Sanjen Hydroelectric Project (SHEP)
Sanjen Hydroelectric Project (SHEP)
PROJECT DESCRIPTION
Sanjen Hydroelectric Project (SHEP):
Sanjen Hydroelectric Project utilizes the tail water from the Sanjen (Upper) Hydroelectric Project, and therefore, it’s a cascade run-of-river scheme. The whole scheme is divided into three work sites, viz.Headworks Site that covers Chhupchhung feeder system, spillway, intake/forabay and pressure conduit, Underground Works that covers headrace tunnel, rocktrap, surge tank, penstock shaft (inclined and horizontal) and construction adits, and Powerhouse Site that covers powerhouse structure, tailrace and switchyard.
The headworks site is located at Simbu Village of Chilime VDC. The headwork consists of overflow spillway, intake/forebay of size 80m long and 30m wide, a 115m long low pressure conduit leading to headrace tunnel portal and complete Chhupchhung intake and feeder system.
Headrace tunnel is 3630m long, inverted D shape of excavated section 3.5m x 3.75m and is partly unlined, partly shotcrete lined and partly concrete lined. Whereas surge tank is restricted-orifice type of height 51m and diameter 5.5 m. Similarly, underground penstock shaft (inclined and horizontal) is 1030m long. Surface powerhouse is located at Chilime Village of Amachhodingmo Rural Municipality, which accommodates three units of vertical axis Pelton turbines of capacity 15 MW each and three units of 3-phase synchronous AC generators of capacity 16.85 MVA each. Three numbers of tailrace pits are joined at tailrace manifold, which will discharge the tail water to the approach canal of existing Chilime Hydropower Plant. The Surface switchyard is located adjacent to the powerhouse complex.
The generated power from Sanjen Hydroelectric Project will be evacuated through a 2km long 132 kV double circuit transmission line which is connected to the Chilime Hub of NEA. The Chilime hub will be connected by the national grid of 220 kV double circuit line up to Trishuli 3B hub of NEA.
HYDROLOGY
The tail water of the upper scheme of cascade development named Sanjen (Upper) Hydroelectric Project SUHEP feeds in to the intake arrangement of lower scheme of cascade development, the Sanjen Hydroelectric Project (SHEP). In addition, SHEP utilizes 0.5 m3/s flow from Chhupchhung Khola. The catchment area of Chhupchhung Khola at the weir site is 24 km2. Annual precipitation is 1200 mm and monsoon precipitation is 1000 mm. The long term mean monthly flows at Chhupchhung weir site reveals a maximum of 3.58 m3/s in August and minimum 0.28 m3/s in April. 100 years design flood is 71 m3/s.
GEOLOGY
The project area is situated in the Higher Himalaya and the Lesser Himalaya, Central Nepal.
Sanjen Hydroelectric Project (SHEP):
Chhupchhung weir lies in recent alluvial. Forebay/Intake of SHEP is in a gently sloping terrain consisting of about 25-30m thick deposits with angular gravel to boulder sized rock fragments of schist, quartzite and slate in loose soil sediments.
Common rocks along the headrace tunnel alignment are fair to good.Surface mapping reveals thin colluvial masses i.e. less than 1 m thick on downhill slope in surge tank area and rock cliff on its uphill section.Rock mass along the penstock is of mixed lithology. Thickness of the quartzite bands range from 5 to 20 m.The powerhouse site is proposed in a flat alluvial terrace. The switchyard is proposed in terrace deposits characterized by unconsolidated alluvium deposits.
Sanjen Hydroelectric Project (SHEP):
Sanjen Hydroelectric Project utilizes the tail water from the Sanjen (Upper) Hydroelectric Project and therefore is a cascade run-of-river scheme. The whole scheme is divided into three work sites, viz.Headworks Site that covers Chhupchhung feeder system, spillway, intake/forabay and pressure conduit, Underground Works that covers headrace tunnel, rocktrap, surge tank, penstock shaft (inclined and horizontal) and construction adits, and Powerhouse Site that covers powerhouse structure, tailrace and switchyard.
The headworks site is located at Simbu Village of Chilime VDC. The headworks consist of overflow spillway, intake/forebay of size 80m long and 30m wide, a 115m long low pressure conduit leading to headrace tunnel portal and complete Chhupchhung intake and feeder system.
