Water Power and Dam Construction. Issue April 2010
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Foundations
Cut-off Walls
Ground Improvements
Excavation pits
PASSION FOR
PROGRESS
20 APRIL 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
ASIA
L
AO PDR is one of the world’s least developed countries.
However, the Lao government is taking steps to alleviate
poverty and move the country away from this ‘least devel-
oped’ status by 2020. The hydro power sector, which is one
of the county’s major sources of growth, has the potential to gener-
ate significant revenue and play a vital role in this regeneration.
The potential for hydro power projects on the Nam Theun river
was first identified in the mid 1970s. In the early 1990s the govern-
ment of Lao viewed the 1070MW Nam Theun 2 hydro power project
in Khammouane province as being key to social and economic devel-
opment within the country. Detailed studies of project proposals were
carried out over the following decades.
During 1989-91 a World Bank feasibility study was undertaken by
the Snowy Mountains Engineering Corp. Then in 1993 an agreement
to develop the project, in accordance with World Bank guidelines, was
signed between the government of Lao PDR and private sponsors.
The Asian financial crisis during 1997-8 forced a delay in developing
the project. While the design and preparation of comprehensive social,
economic and environmental safeguards took more than ten years, con-
struction finally got underway in earnest in June 2005. All construction,
environmental and social activities are currently on track for the sched-
uled start of commercial operation in December 2009. The environmen-
tal and social programme is set to continue from 2010-2015.
Independent panels of experts describe the Nam Theun 2 project
as having the greatest potential to achieve the country’s develop-
ment goals. With a total cost of almost US$1.6B, equivalent to more
than 85% of annual GDP, the project is pivotal to the country’s
economic fortunes. The scheme is forecasted to generate average
annual revenues of US$80M to the Lao PDR in the form of taxes,
royalty charges and dividends over the life of the project concession.
Under the terms of a revenue-generated management programme
to be implemented by the government and under supervision of the
World Bank and the Asian Development Bank, more than US$2B
of income revenue will be generated over the project’s initial 25-year
operating period. This will be used to reduce poverty and assist
development in the country.
At the end of the concession the project will be transferred to the
government free of charge with all revenue then accruing to the gov-
ernment. It is predicted that Nam Theun 2 will be one of the largest
single sources of foreign exchange income to Lao PDR.
The project is seen to exemplify how the government is working
with the private sector and multilateral organisations to develop a
model of sustainable development, with a strong focus on economic,
social and environmental factors. A robust environmental and social
impact safeguards programme has been designed with several of the
participating financial institutions, and will be fully funded as part of
the project’s budget.
POWER AG REEME NTS
Nam Theun 2 is a 1070MW transbasin hydro power scheme. It will
divert the upper flow of the Nam Theun river from the Nakai plateau,
into the Xe Bang Fai river in the Khammouane plain in Lao PDR. It
is capable of producing 6000GWh per year.
Of the total installed capacity, 995MW will be sold to the Electricity
Generating Authority of Thailand (EGAT) on the basis of a long
term, take-or-pay power purchase agreement which was signed in
2003. Electricite du Laos (EDL) will also be supplied with 75MW of
generating capacity.
The project is owned by the Nam Theun 2 Power Company
(NTPC), which is a limited company incorporated under the law
of Lao PDR. NTPC will build, own, operate and then transfer the
project to the government at the end of a 25-year operating period.
NTPC’s shareholders are:
U 35% – Electricitie de France (EDF). NTPC has also contracted the
main construction activities at Nam Theun 2 to EDF, where it will
act as head contractor under a turnkey contract. EDF is one of the
Profiling Nam Theun 2
Nam Theun 2 is one of the largest foreign investment project ever undertaken in Laos
and is being developed as a venture with neighbouring Thailand. As the project begins full
commercial supply to Thailand, we take a look at the history behind this important scheme
Main image above: View of the project area; Above: Work preparing the site
for the power house
WWW.WATERPOWERMAGAZINE.COM APRIL 2010 21
ASIA
largest electric utilities in the world with a total generating capac-
ity exceeding 100,000MW in France, 21,000MW of which comes
from hydro power.
U 25% – Lao Holding State Enterprise (LHSE). This is a state-owned
company under the jurisdiction of the Ministry of Finance in Lao
PDR. It was established in February 2005 to have responsibility
for holding the government of Lao PDR’s shares in NTPC. It was
created as an entity through which the government’s Nam Theun
2 revenue will pass.
