hydropower plants

7/27/2019 Hydropower Plants

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Presented By:

Osama Elhassan Mohamed054017

Mohamed Baha-Eldin Sid-Ahmed

054055

Moez Mohamed Abd-Alrahman054084


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Mohamed Baha


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Hydropower (from hydro meaning water) is

energy that comes from the force of moving

water.

Hydropower is called a renewable energysource because the water on the earth iscontinuously replenished by precipitation. As

long as the water cycle continues, we wont

run out of this energy source.


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To generate electricity, water must be in

motion. This is kinetic (moving) energy. When

flowing water turns blades in a turbine, the

form is changed to mechanical (machine)energy. The turbine turns the generator rotor

which then converts this mechanical energy

into electrical energy


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Irrigation

Flood mitigation.

Clean water supply


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Diversion (Run of river plants)

Impoundment (Storage/reservoir plants)

Pump storage plants


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The running water of the river is used for the

generation of electricity. There is no facility

for storing the water. Whenever the water is

available the hydroelectric power plantgenerates electricity and when there is no

water no power is generated. During rainy

seasons when there is maximum flow of

water available in the rivers, they produce

maximum power

It is suitable for low consumption at remote

areas


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Usually requires construction of a dam or

dams to create new lakes.

Attractive because they can provide stored

power during peak demand periods.Creation of small hydro plants is not

financially viable except, at isolated

locations where the value of energy is very

high.


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When the demand for electricity is low, a

pumped storage facility stores energy by

pumping water from a lower reservoir to an

upper reservoir. During periods of high

electrical demand, the water is released

back to the lower reservoir to generate

electricity.

The recycling of water results in a netconsumption of energy, so energy used to

pump water has to be generated by other

sources.


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Dam

Penstock

Spillway

TurbineGenerator

Power lines


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Impulse turbine+ Pelton

+ Cross-flow

Reaction turbine

+ Propeller

- Bulb turbine - Straflo

- Tube turbine - Kaplan

+Francis

+ Kinetic


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PELTON Turbines

FRANCIS Turbines

KAPLAN Turbines


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How it works?

Water passes through nozzles and strikes buckets, which causes

the runner to rotate, producing mechanical rotational motion of

the turbine that is transmitted by the shaft to a generator.

How to control?

Can be controlled by adjusting the flow of water to the buckets.

Alterations in the load on the generator necessitate small

adjustments by a device which deflects part of the water jet

away from the buckets.(sometimes shut the valve off)

Efficiency Multi-jet units are specified to increase the flow range over

which high turbine efficiencies can be obtained.


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Advantages

It can operate on silt laden

water.

Nozzle and deflector plate canbe easily repaired, and after

longer periods the runner can

be repaired by welding.

Speed-load control is usually

carried out by the deflector,which ensures no pipeline surge

even on full load rejection.

No danger of cavitation damage

to the runner or casing.


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Features:

Contains a runner

that has water

passes through it

formed by curved

vanes or blades.

The runner blades,

typically 9 to 19 in

number and cannotbe adjusted.


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Moez Mohamed


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Turbine governors are equipments for the

control and adjustment of the turbine power

output and evening out deviations betweenpower and the grid load as fast as possible.


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The turbine governors have to comply with

two major purposes:

1.To keep the rotational speed stable andconstant of the turbine-generator unit at any

grid load and prevailing conditions in the

water conduit.

2. At load rejections or emergency stops the

turbine admission have to be closed down.


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The governor function for a turbine with

water conduit is shown in the block diagram


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The input reference signal is compared with

the speed feedback signal. By a momentary

change in the load a deviation between the

generator power output and the load occurs.

This deviation causes the unit inertia masses

either to accelerate or to decelerate. The

output of this process is the speed, which

again is compared with the reference.


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A simple but classic example of a turbine

governor is shown schematically in the

figure:


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This is a governor with a belt driven

centrifugal pendulum. For explaining the

governor actions it is chosen to start at a

moment of stable equilibrium between

power and load. In this condition the control

valve is closed by the spool, which is in the

neutral position.


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When a decrease in the grid load occurs, the

rotational speed starts increasing and the

pendulum sleeve and the connected end of

the floating lever moves upwards. The lever

moves the spool accordingly upward out of

the neutral position and opens the hydraulic

conduits to the servomotor. High-pressure oil

flows to the piston topside.


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The piston moves downwards and reduces

the gate opening and the turbine power. At

the moment when the power is equal to the

load, the rotational speed culminates.


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At this moment however, the spool valve

is still open. The piston movement

continues and the power output

decreases even more. Consequently the

speed decreases and the pendulum sleeve

and the spool are moving downwards

again. During this movement the spool

valve passes the neutral position and

opens


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then for high-pressure oil flow to the

opposite side of the piston. The piston

movement is thereby returned and the

power output increasing. Next time the

rotational speed culminates the power

again is equal to the load and

therefore a succeeding swing in thespeed and power output take place as

previously described


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An electronic load governor works by

automatically adjusting the load so the

generator always turns at exactly the right

speed.

