shape the dam may of trapezoidal section & b) Based on the shape the dam may of trapezoidal section & arch type.

c) The materials used for constructing dams are earth, rock pieces, stone masonry, reinforced concrete.

d) According to structural design the dam maybe classified as:

i. Gravity dam

ii. Arch dam

iii. Buttress dam

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Gravity dam:

Resist the pressure of water by its

weight.

Construction of material used for his

dam, is solid masonry or concrete.

Arch dam: Hoover

Types of Dam

Arch dam:

It resist the pressure of water partly due

to its weight and partly due to arch

action.

Buttress dam:

Buttress supporting a flat slab.

When cost of reinforced concrete is high

such type of dam is selected.

Hoover

Dam

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Spillway:

• Excess accumulation of water endangers the

stability of dam construction. Also in order to

avoid the over flow of water out of the dam

especially during rainy seasons spillways are

provided. This prevents the rise of water level

4. Water ways. Water ways are the passages, through which the water is conveyed to the

turbines from the dam. These may include tunnels, canals, flumes, forebays and

penstocks and also surge tanks.

A forebay is an enlarged passage for drawing the water from the reservoir or the

river and giving it to the pipe lines or canals.

provided. This prevents the rise of water level

in the dam.

• Spillways are passages which allows the

excess water to flow to a storage area away

from the dam.

Gate:

• A gate is used to regulate or control the flow

of water from the dam.

Penstock:

• It is a passage that carries water from the

reservoir to the surge tank. 19

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The gate controlling the water

flowing into the channel.

The penstock conveying water

from the intake to the power

house. Concrete (low heads) or

steel (all heads) material.

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Surge tank:

• A Surge tank is a small reservoir or tank in which the water levelrises or falls due to sudden changes in pressure.

Purpose of surge tank:

• To serve as a supply tank to the turbine when the water in the pipeis accelerated during increased load conditions and as a storagetank when the water is decelerating during reduced load conditions.

• To reduce the distance between the free water surface in the dam

4. Water ways (continues…)

• To reduce the distance between the free water surface in the damand the turbine, thereby reducing the water-hammer effect onpenstock and also protect the upstream tunnel from high pressurerise.

Water-hammer effect :

• The water hammer is defined as the change in pressure rapidlyabove or below normal pressure caused by sudden change in therate of water flow through the pipe, according to the demand ofprime mover i.e. turbine.

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Number of penstock

A hydro Power Plant uses a number of turbine which are to

be supplied water through penstock.

• To use a single penstock for the whole a plant.

• To use on penstock for each turbine separately.

• To provide multiple penstock but each penstock supplying

water to at least two turbine.water to at least two turbine.

Factors for Selecting number of penstocks:

• Economy.

• Operational safety.

• Transportation facilities.

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5. Power House.The power house is a building in which the turbines, alternators and theauxiliary plant are housed. Some important items of equipmentprovided in the power house are as follows:

i.Turbines

ii.Generators

iii.Governors

iv.Relief valve for penstock setting

v.Gate valve

vi.Transformervi.Transformer

vii.Switch board equipment and instruments

viii.Oil circuit breaker

ix.Storage batteries

x.Outgoing connections

xi.Cranes

xii.Shops & offices

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� Turbine’s function is to convert the K.E of moving water into

mechanical energy.

� The water strikes and turns the large blades of a turbine,

which is attached to a generator above it by way of a shaft.

24The runner of the small water turbine

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A hydroelectric generator converts

this mechanical energy into

electricity.

The operation of a generator is

based on the principles discovered

by Faraday. He found that when a

magnet is moved past a conductor

(in this case, coils of copper wire),(in this case, coils of copper wire),

it causes electricity to flow through

the wire.

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6. Draft tube, Tail water level and Tail race:

• Draft tube is connected to the outlet of the turbine and itallows the turbine to be placed above the tail water level.

• Tail water level is the water level after the discharge fromthe turbine. The discharged water is sent to the river, thusthe level of the river is the tail water level.

•After passing through the

turbine the water returns

to the river trough a short

canal called a tailrace.