U 25% – Electricity Generating Public Company (EGCO) of Thailand.
This is a leading owner and operator of independent power plants
in Thailand.
U 15% – Italian-Thai Development Public Company Limited of
Thailand. ITD is the largest publicly listed infrastructure construc-
tion company in Thailand.
INNOVATIV E FINANCING
Financial close for the project was achieved in June 2005 and is
described as being complex, innovative and ambitious. In total, 26
financial institutions provided debt finance for the project under 11
different debt facilities. As such the Nam Theun 2 project represents
the largest and most diverse form of project financing ever under-
taken in Asia.
Many of the solutions pioneered in this financing are expected to
establish NT2 as a valued model of project finance for public-private
partnerships.
A total of US$1.58B in capital commitments for NTPC was
completed in May 2005 to finance the total base project cost of
US$1.25B, plus additional amounts for contingency and ancil-
lary bonding facilities. The senior debt facilities include political
risk guarantees from the Asian Development Bank (ADB), the
World Bank and the Multilateral Investment Guarantee Agency
(MIGA). Export credit support was provided by COFACE of
France, EKN of Sweden and GIEK of Norway. Direct loans were
also provided from a number of multilateral and bilateral devel-
opment agencies including the ADB, Nordic Investment Bank,
Agence Francaise de Development, PROPARCO and the Export-
Import bank of Thailand.
Long term loans are being provided to NTPC by:
U Nine international commercial banks – ANZ, BNP Apribas, BOTM,
Calyon, Fortis Bank, ING, KBC, SG and Standard Chartered.
U Seven Thai commercial banks – Bangkok Bank, Bank of Ayudhya,
Kasikornbank, Krung Thai Bank, Siam City Bank, Siam Commercial
Bank and Thai Military Bank.
In addition to senior loan facilities, shareholders are completing the
project financing by contributing equity pro-rata their respective par-
ticipation in NTPC. The equity contribution of LHSE is financed by
loans, grants and other financing from institutions including the AFD,
ADB, European Investment Bank and the World Bank.
The project is a prime example of the changes which have taken
place in structuring project-financed deals, such as detailing political
risk mitigation, currency risk beyond historical exchange rates and
greater environmental assessment work.
POLITICAL RISK MITI GATIO N
The challenges of a cross-border deal and an undeveloped regulatory
framework had to be overcome in order to work out the mechanisms
for successful financing of the Nam Theun 2 project.
The contractual structure was developed under two aspects: to
ensure that Thai political risks were satisfactorily addressed under the
PPA with EGAT; and that the Lao PDR political risks were allocated
to the government under the concession agreement consistent with
precedents for emerging market projects.
But the risk allocation proved to be problematic as neither the gov-
ernment nor EGAT was prepared to bear risks across the Mekong
river boundary. Furthermore, the backers would not assume the con-
sequences of force majeure in the other’s country or the other partner.
And, should the project not get that far in development there was
a need to have clarity, and agreement, on any potential competing
claims if Nam Theun 2 had to be shelved. Clearly, there were many
barriers to overcome and have the parties amicably work together.
There were further challenges at the start of the concession nego-
tiations for NTPC and its advisers. A strategy was also implemented
to compensate for uncertainties surrounding the legal framework
in Lao PDR which, some believed, was not sufficiently developed
in a number of areas. NTPC gained clarifications on contradictory
existing laws as concession arrangements moved through the legal
approval process.
A key major risk mitigation factor was the involvement of the major
finance organisations, including the World Bank, Asian Development
Bank (ADB), European Investment Bank (EIB), Nordic Investment
Bank (NIB), European development finance institutions and export
credit agencies. They were to provide a combination of both debt and
equity-related financing. In addition, the institutions would ensure,
through ongoing monitoring, that the revenue management pro-
gramme would be properly implemented, and that royalty, tax and
dividend revenues would be channelled as appropriate to fund social
and economic development.
In respect of potential Thai political risks, the highly attractive
2009 tariff of approximately US$0.04/kWh meant that EGAT would
enjoy sustained economic advantages from the PPA, thus reducing
the risks of breach of contract. Comfort was also drawn from the
unbroken 30-year history of cross-border sales between Lao PDR
and Thailand, and the memorandum of understanding on electricity
exchanges between the countries. The involvement of all the major
Thai commercial banks and Thai-Exim added a further level of reas-
surance to the non-Thai parties.
As such, it became increasingly evident during the project’s devel-
opment that the single greatest risk mitigant was the project itself.
It was not in the interests of any party to do anything to prejudice a
project that was both a supplier of cheap electricity to EGAT and a
significant source of revenues for Lao PDR.
Left, top: A ROC D7 cut through the mountain to create an access road
on Nam Ngum 2; Left, bottom: One of the first Rocket Boomer rigs
approaching the Laos border via the Mekong river
Profiling Nam Theun 2
22 APRIL 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
ASIA
LIMITING FOREIGN EXCHANGE RISK
Structuring the currency profile of the funding to match that of the
upfront project costs and later revenues, mitigated currency risk and
provided a natural hedge against the tariff structure. This required
that the underlying long-term debt structure be dominated half in
Thai baht, raised from Thai commercial lenders, but the volume was
significantly higher than for any other Lao PDR project.
ENVIRONMENTAL AND SOCIAL IMPACT MITIGATION
From the earliest stage of development, the sponsors were keenly
aware of the requirement to establish the highest standards for the
mitigation of environmental and social impacts, while conforming to
the requirements of a project-financed deal and the accessible skills
of developers in the energy sector.
The involvement of the World Bank, ADB, EIB, other organisa-
tions and commercial banks meant that the project was required
to meet an unparalleled number of institutional requirements and
international guidelines. The environmental and social mitiga-
tion obligations of the sponsors were developed in liaison with a
number of agencies, public consultation, and workshops guided
by safeguard planning documents, enshrined within the conces-
sion agreement.
The project was contractually committed to spend more than
US$100M in mitigating environmental and social impacts during the
construction period, meaning the obligations were significant. The
sum included US$60M on technical design modifications following
discussions with affected parties. On top, a further US$60M was allo-
cated for livelihood improvement, watershed management protection
and related costs during the concession period.
REDUCING POVERTY
NTPC and the government have the joint responsibility for the imple-
mentation of resettlement and social development activities. NTPC
says that it is committed to achieving its ultimate goal of ‘harnessing
Lao PDR’s strength of hydro power, and the will and commitment of
its people, into a development success story capable of improving lives,
reducing poverty and giving Lao citizens a better hope for the future.’
The government has agreed with the World Bank to imple-
ment a poverty reduction fund that is being sourced initially from
International Development Agency (IDA) funds and then from
government taxes, royalties and dividend revenues once the project
starts operation. Special administrative units have benn established to
ensure the effective management and allocation of financial resources
gained from the project.
The project has been described as being a cornerstone for the reduc-
tion of poverty in Laos. Direct benefits for the local people include:
U 270km of roads to be built or upgraded – 150km of national road
and 120km of local road.
U Major improvements in living conditions for the 6500 people who
have had to resettled.
U A US$16M development programme for 221 villages in the down-
stream areas.
U Employment for 5-7000 Lao workers for a period of 3-5 years.
U US$1M per year, paid for by the project for the protection of the
4000km
2
Nakai Nam Theun National biodiversity catchment area.
As HE Khambai Damlath, governor of Khammouane Province, said:
“The development of the Nam Theun 2 project is something that the
Khammouane people have been waiting for a long time to have the
chance to contribute to the socio-economic development of our prov-
ince and country. NT2 does not only produce electricity for export
to other countries and for domestic consumption, but it also encom-
passes development of infrastructure, human resources, community
and preservation of the environment of the province. It also provides
a lot of job opportunities for people.
“This is why we can say that this project is truly multi-purpose in
terms of its contribution to the development of Khammouane prov-
ince and poverty reduction for the people,” he said.
PROJECT DETAILS
The Nam Theun 2 project encompasses an area of 200x50km and
involves three provinces: Bolikhamxay – dam area; Khammouane –
reservoir, power plant, channel and roads; Savannakhet – transmis-
sion lines to Thailand.
The scheme makes optimum use of the area’s unique topographi-
cal situation. The natural geography of the Nakai Plateau and sur-
rounding area allows for a hydro project with a significant head
of water without the need for a high dam. Water from the reser-
voir drops 350m to the power station at the bottom of the Nakai
escarpment.
U 39m high, 436m long concrete gravity dam with a crest length of
325m. It has an integrated spillway with 13 small earthen saddle
dams along the west bank of the reservoir.
