Hydro Turbines Bulb

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BULB UNITS THE COMPLETE SOLUTION FOR LOW HEADS POWER

Transcript of Hydro Turbines Bulb

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BULB UNITSThe compleTe soluTion for low heads

power

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Alstom Hydro is the number one global provider of clean power solutions accounting for around 25% of the world’s installed hydro base and offers the world’s most compre-hensive range of hydropower generation facilities and equipment.

it is not surprising then that alstom bulb units provide the most eff icient solution when faced with very low and low heads up to 30m. Bulb units have now virtually replaced Kaplan turbines for low head situations.

The name “bulb” comes from the shape of the upstream watertight casing which contains a generator located on a horizontal axis. units are submerged in the water passage and, as the turbines are usually double regulated, are able to handle signif icant discharge variations.

The straight water passage in the draft tube improves the hydraulic behaviour of the unit, and also results in a low submergence. This, in turn, allows for a reduction in size, cost

and civil works requirements of up to 25%. There are hundreds of alstom bulb units now in operation around the world with more than 35 large units commissioned in china alone during the last ten years.

The company has been an ardent pioneer in the development of bulb units introducing many outstanding innovations in size, design and operational efficiency and will continue the research and development programme to extend the application range. Both standard- ised and customised solutions are offered. Specific technologies have been developed to adapt to customers’ needs and site surround-ings such as the use of mobile or fixed guide vanes and runner blades, shaft lines on 2 or 3 bearings, and pit turbine technology with a speed increaser.

Alstom has gained outstanding knowledge and experience in design, manufacturing, installation, commissioning and manage-ment of complex bulb projects in a vast range of environmental conditions, making Alstom bulb units without doubt the world’s most reliable solution.

Alstom bulb unitsfor BeST performANce

alstom bulb units application range

model scale bulb runner

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coNSTANT r&D To meeT eNvIroNmeNTAL coNcerNSAlstom is also committed to helping custom- ers balance commercial objectives with environmental and social responsibilities.

increasing environmental concerns are taken into account resulting in fish-friendly turb- ines. in bulb turbines fewer but longer blades decrease the fish mortality, while maintaining efficiency levels.

oil-free operations that prevent the pollution of rivers have also been developed, resulting for example in runners lubricated by water in many bulb units.

pLANT INTeGrATorin the field of power generation, alstom is the plant integrator specialist, combining skills in component design, auxiliary systems, construction and plant optimisation. alstom’s answer to the market’s growing need for turn- key solutions is a unique combination of in-house core components and customised plant solutions based on the integration of complementary packages.

this original combination creates more value for customers than the simple addition of individual packages by optimising:

• Investmentcosts • Leadtimes • Performanceandavailability • Retrofitsolutions • Plantlifecycle

Customer value-drivenGLoBAL opTImISATIoN

an alstom bulb unit delivers maximum customer value and return on investment. equipment investigation and design is carried out by experienced interdisciplinary teams as part of the total system optimisation.alstom’s global geographical coverage and the largest installed base allow the feedback of experience to be taken into account for each new project, whilst its local pre-sence guarantees a perfect understanding of regional variations.

Thanks to a global r&d organisation, the main design parameters are def ined by hydraulic, mechanical and electrical engineers working in close collaboration. This leads to improved results for the bulb outer dimension by considering and evaluating factors such as productivity, global efficiency, civil work, investment and reliability of the power- generating unit.

the ability to of fer the world’s broadest scope of power generation equipment and systems enables Alstom to deliver complete optimised solutions, from turbines and gen- erators to control systems and balance of plant, including a full turnkey service.

The alstom product range covers complete electromechanical and hydro-mechanical equipment for new hydropower plants, as well as for the rehabilitation of existing plants.

DISTrIBUTeD coNTroL SYSTem alstom has a proven worldwide experience in control systems for the power industry. over 500 thermal, hydraulic and nuclear units have been equipped in 25 years.

Taking advantage of its in-depth knowledge of the hydro power plant processes, alstom has developed a comprehensive control and instrumentation system, providing modern operating control for hydro power plants.

Alstom’s automation product, commonly knownasALSPAP320®system, is themost suitable system to control and monitor Alstom hydro power plant.

The system comprises three major parts:• Centralog provides the operator control inter-

face and control room environment with high availability and high performances

• Controbloc automation cells execute the control and protection functions of the machines and connect to the process.

