Commissioning Hydro Electric PowerPlants

1. COMMISSIONING
HYDRO POWER STATION

3. Dam
Reservoir
Power intake (Penstock)
Power house
•Turbine
•Draft tube
•Main inlet valve
•Generator
•Bus Duct
•Field Excitation System
•Governing System
•SCADA System
•Station Transformer
•Balance of Plant
•Protection system & switchgear
•LV/ HV distribution
•DC, UPS Battery
Switch Yard
Following are the main components of a Hydroelectric Power Plant
INTRODUCTION

4. Dome
Stator
Rotor
Generator Shaft
Turbine Shaft
Spiral Casing
Stay Ring
Runner
Draft Tube

9. COMMISSIONING
Definition
•Testing of new equipments to check
its conformity with contractual
specifications, as well as operation of
the equipment until formally
accepted by the Customer.
•Commissioning usually occurs after
first erection of a new unit.

10. Commissioning
activities consist
of various tests:
•Pre-commissioning tests
•Prior to filling waterways
•After filling waterways
•Initial Run test
•Test Run
COMMISSIONING

11. READINESS CRITERION
Commissioning activities in hydro project begin with the filling of waterways on
the down stream side (common tailrace) and up stream side (Head Race or
Penstock) of the machine. This implies readiness of hydro set which broadly
comprises of following equipments and their readiness criteria :
1. Draft Tube and Liner, Spiral casing, Tail Race Channel, Penstock and gates etc. for
their erection and checks from the point of view of cleanliness, civil grouting work for
the hollow portions between metal and concrete contact surfaces etc.
2. It is to be ensured that there is no impediments in the free flow of water from any
projecting lumps of concrete/reinforcement rods etc.
3. The grouting plugs have been welded and flush grinded as per Drawing requirement
and no obstruction exists from any local bending of metallic liners etc. in the water
path.
4. Painting work of underwater parts with black anticorrosive paint has been completed.

12. The Machine itself has been made ready mechanically along with its auxiliaries. This will
include the following major equipments/systems/works and other preparations :
Turbine & Turbine Pit :
1. Runner blade and chamber clearances have been checked and found OK to ensure that
no rubbing is likely to occur during start up and running.
2. Air inflated repair seal of Turbine shaft is ‘OFF’ and cooling water to working seal will
be available when CW system is charged.
3. Turbine bearing oil is at proper level – neither too high nor too low – let the drawing be
followed at this stage. Keep record of pumping holes in the skirt if provided-whether
plugged and how many.
4. Manual/Auto greasing of guide vanes etc. has been done for smooth operation.
5. Easy mobility along with sufficient lighting both AC/DC provided in the pit.
READINESS CRITERION

13. 6. Dry stroking of guide apparatus/ MIV have been done upto full rated oil pressure of
OPU through governor. Record Opening/Closing and damping times.
7. Dowelling work etc. of bearing housing etc. has been completed.
8. Fulfillment of all requirements given in O&M manuals/check lists of the project to
be ensured.
9. De-watering of draft tube checked twice by closing the draft tube gates.
10. Turbine top cover drainage system is operational and in Auto to avoid turbine pit
flooding during first filling of TRC and subsequently during penstock filling etc.
Preferably additional pumping arrangement, not dependent on Electric Supply (i.e.
Air Operated) be provided as quantity of leakage water from shaft, Guide vane cup
seals, etc. is not known at this time. This is more necessary when starting a machine
after a long delay after erection.
READINESS CRITERION

14. Generator & Generator Barrel :
1. Generator and its sub assemblies have been fully erected as per drawing and cleaned
with dry compressed air/cloth. Check top and bottom air guide clearances which
should be at least 8-10 mm ( as per drawing requirement) from the rotor fan blades.
2. Stator/Rotor gap must be free from any foreign object which is usually checked by
taking a rope all around the gap along the full height of the stator core.
3. Check and ensure that Generator barrel/bracket areas are free from foreign objects,
hanging wires/cables, loose electrical connections, loose clamps etc.
4. Bearing vapour seal segments may not be assembled in position during initial runs to
avoid likelihood of rubbing until performance in terms of vibration and wobble is
proved up to full speed (This is not applicable for vapour seals of wool felt type).
5. Initial bedding of slip ring carbon brushes, cleaning of slip rings etc. has been done.
Carbon brushes to be kept disengaged from the slip rings, during initial runs as no
excitation is to be given during this time. Should be in for proper bedding .
READINESS CRITERION

