Download WITHOUT COMPROMISE ! Self Healing VIT Recloser and VIT

NEW !
WITHOUT COMPROMISE !
Self Healing VIT Recloser and VIT Sectionalizer
with SEF, HIF, Open Conductor Protection
 Enhanced Loop Operation
 VIT Recloser, VIT Sectionalizer
 No Communication
 Isolate source and load side of faulted section before tie switch close
 No Fault Impact to Healthy Network
 No Series Coordination Problem of Large Number of Protection Device
 No Close into Fault by Sectionalizers
 The Recloser of Healthy Feeder Maintain Security, Sensitivity through
Load Encroachment Algorithm
 Automatic Setting Group Change
 Enhanced Ground Fault Protection
 VIT Recloser, VIT Sectionalizer
 Directional SEF Protection
 Directional HIF Protection
 Open Conductor Fault Protection
 The Sectionalizer isolate the small ground fault by itself
SHINSUNG INDUSTRIAL ELECTRIC
The Self Healing Feeder Automation System using VIT Recloser & VIT
Sectionalizer
1. Overview
The VIT self healing system can make multi source loop system without using communication.
It can isolate the both sides of faulted sections before automatic close of tie switch, so there is no
fault impact to the healthy network, and can avoid the series coordination problem of large
numbers of protections devices.
The VIT recloser and VIT Sectionalizer have the functions of directional sensitive earth fault, high
impedance fault protection and open conductor fault protection, so it can improve the safety,
reliability of the distribution line.
The VIT sectionalizer works not only as conventional radial sectionalizer, but also loop
sectionalizer and direct protection device from SEF, HIF, Open conductor faults.
The VIT sectionalizer isolate the high fault current through fault current counting and clears the
small ground current (SEF, HIF, Open conductor fault) by itself.
2. Enhanced Loop Operation
The automatic loop operation during permanents fault can reduce the outage time and outage
area dramatically compared to radial network. If the feeder divided into 4 sections and connected
by normal open switch, 75% of the network can restore the service within short time.
The conventional 5 recloser loop scheme was widely used, because it can reconfigure the feeder
automatically without communication, but also it has serious draw backs.
The main problem is that the load side of faulted section can not be isolated before tie switch
close, so there are coordination problems of many protection devices and it inevitably makes the
short circuit impact to the healthy network when the tie switch close.
The other problem is the possibility of mistrip of healthy feeder recloser because of the increased
load current.
To overcome above problems, peer to peer communication, centralized communication, pulsed
reclosing solutions are suggested, but the system is expensive and still can not fully solve the
problems.
The VIT self healing system isolate the source side of faulted section through the sequential
operation of recloser and fault counting of sectionalizer. The load side of faulted section also can
be isolated through voltage counting during the sequential operation of C.B or recloser.
If the load side of faulted section can be isolated, then the sectionalizer can be used in loop
network, and the results are better coordination, more sectionalizing segment, low cost and no
short circuit impact to the healthy network.
2.1 Mid Point Recloser
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Source Side Isolation of Faulted Section
Clears temporary and permanent faults through sequential operation.
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Load Side Isolation of Faulted Section
 If the upstream protection device clears the fault, so if it senses loss of voltage, then
it trips and counts the number of loss of voltage. If the counts satisfy the setting
then it goes to lockout, but if the counts are more or less than set counts, then it will
close again, when the voltage is restored. The close timer should be longer than
maximum clearing time of upstream C.B or recloser
VIT SELF HEALING SYSTEM
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Load Encroachment Logics
If the tie switch close, then the recloser of healthy feeder will supply more current than
the normal and it may mistrip the recloser.
To avoid mistrip and to maintain sensitivity, the control has two operation current levels.
The first level will be qualified by both amplitude and load angle, the second level will be
qualified by amplitude.
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Automatic Setting Group Change
The load side recloser will supply reduced current than normal and needs different
setting group. If the load side restore the voltage first, then it automatically changes the
setting group and if the line reconfigured after maintenance to the original network, then
the setting group changes again to the normal setting group.
.
