variable frequency drive fundamental and circuit

vfd ppt

1. RECTIFIER INVERTER
REACTOR
BRUSH
LESS
Exciter
SYNC.
Motor
AC Line
DC Link
1 35
4 62
2 6 4
135

2. 2
5
6
4
3 1
Fld.
WdgExciter
Phase
controll
ed
switches
415 V Power
LCI BRUSHLESS EXCITER
Exciter is an induction
frequency changer

3. EFFECIENCY CURVE OF VARIOUS FLOW CONTROL EFFECIENCY CURVE OF VARIOUS FLOW CONTROL
DRIVESDRIVES
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.

7. CONTROL BLOCK DIAGRAM
CURRENT
CONTROL
START-UP
CONTROL
SPEED
CONTROL
FIELD EXC.
CONTROL
VOLTS / HERTZ
POWER
SOURCE
SOURCE
SIDE
CONVERTER
LOAD
SIDE
CONVERTER
SYNCHRONOUS
MOTOR
S
P
E
E
D
SPEED
REFERENCE

8. How much power saving?
Gen.Gen.
MWMW
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 VFDFans with VFD
Power Power
SavingSaving
200200 38003800 850850 29502950
240240 41504150 950950 32003200
280280 44504450 10501050 31003100
320320 48004800 12501250 35503550
360360 50505050 14201420 36303630
400400 53505350 18501850 35003500
440440 56005600 25002500 31003100
500500 59005900 30003000 29002900

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.

10. BHEL VFD
FOR ID FANS
OF 500 MW
UNITS : AN
OVERVIEW

11. Panels related to VFD in VFD roomPanels 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)
PanelPanel
PSFF
Power
Supply
module
70V
Gate
Supply
module
Exciter
Module
SEM Rack
(Microprocessor
& other control
cards)
IOM A
(Input / output
module)

13. Fan & Filter PanelFan & 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 FansCooling Fans
INTER
FACE
INTER
FACE
REACTOR
CONTROL &
EXCITATION
PA NEL
CONTROL &
EXCITATION
PA NEL
INTER
FACE
INTER
FA CE
REACTOR
Control
Control
Cooling FansCooling 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

17. THYRISTOR FIRING
1 53
2
1
4 66 2
1 2 3 4 5 6 1 2 3
120 deg.

18. 1 3
4 6
5
2
I
DC
Voltage
Source
Synchronous Motor
Stator Winding
R Ph
Y Ph
B Ph
 

19. 1 3
4 6
5
2
I
DC
Voltage
Source
Synchronous Motor
Stator Winding
R Ph
Y Ph
B Ph
 

20. 1 3
4 6
5
2
I
DC
Voltage
Source
Synchronous Motor
Stator Winding
R Ph
Y Ph
B Ph
 

21. 1 3
4 6
5
2
I
DC
Voltage
Source
Synchronous Motor
Stator Winding
R Ph
Y Ph
B Ph
 

22. 1 3
4 6
5
2
I
DC
Voltage
Source
Synchronous Motor
Stator Winding
R Ph
Y Ph
B Ph
 

23. 1 3
4 6
5
2
I
DC
Voltage
Source
Synchronous Motor
Stator Winding
R Ph
Y Ph
B Ph
 

24. 1 3
4 6
5
2
I
DC
Voltage
Source
Synchronous Motor
Stator Winding
R Ph
Y Ph
B Ph
 

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 SUPPLIESPOWER SUPPLIES
In control panel of VFD room there
are following supplies for different
interlocks & distribution:-
1.0 3Phase, 415 V AC supplies –
02Nos. (1
st
from Ch # 1 LCI Panel &
2
nd
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’sTesting of ID Fan VFD’s

Pre-commissioning testsPre-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 CCPE&C panels to CCP
E&C panels to load breaker panelsE&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 panelsE&C panels to F&F panels to converter panels
Reactor cabinet to CCPReactor cabinet to CCP
VFD trf MB to CCPVFD trf MB to CCP
- Testing of reactors - Testing of reactors
-Testing of CLC panels -Testing of CLC panels

32. Site Tests/ ChecksSite 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 removedfound 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 voltagewith 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/ ChecksSite 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 balancingsource voltage signal phasing and balancing
set source under voltage detectionset source under voltage detection
set source over voltage detectionset 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 balancingload voltage signal phasing and balancing
set load over voltage detectionset load over voltage detection
set motor voltage and speed indicationset motor voltage and speed indication
set over speedset over speed

