3. EFFECIENCY CURVE OF VARIOUS FLOW CONTROL
EFFECIENCY CURVE OF VARIOUS FLOW CONTROL
DRIVES
DRIVES
100
% Efficiency
80
60
40
20
0 20 40 60 80 100
% Speed / Flow
Hydraulic Coupling
Inlet Guide Vane
Outlet Damper Throttling
LCI or VFD Drive
4. CONTROL SYSTEM
•The speed reference from the process controller is a
compared to a speed feedback derived from the
integrated motor voltage & error is fed to a speed
regulator.
•The output of speed regulator is a torque command.
•This torque command is sent to the field controller and
to a current controller as a current command.
•By proper control of stator current & field excitation ,
the machine has a fairly linear torque-per-ampere
characteristic.
•The most straight forward approach is a speed
controller with a V/f controller for field excitation.
5. CONTROL SYSTEM
•There are three controllable element which can
be used to control the power to the motor:
- The source side converter
- The load side converter
- the field exciter.
•All three of these use phase control of thyristor
gating angle to control output.
•Major function of load side converter control is
to maintain a minimum margin angle which will
keep the power to the motor at the highest
possible power factor.
6. CONTROL SYSTEM
•A current feedback signal is derived from the
AC current into the source side power converter.
•The output of the current controller is used to
control the gate firing angle α of the source side
converter to adjust the DC link voltage
necessary to produce the commanded current.
8. How much power saving?
Gen.
Gen.
MW
MW
ID’s Total
ID’s Total
Power (w/o
Power (w/o
VFD) (KW)
VFD) (KW)
Total power
Total power
(KW) by ID
(KW) by ID
Fans with VFD
Fans with VFD
Power
Power
Saving
Saving
200
200 3800
3800 850
850 2950
2950
240
240 4150
4150 950
950 3200
3200
280
280 4450
4450 1050
1050 3100
3100
320
320 4800
4800 1250
1250 3550
3550
360
360 5050
5050 1420
1420 3630
3630
400
400 5350
5350 1850
1850 3500
3500
440
440 5600
5600 2500
2500 3100
3100
500
500 5900
5900 3000
3000 2900
2900
9. How much power saving?
•From table it is seen that power saving
ranging from 2900 KW to 3630 KW at various
gen. Points
•Considering an average saving of 3200MW
and 300 days in operation a net saving of
Rs.288 lakhs @ generating costRs.1.25/unit
•Capital investment on VFD Rs.500 Lakhs
•Payback period less than 02 years.
11. Panels related to VFD in VFD room
Panels related to VFD in VFD room
Control Panel
(all external
interlocks,
alarms, Power
supplies
available here)
C&E Section
(Control and
excitation)
Bridge
blower &
Filter
section
LCI,
Section
(Converter
& Invester
bridges)
Load
breaker
(VCB)
Common for both chanels in one ID
Fans, but interlocking & trip relays are
seperately mounted in this panel for
each channel
LCI Panel
12. C & E (Control & Excitation)
C & E (Control & Excitation)
Panel
Panel
PSFF
Power
Supply
module
70V
Gate
Supply
module
Exciter
Module
SEM Rack
(Microprocessor
& other control
cards)
IOM A
(Input / output
module)
13. Fan & Filter Panel
Fan & Filter Panel
AIR
FAN 1
FAN 2
Filter Resistors
and capacitors
Air flow
monitor
sensor
14. H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
H P T K X P T N
S
T
M
1
S
T
M
3
S
T
M
5
L
T
M
4
L
T
M
6
L
T
M
2
S
T
M
4
S
T
M
6
S
T
M
2
L
T
M
1
L
T
M
3
L
T
M
5
STM - Source Thyristor Module
LTM - Load Thyristor Module
HPTK - Gate firing card
XPTN - Attennator fead back card
LCI (Load
Commuted
Inverter)
Thyristor
Bridge
15. NOTE: In each Thyristor stack there are
three Thyristors in series. Each Thyristor is
having one indication card with neon lamp.
In case of Thyristor short circuit this neon
lamp will not glow. One Thyristor short
circuit in a stack is allowed. If two
Thyristors get shorted load / source
commutation failure will arrive depending
upon which thyristors have failed and
channel will get tripped.