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Classification of hydro-Electric power plant

The classification of hydro electric power plant depend on the

following factors:

1)Classification based on the hydraulic features

a)Storage plant.

b)Pumped storage.

c)Run-of-the-river plant.c)Run-of-the-river plant.

d)Marine.

e)Underground.

2)Availability of Head of Water:

a)Low head plant. Operating head < 15m.

b)Medium head plant. Operating head 15 to 50m.

c)High head plants Operating head > 50m.

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Storage plant (already seen)

• Most hydroelectric power comes from the potential energy

of dammed water driving a water turbine and generator

• The power extracted from the water depends on the

volume and on the difference in height between the source

and the water's outflow

• This height difference is called the head

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• This height difference is called the head

• The amount of potential energy in water is proportional to

the head

• A large pipe (the "penstock") delivers water to the turbine

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Pumped-storage

• This method produces electricity to supply high peak

demands by moving water between reservoirs at different

elevations

• At times of low electrical demand, excess generation

capacity is used to pump water into the higher reservoir

• When there is higher demand, water is released back into

the lower reservoir through a turbine

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the lower reservoir through a turbine

• Pumped-storage schemes currently provide the most

commercially important means of large-scale grid energy

storage and improve the daily capacity factor of the

generation system

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Run-of-the-river• Run-of-the-river hydroelectric stations are those with small

or no reservoir capacity, so that the water coming from

upstream must be used for generation at that moment, or

must be allowed to bypass the dam.

• It may involve a diversion of a portion of the stream

through a canal or penstock, or it may involve placement

of a turbine right in the stream channel. Run-of-the-river

systems are often low-head.

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systems are often low-head.

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Marine Power

�Marine current power, which captures the kinetic energy from

marine currents

�Tidal power, which captures energy from the tides in horizontal

direction:

� Tidal stream power, usage of stream generators, somewhat

similar to that of a wind turbine

� Tidal barrage power, usage of a tidal dam

� Dynamic tidal power, utilizing large areas to generate head.

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� Dynamic tidal power, utilizing large areas to generate head.

�Wave power, the use ocean surface waves to generate power.

Wave device

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Underground

An underground power station makes use of a large

natural height difference between two waterways, such as a

waterfall or mountain lake

• An underground tunnel is constructed to take water from

the high reservoir to the generating hall built in an

underground cavern near the lowest point of the water

tunnel and a horizontal tailrace taking water away to the

lower outlet waterway

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lower outlet waterway

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Low head plant

• Operating head is less than 15m.

• Small dam is required.

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Medium head plant

• Operating head is less than 15 to 50m.

• Forebay is provided at the beginning of the penstock.

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High head plant

• Operating head exceed 50m.

• Surge tank is attached to the penstock to reduce water

hammer effect on the penstock.

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Advantages of hydro power production

• Water is a renewable energy source. Hydropower storage

systems complement other sources of renewable energy (i.e,

wind, solar, etc.).

• Maintenance and operation charges are very low. No costs for

fuel.

• The efficiency of the plant almost does not change with age.

• In addition to power generation, hydro-electric power plants are

also useful for flood control, irrigation purposes, fishery and

recreation.

• Long life time (100 to 125 years). Limited labor costs, easy

automatization.

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Comparison with other methods of power generation

• Hydroelectricity eliminates the flue gas emissions from fossil fuelcombustion, including pollutants such as sulfur dioxide, nitric oxide,carbon monoxide, dust, and mercury in the coal

• Hydroelectricity also avoids the hazards of coal mining and theindirect health effects of coal emissions

• Compared to nuclear power, hydroelectricity generates no nuclear

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• Compared to nuclear power, hydroelectricity generates no nuclearwaste, has none of the dangers associated with uranium mining, nornuclear leaks

• Compared to wind farms, hydroelectricity power plants have a morepredictable load factor

• If the project has a storage reservoir, it can generate power whenneeded. Hydroelectric plants can be easily regulated to followvariations in power demand

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World hydroelectric capacity

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World renewable energy share (2008), with hydroelectricitymore than 50% of all renewable energy sources

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Disadvantages of hydro power production

• The initial cost of the plant is very high.

• Since they are located far away from the load center,

costs of transmission lines and transmission losses are

relevant.

