ALSTOM HYDROPELTON POWER PLANT

POWER

Producing cos t e f fec t ive clean renewable energy has become an issue of growing importance in the current context of climate change, increasing cost of fossil fuels, and the need for individual country energy independence.

Hydropower is by far the world’s leading renewable energy source because it is a mature technology and one of the most economic power sources available.In addition, it has a number of specific advantages that other renewable energy sources don’t have, such as the possibility to store large quantit- ies of energy for several weeks or months, only releasing this energy

when it is most needed, to meet power consumption levels during peak demand periods.

Pelton hydropower plants are particul- arly well adapted for sites with high heads. The high energy density levels associated with these sites require a relatively low investment per MW capacity, resulting in competitively priced electricity.

Furthermore, these types of power plants are characterised by fast response times and one of the widest power adjustment capabilities poss- ible. These plants are thus an ideal solution for providing ancillary ser-vices such as primary and secondary

network regulation, spinning reserve or black start.

Based on the combination of compet- itively priced electricity, peak power sales revenues and the supply of ancillary services, Pelton hydropower plants show very favourable economic performance levels, in open electricity market environments.

ALSTOM HYDRO PELTON POWER PLANT

2

WHY CHOOSE A PELTON HYDROPOWER PLANT?

MAIN FUNCTIONS• Can store large amounts of energy for weeks or months• Act as a quick response for peak load energy supply • Provide ancillary services (network frequency & voltage regulation, reserve capacity, black start capability, react-

ive power production)

KEY ADVANTAGES• Clean, renewable power source• Relatively low cost per installed MW • High efficiency over a wide range of power output • Fast output adjustment capability (very complementary to thermal power plants)

Alstom Hydro provides a complete range of Pelton hydropower plant electro-mechanical equipment. This includes turbines, generators and control systems as well as optimised hydro-mechanical and balance of plant equipment.

Depending on the customer prefer- ence, these can be supplied either separately or as an integrated turnkey plant. In the latter case, specialised Alstom teams have developed specific skills for optimising the complete plant configuration so that the highest global water-to-wire performance is achieved.

ALSTOM HYDRO – THE PLANT INTEGRATOR™

Turbines

Generators

Hydro-mechanical equipment

Control systems & BOP

3

Alstom Hydro developed and qualif- ied specific control system solutions as well as dedicated machine control equipment, in order to guarantee safe, optimised power plant operations.

In 2008, Alstom Hydro launched the ALSPA® CONTROPLANT™ Series 7 control system, a major evolution for Alstom Hydro control systems. The turbine speed load governor (NEYRPIC® T.SLG) and the automatic voltage regulator (CONTROGEN™ AVR), both Alstom Hydro proprietary equipment, are integrated in the ALSPA CONTROPLANT system.

This new CONTROPLANT solution was designed to meet three key re-quirements: reliability, modularity, and openness.• Reliability of the system is aimed

at meeting the highest plant avail-ability standards. This is guaranteed through the use of industrial prod-ucts from carefully selected market leaders, the use of secured commun-ication networks and the capability

of the system to implement redund- ancy at all levels.

• Modularity allows to define cost effective customized solutions by using pre-qualif ied modules, for medium to large new or retrofit plants, in simplex or non-redundant configurations.

• Openness is achieved through the use of Ethernet at all levels, support- ing both a large set of international communication protocols and gate-ways to connect third party equip-ment.

A complete set of dedicated plant control software is provided with the CONTROPLANT system, providing all standard control room functions, enhanced human-machine interface (HMI) with advanced information management tools, remote access through web server, report generation, alarm management, statistics etc.

Complementar y CONTROC AD® engineering software tools are provid-ed for maintenance and configuration

of ALSPA CONTROPLANT, and a plant simulator is available for personnel training.

Finally, the Hydroset sof tware package provides a complete set of advanced hydro process functions such as joint unit control, dam control and valley control optimisation. The latter is achieved through long term and short term forecasting tools.

PELTON HYDROPOWER PLANT CONTROL SYSTEMS

4

Pelton turbines are particularly well suited for heads between 200 m and 1800 m. Since 1927, Alstom Hydro has supplied over 300 Pelton turbines worldwide, with power ranges between 1.2 MW and 202 MW, for heads between 120 m and 1247 m. Alstom Hydro Pelton turbines have either one or two injectors for horizontal shaft and between one and six injectors for vertical shaft configurations.

