ARUN 3 HEP PROJECT

ARUN 3 HEP PROJECTINDUSTRIAL TRAINING PROJECT

VIJAY KARAN ROLL NO- 121677CONTENTS SJVN-A ProfileAbout the projectNeed of the projectLocation of the ProjectProject Salient FeaturesProject componentsDiversion DamIntake and Desilting ArrangementHead Race Tunnel (HRT)Surge ShaftPressure ShaftPower House ComplexTail Race Tunnel (TRT)About the Project

The project has been awarded by NEA through ICB route for implementation to SJVN Ltd., a joint venture of Govt. of India and Govt. of Himachal Pradesh. The award is on boot bases for a period of 30 years; MoU in this regard was signed on 2.3.2008 with an objective of export 78.1% power for Nepal to India through Arun-Dhalkebar-Muzaffarpur.The project installed capacity has been estimated to be 99Mw.The project is progressing under design of foreign project wing of SJVN Ltd. & is currently under PLANNING STAGE.

SJVNL A PROFILE

SJVN Limited, A Mini Ratna & Schedule 'A' PSU under the Ministry Of Power, Govt. Of India, Is A Joint Venture Between The Govt. of India & Govt. Of Himachal Pradesh. Incorporated In The Year 1988, The Company Is Fast Emerging As A Major Power Player In The Country. The Present Authorized Capital Of Sjvn Is INR 7000 Crores.Sjvn Is Successfully Operating the Countrys Largest 1500 Mw Nathpa Jhakri Hydropower Station and Is Setting New Benchmarks in Generation and Maintenance Year After Year, After Having Tackled the Silt Erosion Problems in Under-Water Turbine PartsBeginning From A Single Hydropower Project Company, Sjvn Today Has A Footprint In A Diversified Set Of Power Projects, Which Includes Hydroelectric Projects In Himachal Pradesh, Uttrakhand, Arunachal Pradesh And In The Neighboring Countries Of Nepal And Bhutan.The Flagship 1500 Mw Nathpa-Jhakri Hydro Electric Power Station In Himachal Pradesh Was Commissioned In 2003-04. Companys Generation Capacity Is Set To Increase With The Commissioning Of 47.6 Mw Khirwire Wind Power Project In Maharashtra And 412 Mw Rampur Hydro Electric Project In Himachal Pradesh.NEED OF THE PROJECT

Although gift with tremendous Hydro Power resources, only about 40% of Nepals population has access to electricity. Most of the Power plants in Nepal are of run-of-river type with energy available in access f in country demand during the monsoon season and deficit during the dry season. Having immense potential of Hydro Power development, it is important for Nepal to increase its energy dependency with Hydro Power development. The development of Hydro Power will help to achieve the millennium development goals with protecting environment, increasing literacy, improving health of children and women with better energy. Increased nationwide availability of reliable electric power will increase productivity, stimulate Nepals economic development, and reduced reliance on Nepals primary resource of energy-fuel wood.

Location of the project The dam site is located on Arun River, a principal tributary of Sapt Koshi, near Num village and Power House Site is near Diding Village of Sankhuwashbha District in Nepal. Various project components are located on the left bank of the river with its power house at about 18.5 km downstream from the dam axis, near to Diding Village. The dam site is located at about 60 km from Tumlingtar, where exists, an airstrip connected to Kathmandu to Tumlingtar airport near Arun-3 project site. Tumlingtar is also connected by a road with a distance of about 680 km from Kathmandu.

Project Salient Features1) PROJECT AREA - Latitude 27 30N to 27 35N Longitude 87 12E to 87 20E River - Arun, a tributary of koshi river in Eastern Nepal Dam Site - Near Num village Power house - near diding village District - Sankhuwasabha2) Reservoir Maximum water level 847.73m Full reservoir level 845m Minimum draw-dawn level 835m Total Volume 13.94Mm3 Surface area at FRL 66.3ha