16. Control
Control
Cooling Fans Cooling Fans
INTER
FACE
INTER
FACE
REACTOR
CONTROL &
EXCITATION
PANEL
CONTROL &
EXCITATION
PANEL
INTER
FACE
INTER
FACE
REACTOR
Control Control
Cooling Fans
Cooling Fans
UA
11kV
BUS
UA
11kV
BUS
Transformer
11/ 2.3KV
(Dyn), 3kvA
Transformer
11/ 2.3KV
(Ddo), 3kvA
ID Ch # 1
415V 3 Phase
supply form ESP
415V 3 Phase
supply form ESP
Source
breaker
Source
breaker
ID Ch # 2 POWER CONVERTER BRIDGE
POWER CONVERTER BRIDGE Load
breaker
Load
breaker
BRUSHLESS
SYNCHRONOUS
MOTOR
Channel 1
Channel 2
25. R Ph
Y Ph
B Ph
1 2 3 4 5 6 1
FIRING SEQUENCE & PHASE CURRENTS
26. VFD Data for Motor:
kW rating - 4286 kW
Armature current - 2 X 607 Amps
Armature Voltage - 2 X 2350 V
Speed / frequency - 565 rpm / 47.08 Hz
Exciter Data:
Rated DC Current - 360 Amps
Rated DC Voltage - 100 Volts
Rated AC Current - 64 Amps
Rated AC Voltage - 345 Volts
Nominal source voltage - 2300 V AC
27. POWER SUPPLIES
POWER SUPPLIES
In control panel of VFD room there
are following supplies for different
interlocks & distribution:-
1.0 3Phase, 415 V AC supplies –
02Nos. (1st
from Ch # 1 LCI Panel &
2nd
from Ch # 2 LCI Panel) which in
turn fed from 415V ESP SWGR.
28. 415 V AC supplies stepped down to 110V
AC, 1phase and 220 V AC, 1phase supplies
through transformers.
110V supply used for control & interlock
relays of both channels in control panel
itself.
220V supply is used for space heaters of
panels, motor, reactor, cubicle illumination
lamps, door mounted printer and line
drivers, temperature scanner, reactor temp.
indicator, motor water leakage detector etc.
29. 24V DC: 24V AC stepped down from
415V and then rectified to 24V DC for
control panel indication lamp.
Another 24V DC supply from FSSS for
starting / stopping circuit of ID Fan
channels.
220V DC: supply from station battery
supply for source breaker tripping
interlocks & for Load breaker panels.
30. Power supplies in LCI Panel:
1. 2.3 KV main supply connected to Source Bridge in
bridge panel.
2. 415 V 3 phase supply to C&E panel which is drawn
from ESP board (separate source for each C&E panel for
Ch # 1&2).
415V supply stepped down to 220V & 110V AC
220VAC UPS supply is used for fan flow indicator &
SEM rack fan.
110V AC, 1phase is used for power supplies to all
control cards through PSFF and gate circuit 70V DC
through PS7 module.
415V 3phase supply is also tapped for blower fans
1&2 in F&F panel.
415V 3phase supply is tapped for exciter module in
C&E panel which gives 3-phase supply to exciter.
31. Testing of ID Fan VFD’s
Testing of ID Fan VFD’s
Pre-commissioning tests
Pre-commissioning tests :
:
-Testing of VFD Transformers
-Testing of VFD Transformers
-Readiness for idle charging of VFD transformers
-Readiness for idle charging of VFD transformers
-Testing of Load Breaker panels for CT/PT, relays, breaker
-Testing of Load Breaker panels for CT/PT, relays, breaker
and inter-panel wiring etc.
and inter-panel wiring etc.
- Checking of all cable interconnection b/w
- Checking of all cable interconnection b/w
E&C panels to CCP
E&C panels to CCP
E&C panels to load breaker panels
E&C panels to load breaker panels
CCP to source breaker panels (ensuring source breaker
CCP to source breaker panels (ensuring source breaker
closing & tripping from Common control panel)
closing & tripping from Common control panel)
E&C panels to F&F panels to converter panels
E&C panels to F&F panels to converter panels
Reactor cabinet to CCP
Reactor cabinet to CCP
VFD trf MB to CCP
VFD trf MB to CCP
- Testing of reactors
- Testing of reactors
-Testing of CLC panels
-Testing of CLC panels
32. Site Tests/ Checks
Site Tests/ Checks
-Testing of Synchronous motor:
-Testing of Synchronous motor:
Exciter stator end lead joint below the cooling duct
Exciter stator end lead joint below the cooling duct
found to have SS nut & washer b/w lugs is removed
found to have SS nut & washer b/w lugs is removed
Measurement of exciter stator inductance is carried
Measurement of exciter stator inductance is carried
out.
out.