Alstom Hydro produces turbines that are adapted to the needs of each pro-ject and take into account customer specifications such as water head, water discharge, operating range and power generating requirements, in addition to power plant space consider- ations.

As turbine efficiency is of key import- ance in power plants, Alstom Hydro has heavily invested to create a Glo-bal Technology Centre in Vadodara, India to make further developments in this area. The centre, which was built in 2008, includes a Pelton scale model test laboratory with one of the highest head testing capacities for Pelton turbines in the market.

The most up-to-date design technol- ogy is used in both of the Alstom Hydro Global Technology Centres (Grenoble, France and Vadodara, India), to create optimised shapes for Pelton turb- ines. This covers all hydraulic water passage parts, such as the manifold, injectors, runner, housing and the tail water channel. Alstom engineers use the latest in-house and market computational fluid dynamics (CFD) software, sophisticated 3D surface generating tools and Finite Element Method (FEM) techniques for this purpose.

After this, the complete turbine is model tested in its complete operat- ing range in the hydraulic scale model test laboratory.

Real life power plant conditions are simulated in the laboratory in order to test how the life-size horizon-tal and vertical Pelton turbines will operate on site. Experimental tests are carried out using a scale model of the turbine, which includes all hydrau-lic parts, in order to optimise turbine efficiency, overall hydraulic behaviour and the final hydraulic design. Tests cover a variety of aspects including head, discharge, output, efficiency and runaway.

ALSTOM HYDRO REINFORCES PELTON TECHNOLOGY

Computational fluid dynamics

Horizontal shaft Pelton test-rig

Pelton scale model test laboratory

5

Alstom Hydro Pelton turbines have a number of advantages compared to Francis turbines for high heads, because they provide:• Increased flexibility with a jet dis-

patching capability• Increased safety using deflectors in

case of overspeed• Easier access to the runner for main-

tenance and dismantling (particular-ly important in case of silt abrasion)

Alstom Hydro manufactures both cast and forged runners for Pelton turbines. Although more expensive, the forged version offers the best material qualit y. A lstom Hydro customers can benefit from specific technology initiatives:• An optimised manifold design for

improved jet quality and runner efficiency

• A specific needle design for self-

closing injectors, for improved jet quality and head loss reduction

• A specific advanced jet dispatcher governing function

• A specific spherical valve design for increased safety and flexibility

• A Hooped Pelton patented runner design that minimises fatigue stress, vibration levels and replace-ment cost.

WHAT IS DIFFERENT ABOUT ALSTOM HYDRO PELTON TURBINES?

Manifold hydraulic design

6

One of the key advantages of Pelton turbines is their broad range of power output levels.It is possible to select the number of active jets required in order to always ensure turbine operating at optimum efficiency levels.

In order to do this, Alstom Hydro has embedded a specific advanced jet dispatcher function in the NEYRPIC T.SLG, which continuously adapts the number of jets in operation. This advanced function is available as an option in the NEYRPIC T.SLG.

The jet dispatcher also manages the injectors opening and closing sequence, to guarantee load balance

on the turbine, in order to minimise power fluctuations and transverse

mechanical loads, during configura-tion transitions.

A SPECIFIC ADVANCED JET DISPATCHER GOVERNING FUNCTION

The main power plant inlet valve is a critical piece of plant equipment as it plays an important role for both the safety of individuals and the plant it-self, particularly in the case of turbine nozzle closure failure.

Spherical valves can fulf il these functions and are the best solution for Pelton turbines with heads over 300 m. The spherical valve’s design provides a metal-to-metal tightness eliminating head limitations. They also facilitate safe maintenance operations on downstream equipment.

Alstom Hydro can provide spherical valves with diameters and working pressures adapted to customer needs. To date, the biggest diameter produc- ed by Alstom Hydro measured 3.5 m and the maximum working pressure was 1610 mWC. Alstom Hydro prod-

uces three types of spherical valves and is one of the only manufacturers to propose valves with a monobloc welded body.

The Alstom Hydro spherical valve range includes: • Valves with a monobloc welded body• Valves with a body in 2 bolted asymmetrical parts• Valves with a body in 2 bolted sym- metrical parts

ADVANTAGES OF SPHERICAL VALVES WITH A MONOBLOC WELDED BODY• Light weight compact size for easier installation• No risk of water leakage between body coupling flanges• Innovative design for easier bearing and seal maintenance operations, without plug extraction

A SPECIFIC SPHERICAL VALVE DESIGN

Spherical valve with a monobloc welded body

Jet dispatcher efficiency curve

7

Traditional Pelton runner buckets have both a hydraulic function, converting water’s kinetic energy into a force, and a mechanical function, converting this force into torque on the shaft line. This results in cyclical forces on the bucket attachments that cause fatigue and vibrations, necessitating frequent inspection.

