Modi Hydropower VisitPresented by:

Bijay Acharya (069/BEL/212)Binod Paudel (069/BEL/215)Deependra Neupane (069/BEL/218)Devendra Bhattarai (069/BEL/219)Madan Bhandari (069/BEL/229)Sagun Paudyal (069/BEL/237)Siddhartha Paudel (069/BEL/240)Suraj G.C. (069/BEL/243)

Why hydropower in Nepal?? Principle of hydropower

generation Key to rescue form the

energy crises of Nepal Hydropower potential in

Nepal Hydropower constructional

background The hydropower project

practices in Nepal

Modikhola Hydropower

One of the high potential river in country Run off River type plant (ROR) 3 km river section , gross head available is 71 m. 2 generator units with each installed capacity 7.4Mw. average annual energy generation of 91 GWh. Estimated initial cost is US $ 27.2 Dollar construction supervision works were carried out fully by

NEA The project construction was started in May 1996

Civil construction detail Catchment Area 510 sq. km Maximum Design Discharge 27.5 /s Turbine Discharge25 /s Rated Net Head 66.96 m Diversion Weir H=7.5 m, L=33 m Intake L=33 m, H=0.7 m, W=20.5 m Box Culvert 250 m (twin barreled) Desanding Basin (twin chambered) L=154.5 m, W=10 m, H=6.5 m Open Canal 61 m Regulating Pondage 37,900 Total Tunnel length 2071 m Surge tank H=40 m, dia=9 m Powerhouse L=28 m, W= 14.5 m, H=23.5 m Tailrace Box Culvert 281 m

Mechanical details Turbines

TypeVertical, Francis

Number 2 Rated Output 7.4 MW Rated Speed 429

rpm

Shaft Orientation

vertical

Penstock Diameter 3.5m Length

32m Material

Steel

Draft tube Type

cylindrical Pressure

compensation

Electrical Details Generators

Type Vertical Shaft, Synchronous type Number 2 Capacity 8260 kVA Power factor 0.9 Voltage 6600 V Frequency 50 Hz

Transformers Type Three phase Number 2 Capacity 8260 kVA Voltage Ratio 6.6/132 kV

Transmission Line 132 kV, L=37 km Towers 109 nos. Installed Plant Capacity 14.8 MW (2 x 7.4 MW) Total Avg Annual Energy 92.5 GWh

Generator Transformer

Generator Transformer

Motor Induction motor

Used in dewatering system, cooling system, diesel generator starter

Servo motor Used in governing the guide vane during

load fluctuation for frequency control

Electrical Auxiliary

Dry transformer Voltage

6.6kV/110V

Battery 110V, 150A and 48V,

100A

Diesel Generator 6 cylinder, .012

inch rpm 445 Power 131hp

Compressor

Control system Controlling the overall flow

Butterflying valve. Controlling the excitation

AVR system. Controlling the power output

Governing mechanism . Circuit breaking

Relay CT & PT SF6 ACB(Air circuit breaker) VCB(vacuum circuit breaker)

PID control system Mechanical breaking system

Governing mechanism Modi khola is a national grid connected

system Automatic electronic governing mechanism

using plc linked with the hydraulic governer. Hydraulic governer is linked to the guide

vane of the generator which finally regulates the overall flow of the water in the turbine to produce the require amount of power

Fig. Governing Mechanism

Synchronization process

Modi khola hydropower is a national grid connected system.

Two types of synchronizing system. Automatic synchronizing system.

Synchronizing rely. Manual synchronizing system.

Fig. Synchronizing Panel

Excitation control system Plays an important role in maintaing the reactive

power flow in the system. Maintain the power factor of the generator in

specfied limits Maintain the generated voltage in the specfied limits. The excitation system used is burshless excitation

system controlled by the digital automatic voltage regulator.

AVR is the thristor embedded system which compares the output voltage of generator and provides the necessary excitation voltage to the generator

Or grid

One line diagram

Earthing Mat earthing Maintained 0.1

ohm earth resistance

Body earthing and neutral earthing

The lightining arrester.

Switchgear and protection

Circuit breaker Relays

CT PT

Problem and Recommendation 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 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

References www.nea.org.np www.google.co

m Handbook of

Modikhola hydropower

Thank you !!!