microsoft power point - d.02 turbine selection en
TRANSCRIPT
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1 Slide 1
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Selection of
Turbines
2 Slide 2
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Turbines
Various turbine types are used in SHP. Their selectionbasically depends on the head / flow conditions of asite.
As a general rule, impulse turbines such as Pelton are used for high
head and relatively low flow systems, propeller turbines (Kaplan, tube, bulb, S) are used for
low head and high flow applications. Francis and cross-flow turbines are available for low
to medium head sites.
Electro-mechanical Equipment
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3 Slide 3
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
turbine application ranges
4 Slide 4
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
turbine application ranges
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5 Slide 5
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Typical impulse turbine, where the available head isconverted into kinetic energy before the runner.
Turbine consists of a runner with a number of bucketson which one or more water jets impinge.
Flow and hence power output is adjusted by a needlevalve which can increase or decrease the nozzleopening.
For higher flows the number of jets can be increased(up to six for SHP).
Highly efficient turbine also for part-flow operation downto 10 % of design flow.
By installing a jet deflector the pressure surge in thepenstock can be avoided.
Pelton Turbine
6 Slide 6
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Pelton Turbine
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7 Slide 7
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Pelton Turbine
8 Slide 8
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
The cross-flow turbine is also regarded as an impulseturbine, although the free jet impinging the runner isnot as pronounced as with the Pelton.
Cross-flow turbines are very robust and relativelysimple machines and are therefore highlyrecommended for rural electrification where operatorsmight be limited in availability of skills and
maintenance support. The efficiency of cross-flow turbines (up to 80%) is
lower compared to other turbine types.
Crossflow Turbine
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ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
crossflow turbine
10 Slide 10
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
crossflow turbine
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11 Slide 11
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
The Francis turbine is the oldest and probably the best-known reaction turbine. In contrast to impulse turbines, therunner in reaction turbines is completely submerged in thewater.
The runner consists of a row of curved blades which formchannels through which the water is accelerated andredirected.
Regulation of flow is accomplished by a row of adjustableblades, the so-called wicket-gates or guide vanes, whichare arranged concentrically around the runner.
For very low head applications (< 10 m), Francis turbinescome in the form of open flume or pit-type machines. Forhigher heads up to 200 m, spiral casings are used.
Francis Turbine
12 Slide 12
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Francis Turbine (spiral casing, horizontal shaft)
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13 Slide 13
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Francis Turbine (spiral casing, horizontal shaft)
14 Slide 14
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Propeller turbines are also reaction turbines, but flowpasses through the runner in axial direction with littleto no inward deflection.
The oldest propeller type turbine is the Kaplan with ascroll or spiral casing and radial wicket gateconfiguration for flow regulation similar to the Francis.
The classic Kaplan has both adjustable blades and
adjustable wicket gates which gives best efficienciesover a wide range of flow rates.
Propeller turbines are also available in the form oftube, bulb and S-turbines.
Propeller-type Turbines
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15 Slide 15
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Kaplan Turbine
16 Slide 16
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
s-type propeller turbine
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ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Propeller Turbine
18 Slide 18
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
As a general rule, the number of turbines should be kept aslow as possible, i.e., between 1 and 3, in SHP development.
The need to install more than one turbine arises with avariable stream flow (or load in stand-alone systems) with aratio of design flow to minimum flow of more than 2 to 3 forFrancis and propeller machines, and more than 5 to 10 forPelton and cross-flow machines.
As flows (or loads) vary in ratios of more than 3 for most
SHP installations, it becomes clear that Francis andpropeller turbines are not ideal for SHP, and single cross-flow units often tend to be more cost-effective than Francismachines despite the lower peak efficiencies of the cross-flow.
Number of Turbine Units
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19 Slide 19
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
The speed of the turbine in a SHP installation needs to bekept constant in order that the driven generator can produceelectricity of standard quality, i.e., frequency of 50 Hz.
In grid connected systems the leading parameter is poweroutput of the turbine and the corresponding water flow.Generator load is not critical because almost any output canbe absorbed by the grid.
Usual practice today is to monitor forebay/storage waterlevels with a level sensor and adjust turbine flow
automatically using electric servo motors (linear actuators)or oil-hydraulically operated devices acting on nozzle orguide vanes.
Turbine Speed Controlling -- on-grid system
20 Slide 20
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
In stand-alone systems, turbine speed control is morecomplicated because the power absorbed by the load centeris the decisive element and not the water availability.
Conventional governors sense a deviation of speed from thenominal value and adjust nozzle or guide vane openingsaccordingly.
In stand alone systems rapid load changes may occur andflow control becomes very demanding. The installation of a
flywheel can ease such problems to some extent. Load controllers (for plants
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21 Slide 21
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Electronically controlled systems have taken over from thetraditional oil-hydraulic governors because of cost reductionpotentials and because with electronic systems, turbinespeed governing can be more easily incorporated into othercontrol, monitoring and protection systems of SHP plants.
The main disadvantages of electronic control systems are:
Electronic components used for controllers becomeoutdated in a relatively short period of time which may beshorter than the expected service life of an SHP plant(> 20 years).
Lightning strikes have reportedly damaged wholeelectronic systems of SHP plants and only equipment withproven protection systems should be selected.
Electronic Turbine Control Systems
22 Slide 22
ASEAN-German Mini Hydro Project (AGMHP)
Consulting and Engineering
Modern synthetic flat belts are capable of transmitting upto 500 kW of power at highest efficiencies (0.96 to 0.98).Gearing ratios are up to 5 for flat belts.
For higher power ranges and gearing ratios, gear boxesare used. These require less space than flat belts butare expensive and are not maintenance free (oil change,wear and eventual replacement of bearing and gears).
V-belts are readily available and need not as precisealignment of the machinery as flat belts or gear boxesbut are very limited in power transmission capacities andare therefore hardly used in SHP.
Gear Boxes and Couplings