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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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