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ICHPSD-2015
AN INNOVATIVE SOLUTION FOR HARNESSING LOW HEAD
SMALL HYDRO POTENTIAL
AbhishekSwarnkar
Manager-Small Hydro
Voith Hydro Pvt.Ltd
Small Hydro
A - 20 & 21, Sector – 59
NOIDA (UP) - 201 301
JoergLochschmidt,
Product Development Manager
Voith Hydro Holding GmbH & Co.
Small Hydro – h2
Alexanderstraße 11
89522 Heidenheim, Germany
MandarPachegaokar
Sr.Manager-Small
Hydro
Voith Hydro Pvt.Ltd.
Small Hydro
A-20 & 21, Sector-59
NOIDA (UP)- 201 301
INTRODUCTION
Over the last decade, the galloping economies of India, China along with ten countries of
Association of Southeast Asian Nations (ASEAN) have seen shifting of centre of gravity of
global energy systems to Asia. The region’s energy demand has grown two-and-a-half times
since 1990. Extrapolating the current economic fundamentals suggests that further growth in
the energy demand is inevitable given that current per capita energy usage of its populations is
much lower (almost half) than the global average and the same is bound to increase with
growth of economies of this region.
Hydro power will continue to play a very important role in the energy mix of these economies
which stood at 10%of electricity generated in 2011.Access to affordable and reliable energy
services is crucial to reducing poverty and improving health, increasing productivity, and
promoting economic growth in these countries. The lack of access to modern forms of energy
often tends to go hand-in-hand with a lack of provision of clean water, sanitation and
healthcare. Given these socio-economic challenges, the governments of these countries are left
with no option but to look at a rich energy mix of all sources of energy for continued
development of their economies.
The developing countries continue to face challenges in the field of hydro power in terms of
availability of long term finance, environmental and local issues of each state. In many cases
hydro resources are far from demand centres,and increasing environmental and social
challenges are making more difficult to develop them. In order to continuewith local area
development in far flung places, it is therefore becomes important to have innovative solutions
toharness potential of low head streams.
With the recent ecological disaster experienced in northern state of Uttaranchal in India due to
flash floods, thehydro power has come under further scrutiny and criticism of environmental
and public interest groups. There is nodenying the fact that the sustainable growth has to
balance the concerns and the benefits accrued to the society.
There is a strong outcry in most South East Asian countries to review the ecological impact of
large and mediumdams. In order to satisfy the energy demand of the India and developing
countries, with the prevailing financial and environmental constraints, the sustainable
innovative solutions are inevitable and requirement of the day. The investors are looking for
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Feb 05-07, 2015, Dehradun
innovative solutions and the equipment suppliers have to respond with new technologies aided
by strong research and development.
This paper dwells particularly on harnessing the potential of low head streams and existing
dams without the challenge of huge capital expenditure in building civil structures, water
conductor systems and extensive auxiliaries. In addition, most countries have stringent
requirements of installation of equipment in the existing dams since these are also being
utilized for drinking water for the nearby cities. The technical challenge of non-oil filled hubs
and water lubricated bearings has also to be addressed by equipment suppliers.
Voith Hydro has developed a new turbine and generator unit called as “Stream DiverTM”. This
offers applicability to even existing structure and dams. The bulb type design has less civil
structure requirements and with unique water lubricated bearings (derived from the ocean
turbine technology of Voith) along with floating type generator offers extremely low
maintenance demands. The installation of the unit is directly in the waterway which eliminates
the requirements of powerhouse floor and related auxiliaries.
Technical Description –Stream Diver
The Stream Diver TM is of the propeller bulb type construction where in the runner is directly
mounted on shaft of the permanent magnet synchronous generator (PMG Generator). The
target of the Stream Diver TM project was to develop a standardized turbine concept, in a
compact and submersible design without the need of peripheral systems (e.g. hydraulic power
unit, cooling system, dewatering system). Therefore the Wicket gates and runner blades are
not regulated. The bearings are of self-lubricated type operated with water. No peripheral
system is needed to supply the bearings with lubrication medium. The bulb of the Stream
Diver TM is filled with river water to avoid leakage from the surrounding water. The bulb of
the Stream Diver TM is not pressurized. In case or applications where a shaft sealing is
required various filter are integrated in the turbine housing and the Bulb hub to avoid over
pressure. The power unit is equipped with two guide bearings, one downstream close to the
runner integrated in the turbine housing, other upstream connected with the generator housing.
The thrust bearing, for carrying the hydraulic thrust, shall be combined with the downstream
guide bearing. Also a counter thrust bearing has been incorporated.