15. 6. Dowelling of stator frame/brackets etc. has been done and secondary concreting of
Stator and lower bracket foundations have fully cured. Epoxy grouting of foundation
bolts to be ensured. Tightening of all bolts and their locking particularly of the
rotor/rotor lead clamps/pole to pole joints etc. to be carefully checked.
7. Generator Barrel water mist Fire Extinguishing system commissioned and kept ready in
manual/Auto mode, which is to be switched on prior to voltage build up/
synchronisation/loading.
8. Brake system is already tested for reliable lifting and release 10 times from HP
compressor/pressure reducer air system or L P air system along with Limit Switch
operation for indication/control. Free operation of brakes to be ensured. Auto operation
of Brake is to be disabled during initial period (Brake Air Pressure should be adjusted
for 4-5 Kg/cm2 ). Brakes should be applied at a speed as given in design which is usually
20 to 25% of rated speed). Required oil should be filled up in air filter unit.
READINESS CRITERION

16. 9. Generator bearing’s oil should be at proper level as per Drawing and this should be
marked in gauge glass. Operation of low/high level float switches should be checked.
10. Performance of HS Lube system to be proved. Check lifting of Rotor from HS lube
pressure by 4 dial gauges placed at  X and  Y positions i.e at 4 points to know
amount and uniformity of lift all around. The HS Lube pressure should not exceed
specified design value. Safety relief valve to be adjusted depending on the pressure
required for jacking. HP lub oil pressure switches/gauge to be adjusted for normal &
low pressure. Ensure no loose connections in the electrical circuits to avoid sparking
and consequent fire hazard in these enclosed spaces.
READINESS CRITERION

17. 1. 440 V 3 Phase AC supply
2. 240 V 1 Phase A.C. supply
3. 220 V DC or 110 V D.C. Power supply system
4. 48 V DC Power supply system
5. Dewatering, Drainage and leakage collection system and their pumping arrangement.
6. 11 KV or 13.75 KV along with cable etc. for commissioning of excitation system.
7. 24 V DC power supply system.
8. The intake gates, draft tube gates and butterfly valves are tested for safe and reliable
operation and equipped with operator personnel and telephonic connection .
9. Oil supply system.
10. Compressed air system.
11. Completion of cable laying , termination @ earthing
12. 240 V AC UPS supply.
PRE- REQUISITES FOR
COMMISSIONING

18. 13. Readiness of water conducting system .
14. Civil works in the vicinity of active and sensitive electrical and mechanical
machinery/equipment are finalized. Floors are clean and dry.
15. Station earthling system is in full and reliable condition.
16. Main fire fighting system for the power house cavern in safe operating
condition, including the portable fire extinguishers.
17. Ventilation, illuminations, communication, and Air-conditioning available
on a permanent base.
18. Readiness of protective covers, guards ladders and covering of floor holes
and pits.
PRE- REQUISITES FOR
COMMISSIONING

19. PRE-COMMISSIONING
TEST/CHECKS
Pre-
commissioning
Tests:
• Test between completion of
erection of the equipment and
initial run.
• Tests/Checks prior to filling
waterways
• Tests/Checks after filling of
waterways

20. TEST/CHECKS PRIOR TO
FILLING WATERWAYS
1. Inspection of all the turbine waterways and removal of all
foreign or loose objects.
2. Calibration of scales for wicket gate opening and where
applicable, for runner blades, needles and deflectors
including their cam relationships; and also measurement
of clearances.
3. Operation of pressure oil units, MIV, governors, automatic
and manually operated starting and stopping devices and
signaling devices.
4. Oil levels and pressures in governing system; Condition of
all oil filters.

21. TESTS/CHECKS PRIOR TO
FILLING WATERWAYS
5. Protective devices such as oil level and temperature alarms and
relays, with adjustment if needed.
6. Times of opening and closing of governing elements, i.e. wicket
gates, runner blades of turbines with movable blades, needles
and deflectors of impulse turbines.
7. MIV opening and closing times.
8. Bearing and seal clearances and functioning of hydrostatic
lubrication system.

22. TESTS/CHECKS PRIOR TO
FILLING WATERWAYS
9. Operation of drainage pumps and dewatering pumps.
10. Oil, grease and water supply to all bearings and seals
requiring lubrication or cooling.
11. Operation of braking system of the unit.