U Catchment area of 4013km
2
with an average annual runoff of
7527Mm
3
.
U 450km2 reservoir (FSL) with an active storage of 3530Mm
3
.
U Minimum operating reservoir level at 70km
2
.
U Average net head of water of 348m.
U 4km long headrace channel.
U Powerhouse comprising 4x250MW Francis turbines (for supply of
5636GWh of power to EGAT each year) and 2x37.5MW Pelton
turbines (for 300GWh power supply to EDL each year).
U A double circuit 115kV transmission line to Mahaxai in Laos.
U 138km long double circuit 500kV transmission line to the
Thai border
U 160km long double circuit 500kV transmission line from the Thai
border to Roi Et (a substation built and funded by EGAT).
IWP& DC
Nam Theun 2 project progress
1993 – Agreement is signed between the government of Lao PDR and
private sponsors to develop the Nam Theun 2 project in accordance with
World Bank guidelines.
1997 – First series of environmental and social safeguards documents produced.
1997-8 – Asian financial crisis forces the governments of Loa PDR and
Thailand to delay development of the project.
May 2000 – EGAT and NTEC agree on a proposed electricity tariff.
September 2001 – Shareholders agreement signed.
September 2002 – NTEC and government of Loa PDR create NTPC as a Lao company.
October 2002 – concession agreement signed.
November 2003 – Power purchase agreements signed with both EGAT and EDL.
2004 – Completion of safeguard documents and project financing activities.
June 2005 – Financial close, beginning of full construction activities and
implementation of safeguards (including all social and environmental
programmes).
April 2006-April 2008 – Construction of resettlement villages and relocation of
villagers to new homes.
August and October 2007 – First partial and temporary impoundment of the
reservoir (80km
2
).
March 2008 – Completion of concreting of diversion tunnel.
April 2008 – Closure of diversion tunnel and impoundment begins.
June 2008 – Tunnel filling test.
August 2008 – Spillway gates closed on Nakai dam.
March 2010 – Commercial export of electricity to Thailand begins.
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24 APRIL 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
SEISMIC ANALYSIS
A
NUMBER of potential failure modes may be considered
for the seismic loading of structures such as an arch dam.
The process described in this article would be used in
estimating the probability of failure for each potential
failure mode. Risk analysis has proven to be a very effective tool
for decision making at the US Bureau of Reclamation. Detailed
analyses and field exploration form the basis of all estimates that
are made, helping to ensure that the risk analysis is reliable.
COMPLICAT ED DESIGN
East Canyon dam, located in a very narrow, steep walled canyon, is a
double-curvature, thin arch concrete structure with a structural height
of 79m and a crest length of 133m. The spillway is an uncontrolled
overflow-type structure constructed in the crest of the dam adjacent
to the left abutment. Two low angle continuous discontinuities, a
vertical side joint and an assumed release plane define a potentially
movable block in the foundation.
The presence of an old dam, the topography, and the need to main-
tain a reservoir during construction complicated the design of this
new concrete arch dam. In the final design only 2m separated the new
and the old concrete dams at the closest point.
During construction, the stability of the existing dam was assured by
careful control of blasting, checking the structural behavior of the dam
through measurements, and requiring that the undercut portion of abut-
ment rock at the old dam be supported by concrete placements in the
new dam prior to allowing appreciable storage behind the old dam.
A finite element model was created, which included the critical
foundation blocks, the current dam, the 1915 arch dam (immediately
upstream from the current dam) and the reservoir. An unbounded lift
line was modelled in the thrust block. Two foundation rock blocks
were modelled.
The analyses examined the behavior of the dam and foundation block
stability using a coupled analysis under seismic loads. The finite element
programme LS-DYNA was used for the analysis. It consisted of 455,400
nodes and 423,100 solid eight-noded brick elements. All ten dam mono-
liths and the thrust block on the right abutment were modelled.
The concrete and rock material properties used in the nonlinear
analyses were based on calibrations using laboratory test values and
forced-vibration testing performed at the dam. From the forced vibra-
tion testing, the natural frequencies of the dam and damping factors
were also estimated. Down-hole geophysical testing was performed
to determine the in-situ velocity and dynamic deformation moduli of
the concrete and foundation.
The material properties used in the finite element model included
Young’s moduli, densities, and Poisson’s ratios for the rock and the
concrete. In addition, compressive strengths and tensile strengths
were determined. As this structure is very thin the response to tem-
perature loads is important. For this reason analyses were performed
for summer, winter and average temperatures at the dam.