The stator of the generator is equipped with a static sealing to avoid ingress of the water inside
the stator body to avoid damage to the winding. This sealing is placed across the air gap of the
generator. However design modifications (if any) and improvements/optimization wherever
required can be discussed and carried out during detail engineering phase of the project based
on site requirements. International standards have been followed for materials, manufacturing,
designs and testing and are in line with the industry best practices.
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ICHPSD-2015
Typical Application Range and Avenues of Stream Diver TM
The operational criteria for the Stream Diver TM equipped power plant shall be guided by
following important considerations:
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•
•
•
•
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The discharge through turbine for single unit is limited in a range of 2 - 16 m3/s.
Since the StreamDiverTMis non-regulated machine and in order to utilise complete
potential of any site, multiple number of units are required to be installed.
The typical head range for StreamDiverTM is 2 – 6 mt. However in certain cases
where in high head application is required, the standardised design modules can be
engineered for high heads up to 10 mts if the project is economically attractive.
The civil structure shall facilitate the minimum submergence of the machine for
cavitation free operation of StreamDiverTM. If higher submergence is available by
virtue of natural construction of site then two machines in parallel can be mounted
like one above another.
StreamDiverTM uses Modular concept with 5 different runner diameters. Runner
diameter vary between 790mm – 1310 mm
Below 2m head, StreamDiverTM is technical feasible but may not be economically
attractive
Unit flow is limited by runner diameter.
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International Conference on Hydropower for Sustainable Development
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Fig.2: Application Range
Typical Avenues of Application:
•
Check Dams: dams built across the rivers for the purpose of flood control are the
ideal potential source for the power generation with the help of StreamDiverTM
economically, if exiting structure allows the implementation of proposed
configuration.
Project Site
Possible StreamDiverTM Installation
Fig. 3: Typical Picture of check Dam
Fig. 4: Shaft power plant invention of
(Source:
University of Munich with Stream Diver
http://www.bing.com/images/search?q=
TM(Source: Voith)
Check+dam+in+India&FORM=HDRSC2#vi
ew=detail
&id=6CE136BE5D2501777149A719BCB4
E13A2BF8
DA75&selectedIndex=32
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ICHPSD-2015
The idea is to install the StreamDiverTM within the existing structure of dam with minimum
effort. An advantageous solution could be a typical shaft power plant concept that has been
developed by the German technical university of Munich. This concept combines the
advantages of low civil impact and better environmental aspects. The idea is a box that will be
installed in tail water basin and outside foundation of the existing site. The box is covered
with a trash rack that is oriented parallel to the riverbed. Inside the box and covered by the
trash rack will be the StreamDiverTM with trash rack cleaner and intake gate installed. The
power plant will be completely submerged and not visible during operation. Only the power
cable coming out of the water will be visible.
•
Irrigation Dams and Canals: As the irrigation dams and canals offer constant flow
with little variation in the head, this offers very good potential for power generation
with the application of machines like StreamDiverTM. The StreamDiverTM can be
applied for existing irrigation dams and canal system with little renovation in the
structures as well as new irrigation projects can be constructed with suitable
configuration.
Project Site
Possible StreamDiverTM Installation
Fig. 5: Irrigation Canal
Source: Internet Images
Fig. 6: Over flooded plant design with
Stream DiverTM Stream Diver TM (Source:
Voith)
The idea is to use the existing dam as a civil structure. With a flap on top of the dam, the head
water level could be controlled. During dry water season, the dam is visible and can be used to
access the turbines with a mobile crane. The Turbines will be installed in the head water basin.
The closing gate can be either installed at the draft tube exit or the intake. The trash rack
design will adapted to the local site conditions and requirements. Fig. 6 shows that the Stream
Diver TM can be installed without the need of a visible powerhouse with simplest civil
structure required.
Further applications
•
Intake structure and exit structure of Hydro Power Plants: Intake structure of run
off river hydro project, intake structure of spillways and exist structures of
hydropower plants are the potential source of small electric power generation through
application of Stream Diver TM.
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International Conference on Hydropower for Sustainable Development
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•
•
•
Upgrading existing shout -down facilities: Due to its compact design, the Stream
Diver TM can be integrated in old shut-down power plants without extensive
construction measures.