• During drought season the power production may be

reduced or even stopped due to insufficient water in thereduced or even stopped due to insufficient water in the

reservoir.

• The risk of flow shortage may increase as a result of

climate change.

• Part of the water in the reservoir is lost by evaporation.

But these are only the economical disadvantages…..

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Installation of new large hydropower projects today is very

controversial because of their negative environmental

impacts. These include:

�upstream flooding

�declining fish populations

�decreased water quality and flow

�reduced quality of upstream and downstream

environmentsenvironments

Glen Canyon June 1962 Glen Canyon June 1964

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Ecosystem damage and loss of land

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• Large reservoirs required for the operation of hydroelectric powerstations result in submersion of extensive areas upstream of thedams, destroying biologically rich and productive lowland andriverine valley forests, marshland and grasslands

• The loss of land is often exacerbated by the fact that reservoirscause habitat fragmentation of surrounding areas

• Hydroelectric projects can be disruptive to surrounding aquaticecosystems both upstream and downstream of the plant site

• Generation of hydroelectric power changes the downstream riverenvironment

• Water exiting a turbine usually contains very little suspended

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• Water exiting a turbine usually contains very little suspendedsediment, which can lead to scouring of river beds and loss ofriverbanks

• Since turbine gates are often opened intermittently, rapid or evendaily fluctuations in river flow are observed (hydropeaking)

• Dissolved oxygen content of the water may change from pre-construction conditions.

• Depending on the location, water exiting from turbines is typicallymuch warmer than the pre-dam water, which can change aquaticfaunal populations, including endangered species, and preventnatural freezing processes from occurring.

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Failure hazard

• Because large conventional dammed-hydro facilities

hold back large volumes of water, a failure due to poor

construction, terrorism, or other cause can be

catastrophic to downriver settlements and infrastructure

• Dam failures have been some of the largest man-made

disasters in history

• Also, good design and construction are not an adequate

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• Also, good design and construction are not an adequate

guarantee of safety

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Power production depends on:

- Head: difference between upstream and downstream

specific energy [m]

- Flow rate processed by the plant Q [m3/s]

- Hydropower plant efficiency η (0.70 - 0.85): a coefficient which

measures the fraction of hydraulic power actually converted into

electrical power (η <1).

- High efficiency (es. Thermal power plant efficiency = 0.42)

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• Pipe efficiency ηP (0.90 – 0.95): it takes into account distributed

and local energy losses along the pipes

• Turbine efficiency ηT (0.80 -0.90): internal efficiency of the

turbine in turning hydraulic energy into mechanical energy

• Intrinsic efficiency ηO (~ 1): it takes into account losses due to • Intrinsic efficiency ηO (~ 1): it takes into account losses due to

power unit, auxiliary plants maintainance,

The values of efficiency reported here are indicative (actual values

depend on the type of hydropower plants).

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- Hydropower plant efficiency η depends on the speed of the

turbine, on the head, on the flow processed......

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Hydraulic Turbines

Advantages:

Simple in construction.

Easily controllable.

Efficient.

Ability to work at peak load.Ability to work at peak load.

Work on load variation.

Types of turbines:

a)Impulse

b)Reaction

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IMPULSE TURBINES (Pelton):

- the potential energy is first completely turned into kinetic

energy in the distributor and then transformed into

mechanical energy (free surface water moves a suitable

runner)

- operate at normal (atmospheric) pressure

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2. REACTION TURBINES (Francis,

Kaplan):

- the energy of water is not

completely turned into kinetics

energy before the entrance into the

turbine; the mechanical energy is

derived exploiting the combined

action of pressure and kineticsaction of pressure and kinetics

energy)

- water flows through the blades

exerting a force related to changes

in magnitude and direction of the

velocity during the flow path

- operate fully submerged (pressure

gradient across the runner)

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Other Classifications(Streamflow and power)

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Animations

Pelton turbine

http://www.youtube.com/watch?v=Jd5BN7SPkqI

Francis Turbine

http://www.youtube.com/watch?v=3BCiFeykRzo

Kaplan Turbine

http://www.youtube.com/watch?v=0p03UTgpnDU

Virtual turbineshttp://www.youtube.com/watchv=IZdiWBEzISM&list=PLD016622FEE1DF943