The use of fieldbuses allows geographical distribution of the equipment

• Controcad provides a set of advanced engin- eering tools both for the design office and the on-site high quality documentation

alspa p320® provides many features and benefits for the plant owner and operator including:• Hi-tech technologies: object oriented

engineering, internet, fieldbus• Intuitive, user friendly operator interface• Modular design concept• Adaptable multifunction controllers• Distributed control architecture• Open system architecture based on inter-

national standards• High performance, communication net-

works• Integrated comprehensive Plant Manage-

ment system (integration of alstom expert software)

Hydroprocesscentralised plant and dam management software are embedded in the central super-vision system, providing a set of functions managing the active and reactive power production of the power plant as well as the dam and the reservoir water level.

A ls tom’s engineering depar tment has acquired a vast experience in control and instrumentation systems for all kinds of hydro power plants. its expertise in providing tailor made solutions guarantees optimal plant control implementation.

General design of a bulb unit

nina power station (china)

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Alstom has developed advanced technology to optimise all hydraulic parameters. This ensures that turbine designs perfectly match the targeted characteristics of a given pro-ject, while taking into account any necessary constraints.

during the hydraulic design phase, unit per formances are predic ted through theoretical investigation and experimental developments.

Each component of the turbine is finely tuned, from intake, stay vanes and distributor, to runner and draft tube. alstom’s objective is to optimise efficiencies, minimise dimensions and reduce downstream head losses.

THeoreTIcAL INveSTIGATIoN AND ScIeNTIfIc cALcULATIoNS

Alstom has developed many software codes to perfect shape design, from classical ones tothosebasedonfull3Dsurfacegenerationusing global optimisation algorithms. these permit the exploration of new design families andallowthebestshapestobeverifiedonatest rig.

during the design process, deep numerical investigations using the latest cfd codes (computation fluid dynamics) are carried out. These simulate the flow in the turbine over the whole of the expected operating range and help to determine the best adapted turbine shape.

They allow the accurate determination of all hydraulic parameters, such as load analysis, efficiency and cavitation behaviour.

HYDrAULIc DeSIGNstate-of-the-art facilities and toolsfor optimised designs

Downstream velocity field

Turbine pressure field

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moDeL AND SITe TeSTINGOnce a design has been defined theoretically, its performance is validated by model tests in an alstom Global Technology centre.

Two recent test rigs, one of which has been in operation since 2003, are used for bulb turbines, with up-to-date calibration tools and automated acquisition systems.

These advanced facili t ies permit ver y accurate measurements that are also a key tool for performance improvement and act as a further complete check of turbine behav- iour, including efficiency, output, cavitation, runaway and torque on blades.once all the investigations are completed, the full scale turbine is manufactured and tested on site if required. it is due to this continuous process of research, design and testing that alstom remains the world leader in innovative bulb unit technology.

Alstom has more than 100 years of exper- ience in the expert analysis and production of speed governing products.

The speed governor is the brain of hydraulic turbines. It fulfils all the requirements and needs of hydraulic turbine applications.

These systems fulfil various functions:• Speed governing in isolated or inter-

connected networks• Fast unit start and speed stability control

under no-load operating conditions• Automatic unit/network synchronisation

through runner blades, guide vanes or downstream gate control

• Flow or load regulation• Efficiency optimisation with respect to

head and load• Autonomous sluicing operation at variable

or steady flows• Blade/guide vane cam relationship

neYrpic® T.slG (Turbine speed load Governor) is the latest product developed by alstom. it is interfaced with an automated system to ensure flexibility of use.

designed to operate in the most extreme environments, the main benefits are its high level of adaptability, robustness and reliability.

GoverNING system

universal turbine test rig

T.slG governor with actuators

dedicated bulb test rig

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To ensure the safety and reliability of all units, Alstom carries out a continuous mechanical r&D programme on all turbine parts.

during mechanical design, the complete bulb structure is analysed by finite-element calculations covering stresses, deflections and eigenfrequencies to check the static and dynamic behaviour of the entire unit.

STAY rINGThe stay ring is the sole support structure of the unit. This provides many advantages:• Weights and vertical loads are evenly distributed in civil engineering structures• Axial forces carried to the anchor are limited to hydraulic loads• Civil works are simplified

The two vertical arms of the stay ring are hollow for generator bus bar outlet and piping. This also allows easy access to the shaft seal for adjustments.

DISTrIBUTor The conical distributor comprises 16 moving guide vanes. They are guided on self lubricat- ing bearings and controlled by an operating ring.

To ensure continuous operational safety, the distributor can be closed under both normal and runaway conditions.

for units with a downstream gate, the operating ring is actuated by two push-pull servomotors. shear pins are used as safety devices for the guide vanes.

in the case of no downstream gate being installed, the servomotors use a counter weight to close the guide vanes safely.a self-resetting device is then used instead of a shear pin, to avoid the unit shutting down in the event of a guide vane jamming.