In effect, it is always slowing the generator

down just enough to produce correct voltage

and frequency.

Electronic load governors constantly monitorvoltage or frequency, adding or subtracting

electrical loads as necessary to compensate

for human usage.


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An electronic load governor is highlyeffective for small systems up to about

12kW.


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Why it is used:

For automatically determination of the

set of optimal operating angles for thevariable pitch blades of a Kaplan-type

turbine which has movable gates and is

controlled by a governor and anelectronic 3D cam.


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The advantage of using 3D CAM:

The efficiency value is computed for

each of the measured operating points

and are compared to identify a peakefficiency value.


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Sedimentation/Silting:

Deposition of silt in the reservoir

Cause reduction of water storage capacity

Minimized by reclamation/dredging


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Dredging is an excavation activity or operation usuallycarried out at least partly underwater, in shallow seas

or fresh water areas with the purpose of gathering up

bottom sediments and disposing of them at a different

location.

Reclamation is the process of reclaiming somethingfrom loss or from a less useful condition.


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Cavitation:

Formation of water vapor & air bubbles due to

reduction of pressure. Occurs mainly at discharge end of runner and

blades.


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By measuring of pressure fluctuations at the draft tube inlet andoutlet.

By visual or photographic observation of the vapor bubbles on therunner blades.

By observation of the noise and vibration inside the turbine.

Cavitation prevention:

Optimum selection of materials and dimensions of runner.

selection of specific speed

polishing surfaces


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Cracks appears in water flow paths.

Impacts:

Leakage of water.

If arrived critical fatigue, it will make a water

explosion. Caused by:

Fabricated cracks.

High water pressure and/or flow rate.

Detection: By measuring of pressure.

Noticeable leakages.


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Prevention:

Proper selection of materials.Avoid to use turbines out of

safe regions.

Repairing the small cracks.


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E l i l I t


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Ecological Impacts

On lands:

Loss of forests, wildlife habitat, species.

Disrupt transfer of sediment and nutrients compete other uses for land that may be more highly valued

than electricity generation.

Pollution:

Doesn't pollute the air (No emission of Co2, Nox, Sox, etc..).

Rotting vegetation also emits greenhouse gases.


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Social Impacts


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Social Impacts

Humans, flora, and fauna may lose their natural

habitat .

Inundation and displacement of people Structural dam failure risks


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Positive Negative

Emissions-free, with virtually no CO2,NOX, SOX, hydrocarbons, orparticulates

Frequently involves impoundment oflarge amounts of water with loss ofhabitat due to land inundation

Renewable resource with high

conversion efficiency to electricity(80+%)

Variable output dependent on

rainfall and snowfall

Dispatchable with storage capacity Impacts on river flows and aquaticecology, including fish migration andoxygen depletion

Usable for base load, peaking andpumped storage applications

Social impacts of displacingindigenous people

Scalable from 10 KW to 20,000 MW Health impacts in developingcountries

Low operating and maintenance costs High initial capital costs

Long lifetimes Long lead time in construction of large

projects


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Merowe dam:

Impounds River Nile

Locale Merowe, S

udan

Length 9 km

(5.6 mi)

Height 67 m

(220 ft)

Constructio

n cost

1.2 billion

Creates Merowe

Reservoir

Capacity 12.5 km3

(3

.0 cu mi)

Turbines 10 125MW

Installedcapacity

1,250 MW

Annual

generation

5.5 TWh

Pumped storage

No

power generation information

reservoir information


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Oth h d i S d


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Other hydropower sources in Sudan:

DAM CAPACITY

Rosseris (Blue Nile) 280MW

Jabal Awliaa (White

Nile)

30MW

Khashm Algirbah (Atbara

river)

17MW

Sinnar (Blue Nile ) 15MW

Total HydroPower 1592MW


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Official name


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Impounds Yangtze River

Length 2,335 metres (7,661 ft)

Height 185 metres (607 ft)[1]

Width (at base) 115 metres (377 ft) Crest:40 metres (131 ft)

Construction began December 14, 1994

Opening date 2011 Est.

Construction cost 180 billion yuan (26 billionU.S. dollars)

Maintained by China Three Gorges Dam Project

Reservoir information

Creates Three Gorges Reservoir

Capacity 39.3 km3(31,900,000 acreft)

Catchment area 1,000,000 km2(390,000 sq mi)

Surface area 1,045 km2

(403 sq mi)

Power generation information

Turbines 32

Installed capacity 22,500 MW

Annual generation 100


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