Summer i Zing
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Transcript of Summer i Zing
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Types ofHydropower
Facilities
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ImpoundmentHydropower- uses a damto store water. Water may
be released either to meetchanging electricity needs
or to maintain a constantwater level.
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Run-of-River Projects-utilize theflow of water within the natural
range of the river, requiringlittle or no impoundment. Run-
of-river plants can be designedusing large flow rates with low
head or small flow rates withhigh head
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Microhydropower Projects -produce 300 kilowatts (kW) or
less. Microhydro plants canutilize low heads or high heads
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Diversion Hydropower -channels a portion of the river
through a canal or penstock,but may require a dam
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Pumped storage - pumps water from a
lower reservoir to an upper reservoirat times when demand for electricity
is low. During periods of highelectrical demand, the water is
released back to the lower reservoirto generate electricity.
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What is Micro Hydro? Micro-hydro is generally
less than 300 kW.
Hydro power is costeffective in a limited
number of places.
Hydro is moreconsistent than wind or
solar. Hydro is concentrated
solar energy.
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Micro Hydro Costs
High Capital Cost
Labor and Earth Moving Equipment Civil Works and Penstocks
Low Operating Cost No Fuel
Inexpensive maintenance
Especially economic for Do-It-Yourself.
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Micro Hydro is Run-of-River
No water storage.
Much simpler to design and build.
Less environmental impact.
May be seasonally dependent. Some schemes have a small reservoir for
supplying peak daily loads.
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Water Rights Sufficient water must be available.
Fish or riparian habitat must not be affected.
Other licensed users take precedence.
Environmental impact must be addressed.
Erosion due to civil works Water temperature increased due to low
water.
Dams are not recommended.
Easements required if crossing private land.
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AC systems
River flow must exceed peak demand.
Standard wiring and electrical equipment. Components
Generator Induction
Synchronous
Frequency Control and Governors
Voltage Control
Diversion loads11
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Grid Tie Systems
Utility Concerns
Fault Protection Line Worker and
Public Safety
Power Quality Metering Options
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Line Worker and Public Safety
Islanding
Generator supplies an isolated portion of gridduring a power outage.
Poses safety hazard to line workers.
Inverters meet UL standards
Induction Generators (Motors)
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Power
An instantaneous measure.
The ability to do work. Measured in Watts and Horsepower.
746 W = 1 hp
Hp = Flow (cfs) x Head (feet) x .88.8
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Hydro Power
Site Assessment potential power
Loads required power System capacity designed power
Locating the Intake Locating the Powerhouse
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Site Assessment Flow
The design flow will be a percentage of the
measured stream flow. Design flow determines penstock size
Design flow determines nozzle size Head
- Elevation difference between the penstock
intake and the turbine
Penstock length.
Often the major cost.16
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Measuring Flow
Velocity-Area Method
Velocity Head Flow Meter
Weir method Bucket method
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Determining Area
Average Depth = Sum of (N)depths
N
Area = Stream Width x Average Depth
1 2 3 ...
N18
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Measuring Velocity
Stream velocity varies with depth.
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Float Method
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Weir method
21Reference: Canyon Industries Inc., Micro-hydro Design
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Weir Method
22Reference: Inversin, Micro-hydropower Sourcebook
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Bucket Method
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Head
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Vertical distance from inlet to turbine for
impulse turbine. Vertical distance from inlet to tail water for
reaction turbine.
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Measuring Head
Inclinometer
Altimeter Hose and Pressure gauge
Level
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An Inclinometer
Also called an Abney Level.
L is measured with a tape or hip chain.
H = L x sin (a)H3
H2
H1
L1
L3
L2
a1
a2
a3
a
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Altimeters
Measuring relative height, therefore
absolute calibration is not necessary. The interval between measurements must
be short to avoid error from weather
changes.
Best to take multiple readings.
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Hose and Pressure Gauge Accurate and simple method.
Bubbles in hose cause errors.
Gauge must have suitable scale and be calibrated.
Use hose a measuring tape for penstock length.
H1
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Using a Level
Use a person or a measured pole.
Htotal = A + B + C + D
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Static Head vs. Net Head
Static head is the vertical distance from
the intake to the power house Net head takes into account friction loss
Pipe sizing rule of thumbA pipe diameter should be chosen so that only
10 15% of the static head is lost in pipe
friction. Tables are available for every pipematerial, diameter and flow rate.
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Locating the Intake
Choose a site with a stable stream bed.
Constant flow stream Bedrock
Small gradient
The inside of bends accumulate sediment.
The outside of bends are subject to
erosion and flood damage.
Place the intake along a straight section.
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Intake and Powerhouse
Flood conditions must be planned for.
Composition and nature of stream beddetermines erosion and future path
changes.
Natural features can protect civil works.
Locate upstream to avoid competing with
other water users.
Access for construction and maintenance.
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Civil Works
Diversion
Intake Silt Basin
Trash Rack Screen
Penstock Power House
Weir
Direct Intake
Head Race
Trash RackSilt Basin
Penstock34
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Civil Works
The river flow will be
seasonally variable. Sediment must be
removed.
Must be accessible for
construction.
Erosion occurs if water
flows around weirs.
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Diversion
Weirs maintain the water level at the
intake. A Weir does not store water.
