07-busbar protection busbar protection rf
Post on 06-Apr-2015
648 Views
Preview:
TRANSCRIPT
08/0205/02/031 105/02/031
Busbar Protection
Protection & Contrôle / Application
Rev. A JM, September 2004
08/0205/02/032 2
Without Busbar Protection
F2F1
There are fewer faults on busbars than on other parts of the power system. No risk of dislocation of system due to accidental operation of busbar protection.
Argues
08/0205/02/033 3
Without Busbar Protection
F2F1
Slow fault clearance.Busbar faults at F1 and F2 are cleared by remote time delayed protection on circuits feeding the faults:
Time Delayed Overcurrent orTime Delayed Distance Protection
Drawbacks
08/0205/02/035 5
With Busbar Protection
BUSBARZONE
F2F1
Where busbars are sectionalised,Protection can limit the amount of system
disruption for a busbar fault
08/0205/02/0311 11
Busbar Faults Are Usually Permanent
Causes of Busbar Faults :
Falling debris
Insulation failuresCircuit breaker failuresCurrent transformer failuresIsolators switchs operated on load or outside their ratingsSafety earths left connected
Therefore :
Circuit breakers should be tripped and locked out by busbar protection
08/0205/02/0312 12
Busbar Protection must be :
RELIABLE– Failure to trip could cause widespread damage to the substation
STABLE– False tripping can cause widespread interruption of supplies to
customers / possible power system instability
DISCRIMINATING– Should trip the minimum number of breakers to clear the fault
FAST– To limit damage and possible power system instability
08/0205/02/0313 13
Methods of Providing Busbar ProtectionFrame to Earth (Leakage) Protection
Blocking Scheme Protection
Differential Protection : High ImpedanceLow Impedance
Insulation
>I
>I >I >I >I>I
08/0205/02/0314 1405/02/0314
Frame Leakage Protection
Protection & Contrôle / Application
Rev. A JM, September 2004
08/0205/02/0319 19
Can detect only earth faults
Switchgear must be insulated from earth (by standing on concrete plinth)
Only one single earth conductor allowed on switchgear
All cable glands must be insulated
Switchgear sections must be insulated
Frame Leakage Busbar Protection
08/0205/02/0320 20
>I
>I
Frame Leakage Busbar Protection
Neutral Check
False Operation because induced loop
No operation prevents from false trip
08/0205/02/0323 2305/02/0323
Blocking Scheme Protection
Protection & Contrôle / Application
Rev. A JM, September 2004
08/0205/02/0327 2705/02/0327
High Impedance Protection
Protection & Contrôle / Application
Rev. A JM, September 2004
08/0205/02/0334 34
Isolator Auxiliary Switches Current switching
Bus A
Bus B
ab
Current
P1
P2
S1
S2
P1
P2
S1
S2
P1
P2
S1
S2
P1
P2
S1
S2
P1
P2
S1
S2
08/0205/02/0340 40
Bus A
Current
Bus B
ab
Isolator Auxiliary Switches Tripping switching
Tripping ab
08/0205/02/0341 41
Main CT must be identical
Current switching via auxilliary relay is not acceptable.
Requirement of number of position contact (Disconnector switch) is high
Interposing CT are not acceptable
08/0205/02/0343 43
Isolator Auxiliary Switches Current switching
Bus A
Bus B
abCurrent
Bus A
Bus B
abCurrent
08/0205/02/0351 51
Bus A
Bus B
Trip
Bus
A
Trip
Bus
B
Zone AZone B
Isolator Auxiliary Switches Check Zone
08/0205/02/0352 52
Bus A
Bus B
Trip
Bus
A
Trip
Bus
B
Zone AZone B
Isolator Auxiliary Switches Check Zone
Current switching failure
False Tripping
08/0205/02/0353 53
Bus A
Bus B
Trip
Bus
A
Trip
Bus
B
Check Zone
Zone AZone B
Isolator Auxiliary Switches Check Zone
08/0205/02/0354 54
Bus A
Bus B
Trip
Bus
A
Trip
Bus
B
Zone AZone B
Isolator Auxiliary Switches Check Zone
08/0205/02/0355 55
Bus A
Bus B
Trip
Bus
A
Trip
Bus
B
Check Zone
Isolator Auxiliary Switches Check Zone
top related