Transcript Induction - Palang Thai

Introduction to
Hydro Power
15 April 2009
Monterey Institute for International Studies
Chris Greacen
[email protected]
Outline
•
•
•
•
Solar, wind, hydro – brief comparison
Hydro system overview
Some examples from Thailand and elsewhere
Site assessment
–
–
–
–
Head
Flow
Penstock length
Transmission line length
• Civil works
• Mechanical
• Electrical
Sun, Wind, & Water
Micro-hydropower overview
Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.
Thai Potential:
1000s of projects - 700 MW (?)
Mae Kam Pong, Chiang Mai
DEDE + community
40 kW
$130,000 cost
Sell electricity to PEA – $13,000 per year
Huai Krating, Tak
Power: 3 kW
Head: 35 meter
Flow: 20 liters/second
Cost: <$6,000
(turbine - $700 baht)
Kre Khi village, Tak Province
1 kW for school, clinic, church
Cost: <$3,500
(turbine $250)
Head: 10 meters
Flow: 15 lit/sec
Mae Klang Luang, Chaing Mai
200 watts
$120 (turbine: $90)
Installed: 2007
Head: 1.7 meters
Micro-hydroelectricity: Estimating the
energy available
Power = 5 x height x flow
height
Watts
meters
liters per
second
Image Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.
Measuring height drop (head)
• Site level
• Pressure gauge
Sight level method
Hose & 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.
Feet head = PSI x 2.31
H1
Measuring Flow
• Bucket Method
• Float Method
design flow = 50% of dry-season flow
Bucket Method
Float Method
Flow = area x average stream velocity
Civil Works – some golden rules
• Think floods,
landslides
• Think dry-season.
• Try to remove
sediment
• Maximize head,
minimize penstock
– “wire is cheaper than
pipe”
Image source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.
Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.
Weir
A Sluice allows sediment removal.
Locating the Weir
& Intake
Silt Basin
Trash Rack
Intake
Head Race
Weir
Penstock
Intake directly to penstock
• If spring run-off sediment is not severe, the
penstock may lead directly from the weir.
Screened Intake
Weir
Penstock
Side intake
Trash rack: keeps the big stuff out
Screens
• Screen mesh-size should be half the nozzle diameter.
• A self-cleaning screen design is best.
• The screen area must be relatively large.
Screen
Head Race
Silt Basin
Penstock
Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.
Power Canal (Head Race)
• It may be less expensive to run low pressure
pipe or a channel to a short penstock.
Head Race
6” Penstock
4” Penstock
Forebay (Silt basin)
• Located before penstock
• Large cross-sectional area, volume  Water velocity reduced 
sediment (heavier than water but easily entrained in flow) has
opportunity to drop out.
Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.
Penstocks
• A vent prevents vacuum collapse of the penstock.
• Valves that close slowly prevent water hammer.
• Anchor block – prevents penstock from moving
Vent
Valve
Pressure Gauge
Valve
Anchor Block
Penstock
Penstock diameter
Hazen-Williams friction loss equation:
headloss friction (meters)
=(10.674*(F/1000)^1.85)/(CoefFlow^1.85*D^4.87)*L
Where:
F = flow (liters/sec)
CoefFlow = 150 for PVC
D = penstock diameter (mm)
Penstock materials
•
•
•
•
Poly vinyl chloride (PVC)
Polyethylene (PE)
Aluminium
Steel
Anchor and Thrust Blocks
Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.
Locating the Powerhouse
•
•
•
Power house must be above flood height.
Locate powerhouse on inside of stream bends.
Use natural features for protection.
Micro-hydro technology
Pelton
Turgo
Crossflow
Kaplan
Centrifugal
pump
Turbine application
http://www.tycoflowcontrol.com.au/pumping/welcome_to_pumping_and_irrigation/home4/hydro_turbines/turbine_selection (April 18, 2003)
Efficiency and Flow
100%
Efficiency
Pelton and Turgo
Crossflow
Propeller
50%
Francis
0%
0
0.2
0.4
0.6
0.8
Fraction of Maximum Flow
1.0
Generators
• Permanent magnet
• Wound rotor synchronous
• Induction (Asynchronous)
Permanent Magnet Generator
• Rotor has permanent magnets
• Advantages
– No brushes
– Efficient
• Disadvantages
– Generally limited in size to several kW
– field not adjustable (except ESD)
• Some do AC
• Some do AC and rectify to DC
• Some do both
Adjustable permanent magnet generator
DC Alternator (automotive)
• Produces rectified
alternating current.
• Readily available.
• Easy to service.
• Brushes need replacing.
• A rheostat controls
excitation.
DC Alternator (automotive)
• May be rewound for lower rpm at low head.
• The field may need a battery boost to start.
• Use high voltage ac output with a step-down
transformer and rectifier for long transmission
distance.
(wound rotor) Synchronous Generator
•
•
•
•
Used in many all stand-alone applications.
Single phase up to 10 kW.
3-phase up to >100,000 kW
Advantage:
– Industrial standard
– Frequency and voltage regulation
• Disadvantage
– Wound rotor – not tolerant to overspeed
– Harder to connect to grid
(wound rotor) Synchronous Generator
• Most large machines use field coils to
generate the magnetic field.
• Rotating magnetic field induces alternating
current in stator windings.
Exciter Field Winding
Rectifier
Stator Output Winding
Rotor Field Winding
Exciter Winding
AVR
(wound rotor) synchronous generator
small
2,000 watts
Big
50,000,000 watts
Asynchronous (Induction) Generator
• Just an induction motor with negative slip.
