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Lower Likhu Hydropower Project (28.1 MW)

 Technical Summary

Lower Likhu Hydropower Project (LLHP) was identified by Swet Ganga Hydropower and Construction Ltd. The Project is run off the river type with it’s headwork’s located on the right bank of Likhu Khola in Sirise of Saipu VDC, Ramechhap District just upstream of the confluence of Pokali and Likhu Khola. The entire Project area (headworks to Powerhouse area) is located on the right bank of Likhu Khola in Sirise Saipu and Bijulikot VDCs of Ramechhap district, Janakpur Zone, central development region of Nepal.

The general arrangement of project comprises headworks, water conveyance pipe and tunnel of around 5 Km length. The headrace tunnel is D shaped with internal dia of 5 metre. The tunnel section crosses two Kholsi areas at Seti Khola and Poku Khola. The project layout and Longitudinal profile is shown on the figures  below ( Figure 1 and 2).

The Project utilizes 118 metre of gross head and design discharge of 29.75 m3/sec , resulting the Installed capacity of 28.10  MW .The average annual energy generation according to PPA with Power Trade Department of Nepal Electricity and Authority is 166.53 GWh among which  the dry season energy is 30.43 GWh and the wet season energy is  136.10  GWh .

A 27 KM long single circuit 132 kv transmission line has been proposed to evacuate the generated power from switchyard at Larkhubesi, Ramechhap to proposed NEA’s New Khimti Substation at Chubratar, Dolakha.

The required commercial operation date (RCOD) according to power purchase agreement (PPA) is 1st Dec 2021 (15th Mangsir 2078) .The company has already received Generation License for 28.1 MW, Lower Likhu Hydropower project on 2072. 12. 28 for 35 years,. The connection agreement for the project was done with Grid Operation department, NEA on 11th Chaitra, 2072.

Salient Features of the Project:

S. N. Description Value
1 GENERAL  
 Project location Saipu and Bijulikot VDC’s of Ramechhap District and Tarkerabari of Okhaldunga District
Zone Janakpur Zone
Development region Central Development Region
Nearest road-head

Up to Sirise at Headworks

Up to Ratamate at Powerhouse

Climate Sub-tropical
Average temperature Maximum : 36.3 0C in May
Minimum : 4.30C in January
2 GEOGRAPHICAL COORDINATES  
Latitude

270 22’ 47” N to 270 25’ 50” N

(Generation license)

Longitude

860 13’ 17” E  to 860 15’ 38” E

(Generation license)

3 HYDRO-METEOROLOGY  
 Average annual rainfall 1796  mm
Catchment area at intake 718 km2
Annual mean flow 47.30 m3/s
Maximum mean monthly flow 151.36 m3/s
Minimum mean monthly flow 4.34 m3/s (April)
Design discharge 29.75 m3/s
90% firm flow 9.16 m3/s
Flood discharge 870 m3/s
4 WEIR  
Type Concrete ogee
Crest elevation 743 m amsl
Length 63 m
Max Dam height (from existing ground) 5.5 m
5 UNDERSLUICE  
Type Radial Gate Mechanism
Numbers 2
B x H (m) 6.0 x 6.0 (each)
Sill level 736.0 m amsl
6 INTAKE  
Type Side intake
No. of opening 3
B x H 4.5 x 2.85 (each opening)
Intake sill level 739.40 m amsl
7 GRAVEL TRAP  
Type Surface
L x B x H (m) 8.0 x 4.5 x 6.0
8 SETTLING BASIN  
Type Surface
Numbers 3
L x B x H (m) 110 x 12.5 x 8.0 (each basin)
Length of inlet transition (m) 22
Particle size to be settled (mm) 0.2
Normal water level 742.1 m amsl
9 HEADRCE PIPE  
Diameter 3.75
Thickness (mm) 12
Length (m) 280
10 HEADRACE TUNNEL
Type Inverted  U-shape
Length (m) 4960 (alternative 1, option A)
Diameter (m) 5.0
11 SURGE TANK
Height (m) 41 (from invert)
Diameter (m) 12.0
12 PENSTOCK
Material Mild Steel
Vertical and horizontal shaft Length  0 (surface)
Exposed pipe length 231
Diameter 3.75 / 2.65
Thickness 12 – 28
13 POWERHOUSE
Type Semi-surface
Location Bijulikot VDC
Length x Width x Height 27.3 x 22.0 x 24.47
Turbine setting level 623.36 m amsl (center line)
14 TAILRACE
Type Open channel
Length 145
Height 3.5
Width 5.0
Normal Water Level 625
15 TURBINE
Type Francis, vertical axis
Numbers 2
Rated output capacity per unit 14.1 MW
Efficiency 91
16 GOVERNOR
Type Electronic PID control
Adjustment for speed drop Between 0 to 5%
17 GENERATOR
Type Synchronous, 3 phase
No of units 2
Power factor 0.85
Voltage 11 kV
Frequency 50 Hz
Excitation system Brushless
Efficiency Minimum 96
18 TRANSFORMER
Type Oil immersed, ONAN type
No of units 2
Rated output capacity per unit 18 MVA
Voltage ratio 132/11 kV
Efficiency 99 %
19 SWITCHYARD AND TRANSMISSION LINE
Switchyard type Outdoor, conventional

Transmission line length

(New Khimti Substation)

27 km
Voltage level and circuit 132 and single circuit
Conductor ACSR “WPLF”
20 POWER AND ENERGY
Head-water level 743 m amsl
Tail-water level 625.00 m amsl
Gross head 118.0 m
Net head at design flow Approx. 111 m
Net head at lowest flow Approx 115 m
Installed capacity 28.1 MW
Dry energy 30.43 GWh
Wet energy 136.10 GWh
Average annual gross energy 166.53                  Wh
166.54

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