WHAT IS DIffereNT ABoUT ALSTom HYDro peLToN TUrBINeS?MechAnIcALDeSIgn Safety and reliability

finite-element dynamic analysis

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rUNNerS Up To 9m DIAmeTerrunner design is one of the most important tasks that alstom carries out when optimising a unit for each project.

Blades can be directional, driven by a moving servomotor cylinder located inside the runner hub.

Runner hubs are normally filled with oil, but for environmentally sensitive locations, water may be used as a lubricant.

SHAfT LINe AND BeArINGS

two radial bearings ensure the dynamic stability of the horizontal shaft line during operation.

The combined axial-radial bearing is located next to the centre of gravity of the generator rotor. it carries the weight of the rotor and the force of the unbalanced magnetic pull when the machine is in normal operation.

in case of double rotor earth fault, huge rotating forces act not only on the bearing, but also on the bearing and bracket supports. The axial bearing is designed for steady-state conditions of the turbine and also for dynamic hydraulic transients.

The turbine guide bearing is supported by a semicircular plate that allows it to follow the shaft movements. Generator and turbine bearings are both shell type bearings.

Thrust and counter-thrust bearing pads are designed to handle the axial hydraulic force. The counter-thrust bearing is stressed for a few seconds in case of load rejection.The thrust bearing pads are supported by membranes to ensure even load distribution, independent of the shaft movements.

Bearing and thrust-bearing lubrication is carried out by gravity from an oil tank located above the unit. This very simple process has proven to be extremely reliable.

DoWNSTreAm GATea draft tube gate provides a reliable protective system for bulb units.

The downstream gate is sufficiently remote from the runner to have a limited effect upon the design of the draft tube. its shape is designed to avoid the accumulation of solid deposits on the side grooves.

downstream gate functions are:• Protection against runaway conditions• Downstream isolation during unit dewater-

ing• Sluice operation

for units without control devices (f ixed distributor), the downstream gate also initiates unit starting, coupling, progressive loading and shutdown.

since the draft tube is embedded into concrete as a first stage, the stay ring is set into the civil engineering structures. Then the shop-assembled distributor is fitted. The shaft, pre-fitted with bearings, thrust bearing and counter-thrust bearing, is then inserted into the assembly.

The shaft line is adjusted on site so that the generator rotor and the turbine runner are centred on the theoretical axis of the unit.

an initial adjustment is made by eccentration of the guide bearings following the shaft line calculation. The final process is completed on site, centring the stator on the rotor and the runner chamber on runner blades.

The following operations are carried out simultaneously:• Erection of rotor, stator and bulb nose in

the upstream pit• Erection of the runner hub, blades, turbine

cone and runner discharge in the down- stream pit

• Erection of accessories

erection timeopTImISATIoN

runner erection

Bulb shaft line and bearings assembly

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Alstom design concepts ensure reliability in all operating circumstances taking account of the bulb unit’s sensitivity to instability and vibrations due to the horizontal position of the generator. They have been developed to handle conditions such as roundness and air gap concentricity, and have been success-fully applied in bulb units up to 60 mvA.

STATor DeSIGNalstom stator designs incorporate special V-shaped e lement s w i th s igni f i can t operational advantages. They guarantee the necessary stiffness required of the structure, with less radial height compared with trad- itional design concepts. They also ensure the necessary space between stator core and casing required for efficient air circulation through the cooling slots.

The alstom stator key bar design, in combina-tion with the spring effect of V-elements and stator core pressing system, provides vital protection against stator core buckling.

roTor

With the introduction of oblique elements for hydroelectric generators two decades ago , A l s t om launche d a ne w e r a in large generator design, offering outstanding mechanical performance.

oblique arms connect two concentric annular parts, the rotor hub and the rotor rim, allowing them to turn in relation to each other.

The application of oblique elements on the rotor provides improved radial precision and a uniform air gap under all load conditions.

oblique elements are used in the rotor spider to provide optimum resilience regarding thermal expansion, centrifugal force and operational torques.

Compared to classical designs with radial arms, oblique arms offer many advantages. machine torque only stresses the arms in the tensile direction while oblique arms absorb rim expansion due to centrifugal force and thermal dilatation by allowing rotation of the rim in relation to the hub. Alstom rotor design also permits stacked rotor rims withoutshrinkfittotherotorspider.

ADvAnceDGeNerATor DeSIGN

Bulb generator rotor with oblique arms

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vpI INSULATIoN SYSTem The reliabili t y of the stator winding is determined primarily by the quality of its insulation. a generator is heavily stressed thermally, electrically and mechanically during operation. This makes the heaviest demands on insulation.

the MIcADuR®vacuumpressureimpreg- nation system (vPI) has been used byAlstomformorethan40years.

t he s ys tem has been cont inuous ly researched and further developed and has produced excellent results on all machines even under severe conditions.