In response to this problem, Alstom Hydro has developed and patented a Hooped Pelton runner design, capable of providing the same hydraulic eff- iciency levels as a standard Pelton, but better able to withstand mechanical stress. Instead of the traditional all- in-one Pelton casing, the Hooped

Pelton buckets are manufactured se-parately and attached to two hoops. The Hooped Pelton buckets have only a hydraulic function and the hoops carry out the mechanical function by transmitting the torque to the shaft line.

ADVANTAGES OF HOOPED PELTON RUNNERS• Lower maintenance costs and fewer plant outages • Greatly reduced vibration levels (by up to 90%)• Reduced replacement costs • Shorter delivery time • Increased material quality levels • Higher quality silt abrasion protect-

ive coating

Fatigue stress levels are reduced by replacing the individual bucket attach- ments with the Hooped system. This eliminates the need for repeated quality inspections and associated labour costs and plant outages. Replacement costs of ageing runn- ers are reduced, as it is possible to

replace individual buckets instead of the complete runner. As Hooped Pelton runners are manufactured in several parts, this enables better optimisation of the supply chain and a significant reduction in delivery time for customers. A high level of mater- ial quality is guaranteed as buckets are cut out of high quality small cast or forged stainless steel pieces. The individual buckets provide optim- al conditions for the application of silt abrasion protective hard coating to all areas.

THE HOOPED PELTON RUNNER DESIGN CONCEPT

Computational fluid dynamics

Hooped Pelton system

8

ALSTOM HYDRO SILT ABRASION PROTECTIVE SOLUTIONS

Caused by the presence of solid silt particles in water, silt abrasion causes severe damage to turbines and plant outages in extreme cases. In Pelton turbines, silt abrasion can impact the needle tip, nozzle seal rings and runner buckets resulting in lower turb- ine performance and shorter turbine operating life.

Alstom Hydro develops, case by case, design and coating solutions for customers to combat silt abrasion problems through:• The application of a protective layer of hard coating to components • The development of turbine designs

that take into account critical eros- ion zones

ALSTOM HYDRO HIGH VELOCITY OXY FUEL (HVOF) HARD COATINGThis technology is particularly well suited to Pelton runners. Coating is sprayed onto all surface areas using a robot. The high abrasion and fatigue resistance of the HVOF coating is achieved using a metal substance embedded with tungsten carbide cer- amic powder. The application techniq- ue used creates a high-density layer of coating with very strong bonding capabilities, which is on average 0.3 mm thick.

SPECIFIC HYDRAULIC DESIGNINITIATIVES • Analysing the flow dynamics in

order to adjust the turbine design profile in areas that are more prone to erosion

• Use of numerical computational fluid dynamics simulation tools to predict effects of silt abrasion on turbine performance

LABORATORY ABRASIONMEASUREMENT TECHNIQUESIn 2008, Alstom Hydro installed a new high-tech silt abrasion test-rig in their Global Technology Centre in Vadodara, India.

The abrasion test-rig is designed to carry out experimental research on severe turbine silt abrasion by simulat- ing conditions comparable to those on site. It is designed to take into account a water jet flow speed up to

65 m/s and silt concentration levels up to 10 kg/m3. The results of these tests enable Alstom Hydro to evaluate the life span of existing coating solut- ions and to develop even better high performance solutions for customers.

HVOF protective coating spraying

Silt abrasion test-rig

9

MODERN GENERATOR DESIGN TECHNIQUESAlstom Hydro has extensive exper-ience with all types of horizontal and vertical generators driven by Pelton turbines. Design concepts are based on the most up-to-date calculation methods, ensuring both reliable and economic operating.

In reply to design requirements for high-speed units and in order to guarantee high availability and stab- ility of the power-generating unit,

Alstom Hydro generator main featu-res include:• Structural design with oblique elements• Permanently pre-stressed stator core• Vacuum Pressure Impregnation in- sulation system (VPI) & slot ripple spring• Self ventilated rotor rim (standard or high speed design)• Self pumping bearing pads

OBLIQUE ELEMENTSOblique elements are designed to meet requirements like roundness, concentricity and stability of the generator in all operating conditions. The oblique element stator frame provides a rigid connection against eccentric displacement but allows free concentric thermal expansion. This arrangement also avoids buckling of stator laminations, which occurs in rigid frames with non-flexible foundation connections. In addition, the connection to the base plates is totally maintenance-free.

