Introduction to Hydro Power 15 April 2009 Monterey Institute for International Studies

Introduction toHydro Power

15 April 2009Monterey Institute for International Studies

Introduction toHydro Power

15 April 2009Monterey Institute for International Studies

Chris Greacenchris@palangthai.org

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.

Mae Kam Pong, Chiang MaiDEDE + community40 kW$130,000 costSell electricity to PEA – $13,000 per year

Thai Potential:1000s of projects - 700 MW (?)

Huai Krating, TakPower: 3 kWHead: 35 meterFlow: 20 liters/secondCost: <$6,000

(turbine - $700 baht)

Kre Khi village, Tak Province1 kW for school, clinic, churchCost: <$3,500

(turbine $250)Head: 10 metersFlow: 15 lit/sec

Mae Klang Luang, Chaing Mai200 watts$120 (turbine: $90)Installed: 2007Head: 1.7 meters

Micro-hydroelectricity: Estimating the energy available

Image Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.

heightPower = 5 x height x flow

Watts meters liters per second

Measuring height drop (head)

• Site level• Pressure gauge

Sigh

t lev

el m

etho

d

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 Methoddesign flow = 50% of dry-season flow

Bucket Method

Float Method

Flow = area x average stream velocity

Image source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.

Civil Works – some golden rules

• Think floods, landslides

• Think dry-season.• Try to remove

sediment• Maximize head,

minimize penstock– “wire is cheaper than

pipe”

Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.

Weir

A Sluice allows sediment removal.

Locating the Weir & Intake

Weir

Intake

Head Race

Trash RackSilt Basin

Penstock

Intake directly to penstock

• If spring run-off sediment is not severe, the penstock may lead directly from the weir.

Weir

Penstock

Screened Intake

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

PenstockHead Race

Silt Basin

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.

4” Penstock

6” Penstock

Head Race

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

Penstock

Valve

Vent

Pressure GaugeValve

Anchor Block

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 PVCD = 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

0.2 0.80.60.4 1.0Fraction of Maximum Flow

Eff

icie

ncy

50%

00%

100%Pelton and Turgo

Crossflow

Francis

Propeller

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.

• 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

(wound rotor) Synchronous Generator• Most large machines use field coils to

generate the magnetic field.• Rotating magnetic field induces alternating

current in stator windings.

AVR

Rotor Field WindingExciter Winding

Exciter Field WindingStator Output WindingRectifier

(wound rotor) synchronous generator

Big50,000,000 watts

small2,000 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

Single-phase 230 volt power to the resort grid

Fused cutout, 230 volt

Volt-meter (0-500 volt)

flow switch (open-circuit when no-flow) HFS-25

LN

X

Indicator lamp

V

Single-phase 230 vac 50 Hz kWh meter

AC Ammeter (0 to 5 Amp)

A

Wires from electrical panel to pump 5.5 meters

Outflow pipe

Induction generator (mini) grid-tie example

Wires from electrical panel to flow switch 5.5 meters

Induction grid-tie example1 MW Mae Ya

15A 10A

ToVillage

TotalCurrent235V

3000W

ELC

BallastCurrent

3kW Ballast Load

380V

Motor Run Capacitors

in Box

6A

4 kVA 380V

C25μF

2C50μF

Huai Krating:‘pump as turbine’ off-grid induction “C-2C”

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

power lines: single phase 230 vac to village. 2 @ 25 mm Al

Capacitor 70 microfarad

Volt-meter (0-500 volt)V

A Ammeter 15 amp

A

V

Knife switch

Volt-meter (0-500 volt)

Ammeter 15 amp

Leonics controller Ballast load

A Ammeter 15 amp

Three phase 230 vac delta

Powerhouse

SchoolTo village loads…

Capacitor 140 microfarad

Mae Wei – ‘pump as turbine’ off-grid induction

RegulationWith 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

• Types1. Phase angle2. Binary controller3. 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

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ps

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lts

Current 1 Current 2 Current 3 Voltage

Mae Kam Pong Microhydro Unit #2 Voltage andCurrent (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

5am

7am

9am

11am

1pm

3pm

5pm

7pm

9pm

11pm

S1

0

100

200

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400

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600

wat

ts

Circuit breakers: a technical fix for a common property problem

XkWh meter

OKMini-circuitbreakerMini-circuit breaker can encourage peak load reduction

5:00

6:00

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9:00

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1985

1988

1991

1994

1997

2000

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1000

2000

3000

4000

5000

6000

7000

Watts

Time of day

Year

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.

Contribution to evening maximum peak demand by appliance, for the years 1985 – 2001.

0

1000

2000

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7000

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9000

10000

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Wa

tts

other

water boiler

rice cooker

iron

fridge

TV

lights

Thank you

… and please bring tools for Saturday hands-on PV workshopwrenches

pliersscrew driversleatherman

For more information, please contact chris@palangthai.org

This presentation available at:www.palangthai.org/docs