The uniform Vpi production process ensures a high insulation quality with the following properties:• The requirements of temperature class F

are met• High dielectric strength and voltage en-

durance values with low loss factors• Proven system for all types of electrical

machines up to 30 kV• Excellent corona-resistance• Very good resistance to oil, water and other

coolants• Excellent mechanical properties

other Vpi insulation systems can also be provided.

AIr cooLING SYSTemThe closed air ventilation system is designed for safe operation at maximum output and maximum river water temperature.To guarantee high unit availability, the cooling system is generally installed with a redundant complete cooling device.

in order to provide maximum value to customers, alstom offers integrated solutions in combination with the secondary cooling circuit. Thanks to its vast experience in bulb generator design, alstom always delivers maintenance-free and reliable solutions.

A reliable excitation system is the key to trouble-free generator operation. It ensures fast and efficient reactive power and voltage control, and the best possible generator performance overall.

alstom automatic voltage regulators and excitation systems have been produced for more than 35 years with the installation of 2,850 systems controlling 315,000 mVa in 130 countries.

To guarantee optimal results, all alstom gen- erators come with a high quality excitation system as a standard.

for medium and high speed machines, brushless excitation systems are provided. synchronous machines are supplied with rotating diodes. This supplies dc-current to the rotor without any brushes or slip rings, which are commonly subject to wear and tear. Both solutions are equipped with the latest automatic voltage regulation (p 320 aVr) technology.

all alstom static excitation systems in- corporate state-of-the-art technology and the required redundancy provision.

FieldexcITATIoN

wedging of the stator bar in stator core

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WorLDWIDeProjecthighlights

cANADABromptonville1997-1unit,11MW,run.dia.:3.75m.

Saint Lambert1995-1unit,6.2MW,run.dia.:4.50m.

USAWorumbo1989-2units,10MW,run.dia.:4.25m.

Greenup1982-3units,25MW,run.dia.:6.10m.

rock Island1978-8units,58MW,run.dia.:7.40m.

BrAzILourhinos2004-3units,15MW,run.dia.:4.25m.

canoas1999-6units,27MW,run.dia.:4.70m.

Igarapava1999-5units,gen.:44MvA.

AUSTrIApfarrwerfen1995-2units,gen.:11MvA.

croATIAcakovec1982-2units,42MW,run.dia.:5.40m.

frANceSaint egreve1990-2units,23.4MW,run.dia.:5.60m.

Argentat 1989-1unit,17MW,run.dia.:4.10m.

Sault Brenaz1986-2units,23MW,run.dia.:6.25m.

chautagne/Belley1980-4units,46MW,run.dia.:6.40m.

caderousse1975-6units,32MW,run.dia.:6.90m.

Sauveterre1973-2units,33MW,run.dia.:6.90m.

La rance1966-24units,10MW,run.dia.:5.35m.

GermANYHeidelberg1997-2units,2MW,run.dia.:3.35m.

Guttenbach1992-1unit,3MW,run.dia.:3.16m.

HUNGArYTisza1973-4units,7MW,run.dia.:4.30m. LUxemBoUrG

Schengen1995-2units,2.4MW,run.dia.:3.50m.

porTUGAL crestuma1987-3units,43MW,run.dia.:6.80m.

TUrkeYSeyan21992-3units,3MW,run.dia.:3.50m.

SWITzerLANDrheinfelden2007-4units,gen.:25MvA.

ruppoldingen2000-2units,gen.:12MvA.

la rance, france 1966

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Alstom has equipped more than 250 bulb units in the world for a total output of approximately 5,000 mW.

SoUTH koreANam Gang2000-2units,7MW,run.dia.:3.00m.

paldang1999-4units,31.5MW,run.dia.:5.20m.

cHINAchang zhou 2007 - 3 units, 42.9MW, run. dia.:7.50m.

Tong Wan2007-4units,46.2MW,run.dia.:7.10m.

Qiao Gong2007-4units,58.5MW,run.dia.:7.45m.

Wu Jin xia2007-4units,36.1MW,run.dia.:7.00m.

zhi GangLaKa2005-4units,39.0MW,run.dia.:6.10m.

Ni Na2003-4units,41.0MW,run.dia.:6.00m.

Hongjiang2003-5units,gen.:47MvA.

Gong chuan 2001 - 2 units, 22.2MW, run. dia.:5.50m.

Sha xian1999-3units,16.5MW,run.dia.:4.90m.

INDIA Sone Link canal 1986 - 6 units, 2MW, run. dia.:3.22m.

rock island, usa 1976 wu Jin Xia, china 2005

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www.power.alstom.com/hydro

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