3) Hydrology Catchment area 26747km2 Annual avg. flow at Dam site 296m3/sec 90%dependable year flows 198.91m3/sec Design flood PMF 8880m3/sec GLOF 6830m3/sec4) Diversion Tunnel Location Right Bank Length 466m Design discharge 1300m^3/sec Diameter 11m,circular shaped gates5) U/S Coffer DamType Concrete DamTop level 816mHeight 23m6) D/S Coffer DamType Rock fill DamTop level 797.5mHeight 7.5m7) DamType Concrete gravity damTop of the Dam 849mAvg. river bed elevation 790mHeight above deepest foundation level 70mLength 197.3m

8) Spillways2nos. slide type gate of size 4.1m(W) 5.5m(H)9) Head Race TunnelLength 11.74kmDiameter 9.5mSectional Area 70.88m2V design discharge 4.86m/sInvert level at start 818.23m Invert level at end 779.36m Bed Slope(avg.)1/300Design Discharge344.68m3/secOver loading discharge379.15m3/sec10) Desilting ChambersAlignment N19 W S19 ESize4Nos. 420m(L) 16m (W) 24m(H)Particles size to be removed0.2mm & aboveGates4Nos.4.7m 6m Top Branch 440m, 7m (D-Shaped)Bottom Branch 414m ,7m(D-shaped)

12) Surge shaft open to skyTypeDiameterHeightType of LiningOrifice Diameter13) Pressure ShaftNos. / Type2Nos. steel linedDiameter5.5mLength-Horizontal length top104.92mVertical -259.11mc/c distance between 75mPressure shaftInclination with horizontal 7.25m/sMaximum design discharge 3.58m/s

14) Power house complexPower house Cavern192mSize10mShape CircularType of flowPressure flowTail water level 534mOutfall gates 2nos.fixed wheel Type gates 15) Tail raceLength of tail race tunnel 192mSize 10mShape Circular Type of flowPressure flowTail water level 534mOutfall gates2nos.Fixed wheel type gatesSize6m(W)10m(H)

PROJECT COMPONENTS1) Diversion Dam The diversion dam is envisaged to be a concrete gravity dam of about 70m in height with its top level at El 849m, FRL at El 845m and MDDL at El 835m.The dam is provided with 6 sluice radial gates each of 9m 14m with one auxiliary spillway gate to surpass design discharge of 15710m3/sec (PMF of 8880 cumecs plus GLOF of 6830 cumecs). 2) Intake and Desilting Arrangement The intake structure shall consist of trash rack with four bell mouth opening leading to four no. intake tunnels of 6m dia. There are four underground desilting chambers of 16m24m420m to take care of silt particle more than 0.2mm. 3) Head Race Tunnel (HRT) A 11.740 km long 9.5m dia circular concrete lined HRT has been designed to carry a discharge of 344.68m3/sec. Four adits have been proposed to facilitate the construction activities of the tunnel. 4) Surge Shaft (open to sky) A 149m high, 24m dia restricted orifice type surge shaft has been designed to take care of the maximum surge effect up to El 880m as well as to minimize slope stabilization.

5) Pressure Shaft Two vertical steel lined underground pressure shafts, each of 5.5m dia with bifurcation into four of diameter 3.2m to feed the four Francis turbine of 225MW each.6) POWER HOUSE COMPLEX An underground cavern of 179.49m long 22.5m wide 49.5m high has been provided to house 4 units of 225MW Francis turbines(total capacity 900MW) and spherical type main inlet valves. A underground Transformer cavern at elevation 552m of size 153.94m(L) 16m(W) 22.5m(H) has been provided to accommodate (12+1spare) nos. single phase 400kV transformers, each of 92MVA capacity.7) Tail Race Tunnel One 10m (circular-shape) concrete lined tunnel has been proposed to discharge the tailrace water directly into the river8) Transmission System The power from the project is proposed to be evacuated to India through 400kV double circuit transmission line from Arun 3 project in Nepal to Muzffarpur in India with LILO of one circuit at Dhalkebar Sub-station in Nepal to provide GoN power share.

