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VISHNUGAD PIPALKOTI H.E. PROJECT
Features
SALIENT FEATURES

LOCATION

State                                                       

Uttarakhand

District                                                        

Chamoli

River                                                     

Alaknanda

Dam site

Near Village Helong

 

(E- 790   29'30"), (N-300  30' 50")

Power House site (underground)

Near Village Hat

 

(E- 790  24'56"), (N-300  25'31")

HYDROLOGY

Catchment area at dam site

4672  Sq. Km

Annual mean flow 

5682.6 M Cum

Submergence area                        

24.5 ha

Design Flood 

SPF 6700 m3 / sec (For Design)

PMF 10840 m3 / sec (For Checking)             

Diversion Flood                   

( 1:25 yr Non Monsoon flood ) 

Normal Water Level in Non Monsoon season at Dam site

HFL at Dam site

Normal Water Level in Non Monsoon season at TRT Outlet site  

HFL at TRT outlet site

 

725 m3 /sec

 1232 m.

1238 m

 1033  m

 

 1040 m

RESERVOIR

 

Full reservoir level

EL.1267 m  

Maximum water level

EL. 1269 m (PMF)

Minimum Draw Down level

EL.1252.5 m

Gross storage at FRL

3.63 Mcum

Storage at MDDL

1.16 Mcum

Live storage

2.47 Mcum

Surface Area at FRL

24.5 Ha.

TECHNICAL FEATURES

 DIVERSION ARRANGEMENT

 

A. DIVERSION TUNNEL

Location

Left bank

Length

425 m

Diameter

10m, Circular

Design Discharge

725 m³ / sec

Gates

10m x 10m, Vertical lift fixed wheel

Invert level at Entry

1228 m

 

 

B. U/S Coffer Dam

Type

Colcrete

Length

60 m

Height

15 m

Top Elevation

EL 1242 m

C. D/S Coffer Dam

Type

Rock fill

Length

40 m

Height

6 m

Top Elevation

EL 1229 m

DIVERSION DAM

Type of Dam 

Concrete, Gravity Dam

Height of dam above deepest

65 m

Foundation level 

 

Top of Dam 

EL 1270 m

River bed level 

EL 1225 m

Foundation level

EL 1205 m

Length

89.55 m (NOF 28.65 m, OF 60.9 m)

SPPILING ARRANGEMENT

A.  Sluices

 

Nos.

4

Design Flood

8004 m³  /sec

Size of sluice

7.2 m (W) x 15 m (H)                  

Type of gate

Radial                   

Stoplog (1 no. 7.2 m x 22.5 m)

Crest level of sluice

1233 m

B. Diversion cum spillway tunnel

Diameter 10 m (), Circular

Invert  level at Entry

1249 m

Length

100 m

Design Discharge

1074 m³  / sec

Gate

2+1 no., 4.1 m x 10m 

(Vertical lift fixed wheel Gate)

 

C. Spill Tunnel (12m ) :

 

Size

12m ,  (Circular)

Invert level at Entry

1228 m

Length

205 m

Design Discharge

1618 m³  / sec

Gate

2+1 no; 4.8 m x 12m 

(Vertical lift fixed wheel Gate)

D. Ogee Spillway

 

No.

1

Type of gate

Vertical

Size

7 m (H) x 6 m (W)

Design Flow

310 m³ / Sec

Crest Level

EL 1260 m

POWER INTAKE

Location

Right bank

Nos.

3

Type

Straight intake with bell mouth

Maximum discharge

274.63 m³ / sec

Intake Invert level

EL 1242.5 m

Size

6 m modified Horse shoe type

 

Gates

3+3 Nos., 5.2 x 6 m x 6 m  

Vertical lift fixed wheel gate

(service gate + emergency gate)

Silt FlushingTunnel (Below Intake)

 

Size of Intake

3 nos. of 3 m x 3 m

Size of SFT  ducts

3 nos. of 2 m x 5 m

Gate

Design discharge capacity

3+3 nos. of 3 m x 3

380 Cumec

DESILTING CHAMBER

Nos.

3

Size

390m (L) x 20 m (W) x 17.5 m (H),

Particle size to be removed

0.2 mm and above

Gates

3 Nos., 5.24 m x 6 m (H),   

Vertical lift fixed wheel

Operation Level

EL 1270 m

SILT FLUSHING TUNNEL

 

Silt Flushing Tunnel

 

Size

3.6 m x 4.0 m  ( D-Shaped )

Flushing Discharge

45.8 m³/Sec

Length

680 m

Gates

3 Nos., 2.5 x 2.85 m,        

Vertical lift slide Gate

Operation Level

EL 1237 m

 

 

HEAD RACE TUNNEL

Length

13.4 Km

Diameter

8.8 m (Horse shoe by DBM & 12 Km Circular by TBM)

Design discharge

228.86  m³/Sec

Velocity

3.56 m / sec.

Bed Slope ( average )

1:121 (before Maina river  1.321 (After Maina River)                             

No of Adits

2

UPSTREAM SURGE SHAFT

Type                                                   

Restricted Orifice type

Diameter

15/22 m 

(15m from EL.1165m to EL 1240m

                                   

(22m  from EL.1240m to EL. 1305m)

Height ( from HRT invert )

140 m

Top EL

1305 m

Orifice Level

1165 m

Orifice Diameter

1.5 m, 3 Nos.

Tunnel invert

EL 1155 m

PENSTOCK ASSEMBLE CHAMBER

Size

50m (L) x 9.8m (W) x 19m(H

 

 

PRESSURE SHAFT

Nos.

 2 / 4

Type                                                   

Circular

Diameter

5.2 m / 3.65 m

Length of each PS

310 m / 35 m

Design Velocity

5.39 m/Sec

POWER HOUSE

Type

Underground

Size of P/H Cavern

146 m x 20.3 m x 50 m

Size of Transformer Cavern

142 m x 16 m x 24.5 m

Nos. of units

4

Rated unit capacity

111 MW

Installed capacity

4 x 111 MW = 444MW

Type of Turbine

Francis

Gross head

237.0 m

Rated Head

212.46 m

Centre line of unit

EL 1022.0 m

Service bay level

EL 1038m

Maximum flow through each unit

57.22 m³/sec

Generator :

 

Synchronous speed of Generator

250 rpm

Power factor, Generator voltage

0.9, 13.8k V

 

 

Transformers- Type, Nos., No of phases

OFWF, 4, 3 Single phase

46 MVA , 13.8/420√3kV 

Step-up voltage, Capacity

400 kV

Energy Generation

(on 90% dependability basis                                         

1813.03 GWh

D /S SURGE TANK

Type

Underground

Size

120m (L) 16m (W) x 35m (H)

Maximum Surge level

1040 m

Minimum surge level

1026.50 m

TAIL RACE TUNNEL

Size

8.8 m  (Horse Shoe)

Length

3.07 Km

Maximum TWL

1030.0 m (With all M/C running)

Minimum TWL 

1028.2 m (With 10% load)

TRT Invert level

EL 1025.0 m

SWITCH YARD

Type of Switchyard

GIS

No. of bays in the switchyard

8 bays

Voltage level

420 KV

Size of Potyard

40m x 67m

POWER GENERATION

 

Firm Power

51.47 MW

Annual Energy

1696.31 GWh

 

 

Annual Load Factor (lean now)

11.72 %

Design Energy

1674.29 GWh