- Checking of power cables & extension of 415 AC
Checking of power cables & extension of 415 AC
supply, 24 VDC supply & 220 VDC Supply, 240 VAC
supply, 24 VDC supply & 220 VDC Supply, 240 VAC
UPS supply:
UPS supply:
- Power cable screen earthing checking: IR of screen
Power cable screen earthing checking: IR of screen
with low voltage
with low voltage
Physical verification of all components including
Physical verification of all components including
cards for LCI, F&F, bridge panels and control &
cards for LCI, F&F, bridge panels and control &
excitation panels including tightening check of all
excitation panels including tightening check of all
terminals
terminals
33. Site Tests/ Checks
Site Tests/ Checks
Megger test of bridge SCR’s, power buses
Megger test of bridge SCR’s, power buses
Continuity check of bridge cells
Continuity check of bridge cells
Charging of auxiliary power supplies,
Charging of auxiliary power supplies,
running of converter cooling fans
running of converter cooling fans
Charging & Checking of electronic P/S,
Charging & Checking of electronic P/S,
gating P/S, signal I/P P/S
gating P/S, signal I/P P/S
Initialization of electronic modules and
Initialization of electronic modules and
setting up the load printer.
setting up the load printer.
Self test of SEM.
Self test of SEM.
Adjustment of the set point voltages.
Adjustment of the set point voltages.
Bridge current feedback calibration.
Bridge current feedback calibration.
SCR gate test
SCR gate test
34. Contd…
Contd…
Extending source voltage up to bridge converter panels
Extending source voltage up to bridge converter panels
Source no-load test at full voltage
Source no-load test at full voltage
source voltage signal phasing and balancing
source voltage signal phasing and balancing
set source under voltage detection
set source under voltage detection
set source over voltage detection
set source over voltage detection
Load test using voltage signals from source side bridge
Load test using voltage signals from source side bridge
load voltage signal phasing and balancing
load voltage signal phasing and balancing
set load over voltage detection
set load over voltage detection
set motor voltage and speed indication
set motor voltage and speed indication
set over speed
set over speed
Excitation tests (phase seq. & EVC power test)
Excitation tests (phase seq. & EVC power test)
Crowbar test & Ammeter calibration, SRC_SUPP
Crowbar test & Ammeter calibration, SRC_SUPP
Uncoupled running of motor with one channel
Uncoupled running of motor with one channel
Uncoupled running of motor with two channels
Uncoupled running of motor with two channels
37. Commissioning tests
Commissioning tests
- verification of load CT signals with SIG
verification of load CT signals with SIG
- Motor DOR & checks for DOR correction if
Motor DOR & checks for DOR correction if
required
required
- Speed ramp test
Speed ramp test
- Excitation changeover test
Excitation changeover test
- Torque signal exchange
Torque signal exchange
- Verification/calibration of speed indication
Verification/calibration of speed indication
with actual speed/SPD, CUR, PF, KW
with actual speed/SPD, CUR, PF, KW
indication verification & matching with both
indication verification & matching with both
channels
channels
- Commissioning of O&M panel.
Commissioning of O&M panel.
40. TROUBLE SHOOTING
Source breaker tripping initiated through VFD
system:
(This is other than protection tripping from HT
S.W.gear)
Source breaker tripping through an aux. relay
(hand resettable flag relay) mounted on “control
panel”. VAA13 relay for each channel.
In case of source breaker tripping check this
relay has operated on “CCP” of VFD room. If this
relay has not operated tripping is from HT breaker
trip circuit relays & interlocks.
Also you cannot close the source breaker if this
flag relay on “CCP” is not reset.