Gravity loads were applied over time and the model was allowed to
reach a steady-state prior to application of the dynamic loads.
Uplift pressures acting perpendicular to the rock foundation joints
and bedding plane based on piezometer readings were applied as
pressure loads.
For these analyses, ground motions, obtained from the Geophysics
and Seisomology Group, corresponded to the median annual
exceedence probabilities (AEP) of 1/5,000yr, 1/10,000yr and
1/50,000yr. A suite of three-component ground motions was pro-
vided for each AEP, with motions provided in upstream-downstream,
cross-canyon, and vertical components. Contact surfaces were used
to model the interaction in the contraction joints between:
U The foundation rock block and the surrounding foundation.
U The dam monoliths and the foundation.
U The water and the dam and the water and the foundation.
U The two sections of the reservoir (one upstream and one down-
stream of the old dam).
The dynamic finite element analysis of the dam-foundation-reservoir
system was subjected to various combinations of temperature, reser-
voir elevation and seismic loads.
The results from these analyses were used by a team consisting of a
geologist, geotechnical engineers, structural engineers, and a facilita-
tor to determine the potential risks associated with this structure.
Risk analysis is used as a decision making tool by the USBR dam
safety office. All of the analyses and field work previously discussed are
used to estimate the likelihood of events occurring that lead to a poten-
tial failure of the structure or foundation. A possible event sequence
that would be considered for East Canyon dam is the following:
U Reservoir water surface elevation.
U Seismic load ranges.
U Response of concrete dam is sufficient to cause horizontal cracking
in the dam.
U Response of concrete dam is sufficient to cause diagonal/vertical
cracking in the dam.
U Cracks are continuous through the section of the dam.
U Isolated blocks formed in the dam rotate and are released down-
stream initiating uncontrolled release of the reservoir.
Since there have been no known arch dam failures as a result of
earthquake shaking, there is no direct empirical evidence to indicate
how an arch dam would structurally fail under this type of loading.
Therefore, shake table model studies have been performed to gain
some insight into what might happen (Harris, 2002).
In the models, an attempt was made to maintain material simili-
tude between the model material and typical dam concrete. The
model foundation and abutments were essentially rigid (built of
conventional concrete). Some models included contraction joints
and/or weak lift joints by inserting plastic sheets in the modeling
material as it was placed.
However, it was not possible to maintain similitude with the res-
ervoir, and water was used in the models. Therefore, it is difficult to
conclude anything about the level and duration of shaking that could
lead to failure from the models. But the failure modes were relatively
A risky business
The US Bureau of Reclamation (USBR) has developed a procedure using risk
analysis to evaluate dams for loading conditions, including seismic loads. Here
Larry Nuss, Barbara Mills-Bria and Phoebe Percell give a detailed example of this
procedure for USBR’s East Canyon dam in Utah
WWW.WATERPOWERMAGAZINE.COM APRIL 2010 25
SEISMIC ANALYSIS
consistent, and provide some indication as to how an arch dam might
fail under earthquake shaking. In these tests:
U Failure initiated by horizontal (cantilever) cracking across the lower
central portion of the dam.
U This was followed by diagonal cracking parallel to the abutments.
U The cracking propagated through the model forming isolated blocks
within the dam.
U Eventually, the isolated blocks rotated and swung downstream
releasing the reservoir.
With this description forming the sequence of events for potential
failure, an event tree is used to estimate each step in the potential
failure process. It is necessary to perform structural analyses, such as
discussed earlier, at various earthquake loading levels to evaluate the
potential for each subsequent step in the tree.
If the reservoir fluctuates significantly over the course of a year,
and the response changes dramatically with reservoir elevation, it
may also be necessary to include different reservoir load ranges (with
the appropriate temperature conditions) in the tree as well. Similarly,
if the concrete temperature conditions control the initial static stress
conditions, and the results are highly sensitive to these initial stresses,
it may be more appropriate to set up the tree with the various tem-
perature conditions (and corresponding reservoir elevations).
For each reservoir and seismic load range that is established for the esti-
mating process, the likelihood of cracking at various orientations (over
significant areas – not just localised cracking), and cracking through the
dam body must be estimated. The best approach for this is to perform
three-dimensional dynamic time-history finite element studies.
