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Small Hydro
PowerSystems
Power Generation
http://en.wikipedia.org/wiki/Image:Orontes.jpg
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Power (kW) = f (Head, Discharge, Efficiency)
P = f (H, Q, η)
Q
H
Power
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Hydrology
Flow prediction by area-rainfallmethod
Flow prediction by correlation method
Head measurement
Flow measurement
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Area-rainfall method
Catchment area with contour maps
Select the highest head (less turbine cost)
Find annual average daily flow using rain-
gauge data Calculate net flow available after
evaporation, use of water, seepage, etc.from data
Account for flow variation during months Calculate the lowest flow
Construct FDC
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Flow Duration Curve (FDC)
DefinitionA graphical representation of aranking of all the flows in a given
period, from the lowest to thehighest, where the rank is thepercentage of time the flow valueis equalled or exceeded.
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Correlation method
Conduct sample field measurements
10 / year or 6 / lean period
Correlate FDC with data from Govt.agencies
Correct FDC with site data
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Head Measurement
Water filled tube (with scales or person)
Water filled tube and pressure gauge
Spirit level and plank (or string)
Altimeter (9 mm Hg/100 m)
Sighting meter
Sighting with spirit level
Dumpy level / theodolite
Electronic Digital Levels
GPS (Global Positioning System)
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Head Measurement using
Abney-level Method
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Head measurement using
spirit level and plank
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Topographic Maps
Used to locateheads
Used to locatevarious
components ofSHP plant
>100m, use1:50,000 maps
Smaller mapswith 10mcontours areuseful
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Flow Measurement
Salt gulp method (turbulent flows)
Bucket method
Float method
Propeller devices
Weir method
Stage control method(for little large dams)
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Salt gulp method
100 g salt for 0.1 m3/s flow over 50m distance (estimate salt required)
record conductivity each 5 sec. andplot
Q = mass of salt / (factor * area
under curve)
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Bucket method
Divert entire flow to bucket
record time
suitable for small streams only
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Float method
Approximate method only
use different floats and average thetime
reduce surface velocity by:large, slow, clear stream : 0.75
small regular channel, smooth stream : 0.65
shallow (0.5m) turbulent stream : 0.45very shallow, rocky stream : 0.25
Q = A * V
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Weir Method
Natural sections
Rectangular weirQ = 1.8 (L-0.2 h) h**1.5
Triangular weirQ = 1.4 h**2.5
L in m, h in cm, Q in m
3
/s
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Fl M t i I t t d
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Flow Measurement using Integrated,
handheld meter
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Reconnaissance Study Data Collection (Basic Reference Materials)
Topographic maps (Minimum Requirement) Detailed maps with a scale of at least 1/50,000 Landform, location of villages, slope of river, catchment area
of proposed site, access road
Rainfall data
Monthly and annual rainfall data of adjacent areas Isohyetal maps
Hydrological data (Minimum Requirement) River discharge data from the adjacent areas
Socio-economic information
Others Climate map
Distribution line map
Existing proposal from local government and residents
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Map Study
Catchment Area
(Drainage Area)
1. Trace Maintain ridge
2. Measure the areawith a planimeter
3. Determine River
Gradient & Profile
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Assessment of Power Potential
Power potential is the product of availablehead and quantity of water at any point oftime and is determined by using the followingformula:
P = 9.81 ηQH
Where, P = Power output in kW
Q = Discharge in m3 /sH = Head (Net head) in m
η = Overall efficiency (0.5 to 0.7)
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Examples
Calculate flow needed to run a 50 kWfactory with a water fall of 20 m height
Pnet = 9.81 η Q H
Q = 50 / (10*0.5*20)
= 0.509 m3 /s
Calculate Power when the flow is 150 lt/s
and head is 90 ft.Pnet = 9.81 * 0.5 * 0.15 * 30
= 22.07 kW
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Assessment of Power Potential – contd.
Small run-of-the-river schemes generallyhave meager discharge data and data forstudies has to be generated by hydrological
approaches. The power potential for a small hydro
scheme is determined corresponding to 75%and 50% water availability.
The power potential may be computed on thebasis of monthly or 10 days average flow.
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Cut-away
drawing of awater
turbine
generator
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Turbines
Head Pressure(40m) (3-40m) (
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Impulse turbine
Water jet from nozzle impact -deflection of water - momentumtransfer - rotates runner
operates in air; no pressure dropacross runner
casing only to control splashing
cheaper
smallest runner preferred
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Pelton wheel
and nozzles
http://localhost/var/www/apps/conversion/tmp/scratch_4/Pelton%20wheel%20_%20Pelton%20turbine%20_%20Hydro-power%20(3D%20animation).flvhttp://localhost/var/www/apps/conversion/tmp/scratch_4/Pelton%20wheel%20_%20Pelton%20turbine%20_%20Hydro-power%20(3D%20animation).flv
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Reaction turbine
Rotating element is fully immersed
enclosed in a pressure casing
clearance between runner & casing
minimised
runner blades are profiled to havepressure drop - lift forces - causes
runner to rotate
http://localhost/var/www/apps/conversion/tmp/scratch_4/Kaplan%20turbine%20_%20Run-of-the-river%20hydroelectricity%20-%20How%20it%20works!%20(Animation).flv
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Kaplan Turbine
http://localhost/var/www/apps/conversion/tmp/scratch_4/Kaplan%20turbine%20_%20Run-of-the-river%20hydroelectricity%20-%20How%20it%20works!%20(Animation).flvhttp://localhost/var/www/apps/conversion/tmp/scratch_4/Kaplan%20turbine%20_%20Run-of-the-river%20hydroelectricity%20-%20How%20it%20works!%20(Animation).flv
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Francis Turbine
http://localhost/var/www/apps/conversion/tmp/scratch_4/Francis-Turbine%20(3D-Animation).flvhttp://localhost/var/www/apps/conversion/tmp/scratch_4/Francis-Turbine%20(3D-Animation).flv
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Bulb Turbine
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Pump as Turbine (PAT)
Cheaper (due to large scaleproduction of pumps)
Disadvantages:
poorly understood characteristics
lower efficiencies
unknown wear characteristics
poor part flow efficiency
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Selectionof Turbine
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Typical Turbine Efficiencies
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