2.2 Tie Recloser
The tie recloser close automatically if the one side voltage is lost but if the fault was at the
zone of tie recloser, it goes to lockout unlike conventional Tie recloser and automatically reset
when both side voltages are restored.
The tie recloser has two setting groups according to the power direction and automatically
changes the setting group.
If the tie recloser open not automatically, then it goes to lockout, so it will not close even one
side voltage is lost, and the lockout state will be reset automatically when the both side
voltage are restored.
2.3 Mid Point Sectionalizer
The Sectionalizer can be used in loop network, so the series coordination problem of
conventional five recloser loop scheme can be solved and the sectionalizing points can be
increased.
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Source Side isolation of Faulted Section
Isolate the permanent fault through fault current counting during the sequential
operation of upstream C.B or Recloser.
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Load Side isolation of Faulted Section
The sectionalizer isolate the source side of faulted section through voltage counting
before the tie switch close.
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Load Encroachment Logics
During loop operation, the sectionalizer of healthy feeder will supply more current than
the normal and it may cause miscount.
To avoid this miscounting, the sectionalizer has similar load encroachment logics with
recloser.
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Automatic Setting Group Change
The sectionalizer can have two setting groups and it changes the setting groups
according to the power direction automatically and if the line is restored to original state,
then it changes the setting group again.
2.4 Tie Sectionalizer
The sectionalizer can be used as tie switch because both of the faulted sections are already
isolated and the tie switch will go to lockout and will not try to close into fault, if the fault was
at the zone of tie sectionalizer.
If the sectionalizer is used as tie switch, then it may be set to one count to open, so if there is
second fault during loop operation, the newly connected load will be removed after one
operation of recloser.
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SHINSUNG INDUSTRIAL ELECTRIC
The tie sectionalizer close automatically if the one side voltage is lost but if the fault was at
the zone of tie sectionalizer, it will be lockout unlike conventional tie switch. It automatically
reset
when both side voltages are restored. If the tie sectionalizer open, not automatically then it
goes to lockout and the lockout state will be reset automatically when both side voltages are
restored.
2.5 Loop System more than Two Sources
If the feeder has no enough marginal capacity, so only 33% of the load can be supplied from
other source, then it will be 3 section, 3 source interconnected loop scheme. The VIT self
healing system can support multi source loop system through loss of voltage lockout features.
3. Enhanced Ground Fault Protection.
3.1 SEF (Sensitive Earth Fault)
The SEF current is small but continuous, so it differs with HIF current from the points of no
random, no arc burst, no high harmonic content etc.
(1) 3 Phase 3Wire System
The 3phase-3wire system has very small residual current during normal operation,
because there is no phase to ground load.
The sensitivity is limited by unbalanced phase to ground leakage current and the
sensitivity of zero current transformer.
The VIT recloser and VIT sectionalizer can detect sensitive residual current (below 100mA
residual current at full load).
To distinguish between forward and reverse fault, the phase angle between zero phase
Voltage (Vo) and zero phase current (Io) should be compared. The maximum torque
angle are different according to the grounding system and some times it needs fields
tuning process to set exactly. The threshold level of Vo, Io and the MTA(maximum torque
angle) between Vo and Io, the TAW(torque angle width) can be programmed.
The SEF algorithm is based on continuous arc current, so if the arc current is not
continuous, it will be covered by HIF algorithm.
(2) 3 Phase, 4Wire Solidly Multi-Grounded System
In case of 3 phase 4wire system, the SEF, HIF Protection are much more difficult than
3phase-3wire system because of high normal residual current.
To achieve sensitive earth fault and high impedance fault, the continuous arc range
should be lowered as far as possible. If the ground pick up level is lower than max phase
current, it is needed to use directional ground protection to avoid mis-operation during
source side fault.
If the ground pick up level is fixed, then the sensitivity can not improved lower than
maximum residual current during normal operation.
To overcome this problem, the residual current ratio I0/I1 can be used to get better
sensitivity.
The open conductor fault algorithm also can improve the ground fault sensitivity if there is
detectable increase of unbalance current because of open conductor, because the open
conductor fault also can cover SEF, HIF and even just in-hang situation.
If the ground fault current is small, then it has a tendancy to become random arc (HIF), so,
it also need special random arc detection algorithms.
