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Detailed
Technical Description of the Plant
Fully
computerised control system: Advant Controller Hydrology
(Intake) |
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The
project utilises a gross head of 684m in the Khimti Khola
river between the intake, at elevation 1,270m, and the tailrace
water in the Tama Koshi river at an elevation of 586m. Total
length of the waterways including headrace and tailrace
tunnel is in excess of 11 km.
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The
hydraulic works commence with the head-works (intake) consist
of a low concrete/boulder sill structure in the steep river, deverting
water to a two chambered settling basin. The basin is located
in the open and clear of floods on the right river banks, and
includes a flushing system. Desanding is particularily important
in the "young himalayan mountains" with large amounts
of loose material and heavy monsoon rains. this challange has
been solved in a realtively short geographical area through a
flushing system called the S4. After the water leaves the flushing
system it is lead into the headrace tunnel.
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The
tunnel is 7,885m long with a nominal 11.5m2 cross
section, and ends in a surge chamber, from where a 1,000m
long 45o inclined penstock shaft, with steel
lining embedded in concrete, leads to the power house. A
1,433m long free flow tailrace tunnel with a cross section
of 15.5m2 brings the water into the Tama Koshi
River.
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Control
Room with fully computerised control syster |
An
890m long tunnel with a cross section of 22m2 provides
access to the underground power house at Kirne in the Tama Koshi
Valley, just upstream of the confluence with the Khimti River.
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Outdoor
Control Building and Swithyard at Kirne
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The
installation in the power house consists of five double
jet Pelton turbines with runners fitted on the extended
shaft of the 12,500 kilowatt, 750 RPM alternators. The power
is transferred at 10kV generator voltage through bus-bars
in the access tunnel to outdoor transformers where the voltage
is stepped up to 132kV for supply to the national grid and
to 33kV for local supply.
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The outdoor
switchyard is located near the powerhouse access tunnel portal,
at Kirne Besi. The anticipated total annual production is in excess
of 350 GWh.
TECHNICAL
SPECIFICATION
| Hydrology
(Intake) |
| Catchment
Area |
358
km2 |
Average
Precipation (Jiri) |
2,212mm |
| Average
flow at intake |
31.5m3/s |
Minimum
daily discharge |
3.5m3/s |
| Probable
maximum flood (PMF) |
3,900m3/s |
Firm
flow (90% exceedence) |
4.11m3/s |
|
Head-works
(Intake)
|
| Diversion
weir crest elevation |
1,272
m |
Diversion
capacity |
11.65
m3/s |
| Diversion
height |
~
2.5 m |
De-sanding
chambers |
2
(two) |
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|
Chamber
dimensions |
90m
x 12m x 2m |
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Waterways
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| Headrace
tunnel - Length |
7,885
m |
|
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| Steel
lined penstock - Length |
1,000
m (inclined) |
Steel
lined penstock Diameter |
1.8-2.0
m |
| Tailrace
tunnel - Length |
1,433
m |
Access
tunnel - Length |
890
m |
| Powerhouse,
Turbine, Generators etc. |
| Powerhouse |
Underground |
|
|
|
Pelton turbines |
|
Generators |
|
|
Number of Units |
5 |
Number of units |
5 |
|
Rated capacity |
12.5
MW |
Rated Capacity |
14.2
MVA |
|
Running speed |
750
rpm |
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Maximum static head |
677
m |
Transformers |
|
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Design head (net, full
load) |
660
m |
Number of Units |
3 |
|
Rated flow at design
head |
2.15
m2/s |
(2
x 28.4 MVA and 1 x 14.2 MV)
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| Power
and energy output |
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Installed capacity |
60
MW (net capacity after auxiliary use.) |
|
Energy |
350
GWh/yr (approx annual energy generation) |
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