23. TESTS/CHECKS
AFTER FILLING WATERWAYS
1. The Tail water gate shall be opened first after filling the draft
tube and spiral case up to tail water level through a filling
valve of the draft tube gates. Check for leaks is to be made.
The whole waterway should be filled slowly and manually
through a bypass valve of the penstock.
2. Operation of emergency protection devices which actuates
the intake gate/MIV and closure of guide vanes and stoppage
of machine is to be checked.
3. If the protective devices and emergency closing system work
satisfactorily, and no unusual leakage or deformation is
observed, Initial run of the Machine can be initiated.

24. INITIAL RUN
After the permission for initial run, locking devices and brakes are
released and the turbine wicket gates or needles are opened
under manual control, slowly as per manufacturer’s
recommendations and bring the speed up to at least the minimum
stated value.
If any noise, scraping or other abnormal phenomena is observed,
the unit should be shut down immediately and thorough inspection
is to be carried out to find out the cause of the problem and rectify
the same.

25. •Time
•Unit speed
•Servomotor stroke
•Temperature of bearing
•Shaft run out
Measurements
Items:
•Tachometer
•Dial indicator
Instruments to
be used:
INITIAL RUN

26. TEST RUN
•Mechanical Spinning
without Excitation
•Spinning with Excitation
•Synchronization with the
grid
•Load run and Load
Rejection Tests
Test
Run
consists
of :

27. MECH. SPINNING WITHOUT
EXCITATION
1. The unit is kept under manual control at or above starting
speed until bearing temperatures are stabilized.
2. If any temperature is excessive or increases too rapidly, the
unit shall be shut down and the causes of this phenomenon is
to be investigated and corrected.
3. If all goes well, the unit speed shall be increased in
prearranged steps up to the rated value, remaining at each
successive speed until the rate of rise of all bearing
temperatures is satisfactory to the manufacturer's
recommendation.

28. During each speed step of test run, at least the following
measurements / observations should be made:
1. Deformation of covers and bearing supports
2. Noise or vibration in the turbine and/or generator
3. Operating conditions for the oil pressure and other pumps.
4. Condition of oil in the bearings and pressure oil systems. If
water is observed in oil, the leaks shall be located and
eliminated. If oil foaming is observed, the cause shall be
located and eliminated.
5. Temperatures of bearings and lubricating oil.
6. Shaft run out at turbine and generator bearings and axial
displacement of rotating parts is measured.
7. At some agreed speed value, the action of braking system
shall be checked.
MECH. SPINNING WITHOUT
EXCITATION

29. • Tachometer
• Vibration meter (Structure)
• Dial indicator
• Thermometer
Instruments
to be used:
MECH. SPINNING WITHOUT
EXCITATION

30. SPINNING WITH EXCITATION
 After bearing run, the machine is prepared for short
circuit test.
 For this test, we do three phase shorting at generator
terminal then the excitation is increased from zero up
to the full load stator current.
 During this test, operation and stability test of
differential protections are also checked.
 After SCC test, we go for high voltage test for stator
winding.
BASIC TEST CIRCUIT
FOR SCC TEST

31. SCC TEST
A
B

32. C
SCC TEST

33. SCHEMATIC CONNECTION DIAGRAM FOR
SCC TEST

34. HV TEST FOR STATOR WINDING
 Used for testing the dielectric strength of generator
stator winding insulation.
 For less than 10MW, test voltage (r.m.s.) shall be
1000V+2*Rated voltage; subject to minimum of 1.5kV.
 For machines with a rated voltage 6 kV or greater,
when power frequency equipment is not available, then
by agreement a DC test may be carried out at a voltage
1.7 times the r.m.s. values to be chosen in case of AC
test.
 For more than 10 MW, Test Voltage (r.m.s.) shall be
For voltage less than and equal
to 24kV
2*Rated voltage + 1000 V
For voltage more than 24kV Subject to agreement

35. OCC TEST
 After successfully completing the HV test, OCC test is
carried out.
 In OCC test, excitation cable is restored and voltage is
build up to rated voltage in steps of 1KV. Then, Open
Circuit Characteristic Curve is drawn.
 Operation of Stator earth fault protection is also checked by
creating actual earth and performance test of all voltage
relays is also carried out .
BASIC TEST CIRCUIT
FOR OCC TEST

36. SCHEMATIC CONNECTION DIAGRAM FOR
OCC TEST

37. SYNCHRONIZATION WITH THE GRID
• Phase sequence of Generator voltage and Grid
voltage must be the same.
• Two voltages must be equal, i.e. IV1I - IV2I=0.
• The generator frequency must be nearly equal to
the Grid frequency, i.e. f1- f2 ≈ 0.
• At the instant of synchronizing, the two voltages
must be almost co-phasal, i.e. Ø1 – Ø2 ≈ 0.
The
following
conditions
must be
satisfied:
Finally the machine is synchronized with the grid at
the partial load.

38.  The degree of criticality of these parameters are in the
following order:
∆Ø, ∆V, ∆f.
 The inertia of the incoming machine being very small
against that of the grid, even with considerable ∆f, the
machine will easily be pulled into synchronism.
 Voltage difference, if large, can result in heavy exchange of
VAR and can result in voltage fluctuations, if large enough
leading to instability.
 Large ∆Ø can result in heavy exchange if MW, often good
enough to cause torsional damage to the shaft system.
SYNCHRONIZATION WITH THE GRID

39. LOAD RUN AND
LOAD REJECTION TESTS
When the generator and switching equipment has been
declared ready for operation , the unit is synchronized.
During the load rejection tests, all necessary precautions shall
be taken to ensure that rated values of penstock and
turbine stresses will not be exceeded. Such precaution
may include setting governor timing.
When adjustments are made on governor or regulating devices
all tests which might be affected by the adjustment shall
be repeated.

40. • To check the output of the unit with an agreed
accuracy.
• To check the unit for instability, vibration or
cavitations in the range of guaranteed loads.
• To check the functioning of governor and
regulating devices, as well as that of the entire
unit.
• To determine the momentary pressure and speed
variations of the unit and to find their extreme
values. To adjust the closing times of the wicket
gates, needle valves and deflectors to minimize
over speeding of the unit within the permissible
limit of pressure variation
• To permit testing of the operation of other
hydraulic and electrical equipment, including
protection and other automatic devices.
PURPOSES:
LOAD RUN AND
LOAD REJECTION TESTS

41. PROCEDURE:
 The load shall be increased in steps and load rejection test made at
successively higher loads up to the maximum expected to be placed
on the unit. For example: rejections may be made at 25%, 50%, 75%
and 100% of the rated load as well as from the maximum load that
may be agreed upon.
 Two rejections shall be made at each load. One rejection is made
under governor control to no load gate or needle opening, the other
may be an emergency shutdown by stop solenoid.
 If specified, load rejection tests shall be made by means of the
emergency valve or by any other emergency device.
 After the completion of each load rejection test, the pressure rise and
turbine speed rise data shall be analyzed to ensure that the specified
safe limits will not be exceeded during the next higher load rejection
test.
LOAD RUN AND
LOAD REJECTION TESTS

42. Observations, Measurements and Recordings:
LOAD RUN AND
LOAD REJECTION TESTS
• Head and tail water level
• Generator output.
• Wicket gate or needle opening (where applicable)
• Pressure at turbine inlet and outlet
• Pressures and levels in oil pressure systems
• Operating times of oil pressure pumps.
• Temperatures in bearings.
• Noise levels, if values are specified in the
contract.
• Abnormal noises if any.
• Vibration and other displacement of rotating and
fixed parts.
• Action of air-admission devices if any.
Applicable
for Steady
State
Operation:

43. Observations, Measurements and Recordings:
LOAD RUN AND
LOAD REJECTION TESTS
• Head and tail water levels
• Generator output
• Strokes and closing times of wicket gates or
needles where applicable.
• Pressure at the turbine inlet and outlet.
• Level variations at intake and surge tanks
• Pressure drop in the oil pressure system in the
process of governing, and variation of level in
the oil pressure reservoir.
• Noise levels, if values are specified in the
contract.
• Abnormal noises, if any.
• Vibration and other displacement of rotating and
fixed parts.
• Action of braking jets in case of Pelton turbine.
Load
rejection
and
subsequent
tests:

44. COMMERCIAL RUN
After meeting all the
contractual requirements of
operation, the machine can
be declared ready for
Commercial Run.

45. ILLUSTRATIVE
PHOTOGRAPHS

46. Generator Barrel & Turbine Pit

47. LOWERING
OF STATOR

48. STATOR SECTION

49. GENERATOR
ROTOR

50. LOWERING OF ROTOR

51. DRAFT TUBE
ERECTION

52. STAY RING
SPIRAL CASING

53. HYDROSTATIC
TESTING

54. TURBINE RUNNER

55. TURBINE SHAFT

56. TOP COVER & TURBINE
ASSEMBLY

57. LOWER BRACKET

58. ASSEMBLY OF MIV
BUTTERFLY TYPE SPHERICAL TYPE