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VIT SELF HEALING SYSTEM
So the I0 pick up, I0/I1 pick up element needs directional protection and also random arc
protection. The protection level may be as follows
The protection level may be as follows;
1st level
2nd level
3rd level
IG ≥ IP max.
Non Directional
0.5 IP max.< IG < IP max. Directional
I0/I1
Directional
3.2 HIF
The SEF is also kinds of HIF, but the SEF is continuous arc and HIF has characteristics of
high harmonics or random, arc burst. Generally, SEF and HIF use the same threshold level,.
- Randomness
- Arc Burst
- Harmonic Content Analysis
At the loop network, the SEF, HIF fault will be cleared first by VIT recloser, because at loop
network, the load side of faulted section should be isolated during the sequential operation of
recloser.
If the SEF, HIF fault are at the radial network, then it will be cleared by VIT sectionalizer
without tripping main line recloser.
3.3 Open Conductor Fault
The open conductor fault may make normal ground fault, SEF, HIF, load side touched ground
fault, or just in-hang (not touches the ground).
If the fault was at the main line (not small branch line) and if there is VIT sectionalizer at the
load side, the open conductor fault can be cleared with high sensitivity and with high security.
The O.C algorithm has longer time delay than SEF, HIF, so if the fault can not be detected by
SEF, HIF, then finally the O-C algorithm clears the fault.
(1) Source side isolation of open conductor
The source side of O.C detect abnormal unbalance current I2/I1, but the system voltage
is stable, in this condition the open conductor fault timer start and if timed out, the switch
open and lockout.
The upstream switch has longer delay time than downstream switch and if the
unbalance current disappear, then the timer will be reset.
(2) Load side isolation of open conductor
The load side switch detect strong unbalance voltage, so the zero phase voltage ratio
(V0/V1) can detect open conductor situation.
If the switch detect V0/V1, and detect no voltage during the open time window of
upstream switch, then it will open and be lockout.
4. Built in RTU Functions
The VIT self healing system fulfill the requirements of self healing feeder automation system
without using communication, but if it is connected to the computer system through
communication, then it will be much more flexible, convenient and powerful.
1st Step
Self Healing Automation System
* VIT Recloser, VIT Sectionalizer
* Fault Isolation, Service Restoration
* Automatic Setting Group Change
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SHINSUNG INDUSTRIAL ELECTRIC
2nd Step
Computerized Distribution Automation System
* Adding the modem
* VIT Self healing system works as redundancy system
* Remote Monitoring
* Remote Operation
* Remote Measurement
* Remote Setting Change
5. Application
5.1 The Problems of Conventional 5 Recloser Loop Scheme
SR 1
C.B 1
F1
MR 1
F2
F3
TR
C.B 2
SR
MR
TR
SR 2
MR 2
Sectionalizing Recloser
Mid Point Recloser
Tie Recloser (Normally Open)
The conventional recloser loop scheme can isolate the source side, but can not isolate
the load side of faulted section. So during tie recloser close, 4~5 protection device
should coordinate properly and can not avoid fault impact to the healthy network.
The healthy feeder recloser have to supply more load current, so without changing the
setting, it may mis-trip or have to sacrifice the sensitivity, so they say it needs
communication.
To solve above problems, they suggest the recloser use as Sectionalizer during normal
operation, but still operate it as recloser during loop operation to remove the fault, but
it can not avoid short circuit impact to the healthy network.
The pulsed reclosing techniques are introduced to solve the problems, but it still can not
be the fundamental solution.
The VIT self healing system solve above problems through “both side isolation of faulted
section before tie switch close” and the sectionalizer can be used even for loop
operation with better coordination, more sectionalizing points, reduced cost.
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F1 fault
CB 1
SR1
TR
Lockout after sequential operation
Open lockout after sense loss of voltage more than livebus timer
Close after sense loss of voltage of one side more than close timer.
F2 fault
SR 1
TR
MR1
Lockout after sequential operation
Close after sense loss of voltage of one side more than close timer
Trip and lockout
VIT SELF HEALING SYSTEM
NOTE: The series coordination between CB2, SR2, MR2, TR and MR1, will be very
difficult and healthy feeder experience unnecessary fault impact.