Examination of output stresses and their duration indicates whether
the estimated dynamic tensile strength of the concrete is exceeded at
the dam faces during seismic response. The orientation of the principal
stresses can be used to gauge the likely crack directions for various times
during the earthquake loading. As the amplitude of these stresses and
number of excursions above the tensile strength increase, the likelihood
of cracking also increases.
One or two excursions above the tensile strength do not necessarily
equate to a high likelihood of cracking, particularly if the amplitudes
do not exceed the tensile strength by a significant amount. If con-
traction joints are modeled in a nonlinear analysis, it is possible that
diagonal principal stresses will not develop due to ‘opening’ of the
contraction joints. In this case, the potential for ‘stair-stepped’ crack-
ing roughly parallel to the abutments must be assessed.
If the shaking is severe enough, the cracking can extend through the
structure forming an adverse cracking pattern. This is typically evalu-
ated by examining the magnitude and duration of tensile stresses that
exceed the dynamic concrete tensile strength on both the upstream
and downstream faces. Again, judgment is required on the likelihood
of cracking through the structure at various earthquake (and possibly
reservoir/temperature) levels.
If the arch cracks all the way through, the likelihood of isolat-
ed blocks rotating and displacing downstream is next estimated.
Information typically used to make this assessment includes the
duration of strong shaking and stresses. The primary questions to be
asked are: How likely is it that there will be sufficient energy left in
the earthquake to move blocks downstream after they have cracked
through?; How likely is it that the cracking pattern will be adverse
enough that the portion of the dam isolated by the cracking will be
unstable statically following the shaking?
For the latter to occur, the ‘semicircular’ cracking pattern that
typically results in the upper part of the dam must be smaller on the
upstream face than the downstream face, such that the cracks diverge
in the downstream direction. It would be assumed that if the poten-
tial failure mode progressed to this point, a breach and uncontrolled
release of the reservoir would result. The estimates made for each of
these nodes is combined to an estimate of the probability of failure
for the given potential failure mode.
Larry Nuss, Technical Specialist at the US Bureau of
Reclamation, Email:Lnuss@usbr.gov; Barbara Mills-Bria,
Structural Engineer, bmillsbria@usbr.gov; Phoebe Percell,
Structural Engineer, ppercell@usbr.gov
IWP& DC
Water Mesh
(Upstream from Old
Dam and Between Dams)
Mesh of Old Dam
(under water)
Foundation Mesh
New Dam with Contraction
Joints and Spillway
Mesh of Rock Blocks
Entire Finite Element Model
(Mesh Not Shown)
26 APRIL 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
OPERATION & MAINTENANCE
T
HE Tennessee Valley Authority (TVA) is the US’ larg-
est public power company providing wholesale power to
approximately 9M people in Tennessee and portions of
six other contiguous states. With a diverse set of assets
under its management – including hydroelectric dams, solar gen-
eration sites, fossil plants, nuclear plants, and turbine sites –TVA
wanted to embark on a project that would: standardise and stream-
line its work across the fleet to improve the business environment;
and increase efficiencies by operating as a single system.
The result, with IBM’s help, was that in February 2010 TVA
embarked successfully on the largest and most integrated enterprise
asset management (EAM) solution performed by any US utility.
INTEGRATI ON
Today, TVA generates electricity at 29 hydroelectric dams, a pumped
storage plant, 11 coal-fired plants, 11 combustion turbine sites, three
nuclear plants, and 18 green power sites that employ wind turbines,
methane gas and solar panels. The energy travels through some
26,000km of transmission lines and a network of 158 local distribu-
tors to reach homes and businesses. The scope of the EAM project
reflects the highly diverse and widespread set of assets, software and
processes under TVA’s command.
The project, which took two years to complete and serves up to 8000
concurrent users, integrated two dozen legacy applications with IBM’s
Maximo software and eliminated more than 70 legacy systems. The
scope of the project ranged from enterprise systems such as work man-
agement, supply chain, financial management and reporting software,
to a new web portal promoting collaboration, to security measures
such as a new single sign-on solution. The net effect of this integration
was to create a centralised data-and-command center for TVA for sus-
tainable performance improvement on an ongoing basis.
IBM’s joint global services and Maximo asset management teams
joined forces with TVA subject-matter experts from all business units
to form one technical team and one business team with the goal of
consolidating the work management systems. The technical team
ensured seamless planning and execution, transfer of knowledge,
performance testing and tuning and independent oversight, while the
business team supplied dedicated subject matter experts, a dedicated
testing team, and integrated best practices across TVA.