Residual Flow applications
Penstock applications
Assembly and Service
The typical Stream Diver TM power plant foresees a limited access to the turbine parts during
operation. To service the turbine, the complete power unit need to be removed out of the
power plant. (Refer to fig. 7). The shutdown of the turbine occurs via an automatic shut-off
device (gate valve). The power unit will be removed out of the water via an opening of the
trash rack. To avoid requirement of divers and time consuming mounting procedures, the
turbine will be supported with a steal structure. The supporting structure allows an assembly
similar to a stop log system. The maximum weight of the Stream Diver TM will be kept below
10 Tons to allow the handling via a mobile crane.
Fig. 7: Assembly procedure of the StreamDiverTM
The service of the turbine can be undertaken after disassembly in the factory work shop. The
assembly time and tools required for the Stream DiverTM is very less compared to
conventional hydraulic turbines. The alignment of shaft and bearing is very easy and less time
consuming. The focus in the development was to avoid special alignment procedures. The
disassembly of the Stream Diver TM in its main parts is a 4step process. (Refer to Fig. 8).To
handle the generator without risk, in the event of high magnetic forces, the rotor is fixed by
positioning devices after removing the bearing shields.
Fig. 8: Factory assembly of Streamdiver
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Development and Prototype Results
Since August 2012, a full scale prototype of the Stream DiverTM is in operation in a power
plant close to Vienna.(Refer to fig. 9 and 10). The over flooded power plant is equipped with
12 small Turbines. To test the new Voithtechnology, the owner of the power plant offered to
remove one of the turbines and installed a 450 kW Stream Diver TM. Up to now the prototype
is running for more than 10.000 operation hours without any break down maintenance.
Subsequently, besides the test of the new bearing and generator design, different grid
connection types are also under investigation. As a standard solution the PMG generator of the
Stream Diver TM will be connected directly to the grid. In case turbine flow control is
favourable the generator of the Stream Diver TM can be connected via a frequency converter
to the grid. In this case the turbine can be operated with variable speed. A further advantage is
that there active power can be controlled via the frequency converter.
Fig.9: Prototype testing setup
Fig.10 Prototype of Stream DiverTM
installed a Nussdorf power house
The start up and shut down process is described in following text as observed during prototype
measurements.
•
Start-up process: (Refer to fig. 11)
 In case of direct grid connection, the turbine speed will be regulated with a draft
tube gate for the synchronization procedure.
 With frequency converter application, the synchronization is controlled by the
power electronics.
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International Conference on Hydropower for Sustainable Development
Feb 05-07, 2015, Dehradun
Fig.11 Prototype measurements during synchronization procedure with direct grid
connection (left picture) andfrequency converter operation (right picture).
•
Shut-down process and load rejection: (Refer to fig. 12)
 For the normal shut-down process, the turbine power will be regulated by the
gate, before opening thecircuit breaker. In the event of load rejection, overspeed
operation is possible for up to two hours.
Fig.12 Typical shut down process and load rejection behaviour
Beside the full scale prototype installation, further tests have been carried out during the
development. The technology of Stream Diver TM is developed based on the proven hydraulic
profiles of existing VOITH axial flow turbines which are tested in the Laboratory. The
permanent magnet generator technology is developed along with the supplier of the generator.
The water floated PMG is tested in the laboratory for satisfactory operation. The magnets used
for the generator are of high performance type which do not require the active cooling of rotor.
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ICHPSD-2015
The water lubricated bearings are designed based on hard-soft pairing principle. The synthetic
bearing pads and shells with high-strength abrasion surface offer excellent wear resistance.
The wear resistance of bearing materials is tested and analysed in the bench test under real
time behaviour and operating conditions. The Bearing concept is proven design and derived
from other VOITH products, e. g. tidal flow turbines, HyTide and VOITH in line Thruster.
Conclusion
The technological progress and innovation is an important contributor to economic growth and
plays a vital role in the advancement of human life which helps in improving the quality of
human life. However it is also very important to consider the impact of these innovations on
environment, ecology, socio-economic effects. The Stream Diver TM offers new possibility to
design run of river power plants or utilize existing dam structures where conventional
solutions are not feasible for environmental or economic reasons. Some of the advantages of
Stream Diver are:
Oil free Technology
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Minimum maintenance effort and costs due to the reduced technical complexity and
the non-requirement of auxiliary systems in the power plant. The compact design
allows flexible installation possibility and as implification of the civil structure.
Due to the standardized and modular construction of Stream Stream Diver TM, the
delivery and installation time lines are short.
Due to the limited complexity the service and spare part administration is very cost
effective.
This paper highlights the positive prototype experience so far. Also first feasibility studies in
Asia confirm that with the Stream Diver TM Technology existing dam structures can be
utilized with a high profitability.
References
World Energy Outlook Special Report, September 2013 (www.worldenergyoutlook.org)
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