Excitation tests (phase seq. & EVC power test)Excitation tests (phase seq. & EVC power test)

Crowbar test & Ammeter calibration, SRC_SUPPCrowbar 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 channelsUncoupled running of motor with two channels

37. Commissioning testsCommissioning tests
-verification of load CT signals with SIGverification of load CT signals with SIG
-Motor DOR & checks for DOR correction if Motor DOR & checks for DOR correction if
requiredrequired
-Speed ramp testSpeed ramp test
-Excitation changeover testExcitation changeover test
-Torque signal exchangeTorque 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.

38. Speed vs Voltage
0
500
1000
1500
2000
2500
0
2
0
4
0
6
0
8
0
1
0
0
1
2
0
1
4
0
1
6
0
1
8
0
2
0
0
2
2
0
2
4
0
2
6
0
2
8
0
3
0
0
3
2
0
3
4
0
3
6
0
3
8
0
4
0
0
4
2
0
4
4
0
4
6
0
4
8
0
5
0
0
5
2
0
5
4
0
5
6
0
Speed
V
o
lt
a
g
e
voltage vs speed curve

39. Flux Profile
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 0.5 0.8 1
Speed
F
l
u
x
flux

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 StatusMotor 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 StatusLine Breaker Status

Field Contactor StatusField Contactor Status

Emergency StopEmergency Stop

Run permissive missingRun 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
CommissioningCommissioning

Leakage voltages in IOMALeakage voltages in IOMA

XPTN resistor failureXPTN resistor failure

Thyristor failureThyristor 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
problemproblem

Leakage voltages appearing at the load Leakage voltages appearing at the load
breaker aux. Contact terminal blocks.breaker aux. Contact terminal blocks.

Chartless recorderChartless recorder

UPS supply voltage drop in the cable.UPS supply voltage drop in the cable.

53. LIST OF COMPONENTS FAILED IN VFDs DURING/AFTER COMMGLIST OF COMPONENTS FAILED IN VFDs DURING/AFTER COMMG
FAILED COMPONENTSFAILED COMPONENTS QtyQty VFD-5AVFD-5A VFD-5BVFD-5B VFD-6AVFD-6A VFD-6BVFD-6B VFD-7BVFD-7B
HMPG HMPG 0202 ---- ---- 0101 ---- 0101
XPTNXPTN 1717 1010 0101 0303 0303 ----
NSFCNSFC 0202 ---- 0101 0101 ---- ----
NTRFNTRF 0404 ---- 0202 ---- 0202 ----
PS7 COMPLETE MODULEPS7 COMPLETE MODULE 0101 ---- 0101 ---- ---- ----
PSFF COMPLETE MODULEPSFF COMPLETE MODULE 0202 ---- 0101 ---- 0101 ----
HRDDHRDD 0202 ---- ---- 0101 0101 ----
HPTKHPTK 0808 0101 ---- 0303 0101 0303
AIR FLOW MONITORAIR FLOW MONITOR 0606 0202 ---- 0202 ---- 0202
IOMA COMPLETE MODULEIOMA COMPLETE MODULE 0909 0505 ---- 0101 0202 0101
REACTOR TEMP. MONITORREACTOR TEMP. MONITOR 0303 0202 ---- ---- 0101 ----
HAIAHAIA 0101 0101 ---- ---- ---- ----
THYRISTOR STACKTHYRISTOR STACK 3939 0606 1414 0505 1111 0303
NLCBNLCB 0505 0303 0101 0101 ---- ----
NLIBNLIB 0707 0202 0202 0101 0202 ----
DLIB ( L)DLIB ( L) 0606 0202 0101 0101 0101 0101
DLIB ( S)DLIB ( S) 0404 0101 0101 0101 0101 ----
HRIAHRIA 0202 0202 ---- ---- ---- ----
DLCBDLCB 0202 0101 0101 ---- ---- ----
HLCBHLCB 0101 0101 ---- ---- ---- ----

56. SUGGESTION FOR IMPROVEMENTSUGGESTION FOR IMPROVEMENT
SUGGESTION REMARKS
Treated earth pit for electronic earthImplemented 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
IMPROVEMENTIMPROVEMENT
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.

58. THANK YOUTHANK YOU