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Fault Hunting Using
Three-Phase Reclosers
Michael S. Costa
Eversource Energy
Jerome V. Josken
UC Synergetic
IEEE Rural Electric Power Conference
Ashville, North Carolina
April 19-21, 2015
Dennis A. Walder
Eaton
Eversource Energy
• Formerly Northeast Utilities
• New England’s largest energy delivery
company
• Safely and reliably delivering energy to
more than 3.6 million electric and
natural gas customers in Connecticut,
Massachusetts and New Hampshire
• Operates more than:
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4,270 miles of transmission lines
72,000 pole miles of distribution lines
578 substations
449,000 distribution
transformers
• 6459 miles of gas
distribution pipelines
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Eversource Energy
History: Reliability Improvements – Distribution Automation
• Recloser Loop Schemes: driven by
impact of Hurricanes Gloria (1985) & Bob (1991)
• 1985-1998: ~ 1500 reclosers installed
in CT & MA
• 1999-date: added D-SCADA
~ 1500 more reclosers added
retrofit existing reclosers adding
D-SCADA capability.
• Need for Sub-Zone sectionalizing:
driven by rash of recent storms - Hurricanes
Irene (2011) & Sandy (2011), Winter Storms
Halloween (2011), & NEMO (2013)
• