This project is a simple Run-of-River scheme that utilizes the flow in Madi River. Madi River is one of the major tributaries of the Narayani River of the Gandaki basin after mixing with the Seti River. The proposed project has installed capacity of 44MW, design discharge of 18m3/sec and net head of 295m. A simple boulder riprap diversion weir across the Madi Khola diverts the water into the side intake. A gravel trap settles gravels coming through the six orifices of the intake and takes to the headpond through approach box culvert. Two underground settling basins are fed with the discharge by two inlet tunnels from the headpond. An outlet pond after the settling basins feed water into headrace tunnel. The headrace tunnel of length 5905m of finished diameter of 3.6~4.4m and steel penstock pipe of average diameter 2.6m and length 1381m feed water to the three units of vertical axis Pelton Turbines installed in the semi-surface powerhouse to generate 44000kW power. The water will then be discharge back into the Madi River through 281m long tailrace. An underground surge tank is provisioned at the end of the headrace tunnel. An access tunnel to the headworks, two Adit tunnels to access the underground settling basins, three Adit tunnels to access the headrace tunnel and a ventilation tunnel to reach the top of the underground surge tank are provisioned.
The electricity generated from this plant will be connected to the Integrated Nepal Power System (INPS) at the Lekhnath Sub Station at Lekhanath Municipality near Pokhara City through 22km long 132kV single circuit transmission line. The total net energy production will be 243GWh annually.
Salient Features
| Project | Super Madi Hydroelectric Project |
|
LOCATION
|
|
| Development Region | Western Development Region |
| Zone | Gandaki |
| District | Kaski |
| Intake Site | Parch and Namarjun VDC |
| Powerhouse Area | Namarjun VDC |
|
General
|
|
| Name of River | Madi Khola |
| Nearest Town | Pokhara, 23km |
| Type of Scheme | Run-of-River |
| Gross Head | 305m |
| Installed Capacity | 44000kW |
|
Hydrology
|
|
| Catchment Area | 284.1 km2 |
| Mean Annual Discharge | 30.29m3/s |
| Design Discharge | 18m3/s |
| Probability of Exceedance | 40.96% |
| Riparian Release | 1.52m3/s (25% of minimum mean monthly flow) |
| Design Flood Discharge | 1288 m3/s (100 Yr. Flood) |
|
Diversion Weir
|
|
| Type of Weir | Free Overflow with Spillway |
| Total Length of Weir | 60m |
| Height of overflow Weir from river bed | 5m |
| Crest Elevation | 1362masl |
| Design Flood Level | 1368masl |
|
Undersluice
|
|
| Crest Elevation | 1357m |
| Width | 2 x 3m |
| Height | 3m |
| Gate | 2 Radial Gates |
|
Side Intake
|
|
| Type of Intake | Side Intake (Orifice Type) |
| Size of Orifice (W x H) | 2.4m x 1.6m, 6 Nos. |
| Intake Sill Level | 1360m |
|
Gravel Trap
|
|
| No. of Chamber | 1 |
| Size | 21m x 18.5~6m x 6m |
|
Approach Box Culvert
|
|
| Type | Concrete Box Culvert |
| Length | 53m |
| Size (W x H) | 2 Units of 1.85~2.85m x 3m |
|
Inlet Pond
|
|
| Length | 31m |
| Size (W x H) | 12.4m x 4.95m |
| Normal Water Level | 1361.25 masl |
|
Inlet Tunnel
|
|
| Shape | Inverted-D |
| Numbers | Two |
| Length | 52m |
| Size (W x H) | 3m x 3m |
|
Underground Desanding Basin
|
|
| No. of Chamber | 2 |
| Size | 172m x 7.5m x 14.75m (parallel section 160m) |
| Particle Size to be settled | 0.20mm @ 90% efficiency |
|
Inlet Shaft
|
|
| Type | Circular |
| Height | 13m |
| Size | 3.6m dia. finish |
|
Headrace Tunnel
|
|
| Type | Inverted-D Type Tunnel |
| Finish Diameter | 3.6~4.4m |
| Length | 5905m |
| Support | Fully Concrete Lined (800m) Shotcrete Lined (5105m) |
|
Surge Tank
|
|
| Type | Circular, underground |
| Height | 37m |
| Finish diameter | 9m dia. |
|
Penstock Tunnel
|
|
| Type | Inverted-D Type Tunnel |
| Finish Diameter | 2.8m circular penstock |
| Length | 38m |
|
Penstock
|
|
| Material | Exposed Steel Penstock |
| Diameter | Avg 2.6m |
| Length | 1381m |
| Thickness | 12-32mm |
|
Powerhouse
|
|
| Type | Semi-Surface |
| Dimension | 52m (L) x 14m (B) x 28m (H) |
| Turbine Center Level | 1055.5m |
| Number of Units | Three |
|
Tailrace Canal
|
|
| Type | Concrete Box Culvert |
| Length | 160m |
| Size (W x H) | 4m x 2.5m |
| Open canal length | 122m |
| Size (W x H) | 4m x 3m |
| Tail water outlet level | 1047.90m |
|
Turbine
|
|
| Type | Pelton |
| Number | Three |
| Number of Nozzles | Four |
| Arrangement of shaft | Vertical |
| Design discharge per unit | 6m³/sec |
| Rated Net Head | 295.34m |
| Rated Efficiency | 89.5% |
| Rated output capacity per unit | 15540kW |
| Rated Speed | 428.57 rpm |
|
Generators
|
|
| Number of units | 3 |
| Type | Synchronous, 3 phase Salient pole, vertical shaft |
| Rated Output | 17568 kVA |
| Rated Voltage | 11 kV |
| Rated frequency | 50 Hz |
| Power Factor | 0.85 |
| Rated Efficiency | 96% |
|
Transformer
|
|
| Number unit | 10 (9+1spare) |
| Type | 1-phase, oil immersed |
| Installation | outdoor |
| Rated capacity | 6000 kVA |
| Rated H.V. (Secondary) | 132 kV |
| Rated LV. (Primary) | 11 kV |
| Cooling | ONAN |
| Rated frequency | 50 Hz |
| Rated Efficiency | 99% |
|
Transmission Line
|
|
| Voltage Level | 132kV |
| Length | 22km |
| Connection | NEA Sub-station at Lekhnath |
|
Approach Road Connection
|
|
| External Access Road | Pokhara – Chasu, 18km (existing) |
| Project Access Road (to be constructed) | Chasu- Powerhouse 5kmPowerhouse – Headworks 5.5km
Seti Khola – Surge Tank 4.2km |
|
Energy
|
|
| Net Saleable Annual Energy | 243.125 GWh |
| Net Dry energy | 37.856 GWh |
| Net Wet energy | 205.269 GWh |
|
Construction Period: 4 years (Main Project Works)
|
|
Source : Himal Hydro & General Construction Ltd (website)