In addition to extending Maximo to all TVA business units and pro-
viding TVA with a unified asset management approach, the new solu-
tion also replaces the utility’s legacy computerised maintenance and
supply chain management systems. The supply chain at TVA impacts
more than 10,000 TVA employees and 6000 external suppliers. The
new supply chain solution covers three functional areas: materials,
purchasing and contracts, and also provides a supplier portal for col-
laboration and management. By integrating these areas, TVA is able to
gain more visibility into the entire supply chain process.
Prior to the EAM project, TVA’s use of siloed software asset man-
agement applications was adversely affecting not only costs, but also
the integration of vendor products across the power-generation system.
These challenges – compounded by the pending obsolescence of legacy
asset management software and systems and the desire to lower mainte-
nance costs by consolidating and integrating software systems – added
impetus to TVA embarking on this project with IBM.
HYDRO GE NERATION AS SETS
Maximo is used at a number of major hydro organisations both
at federal and state level to manage dam safety inspections pro-
grammes, identify and repair discrepancies and support the overall
dam safety initiative.
Although IBM doesn’t provide any special solutions for hydro
generation, TVA found that Maximo was being used at many hydro
generation facilities including a major state-run hydro authority that
managed the upgrade of its generating units and documented savings
through better utilisation of resources. The US Bureau of Reclamation
also uses Maximo at 55 dams to manage hydroelectric generation and
the waterway and surrounding recreational areas created by the dam.
In terms of scope of the work, the EAM data conversion project
alone reviewed more than 227M records, reducing that number by
two-thirds in a massive data cleanup that experienced not a single
record conversion failure as a result of coding processes. Asset man-
agement transformation touched nearly 1.4M assets in more than
1.5M operating locations that involved more than 77M records.
Other utilities and plants will probably experience the same challeng-
es TVA faced prior to the EAM project – siloed operations, legacy sys-
tems, time-intensive processes and error-prone manual work is reality
for ageing organisations. The success of the TVA project demonstrates
that these organisations can move into a new reality, one that will help
them manage their systems for the next few decades.
Ron Wallace, EAM Utility Industry Manager,
IBM Software Group
Managing your assets
Software company IBM has been working with Tennessee Valley Authority on an
integrated asset management solution. Ron Wallace gives more information about the US
utility’s efforts to standardise and streamline its operations
IWP& DC
In the wake of a global financial crisis, with the additional concerns of environmental protection
and anticipated effects of climate change, and power shortages hampering socio-economicde-
velopment in some parts of the world, hydropower development has many solutions to offer.
The hydro profession is responding to the needs of a changing world,with innovations in plan-
ning methods, environmental assessments, technological innovation, approaches to financing
strategies, and optimized use of existing assets.
HYDRO 2010 will review progress and achievements, as well as needs and future challenges.
As usual, the Conference will focus strongly on the needs, priorities and plans of the developing
countries of Africa, Asia and Latin America, and discussions will cover technical, economic,
commercial and environmental/social aspects.
A major Technical Exhibition will run alongside the Conference and a full social programme will
offer extra networking opportunities.
Meeting Demands for
a Changing World
International Conference and Exhibition
Lisbon, Portugal ~ 27-29 September 2010
Organized by:
with
HYDRO 2010 CONTACT DETAILS:
Mrs Margaret Bourke,
Hydropower & Dams
, PO Box 285, Wallington, Surrey SM6 6AN, UK.
Tel: + 44 (0)20 8773 7244 • Fax: + 44 (0)20 8773 7255
Email: mb@hydropower-dams.com • Website: www.hydropower-dams.com
SUPPORTING ORGANIZATIONS INCLUDE:
28 APRIL 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
OPERATION & MAINTENANCE
M
ORE than fifty years ago, Alstom designed one of the
first reversible pump turbines. These were historically
low head axial units like those installed at Argentat and
Cambeyrac (1953), as well as Saint Malo (1956) in
France. Then, in 1961, the 24 tidal pump turbine units were ordered
for La Rance. Commissioned in 1966, these are still operating success-
fully in pumping and generating modes in the seawater.
Since then, many pumped storage plants have been put into opera-
tion. Nowadays, centrifugal pump turbines for medium and high
heads are the most common type of unit required in projects. In this
category, Alstom provides both single-stage and multi-stage types.
The first centrifugal pump turbines made by Alstom were:
U Revin (4x188MW/240m head) ordered in 1970 (France).
U Tajo-Encantada (4x92MW/380m head) ordered in 1972 (Spain).
U Montezic (4x212MW/419m head) ordered in 1975 (France).
The company gained additional experience of single-stage units with
diagonal or Deriaz type pump turbines at Naussac in France (58m
head). The pump turbines were specifically designed to guarantee
minimal environmental impact [1&2]. The present trend with cen-
trifugal pump turbines is to equip higher and higher head sites. Over
the past 30 years, more than 125 Alstom reversible pump turbines,
amounting to more than 21,000MW, have been operating safely.
For more compact and efficient operation above 800m, Alstom has
also developed multi-stage units. In this kind of machine, the total
head is divided by the number of stages, which offer less stress and
vibration in machine components. Thus, they offer a greater level of
efficiency and reliability than single-stage units for high heads.
With La Coche (2x75MW/900m head) in 1971, Alstom began
to develop multi-stage centrifugal pump turbines with a fixed dif-
fuser. The company has installed many units up to 1200m head
like Bissorte 2 (4x156MW/1194m head). Adjustable double-stage
machines were also studied for Le Truel (1x 38MW/438m head)
which has been in operation for approximately 20 years, and the
four units of Yang Yang (258MW/798m head) in Korea which was
commissioned in 2006.
RECENT A CHIEV EMENT S
Between 1996 and 2007 Alstom worked on 15 pumped storage
projects around the world. Among those, 11 covered the Asian
market, representing 44 units and more than 12,500MW. Most of
these projects concern single-stage reversible pump turbine units,
although Yang Yang is a double-stage regulated and reversible pump
turbine. This project comprises 4x258MW units under a maximum
gross specific hydraulic energy > 8000J/Kg. Each unit consists of a
double-stage, double regulated and reversible pump turbine and a
motor-generator both designed by Alstom.
Net heads up to 817m in turbine mode and 832m in pump mode
are considered as a limit for conventional single-stage pump turbines.
This is the reason why a thorough comparison was done between
single-stage and double-stage regulated units at Yang Yang. The dou-
ble-stage regulated solution was finally chosen since it offered greater
efficiency due to a higher specific speed and less stresses in turbine
components. The runner manufacturing is also easier as the diameter
is much smaller. Moreover, the achieved commissioning of the units
fully confirmed the good dynamic behaviour of the units particularly
regarding the low level of vibrations [3&4].
DESIGN C ONSIDERATIONS
When designing a pumped storage power plant, several param-
eters have to be considered, such as:
U Reservoir level variation and consecutive head range.
U Optimising the output rating in relation to this head range.
U Minimising submergence.
U Balancing the generated output and pump input.
U Optimising the performance in both generating and pumping modes.
U Minimising the pressure fluctuation and vibration levels.
Some of these requirements are conflicting and require more in-depth
analysis than conventional turbine design, while model test checking
is essential [5]. Apart from high levels of efficiency in a wide range
of operation, required in both pump and turbine modes, the main
specific characteristics of Alstom’s recent projects are:
U A frequency variation range which can reach up to -2 to 2Hz.
U A pressure fluctuation level which must be mastered mainly between
the runner and the guide vane and in the draft tube.
U A pump minimum discharge and a pump maximum input required
respectively for the maximum and the minimum net heads.
U A net head range which can be more or less important.
Designing a pump turbine is an iterative process where all steps
are interdependent [6]. For all components (spiral case, stay vanes,
guide vanes, runner and draft tube), geometry definition is the first
step of the hydraulic design process. This task is achieved by using
geometrical design software developed by Alstom. The capabilities
of recent computer and CFD codes allow increasingly accurate fine
hydraulic computation of all parts of the pump turbine. Navier
Stokes computations are performed using commercial software. The
objective is to check the behaviour of flows in the whole operating
range, in both pump and turbine modes. It also allows verification
to see if hydraulic criteria are satisfied.
Sharing experiences of
pumped storage unit design
The design of pumped storage plant units has to ensure high availability and reliability
for peak load operation. Over the past 50 years Alstom has continuously investigated
and improved its designs to consider the cycling of machines, adjustable speed, efficiency
and reliability. This paper takes an in-depth look at Alstom’s experience of designing
and installing reversible pumped storage plants