Salient Features of Nyadi Hydropower Project (30 MW)

SNo. Description Parameter
1. Location (Longitudes and latitudes of the points bordering the project area)
Latitude 28°19' 20'' N to 28° 21’ 07’’ N
Longitude 84° 25’ 25’’ E to 84° 28’ 00’’ E
District Lamjung
2. Type of Power Plant
Type Run-of-River (RoR)
3. Hydrology
Catchments area at intake site 154.7 km2
Long term annual average flow 16.13 m3/s
Average minimum flow 3.09 m3/s
Design flood at intake (1 in 100 Years) 509 m3/s
90% reliability flow of intake 2.98 m3/s
4. General Hydraulics
Gross head 328 m
Net head 316 m
Design flow 11.08 m3/s
Installed Capacity 30 MW
5. Siuri Tailrace Flow Tapping Arrangements
5.1. Diversion Canal
Type Rectangular with Slab Cover
Size 25.75 m x 1.5 m x 12 m
5.2. Collection Chamber
Type Rectangular
Size 10 m x 5 m x 4 m
5.3. Overhead Reservoir
Type Rectangular
Size 5 m x 4 m x 3.5 m
5.4. Pumping Arrangement
Type 3 nos. Non-submersible Pump (30 m capacity )
Capacity and pumping head 1.1 m3/sec through 0.6 m dia. Steel pipe, 30 m head
5.5. Pipe
Type Surface and buried, Steel pipe
Length 648.091 m
Diameter and thickness 0.6 m, 0.7 m and 8 mm
6 Diversion Weir
Crest length 17 m
Height 10 m above natural river bed
Size of radial gate 5.5 m x 4.5 m
No of radial gate 2
Thickness of guide wall 3.0 m
Crest elevation 1384 masl
Length of stilling basin 30 m
Sewer gate 2.5 m x 3.5 m, Crest Elevation 1381.7 masl
7 Intake Chamber
Type Side intake
Size of opening 7 m x 1.5 m (2 nos.)
Coarse trash rack 7 m wide and 1.5 m high, 2 nos.
8 Intake Tunnel
Type D-shaped RCC
Size 4 m x 4 m
Length 240.27 m
9 Settling Basin (Underground)
No of bays Single
Nominal size of trapped particle 0.2 mm
Trap efficiency 93%
Settling chamber outlet cross section 9.14 m2
Settling chamber inlet tunnel cross section 8.04 m2
Length of inlet transition 15 m
Length of uniform section 60 m
Length of outlet transition 10 m
Width of uniform section 8.0 m
Depth 10 m (Average)
10 Headrace tunnel
Shape Inverted D-shaped
Length 3937 m
X-Section 3.2 m wide x 3.2 m high
Cross-sectional area 9.14 m2
11 Naiche Tunnel Adit – 1
Shape Inverted D-shaped
Length 176 m long including curve
X-Section 3.2 m wide x 3.2 m high
Cross-sectional area 9.14 m2
12 Surge Shaft1
Type Vertical shaft (Underground)
Internal diameter 5.0 m
Height of surge shaft 29.60 m
Connecting Conduit Size Circular with 3.2 m dia. and 6.6 m Height
13 Surge Shaft Adit -2
Shape Inverted D-shaped
Length 65 m
X-Section 3.2 m wide x 3.2 m high
Cross-sectional area 9.14 m2
14 Ventilation Adit
Shape Inverted D-shaped
Length 30 m
X-Section 3.2 m wide x 3.2 m high
Cross-sectional area 9.14 m2
15 Penstock
Type Surface and buried steel penstock
Diameter 1750 mm to 2000 mm
X-Length of surface penstock 774 m
Length of Vertical shaft and horizontal portion before Bifurcation Inclined buried in concrete and surface 160 m before bifurcation support plate thickness 68 mm
Type Surface and buried steel penstock
16 Powerhouse
Type Surface
Size 49 m long, 22.6 m wide and 27.2 m high
17 Tailrace Canal
Shape Rectangular, covered
Size (B X H) 3.10 m x 2.10 m
Length 25 m
Slope 1 in 500
18 Turbines
Type Pelton turbine
Turbine axis elevation 1046.00 masl
Turbine rated output 16063 kW x 2
Turbine efficiency 91.10%
No of units 2 Nos.
Running Speed 500 rpm
Tail water level 1043.27 masl
Max. discharge 2 X 5.54 m3/s
19 Generators
Type Brushless Synchronous
Capacity 18.331 MVA
Voltage 11 kV
Power factor 0.85
Operating range 0.85(lag)- unity - 0.85(lead)
Efficiency 97%
20 Transmission Line
Length 9 km including 3 km addi-tional (along the same locus till Tunikharka to third tower of Bhulbhule-Middle Marsyangdi TL project)
Voltage 132 kV
No. of Circuits Double
Configuration Three phase, six wire
Tower Type Steel lattice Tower
21 Transformer
Type Single phase, 4 no.
Rating 13.3 MVA
Vector group YNd11
Power factor 0.85
Voltage ratio 11/132 ±10% in step of 2.5
Frequency 50 Hz
Efficiency 99%
22 Energy Generation
Mean annual energy per year 172.14 GWh
Dry energy 29.15 GWh
Wet energy 147.43 GWh
23 Access Road
Road Class District Rural Road Class 'A' (DRRA)
Beshishar-Manang road to Bridge site at Marsyangdi River 447 m
Bridge Span (Bailey Bridge) 52 m
From Bridge site to Headwork’s site 10.615 km
From Thulobeshi to Surge shaft 2.393 km
Total length 13.50 km
24 Construction Period 4 Years
© 2019 NHL All Right Reserved.