Headrace tunnel is 3630m long, inverted D shape of excavated section 3.5m x 3.75m and is partly unlined, partly shotcrete lined and partly concrete lined. Surge tank is restricted-orifice type of height 55 m and diameter 5.5 m. Penstock shaft (inclined and horizontal) is 1030m long and underground. Surface powerhouse is located at Chilime Village of Chilime VDC. Powerhouse will accommodate three units of vertical axis Pelton turbines of capacity 15 MW each and three units of 3-phase synchronous AC generators of capacity 16.85 MVA each. Three numbers of tailrace pits joined at tailrace manifold will discharge the tail water to the approach canal of existing Chilime Hydropower Plant. Excess water will be discharged into Chilime River. Surface switchyard is located adjacent to the powerhouse complex.
Generated power from Sanjen Hydroelectric Project will be evacuated through a 2km long 132 kV double circuit transmission line to connect from SHEP powerhouse to the proposed Chilime Hub of NEA and then to the national grid via 220 kV double circuit line up to Trishuli 3B hub of NEA.
PROGRESS STATUS AS OF NOVEMBER END 2023.
Infrastructure Work (Lot 1):
All the infrastructural works including access road to project site and approach to the main working fronts, the camp facilities for the Employer, construction power lines with different packages have been implemented under this package. All of the works under this package have been completed.
Main Civil Work (Lot 2):
The overall Civil Works progress is about 96.57%. Almost all the civil works has been completed. Major installation works in Powerhouse is completed and other minor works are ongoing.
Electromechanical Work (Lot 3)
Overall progress of this Lot is around 85.44%. The works that fall under this lot are Design, Fabrication, Factory Inspection, delivery and installation works of electromechanical equipments. All the design, fabrication, factory inspection and delivery works has been completed. Installation work is in the final stage of completion.
Hydro mechanical Work (Lot 4)
The overall Hydro mechanical work has been completed. The works that fall under this lot are Design, Fabrication, Factory Inspection, delivery and installation works of hydro mechanical equipment. Only, testing and commissioning works are remaining. Under this lot 96.47 % of the work has been completed.
Distribution line (Lot 5)
132 KV Transmission
The transmission lines for both projects have been considered in a single package. It consists of around 6 km long 132 KV single circuit transmission line from SUHEP powerhouse to Chilime Hub and also 132 KV double circuit line from SHEP powerhouse will be connected to the same line upto Chilime Hub. All the works under this lot has been completed. Currently, the power generated from SUHEP is being transmitted through this line. As the construction of Chilime hub is still underway, the power generated from SUHEP is being evacuated by arranging an alternative 11Kv transmission line connected between 132 KV double circuit line (named as lot 5) and 66kV transmission line of Chilime Hydropower Plant.
Overall Progress
The overall Physical Progress of SHEP is approximately 95 %.
SALIENT FEATURES
| Location | Chilime V.D.C. of Rasuwa district. |
| Type of Project | Cascade Run-of-river |
| Hydrology | 202 km2 |
| Catchment area (Dam site) | 2.4 m3/s |
| 90% dependable flow | 11.57 m3/s(including Chhupchhung flow) |
| Design flow | (Q40) |
| Design flow from Chhupchhung | 0.50 m3/s |
| Geology | |
| Rock Type | Medium grade metamorphosed schist and quartzite |
| Head | |
| Gross | 442.0 m |
| Net | 433 m |
| Headworks | |
| Intake Type | Off take from Tail Water of Upper Power Plant |
| Head Pond (Forebay) | 10 min. |
| Headrace Tunnel | |
| Length | 3630 m |
| Section | 3.5 m (w) x 3.75 m (h): D- shaped |
| Surge Tank | Restricted Orifice Type |
| Type | |
| Size | 51.0 m (h), 5.5 ~5.8 m (dia) |
| Size of Orifice | 1.24 m (dia). |
| Penstock | |
| Size | 1020 m (l), 1.06 ~ 2.5 m (dia) |
| Powerhouse | |
| Type | Surface |
| Size | 55.3 m (l) x 13 m (b), 25.8 m (h) |
| Tailrace | 14 m (l) x 5.5 m (b) x 2.7 m (h) |
| Turbine | |
| Type | Pelton, Vertical Axis |
| Capacity | 3 Nos., 15 MW each |
| Generator | |
| Type | 3 Phase Synchronous AC |
| Rated Power | 3 Nos., 16.85 MVA each |
| Installed Capacity | 42.5 MW |
| Transmission Line | |
| Length | 1.5 km |
| Voltage | 132 kV |
| Annual Energy Generation | 251.94 GWh |
| Dry Months Energy | 35.71GWh |
| Wet Months Energy | 216.23 GWh |
| Salable Energy | 241.86 GWh |
| Dry Month Energy | 34.28 GWh |
| Wet Month Energy | 207.59 GWh |
| Project Cost | |
| Total Project Cost (2011 Dec) | NRs. 5024.29 million |
PROJECT MAIN WORKS
