4. GENERAL 0VERVIEW
Located at 70 km north-west of Kathmandu at Trishuli, Nuwakot
Constructed on Trishuli river
Installed capacity 21 MW in 1967 AD consisting of 7 units each of 3 MW
Upgraded to 24 MW in 1995 AD with 6 units each of 3.5 MW and
one unit of 3 MW
Developed By Government of India and Government of Nepal at a
Cost of INR 140 million
Head of station Baburaja Maharjan
5. SAILENT FEATURES
Maximum net head 51.4 m
Average annual flow 45.66 m^3/s
Length of Dam 139.6 m
Length of Waterway 4,792 m
Penstock 71.66 m & 2.3 m , 3Nos., steel
(length &dia.) 89 m & 1.5 m, 1Nos., steel
No. of Bridge 4
Catchment area 2600 sq km
Design generation 163 GWh annually
6. GENERATOR
Rated Output 3889 KVA
Rated Voltage 6.6 KV
Rated Frequency 50 Hz
Power factor 0.9
Power Transformer 5 MVA , 6.6/66 KV Single phase,6 Nos
Transmission Line 66 KV 27.6 km , Double circuit
66 KV 5 km ,Single circuit
TURBINE
Number and type 7, Francis
Rated Discharge 7.8 m^3/s
Rated Output 3620 kw
Rated Speed 500 rpm
12. OVERHEAD FLOW OVER RIVER
o Flow is diverse through residential area with two bridge type canal.
13. SETTLING BASIN (DECENDER)
oIt removes sediment load up to 0.2mm diameter.
oThe greater basin area & lower the through velocity the smaller the particles can settle down.
oOne traits for this case is being used as picnic spot area.
25. TAILRACE
Here centered pipe is used to discharge leakage water (dewatering)
Initially tailrace discharge is mixed to trisuli itself
Now it is used for devighat power plant
29. POWER FREQUENCY CONTROL
The regulator must designed to be insensitive to fast random
changes, otherwise the system will prone to hunting resulting in
excessive wear & tear of rotating machines & control
equipment.
30. EXCITATION SYSTEM
PLC or Human machine interface(HMI) is used to control excitation automatically and remotely.
31. STATIC EXCITATION SYSTEM
Field current:
At no = 157-164.7A @ 77V
At full load = 290-304.2A
At 110% rated load = 306-320A
32. PLC
Programmable Logic Controller is a user friendly, microprocessor specialized computer that
carries out control functions.
oMonitor crucial process parameters and
adjust process operations accordingly.
oCan be programmed, controlled and
operated by a person unskilled in operating
computers.
oPLCs are used in the substation to manage
transformers, voltage regulation, automatic
transfer schemes, custom/automatic reclosing
schemes, automatic service restoration,
remote control, system diagnostics
maintenance
36. CONTROL ROOM
oEach unit have its own control set.
oAt least one technical must be here to monitor whether generation and other operation is
within limit.
43. BATTERY ROOM
oThe control panels and relays require DC supply of 220V.
oNi-Cd batteries are used due to their advantages like low maintenance , longer life
(15-25 years).
oEach cell is of 2V and 6Ah capacity.
o55 cell is connected to 110V charging system.
oNormally charging panel delivers load & give trickle charging to Battery bank
oworks on Auto and Manual mode.
44. FIRE PROTECTION
o A new fire detection and protection system was installed with complete Halogen gas fire,
portable fire extinguishers and fire hose reels and fire hydrants for total protection of power
house.
46. oJunction of four areas network
oBalaju-1 and balaju-2 by double circuit transmission line (27.6Km)
oChilime and devighat (5Km) by single circuit
oAlso distribute power to local area
SUBSTATION
48. TRANSFORMERS
oSix single phase power transformers of rating 5 MVA 6.6/66 kv
oOne 3 phase distribution transformer of rating 10 MVA 6.6/11 kv for local distribution
49. COOLING AND FIRE EXTINGUSHER
oCooling pipe are run along all transformers
oOperate when transformer are overloaded or any abnormal conditions
55. SPECIAL FEATURES
• One of the oldest HPP but still operating well
• Lies on headquarter of Nuwakot
• More number of units making it more efficient
• 3 single phase transformers combine to make three phase has its
own advantage
• Tailrace utilize for another HPP
56. PROBLEMS
• Small area of the settling basin so the sand does not settle properly in the basin.
• Problem in diversion system and intake construction.
• There is no SCADA system in use.
• The amount of silt accumulated in the reservoir is excess.
• Weir and tear on the runner due to silt.
• Manual synchronizing and Governing system.
• The settling basin should be upgraded.
• The direction of the flow of water should be managed at diversion weir.
• The SCADA system should be maintained as soon as possible.
• The number of instrument to clean silt should be increased.
• Governing and overall system should be upgraded to digital.
RECOMMENDATIONS