Natural riverbed features may be used. Weirs may also be :
Concrete
Gabions
Wood
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Weir
The sluice is a short length of pipe for
clearing away sediment.
Artificial Weir
Sluice
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Weir
If spring run-off is not severe, the penstock
may lead directly from the weir.
Screened Intake Weir
Penstock
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Sluice
A Sluice allows sediment removal. 39
Wi W ll
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Wing Walls
Wing walls prevent erosion and flood
damage to the civil works. Natural rock walls along a stream can
serve the same purpose.
Walls may be built from:
Gabions
Concrete
Rock and mortar
Wood 40
I t k D th
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Intake Depth
Pipe intakes should be submerged deep
enough not to draw air.
H = (0.0622) Q2
/ D4
H = intake depth[in]
Q = flow rate [gpm]
D = pipe diameter [in]
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I t k D th
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Intake Depth
Rule of thumb pipe should be
submerged 3x the pipe diameter Screening is the weak point
Intake structures are the mostmaintenance intensive part of hydro
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Sid I t k
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Side Intake
Place a side intake far enough upstream
to avoid silt deposited behind the weir.
Head Race
Weir
Side Intake
Wing Wall
Silt
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Di t I t k
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Direct Intake
A direct intake allows silt to be drawn into
the head race to settle in the silt basin.
Weir
Direct Intake
Head Race
Silt Basin
Wing Wall
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T h I t k
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Trench Intake
A trench intake in a rapidly flowing stream
allows large debris to pass over. The rapid flow keeps the rack clear.
Trash Rack
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Screens
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Screens
Screens should be half the nozzle
diameter. A self-cleaning screen design is best.
The screen area must be relatively large.Screen
PenstockHead Race
Silt Basin46
Trash Rack
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Trash Rack
The trash rack should be at least two pipediameters from the pipe inlet.
If the trash rack is not situated in the mainstream it is easier to clean.
If the head race is a pipe, a rack is
necessary.
Drilled PVC Pipe will serve as a trash rack.
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Ice and Snow
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Ice and Snow
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Frazil ice super cooled
water sticks toeverything
Submerging the intake
allows the ice to float.
Snow may prevent
penstocks from freezing.
Penstock
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Penstock
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Materials
Diameter Friction
Pressure Rating Valves
Gauges Thrust Block
Penstocks
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Penstocks A vent prevents vacuum collapse of the penstock. A pressure gauge should always be installed.
Valves that close slowly prevent water hammer.
50Penstock
ValveVent
Pressure Gauge
Valve
AnchorBlock
Penstocks
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Penstocks
A short straight penstock is least
expensive. A channel or culvert may be used to
reduce penstock length.
Pipe laid in the creek will abrade.
Penstocks deliver water under pressure.
Usually the major expense.
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Slide, Anchor and Thrust Blocks
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,
Prevent unwanted
movement of penstock. Required at bends and
reductions.
Anchor blocks use mass
to prevent movement.
Thrust blocks are used
with buried penstocks.
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After bay and Tailrace
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After bay and Tailrace
Removes water from power
house and turbine. Designed to prevent
erosion.
Must be large with enough
slope to prevent water
backing up in turbine.
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Head Race
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Head Race
It may be less expensive to run low
pressure pipe or a channel to a short
penstock.
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4
Penstock
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Penstock
Head
Race
Turbines
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Turbines
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Water under pressure contains energy.
Turbines convert the energy in water intorotating mechanical energy.
Impulse turbines convert the kineticenergy of a jet of water to mechanical
energy.
Reaction turbines convert potential energyin pressurized water to mechanical
energy.
Selected References
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Selected References
Microhydro by Scott Davis
Microhydro Design Manual by AdamHarvey
Waterturbine.com for picohydro units BC Hydro Handbook
Idaho National Labs
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Impulse Turbines
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Impulse Turbines
Tolerate sand.
Easy to fabricate. Efficient at wide a range
of head and flow. A nozzle converts
pressurised water into a
high-speed jet of water.
57Pelton Turbine Canyon Industries
Pelton Turbines
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Pelton Turbines
At least one jet of water
strike the buckets atatmospheric pressure.
Maximum jet diameter
about 1/3 bucket width.
More jets increase flow
and are used at lowhead.
580.61m Pelton Dependable Turbines Ltd.
Turbine application
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Turbine application
Head (pressure)
Turbine High
(30m +)
Medium Low
(
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Generators
Types of Generators Synchronous
Induction
DC generators
Characteristics of Generators
Selecting a Generator
Voltage Regulation
Governing (speed and frequency) Mechanical
Electronic
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Synchronous Generator
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Synchronous Generator
Used in almost all stand-alone
applications. Single phase used up to 10 kW.
Most three phase are smaller than
equivalent single phase.
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Induction Generator
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Induction Generator
Just an induction motor with negative slip.
Used most often with grid-tie systems. Used by some for battery based systems.
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DC Alternator
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Produces rectified
alternating current. Readily available.
Easy to service.
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Electronic Governing
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g
Frequency governing is used for
synchronous generators. Voltage governing is used for induction
generators
Diversion Loads
A load must always be present.
Water heating or air heating.
Diversion loads may be useful loads.
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