F3 fault
MR 1
TR
TR
Lockout after sequential operations
Close after sense loss of voltage of one side more than close timer
Trip and lockout
NOTE: The coordination between CB2, SR2, MR2 and TR will be very difficult and the
healthy feeder experience unnecessary fault impact even it can not restore the
service.
5.2 Enhanced 5 VIT Recloser Loop Scheme
SR 1
C.B 1
F1
MR 1
F2
F3
TR
SR 2
C.B 2
SR
MR
TR
MR 2
Sectionalizing Recloser
Mid Point Recloser
Tie Recloser (Normally Open)
The VIT Recloser can isolate both side of faulted section before tie recloser close, so it
solves the problem of series coordination of many protective devices and it avoids
unnecessary impact to the healthy network
CB1, CB2
SR1, SR2
MR1, MR2
TR
F1 fault
CB 1
SR1,MR1
CB 1
CB2
SR1
TR
MR1
O-CO-CO
O-CO-CO
No voltage trip
Lockout after voltage count
O-CO-CO
No voltage trip
Lockout after voltage count
Automatic close when one side voltage is lost
Lockout after voltage count
Close
Close
Open
Open
Open
Open lockout
Lockout after voltage count
Close
Close (setting group change)
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F2 fault
SR 1
MR1
SR 1
SR1
MR1
TR
Open
Open
Close
Open
Close
Open, lockout
Lockout after voltage count
Close
F3 fault
MR1
MR 1
MR1
TR
Open
Close
Open
Close open and lockout
Lockout after voltage count, No close into fault
NOTE: 1. The VIT recloser loop scheme isolate the source side and load side of faulted
section before tie recloser close.
So there is no series coordination problem, no short circuit impact to the healthy
network, not necessary to use pulse reclosing techniques, not necessary to use
communication.
2. The reclosers have load encroachment algorithm to avoid mis-tripping during
loop operation.
So, it is not necessary to change the setting of healthy feeder recloser through
communication before tie recloser close.
3. The VIT recloser has SEF, HIF and open conductor fault protection functions.
The operating sequence of SEF, HIF will be the same with above example.
The VIT recloser has two open conductor fault algorithm, load side confirmed O.C
and non load side confirmed O.C algorithms.
At the middle of network, it operates according to load side confirmed O.C
algorithm with high security and sensitivity and at the end of network, it operates
according to non load side confirmed O.C algorithm based on abnormal
unbalance load ratio or negative sequence current ratio.
Even the case of open conductor fault, the both side of faulted section will be
isolated.
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VIT SELF HEALING SYSTEM
5.3 Enhanced VIT Recloser and VIT Sectionalizer Loop Scheme
The sectionalizer could not be used before at the loop scheme, because during tie switch
close, the fault should be removed by recloser (The load side of faulted section was not
removed before tie switch close)
But the VIT Self healing loop system can use recloser, sectionalizer and the coordination
will be better because, the sectionalizer has no time-current characteristics. The VIT self
healing systems are economical, better coordination, more sectionalizing points, better
protections (SEF, HIF, Open Conductor Fault) than conventional recloser loop scheme.
SEC 8
SEC 5
SEC 6
F4
3counts
SEC 1
C.B
F5
2counts
REC 1
F6
2counts
SEC 2
F3
1 count
SEC 3
F2
3counts
2counts
SEC 9
1 count
F1
2counts
SEC 7
SEC 4
Tie
REC 2
C.B
5.4 One Count VIT Sectionalizer with Fuse
The one count VIT sectionalizer with fuse can be used for customer protection or end of
network.
The VIT sectionalizer has the functions;
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One count open
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Over load protection up to 900A
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Over current ground fault protection up to 900A
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SEF up to 900A
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HIF up to 900A
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Unbalance voltage protection up to 900A
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Unbalance current protection up to 900A
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Blown fuse detection
If one or two fuses blown, it opens 3phase.
* If the current is higher than 900A, it interlock the trip circuit and if the current
is decreased lower than 900A, it will trip or works as sectionalizer.