41. Contd..
VAA13 relay can operate on following
conditions:
Through LCI panel source side fault
through ‘SWGR’ relay in LCI panel.
(SUPP2, SRC_SUPP, SRC_OV, NBLF,
μP STALL, EEPROM_TRNS_FAIL,
ESTOP)
Through FLAGRY CH1/2: Oil temp. trip,
winding temperature trip & Buchholz trip.
Emergency push button is pressed.
Trip command from control panel
[CLOSE-NEUTRAL-TRIP] on VFD room.
42. Load breaker tripping through VFD system:
Motor Isolator Status
Motor Isolator Status
RUN Relay (Channel Selector SW,
RUN Relay (Channel Selector SW,
Local/Remote etc.)
Local/Remote etc.)
No Channel Fault String (NSFLT, NBLF,
No Channel Fault String (NSFLT, NBLF,
GNDF, SUVFLT, LD_OV, LD_SUPP, FOREGD
GNDF, SUVFLT, LD_OV, LD_SUPP, FOREGD
FAULTS, FLDL, OS, GSUV, NPSUV, BFNDR,
FAULTS, FLDL, OS, GSUV, NPSUV, BFNDR,
BFDIFSW)
BFDIFSW)
Line Breaker Status
Line Breaker Status
Field Contactor Status
Field Contactor Status
Emergency Stop
Emergency Stop
Run permissive missing
Run permissive missing
43. SOME MAJOR FAULTS: VFD trips on these faults
• Loss of cooling fan (NOT-NBLF after time SQTMR2)
• Source Back up Over-current (SRC_SUPP: P900C/2)
• Load Back up over-current (LD_SUPP: P900C/5)
• Field Loss (FLD_LOSS_FLT = FLDCUR< FCLOSS
with timer SQTMR4)
• Source Over voltage (SRC_OV: P900C/0)
• Load over-voltage fault (LD_OV: P900C/4)
• Bridge differential pressure (BFDIFSW)
• Gating supply under-voltage fault (GSUV after
SQTMR1)
• P105 supply under-voltage (NOT-NPSUV)
44. SOME MAJOR FAULTS: VFD trips on these faults
• Over-speed (OS: P900C/7)
• Ground Fault (GNDF: NTL>0.55V)
• Fan compartment door open (NOT-BFNDR)
• Source Low line or deep under-voltage (SUVFLT after time
SQPLTIM)
• Motor Isolator not closed (MISOL_STATUS_FLT by 0.5 sec)
•Field Current Imbalance (FLTWD/0)
• Field Over current (FCLIM for FCFTIM: FLTWD/1)
• Motor Winding shorted (after TRSPD, Peak Flux value >
previous value by SWINDTOL: FLTWD/2)
• Source Over current (LKLIMS for LKOCTIM: FLTWD/3)
• Load Over current (LKLIML for LKOCTIM: FLTWD/4)
45. SOME MAJOR FAULTS: VFD trips on these faults
Source commutation failure (Diff> LKLIMD for
STRHUTIM: FLTWD/5)
Load commutation failure (Diff> LKLIMD for STRHUTIM:
FLTWD/6)
Source PLL (SPLLTIM: FLTWD/8)
Load PLL (LPLLTIM: FLTWD/9)
Stack fault (FLTWD/11)
Failure to start (FLTWD/12)
EEPROM transfer failure (FLTWD/13)
46. SOME MAJOR ALARMS: Attention needed to check
Motor Over temperature
Link reactor Over temperature
Cooling blower loss
Loss of speed reference
Gating supply under-voltage
Microprocessor alarm
Bridge filter fuse blown
Source under-volts
Transformer alarm
Loss of speed control (Error> SRETOL for SQTMR5)
Run Perm or Start Perm missing
Field Exciter voltage loss
Rotor Position start alarm
I/O addressing Problem
47. START PERMISSIVES FOR THE CHANNELS (To be seen
at VFD room):
• No emergency stop pressed.
