960 likes | 1.16k Views
Hydro Power 21 Oct 2010 Monterey Institute for International Studies. Chris Greacen chris@palangthai.org. Outline. Microhydro Solar , wind, hydro – brief comparison Hydro system overview Some examples from Thailand and elsewhere Site assessment Head Flow Penstock length
E N D
Hydro Power 21 Oct 2010 Monterey Institute for International Studies Chris Greacen chris@palangthai.org
Outline Microhydro • 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 Large Hydro • The good, the bad, and the ugly… Two Lao Hydro stories: NT2 and pico-power
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 meters liters per second Watts Image Source: Inversin, A. R. (1986). Micro-Hydropower Sourcebook.
Measuring height drop (head) • Site level • Pressure gauge
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
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.
Silt Basin Trash Rack Intake Head Race Penstock Weir Locating the Weir & Intake
Intake directly to penstock If spring run-off sediment is not severe, the penstock may lead directly from the weir. Screened Intake Weir Penstock
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 Penstock 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. 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 Penstock 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 PVC D = penstock diameter (mm)
Penstock materials Poly vinyl chloride (PVC) Polyethylene (PE) Aluminium Steel
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 Centrifugal pump Pelton Turgo Crossflow Kaplan
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% Pelton and Turgo Crossflow Propeller 50% Efficiency Francis 0% 0 0.2 0.4 0.6 0.8 1.0 Fraction of Maximum Flow
(break?)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 • Some do AC • Some do AC and rectify to DC
DC Alternator (automotive) • Readily available. • Easy to service. • Brushes need replacing. • A rheostat controls excitation.
(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. Rectifier Stator Output Winding Exciter Field Winding Rotor Field Winding Exciter Winding AVR
(wound rotor) synchronous generator small 2,000 watts Big 50,000,000 watts