9) Project BenefitsThe annual energy from the project has been assessed as 4018.87 GWh on 90% dependable basis and design energy as 3924.03 GWh. The project would provide peaking benefits of 900 MW round the year.10) Project CostThe Project is estimated to cost Rs. 44168.2 million are as under:-Cost of Generation at July, 2013 Price LevelCivil WorksINR 32575.6 million Electrical WorksINR 11592.6 million Total Cost (without IDC & FC)INR 44168.2 million IDCINR 12111.0 million Financing ChargesINR 396.7 million Total Cost of the projectINR 56675.9 million

HYDROLOGYObjectiveTo access the water availability of the proposed project so as to carryout simulation studies for estimation of power potential.To determine the probable maximum floods corresponding to different probabilities so as to ensure safe passage of food as well as GLOF.Assessment of sediment inflow into the reservoirTo determine diversion flood for construction planningAssessment of sediment inflow into the reservoir and estimation of sediment load.

Design Flood studies

The design flood and highest flood level are very much essential for fixing the water way and foundation depths of any hydraulic structure. For a diversion structure, 1000-year design flood or standard project flood value is considered for hydraulic design and for storage projects, probable maximum flood or 10000 year return period flood should be considere

PMF is estimated using hydro-meteorological approach whereas 10000 year return period flood is arrived at using flood frequency approach.

Glacial Lake Outburst Flood (GLOF)

In Nepal, there have been several instances of GLOF floods and hence the effect of GLOF on the project components needs to be considered. The lower Barun Glacial Lake, at the toe of the lower Barun glacial is only potentially dangerous lake identified in the Arun sub-basin of Koshi River basin in Nepal. The lake lies at the foot of mount Makalu. The Barun Khola starts in the Makalu region and is one of the major tributaries of the Arun River in Nepal. The super glacial lake so developed grows bigger in size and in form of an end moraine dammed lake. At the present the lake has grown too much bigger size. The surface area of lake works out to 1.04 approx. km. The detailed studies have been carried out for assessment of peak flood due to GLOF by CWC, New Delhi and WAPCOS Ltd. Based on the above studies the GLOF value of 6830cumec has been considered in addition to PMF value of 8880cumec for reservoir routing and spillway design so as to ensure safety of project structures.

POWER POTENTIAL

The study represents the assessment of power potential and estimation of energy generation of the Arun-3 H.E. project. The power potential of the project is based on available head and discharge(Q) value. The basic equation of hydropower is Power, P= 9.81QH (kW) Where Q= discharge in m3 /sec H = head in m

Project Parameters

FRL of the reservoir is El 845m.MDDL has been fixed at EL 835m. TWL is at EL 534m. Annex-13.1 shows the different level of the project. Heads The various operating heads in this project are as: Maximum head : 289.54m Minimum head : 279.54m Design head : 286.21m

Efficiency (Generating Units)

For determination of power potential, the following efficiency applicable for Francis turbine driven generating units are computed: Efficiency of turbine 94.5% Efficiency of Generator 98.5% Combined efficiency93.00% Computation of 90% & 50% dependable years The planning of hydro-electric plants is based on 90% dependability criteria. The energy generation per year in M years is arranged in descending order and the (M+1) 0.9th year is taken to represent the 90% dependable year. In Arun-3 the 19th ranked year is 90% dependable year. the 50% year is (M+1) 0.5th year would be 11th year as shown in Annex-13.5. Therefore, 2006-07 comes out to be 90% dependable year & 1993-94 comes out to be 50% dependable year.

COMPUTATION OF INSTALLED CAPACITY (IC)

The power potential with different capacity from 650MW to 1250MW is a step of 50MW in 90% dependable year is indicated in Annex-13.6. On observing the hydrological data for the 90% dependable year, lean period is found to be from Dec. 1 to March 2, 10 daily period. For optimization of Installed Capacity, annual energy generation, Incremental Energy generation (dkWh), and the ratio of Incremental Energy generation to Incremental Installed Capacity (dkWh/dkW) have been computed during 90% dependable year. CONCLUSION The design energy of 3924.03 GWh with 95% availability of installed capacity in 90% dependable year shall be considered for financial evaluation. Annual energy generation in 90% dependable year has been computed for energy generation of 900MW (4 225 MW). Hence the project is feasible as per the annual energy generation criteria and should be implemented .