• Used with:
– grid-tie system (up to 1 MW)
– Off-grid stand-alone (often in ‘C-2C’ configuration)
– Can be used with battery based systems
Induction motor/generator
Induction Generator
• Advantages
–
–
–
–
Simple and robust.
Tolerant to overspeed
Readily available
inexpensive
• Disadvantages
– Frequency regulation ‘loose’ in stand-alone applications
– Requires external excitation
• When used in off-grid,
an ‘ELC’ controls voltage
Induction generator
(mini) grid-tie example
Wires from electrical panel to
flow switch 5.5 meters
Single-phase 230 volt
power to the resort grid
N
L
Single-phase 230
vac 50 Hz kWh
meter
V
Volt-meter (0-500 volt)
Fused cutout, 230 volt
A
AC Ammeter (0 to 5
Amp)
X
flow switch (open-circuit
when no-flow) HFS-25
Outflow pipe
Indicator
lamp
Wires from electrical
panel to pump 5.5 meters
Induction grid-tie example
1 MW Mae Ya
Huai Krating:
‘pump as turbine’ off-grid induction “C-2C”
3kW
Ballast Load
ELC
Motor Run
Capacitors
in Box
Ballast
Current
10A
15A
380V
6A
235V
C
25μF
2C
50μF
3000W
4 kVA 380V
Total
Current
To
Village
Capacitors for external excitation of induction
motors: theoretical overview of LC oscillators
Calculating “C” in C-2C
•
•
•
•
•
•
Apparent power (VA): S = √3(IV)
Real Power (W): P = S cos(φ)
Reactive power (VAR): Q = √(S2 - P2)
Reactive power per phase: q = Q/3
Capacitor current: Ic = q/V
Capacitance (micro-F) for delta: C = 106 x Ic / (2πfV)
• … but don’t worry…
it’s all in the spreadsheet.
• Use “motor run” not
“motor start” capacitors
Mae Wei:
‘pump as
turbine’ off-grid
induction
To village loads…
A
V
School
Ammeter 15 amp
Volt-meter (0-500 volt)
Knife switch
A
Powerhouse
Ammeter 15 amp
power lines: single phase 230
vac to village. 2 @ 25 mm Al
Leonics controller
A
V
Ballast load
Ammeter 15 amp
Volt-meter (0-500 volt)
Capacitor 70 microfarad
Capacitor 140 microfarad
Three phase 230 vac delta
Mae Wei – ‘pump as turbine’ off-grid induction
Regulation
With
batteries
AC direct
Permanent magnet
Trace C-40 type,
etc.
Wire to output of
Outback
ELC (voltage)
Synchronous
Trace C-40 type
Governor
(frequency)
AVR (voltage)
Induction
Trace C-40 type
Wire to output of
Outback
ELC (voltage)
Capacitors for
frequency
Regulation – synchronous
generators… typically both voltage
and frequency
• Voltage decreases as load current increases.
• The Automatic Voltage (AVR) regulator
increases the field excitation to compensate.
• Prolonged underspeed can damage an AVR.
• Still required with a load controller because
load power factor can change.
Mechanical Governing
• As load varies, mechanical control keeps
frequency constant by varying water flow
– Advantage:
• Saves water
– Disadvantage:
• Electro-mechanical moving parts
• Slower reacting
• More expensive
Deflector
Electronic Governing
• Types
1. Phase angle
2. Binary controller
3. Pulse Width Modulation
• Dump load:
– water heating
– air heating
– lightbulbs (not recommended)
Mae Wei – ‘pump as turbine’ off-grid induction
Applying Common Property Theory to
Village Power Systems
Definition of a common pool resource (Oakerson
1992; Ostrom 1994):
• System has limited yields
• difficult to exclude individual users from using
too much
0
0
Current 1
Current 2
Current 3
Voltage
Volts
50
8/8/01 18:05
5
8/8/01 12:05
100
8/8/01 6:05
10
8/8/01 0:05
150
8/7/01 18:05
15
8/7/01 12:05
200
8/7/01 6:05
20
8/7/01 0:05
250
8/6/01 18:05
25
8/6/01 12:05
300
8/6/01 6:05
30
8/6/01 0:05
Amps
Mae Kam Pong Microhydro Unit #2 Voltage and
Current (15 minute intervals) 6 Sept to 8 Sept 2001
Low evening time voltage:
symptom of a common property problem
• Rules governing user behavior
should match with the technical
characteristics of the system
• kWh Meters are a mismatch for
microhdyro
• Should be concerned with kW, not
kWh
• Low voltages… kWh meter is a
culprit
Circuit breakers: a technical fix for a
common property problem
600
kWh meter
500
400
watts
X
300
200
100
S1
11pm
9pm
7pm
5pm
3pm
1pm
11am
9am
7am
5am
0
Mini-circuit breaker can encourage peak load reduction
OK
Mini-circuit
breaker
7000
6000
5000
4000
Watts
3000
2000
2000
1000
1997
1994
1985
23:00
22:00
21:00
20:00
19:00
18:00
17:00
16:00
15:00
Time of day
Year
1988
14:00
13:00
12:00
11:00
10:00
9:00
8:00
7:00
1991
6:00
5:00
0
Hourly load curve, by year from 1985 to 2000. Graph based on an appliance
usage survey of 35 families in Mae Kam Pong village, April and June 2001.
10000
9000
8000
7000
other
water boiler
rice cooker
iron
fridge
TV
lights
Watts
6000
5000
4000
3000
2000
1000
0
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Contribution to evening maximum peak demand by appliance, for the years 1985 – 2001.
Thank you
… and please bring tools for Saturday hands-on PV workshop
wrenches
pliers
screw drivers
leatherman
For more information, please contact
[email protected]
This presentation available at:
www.palangthai.org/docs