hydroelectrica plant

1. PRESENTATION OUTLINE
• Introduction to Nepal Electricity Authority
• Electrical Power System in Nepal
• Middle-Marsyangdi Hydroelectric Stations.
• Operating Principles of Hydroelectric plants.
• Hydro electric Power components
01/08/14
1

2. INTRODUCTION TO NEPAL ELECTRICITY
AUTHORITY (NEA)
• NEA is a government owned electricity provider.
• It works on all the part of electrical system.
GENERATION
TRANSMISSION
DISTRIBUTION
CONSUMER PRICING
01/08/14
2

3. Electrical Power System in Nepal
• GENERATION
Voltage level: 11 KV, 3 Phase, AC, 50 Hz
• TRANSMISSION (voltage stepped up)
Voltage level: 110 and 220 KV, 3 Phase, HVAC,
50 Hz
• DISTRIBUTION (Voltage stepped down)
Voltage level: 11KV, 3 Phase, 50 Hz feeder line
220/380 Volts at consumer end
01/08/14
3

4. Middle-Marsyangdi Hydroelectric Stations
Established:
The plant was commissioned on 14 December 2008
Features:
-One of the large power houses in Nepal.
-70 MW generation capacity. Two units of 35 MW.
System Voltage of 11 KV.
-Connected to the National grid at the voltage level of
132 KV.
-The average annual energy output amounts to 398 GWh
(Power x annual operating hours)
01/08/14
4

5. Middle-Marsyangdi Hydroelectric Stations
Middle-Marsyangdi hydro electric power station.
01/08/14
5

6. Middle-Marsyangdi organization Chart (Technical)
01/08/14
6

7. Operating Principles of Hydroelectric Stations
A typical Hydropower Station
01/08/14
7

8. Operating Principles of Hydroelectric Stations
1. Water flowing through Marsyangdi river is
dammed so that required water level is
maintained to pass the water to the intake gates.
Spillways are operated to prevent the flooding.
2. Water then passes through intake gates to
trash rack which prevents large debris from
entering into the tunnel. The trash racks are
cleaned periodically using cranes.
01/08/14
8

9. Operating Principles of Hydroelectric Stations
3. Water then enters the desander where the
sand present in water is removed by
sedimentation. The collected sand is pumped
back into the river through flushing channel.
4. Water almost free from sand then passes
through tunnel to surge tank which prevents
water hammering in penstock pipe and
maintain constant flow through it.
01/08/14
9

10. Operating Principles of Hydroelectric Stations
5. Water then enters the penstock after passing
through the valve chamber and in the penstock;
the discharge of water is measured.
6. The penstock then bifurcates to supply water
for each unit. Each bifurcation is provided with
a bypass valve for balancing the pressure during
maintenance.
01/08/14
10

11. Operating Principles of Hydroelectric Stations
7. Water then passes through the expansion pipe
followed by main inlet valve (MIV) and enters
the spiral casing.
8. Water is guided by the adjustable guide vanes
which then impact the runner, thus rotating the
turbine.
01/08/14
11

12. Operating Principles of Hydroelectric Stations
9. This rotates the turbine shaft which is
coupled with the generator which generates
electricity based on the principles of
electromagnetism.
10. The current so generated is passed to the
transformers which step up the voltage to
provide supply to the national grid.
01/08/14
12

13. Hydropower components
1. Civil Structures like
Dam, Opening etc
2. Some Mechanical Components like
Turbine
Governor, valves etc
3. Electrical Components like
Power Generator
Power Transformer
Excitation System
Switch gear and Protection System etc
01/08/14
13

14. Civil Structures
A typical dam and
opening in Hydroelectric
stations at the Middle
Marsyangdi MMHPS
01/08/14
14

15. Mechanical Equipments (only some are shown)
1. Francis Runner
01/08/14
2. Butterfly valve
Opened
15

16. Mechanical Equipments (only some are shown)
3. Bypass valve
01/08/14
4. Guide Bearing
16

17. Electrical Equipments
1. Power Generator
Generator
Specifications at
MMHPS
: Type: 3-Phase, 2
unit, Synchronous
: Power: 35 MW each
unit.
: Voltage level: 11
KV
: Frequency: 50 Hz
01/08/14
17

18. Electrical Equipments
1. Generator Principles
01/08/14
1-Phase
Faraday’s law of electromagnetic
induction
Three Phase Waveforms
18

19. Electrical Equipments
Brushless Excitation System
To provide the excitation field
(magnetic fields) needed by
synchronous generator.
01/08/14
11 KV/180 volt excitation
system is used at MMHPS
19

20. Electrical Equipments
Power Transformer (Step Up)
Specification:
: 11 KV Primary
(generation voltage level)
: 132 KV
(Secondary national grid
voltage level)
: Delta/Star type
: Power rating 42 MVA
: Purpose: For national
grid connection.
01/08/14
20

21. Electrical Equipments
Station and local Transformers (Step
down)
Specification:
: 132 KV Primary (National Grid level)
: 33 KV (Secondary Station level)
: Star/Delta type
: Power rating 5 MVA
: Purpose: Local Power Supply through Damauli-Udipur 33kv
line
01/08/14
21

22. Thanks for your attention!
01/08/14
22

23. Questions!
01/08/14
23