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Useful links

General information on some dams and associated plants.

http://www.progettodighe.it/main/le-centrali/article/isola-

serafini-monticelli-d-ongina

Turbines:

http://www.arditosrl.eu/turbine.html

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Reservoir Dimensioning

part of the slides courtesy of Gianluca Botter, part of the slides courtesy of Gianluca Botter,

UNIPD

Page 58: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

The ability of humans to exploit natural streamflows as

water resources is by far improved by RESERVOIRS able

to STORE WATER and MODIFY the SEQUENCE of

NATURAL STREAMFLOWS.

Reservoir uses:

a. hydropower (transfer of water in space/time)

RESERVOIRS and WATER RESOURCES

a. hydropower (transfer of water in space/time)

b. irrigation (sink)

c. municipal (sink)

d. industrial (usually a sink)

Need for REGULATION: ensamble of operations to store

and release water volumes during time, in relation to the

storage potential of the reservoir and the request for

civil/industrial uses

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LONG TERM REGULATION: inter-annual regulation,

chiefly corresponds to water savings during years with

larger water availability to satisfy the request on years

with lower water availability.

MID-TERM REGULATION: intra-annual regulation,

corresponds to water savings during months/season with

REGULATION and TIME HORIZONS

corresponds to water savings during months/season with

low request (low economical benefit from water use),

allowing for a more intensive usage during periods with

higher request (& economical rewards).

SHORT-TERM REGULATION: regulations carried out at

the daily level within a given season/month; same as mid-

term regulation but within shorter time horizons.

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LONG TERM REGULATION: require the implementation

of climate change impact studies and associated analysis

of possible evolution of electricity market.

MID-TERM REGULATION: using deterministic inflows

and simplified/idealized schemes for utilizations

(traditional approach). We will concentrate on this.

REGULATION and TIME HORIZONS

(traditional approach). We will concentrate on this.

SHORT-TERM REGULATION: require the adoption of

sophisticated numerical tools, including the intra-seasonal

stochasticity of rainfall and streamflows, and focussing on

the weekly cycles of the water uses.

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PLANT CAPACITY (DESIGN FLOW)

•Plant capacity chosen according to a fixed value of the

duration

•The Net Positive Value (revenues) of the project is

checked a posteriori

•Relies mostly on the designer experience

What is the definition of duration?

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Water discharge curves

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Duration curve (a real one)

FDC adimensionalizzata con la portata media per il bacino del fiume Noce. Per confronto si riporta anche la curva relativa all’Adige a

Trento.

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Power available

�To design an hydroelectric

plant is fundamental the

knowledge of the duration

curve of the streamflows, to

which the “processed”

discharge Q is related.

�Classical design (for high

head plants) foresee a

duration of Qmax of about 2duration of Qmax of about 2

months. The design should

tale into account increases of

construction costs due

increase of Qmax (including

appreciation).

�For small head plants this

value can be increased since

the costs increase rate is

lower.

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Estimate of the flow duration curve

�Extended streamflow data series

�Empirical approaches:

- Rainfall data series

- Sporadic streamflow data

- Similar catchments

- Specific contribution of the catchment (Tonini)

�Analytical method: FDC expressed in terms of physical parameters estimated

from hydrologic/climatic/morphologic data

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Storage of water when flows are high to compensate the

scarse water availability during low flows

80100120140

Mill

ion m

3/m

onth

Reservoir full (hopefully)

Reservoir management

020406080

Mill

ion m average

Deficit

provided by

storage

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Reservoir Dimensioning:long term water balance equation

where Qin represents the natural inflow (result of the

filtering operated by soil moisture on rainfall), Qout is the

sum of the discharge through the spillways and all the other

direct withdrawals (evaporation and direct precipitation are

neglected → catchment area A is much larger than pool

surface S)

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Reservoir Dimensioning:deterministic approach for annual management (mid term)

assign Qin deterministically, prescribe Qout, and study the

reservoir volume required to allow for the prescribed

sequence of inflows/outflows

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Reservoir Dimensioning:deterministic approach for annual management (mid term)

Hypotheses:

annual regulation (reference period = 1 year; every year is

supposed to produce the same dynamics)

total regulation (all the incoming streamflows are released from

the reservoir at the end of the regulation period of 1 year)

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Reservoir Dimensioning:average and typical years

assign Qin during the regulation period in a deterministic manner

(single out deterministic seasonal trends!)

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Flow Duration Curves:average and typical years

The same excercise can be done at daily time scale. It depends

on data availability. The longer the time series the better.

1- = Exceedance probability

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Q95 = 1.12 m3/s

Global duration curve

Q50 = 3.1 m3/s

Q5 = 7.7 m3/s

Flow Duration Curves:global and average years

Duration curve (average discharge)

Q95 = 1.8 m3/s

Q50 = 3.1 m3/s

Q5 = 7.3 m3/s

1-

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Water discharge in the average year

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Reservoir volume

Page 75: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Reservoir Dimensioning:cumulated incoming volumes

Average year

Average year

Average year

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Reservoir Dimensioning:Regulation volume

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Reservoir Dimensioning:Regulation volume

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Reservoir Dimensioning:Graphycal representation

Qin is assigned

Qout is constant

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Reservoir Dimensioning:Conti representation

“Every line comprised betweenthe input cumulated volume curve(solid red line) and its downwardtranslation of a quantity Vreg(dashed red line) is a potentialcurve of the output cumulatedvolumes compatible with VREG,volumes compatible with VREG,provided that a=b (totalregulation) and its derivative ispositive (Q>0).If this line (e.g. the blue line)touches both the red lines, all theregulation volume is used (i.e. thereservoir is both empty and fullalong the year).”

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Example of applicationfor reservoir dimensioning:

excel sheetexcel sheet

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Reservoir Management

part of the slides courtesy of Gianluca Botter, part of the slides courtesy of Gianluca Botter,

UNIPD

Page 82: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Constant Hydropower Production (~ 1960)

Page 83: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Mainly Winter Hydropower Production (~ 1970)

To cover the energy demand peakin the cold months and thedecrease of the production of therun-of-river power plant during thesame months.

The derivative of the outputcumulated volume in the wintercumulated volume in the winterperiod represents the maximumflow that can be diverted forhydropower production (accordingto which the design of the powerplant is carried out).

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Winter & Summer Hydropower Prod. (~ 2000)

Page 85: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Energy market

Recently: hydropower plants integrate constant-like production

of thermal plants and cover peaks of energy demand

(hydropower plants can be indeed started and stopped easily).

Birth of the energy market

- Anyone can produce, import, buy and sell electric energy

- From July, 1 2007 everybody can buy energy on the market

- From the ENEL monopoly to the free market.... Birth of new

companies for each activity involved in the energy production,

transmission, sale and distribution

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TERNA: Property & maintenance of the transmission network

(high/medium voltage)

Energy market

GSE (electric services manager): Management of the

transmission network

ENEL DISTRIBUZIONE + municipal companies: Property &ENEL DISTRIBUZIONE + municipal companies: Property &

maintenance of the distribution network (low voltage)

GME (energy market manager): Management of the electric

energy market

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Page 90: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.
Page 91: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.
Page 92: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Weekly Trend

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Impact on Streamflows

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Flood Protection

part of the slides courtesy of Gianluca Botter, part of the slides courtesy of Gianluca Botter,

UNIPD

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Conceptual model of a reservoir

a RESERVOIR is made of a DAM with (at least) a crest and aprincipal spillways

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Conceptual model of a reservoir

Page 98: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Conceptual model of a reservoir

Page 99: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Conceptual model of a reservoir

Page 100: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Conceptual model of a reservoir

Page 101: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Water balance equation in a reservoir

Page 102: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Water balance equation in a reservoir

Page 103: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

FLOOD CONTROL (event scale)

Page 104: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

The Reference Flood

Page 105: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

The Reference Flood

�Usually centennial rainfall volumes (with different durations)

are generated and empirical or physically based models are

then employed to disaggregate the rainfall and generate the

reference flood wave.

�In general the underlying streamflow volumes are more

relevant than the peakflows to define the behavior of the

reservoir during the flood mitigation.

�The return period of the streamflow volume or of the�The return period of the streamflow volume or of the

peakflow of a given event is obviously different from the return

period of the rainfall event that have generated such event

(soil moisture dynamics!).

�Different events with the same volume may generate

different responses of the reservoir, depending on the shape of

the flood and the initial condition of the reservoir.

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An example: a single unregulated spillway

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An example: a single unregulated spillway

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Selection of site for Hydro-

Electric Production

Page 109: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

The following factors should be taken into consideration while

selecting a site for a hydro-electric power plant:

Water Availability.

Record of observations should be acquired for a reasonable

number of years to understand maximum and minimum

variations from the average discharge. Hydrographs and flowvariations from the average discharge. Hydrographs and flow

duration curves can thus be constructed.

In case data are not available, regionalization or stochastic

approach should be adopted.

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Distance from Load Center.

Routes and the distances should be carefully considered since the

cost of transmission lines and their maintenance will depend upon

the route selected.

Access to Site

It is always a desirable factor to have a good access to the site ofIt is always a desirable factor to have a good access to the site of

the plant. This factor is very important if the electric power

generated is to be utilized at or near the plant site. The transport

facilities must also be given due consideration.

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Water Storage

The output of a hydropower plant is not uniform due to widevariations of incoming streamflow. To have a uniform poweroutput, a water storage is needed so that excess flow at certaintimes may be stored to make it available at the times of lowflow. To select the site of the dam, geological andtopographical studies should be conducted for the design of thefoundations and optimization of the storage volume and headstage.stage.

Head of Water

The level of water in the reservoir for a proposed plant shouldalways be within limits throughout the year.

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Hydrodynamic graphGraph showing altitude of the basin as a function of the cumulated drainagearea. Area below curve (hydrodynamic value) is proportional to the potentialenergy available. Useful to design the correct location of a plant, but doesnot have information on streamflow.

Different tributaries

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Hydrodynamic graph from DTM

DTM (Digital Terrain Model) is a georeferenced matrix of terrain elevation

north:north: 51575605157560

south:south: 51070005107000

east:east: 16734001673400east:east: 16734001673400

west:west: 16152401615240

rows:rows: 50565056

cols:cols: 58165816

--9999 --9999 --9999 --9999 --9999 --9999

--9999 --9999 --9999 --9999 --9999 --9999

--9999 --9999 --9999 --9999 3088.983088.98 3084.553084.55

--9999 --9999 --9999 3091.483091.48 3088.153088.15 3082.823082.82

--9999 --9999 3090.533090.53 3089.863089.86 3085.863085.86 3079.913079.91

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DTM representation

A three-dimensional plot of the DEM of the Fella River Basin [after Rigon, 1994]

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Drainage directions

a2

3 4 5

6

Drainage directions of the Fella River Basin

1 78

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Network extraction

The effect of different cumulated drainage thresold for the network extraction

(At increases from a) to c)). Plot d) represents the network extracted from

traditional cartography [Tarboton et al., 1989]

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GIS Analysis

• http://www.slideshare.net/SlidesAboutHydrology/3-introduction-gis

http://www.slideshare.net/SlidesAboutHydrology/2-hydrogeomorphology

• youtube: http://www.youtube.com/user/udiggis

• Material of Riccardo Rigon’s course

abouthydrology.blogspot.it/2012/02/il-corso-di-idrologia-2012-my-hydrology.html

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Hydrodynamic graph

Hydrodynamic graph can be calculated for selected point along the main

channnels.

2350

2450

2550

2650

2750

2850

0 1000000 2000000 3000000 4000000 5000000

Superficie (mq)

Ele

vazio

ne (

m)

s3

s2

s1

Page 120: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Advanced methods for location selection

Analytical method for streamflow + GIS analsys

Page 121: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Advanced methods for location selection

Analytical method for streamflow + GIS analsys

Page 122: Hydrology for HYDROPOWER PLANTS MODULE - ing.unitn.itrighetti/lezioni HPP/HPP/Hydrology/Lecture1... · How a Hydroelectric Power System Works – Part 2 ... 1. Catchment area. 2.

Numerical example:

a single unregulated spillway

Newton method

Matlab implementationMatlab implementation