PERMANENTLY PRE-STRESSED STATOR COREThe clamping bolts are positioned in the stator yoke and ensure high, constant distribution of the stator core pressing. Spring elements com-pensate any potential settling of the stator lamination in order to maintain the pre-stress in the stator core over long service periods. Alstom Hydro’s stator core lamination pressing system is specially designed for units with high load cycles due to frequent starts and stops.

*Finite Element Method

ADVANCED GENERATOR TECHNOLOGY

Mechanical FEM* calculation of a pole & plate

10

VPI INSULATION SYSTEMThe reliability of the stator winding is determined primarily by the qual- ity of its stator winding technology. Alstom Hydro has been using the MICADUR® insulation system for more than 40 years. Additional research has led to further improve- ments to this system, providing excellent results on units even under severe conditions.

To ensure permanent thermal and mechanical coupling between the stator bar surface and the stator core, the straight portions are supplied with «round-packing» consisting of a double-folded conductive polyester foil, f illed with a curable rubber compound. This system also ensures excellent grounding after installation due to the gap-free installation.

The uniform VPI production process ensures high insulation quality of the MICADUR insulation system with the following main advantages:• Class F temperature requirements are met• High dielectric strength and voltage endurance values with low loss factors• Proven system for all units up to 30kV• Excellent corona-resistance• Highly resistant to oil, water, and other coolants• Excellent mechanical properties

SELF PUMPING BEARING PADSAlstom Hydro has developed a simple and effective oil-fed bearing pad system that can be used for all types of generators.Des igned wi th pumping gaps (pockets), the guide bearings act as pumps as soon as the machine is start- ed. Oil travels through drains located at the end of the pumping gaps, via

hoses, to the warm oil collecting ring, and then on to the external oil cooler before coming back to the cool oil collecting ring, located below the bearing.

The pumped oil flow increases with the speed of the moving bearing sur-faces. Therefore, in case of runaway, much more oil is pumped through the system. This prevents excessive temperatures of both the oil and the bearing. This eliminates the need for external electric driven pumps and

the associated supervision and monit- oring elements and pre-start check functions.

ADVANTAGES OF ALSTOM HYDRO SELF PUMPING BEARING PADS• Failure and maintenance-free system• Increased bearing operating avail-

ability and reliability• Safe run down is ensured in case of failure of the whole auxiliary power supply• Reduced start-up time of the unit• Overspeed security

Self pumping bearing pads

MICADUR stator bar insulation

11

ALSTOM Hydro

4, avenue André Malraux

92309 Levallois Perret Cedex - FRANCE

www.power.alstom.com/hydro

PWS/

LEAF

/TH

PLTN

09/e

ng/H

YD/0

1.09

/FR

/671

2 ©

ALS

TOM

200

9. A

ll rig

hts

rese

rved

. Inf

orm

atio

n co

ntai

ned

in th

is d

ocum

ent i

s pr

ovid

ed w

ithou

t lia

bilit

y fo

r inf

orm

atio

n pu

rpos

es o

nly

and

is s

ubje

ct to

cha

nge

with

out n

otic

e. N

o re

pres

enta

tion

or w

arra

nty

is g

iven

or t

o be

impl

ied

as to

the

com

plet

enes

s of

info

rmat

ion

or fi

tnes

s fo

r any

par

ticul

ar p

urpo

se. R

epro

duct

ion,

use

or d

iscl

osur

e to

third

par

ties,

with

out e

xpre

ss w

ritte

n au

thor

ity, i

s st

rictly

pro

hibi

ted.

- Ph

oto

cred

its: A

lsto

m 2

009

- Des

ign

& La

yout

: ww

w.k

inek

a.co

m.

PLAN

T IN

TEG

RAT

OR

, CO

NTR

OPL

ANT

and

CON

TRO

GEN

are

trad

emar

ks o

f Als

tom

. ALS

PA, N

EYRP

IC, C

ON

TRO

CAD

and

MIC

ADU

R ar

e re

gist

ered

trad

emar

ks o

f Als

tom

.