Information about middle Marshyangdi Hydro Power Station

1. Presentation On
A Field Visit
To
Middle Marshyangdi Hydropower
Station

2. Presented by:
Sudarshan Pandey [071/BEL/45]
IOE,ERC,Dharan

3. OUTLINE
 INTRODUCTION
 CIVIL COMPONENTS
 ELECTRO-MECHANICAL COMPONENTS
 ANNUAL ENERGY PRODUCTION
 DIAGRAMS & CURVES
 PROBLEMS & PROPOSED SOLUTIONS

4. INTRODUCTION
• Located at Siundibar (27 kms north of Dumre).
• Dam Site: Phaliya Sangu(35kms north of Dumre).
• Project Inaugurated on 14TH Dec,2008.
• Commercial Generation started on January of 2009
• Investment – 27.6 Arab
• Jointly financed by : Federal Republic of Germany, Nepal
Government,NEA
continued...

5. Geographical location of MMHPS

6. • Run-of-river type with daily pondage of 5 hours
• Second largest hydro-electric project.
• Max. gross head: 110m
• Net head: 98m
• Installed Capacity: 70MW(two 35MW turbines)
• Annual average energy: 398 GWh

7. CIVIL COMPONENTS
• Dam: combined concrete gravity and rockfill
• Height above foundation :34.5m
• Catchment Area:2728 sq. km
• Reservoir Capacity : 1.65 million m3
• Spillway Capacity :4,270 m3/s
• Spillway Gates :3 radial gates
• W x H = 12 x 19.54 m
continued......

8. Dam site of MMHPS

9. Radial gate

10. • Intake Structure : Submerged Intake with Trash Racks & Gates
• Desander Basin : Underground type
• Dimension of Desander Basin L*B*H=130*15*27
• Power Tunnel (Low Pressure Line): 5230m long, located between
desander outlet and Surge tank
• Power Tunnel (High Pressure Line): 225m long, located between
surge tank and discharge measurement chamber
• Lined Tunnel Diameter : 4.60 m
continued...

11. • Intake structure

12. • Surge tank
1. Vertical, circular tank with net diameter 20m
2. Height of surge tank 45 m.
3. Orifice :2.90 m
• Penstock
1 concrete cased steel pipe
With length: 212-218m
(Located between discharge measurement chamber and turbine inlet valve)

13. ELECTRO-MECHANICAL COMPONENTS
• Turbine
1. 2 Francis Turbines ,each has-
2. Rated Discharge Capacity 42.4 m3/sec
3. Rated Speed :333.33 rpm
4. Rated Output Power : 37.928 MW
• Governor
Electronic Governor
continued...

14. • Valves
1. Butterfly valve controls the flow of liquids through the section of
pipe.
2. By pass valves maintain even pressure.
3. The bypass valves need to be closed first then only the butterfly
valve to prevent malfunctioning.

15. • Generator
1. 2 units : 3 phase Synchronous , 18 poles
2. Output Power Capacity :39 MVA
3. Generating Voltage : 11KV
4. Power Factor : 0.85-0.90
5. Frequency : 50 Hz

16. • Power Transformer
1. 6 single- phase transformer of rating 14.5 MVA
2. 1 three- phase transformer of rating 25 MVA
3. This three- phase transformer supplies local.
4. Buchholz relay protects transformer
5. Forced oil type transformer
• Transmission Line
1. 38.2 km long
2. Nominal Voltage : 132 KV
3. Cardinal Size

17. Transformer

18. • Excitation System
1. Has autonomic voltage regulator (AVR), exciter, measuring
elements, power system stabilizer (PSS) and limitation and
protection unit.
2. Required to produce necessary field current in rotor winding
3. MMHPS has static excitation( self excited DC system)
4. It consists of thyristor or transistor bridge and transformer.

19. • Switch Yard
1. Open Air Type
2. Dimension : 43 m *50m
3. 540 m above sea level
Circuit Breaker
1. SF-6 used
2. Rated Voltage 145 KV
3. Rated Lightning Withstand Voltage : 650 KV
4. Rated Normal Current : 3150 Amp
5. Rated Out Of Phase Breaking Current : 10 KA

20. • Switchyard of MMHPS

21. Potential Transformer
• Primary Voltage: 132000/ √3
• Secondary Voltage: 110/ √3
• Rating 50 VA
Isolator
Single break Isolator

22. • Synchronization
1. Process of matching the speed and frequency of generator to the
running network
2. Line Voltage, frequency, phase sequence, phase angle, waveforms
must be similar as that of the national grid.
3. Synchronization Relays are used .

23. • Total Cumulative Generation
Upto Ashar 31 ,2071 – 3118.02GWhr

24. Single line diagram

25. Load curve

28. • Auxiliary System
1. Back up system consists of diesel generator.
2. Battery backup system supplies excitation in case of primary power
failure
3. 110 volt DC used
• Cooling System
Cold water type

29. • Staffs
1. 70 staffs
2. 1 station chief
3. 5 section chiefs(civil,mechanical,electrical,account & admin)
4. Engineers
5. Officers
6. And other technical , administrative staffs

30. • Problems observed
1. Erosion caused due to slit concentration is high
2. Affected parts: chute,sill beam of radial gate,slidingand fixed
plates,turbines parts
• Solution employed.
1. Online sediment monitoring system at head work inlet and and
turbine intlet

31. Thank you!