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SHINSUNG INDUSTRIAL ELECTRIC
5.5 F1 Fault
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High Fault Current (Recloser Open First)
After two opens of Recloser, the SEC 3 and SEC 4 go to lockout.
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SEF, HIF
After two opens of Recloser, the SEC 3 and SEC 4 go to lockout.
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Open conductor fault (just in-hang, not detected by Recloser)
SEC 3 open and SEC 4 go to lockout.
5.6 F2 Fault
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High Fault Current (Recloser Open First)
After 3 opens of recloser, the SEC 2 and SEC 3 open and go to lockout.
Recloser close again, SEC 4 close, restore the service
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SEF, HIF
Same with high fault current
-
Open conductor fault (just in-hang, not detected by Recloser)
SEC 2 open and lockout
SEC 3 open and lockout
SEC 4 close restore the service
5.7 F3 Fault
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High Fault Current
After 4 opens of Recloser, Recloser lockout
SEC 2 open and goes to lockout
SEC 3 open before close SEC 4
SEC 4 close
SEC 3 Change the setting group and close
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SEF, HIF
Same with high fault current
-
Open conductor fault (just in-hang, not detected by Recloser)
REC 1 open and lockout
SEC 2 open and lockout
SEC 3 open
SEC 4 close
SEC 5 close, change setting group
5.8 F6 Fault
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-
High Fault Current
C.B open
REC 1
open
C.B
close and trip
SEC 1
open and lockout
C.B
close
REC 1
lockout
SEC 2, SEC 3 open
SEC 4
close
SEC 3
change the setting group and close
SEC 2
change the setting group and close
-
SEF, HIF
The C.B should have SEF, HIF functions. If the C.B doesn’t have SEF, HIF
protection, then can enable the SEF, HIF of SEC 1.
SEC 1 open
REC 1 open and after time goes to lockout
VIT SELF HEALING SYSTEM
SEC 2,
SEC 4
SEC 3
SEC 2
-
SEC 3 open before SEC 4 close
close
change the setting group and close
change the setting group and close
Open conductor (just in-hang not detected by C.B)
SEC 1
open and lockout
REC 1
open and lockout
SEC 2, SEC 3
open
SEC 4
close
SEC 3
close change S.G
SEC 2
close change S.G
5.9 F5 Fault
-
High Fault Current
C.B
trip, REC 1 open
C.B
close and open
C.B
close and open
SEC 1 open and lockout
SEC 2, SEC 3 open before SEC 4 close
SEC 4
close
SEC 3
change the setting group and close
SEC 2
change the setting group and close
REC 1
change the setting group and close
SEF, HIF, Open conductor fault
The C.B should have SEF, HIF. If not, the section can not be protected. If using
Recloser control for C.B, then it will be OK.
If moves REC 1 to the outgoing point of C.B, then it works but the segment will be
limited to three segments.
5.10
F4 Fault
-
High Fault Current
REC 1 open three times
SEC 5 open and lockout
REC 1 close again
-
SEF, HIF fault
SEC 5 open and lockout
-
Open Conductor fault
SEC 5 open and lockout
SEC 6 open
If voltage restored SEC 6 close
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5.11
Operation of REC 2
REC 2 has two minimum operation current levels for phase, ground protection. The first level
will be qualified by the amplitude and load angle. The second level may be double of first
level, but qualified only by amplitude.
So during loop operation, it will not mis-operate even the load currents are higher than first
level.
6. Conclusion
The new VIT self healing system achieves the feeder automation without using any
communication and can be expanded to communication systems with minimum cost.
The enhanced functions are:
- Real self healing system without using communication.
- Conventional recloser, Sectionalizer coordination.
- Enhanced Ground Fault, Overload Protection
: Over load phase, ground protection (up to 900A).
: SEF protection (up to 900A)
: HIF protection (up to 900A).
: Open conductor protection (up to 900A).
- Automatic loop operation without forced closing into fault
- Automatic setting group change according to power direction
- Built in RTU functions (remote operation ,measurement .monitoring)
- Step by step Distribution automation.
- Powerful redundancy system even computerized stage.
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VIT SELF HEALING SYSTEM
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