• No motor over-temperature trip persisting
• Bus supervision 24V DC & 220V DC healthy
• Heating & Illumination CB 2 ON
• No water leakage in Motor
• Water flow healthy in motor
• CB3 in control panel ON, all indication lamp circuit healthy
• No transformer alarms persisting
• No transformer trips persisting
48. START PERMISSIVES FOR THE CHANNELS (To be seen
at VFD room):
• No reactor alarm persisting
• No reactor trip persisting
• No Motor over temperature alarm
• No over current trip from Load Breaker
• No MTR of SRC BRK and Source breaker closed
49. CLOSE PERMISSIVES FOR THE SOURCE BREAKER
(To be seen at VFD room):
• No emergency stop pressed.
• No motor over temperature trip persisting
• No motor over temp alarm
• Bus supervision 24V DC & 220V DC healthy
• Heating & Illumination CB 2 ON
• No water leakage in Motor
• Water flow healthy in motor
• CB3 in control panel ON, all indication lamp circuit
healthy
50. CLOSE PERMISSIVES FOR THE SOURCE BREAKER
(To be seen at VFD room):
• No transformer alarms persisting
• No transformer trips persisting
• No reactor alarm persisting
• No reactor trip persisting
• Permit to close source breaker from LCI panel ( from
IOMA card : SWGR. Relay shall not be picked up
51. CHANNEL RUN PERMIT (To be seen at VFD room):
• No emergency stop pressed.
• No motor over temperature trip persisting
• Bus supervision 24V DC & 220V DC healthy
• Heating & Illumination CB 2 ON
• No transformer trips persisting
• No reactor trip persisting
• No MTR of SRC BRK & Source breaker closed
• No over current trip from Load breaker
52. Major Problems Faced During
Major Problems Faced During
Commissioning
Commissioning
Leakage voltages in IOMA
Leakage voltages in IOMA
XPTN resistor failure
XPTN resistor failure
Thyristor failure
Thyristor failure
Card failure
Power cable screen insulation failure
Mal-operation of motor & reactor
Mal-operation of motor & reactor
temperature scanners.
temperature scanners.
Motor exciter rotor winding coil polarity
Motor exciter rotor winding coil polarity
problem
problem
Leakage voltages appearing at the load
Leakage voltages appearing at the load
breaker aux. Contact terminal blocks.
breaker aux. Contact terminal blocks.
Chartless recorder
Chartless recorder
UPS supply voltage drop in the cable.
UPS supply voltage drop in the cable.
56. SUGGESTION FOR IMPROVEMENT
SUGGESTION FOR IMPROVEMENT
SUGGESTION REMARKS
Treated earth pit for electronic earth Implemented since start of
commg
Power cable screen insulation
verification at receiving end &
earthing at source end
Implemented since start of
commg
Reactor temperature scanners to be
located outside reactor cubicle.
Implemented since start of
commg
ACPDB REMOVED & Dedicated
feeder to be provided for UPS supply
to ensure reliable operation; adequate
cable size to be selected to overcome
voltage drop.
Implemented after Unit-5
Commg
Dust Collecting sieves provided on
bridge panel door internal to be fixed
outside
To be implemented.
57. SUGGESTION FOR
SUGGESTION FOR
IMPROVEMENT
IMPROVEMENT
Quality of components and
cards needs immediate
improvement.
These has been taken up with M/s
BHEL/EDN for detailed analysis so
as to improve the quality
Providing source breaker
tripping instead of load
breaker in the event of
bridge panel/fan
compartment door open
signal on safety grounds.
The necessary soft ware logic
modification & concurrence by M/s
BHEL/EDN required.
VFD room A/C & dust
freeness to be regularly
ensured
1. Room partitioning is being
implemented to ensure effectiveness
of AC & prevent dust ingress.
2. Daily wet mopping is being ensured.
3. Room temp indication is being
provided at CCR along temp &
humidity indication at local.
![Contd..
VAA13 relay can operate on following
conditions:
Through LCI panel source side fault
through ‘SWGR’ relay in LCI panel.
(SUPP2, SRC_SUPP, SRC_OV, NBLF,
μP STALL, EEPROM_TRNS_FAIL,
ESTOP)
Through FLAGRY CH1/2: Oil temp. trip,
winding temperature trip & Buchholz trip.
Emergency push button is pressed.
Trip command from control panel
[CLOSE-NEUTRAL-TRIP] on VFD room.](https://image.slidesharecdn.com/vfdbhel-250304144659-3a42e916/85/variable-frequency-drive-fundamental-and-circuit-41-320.jpg)
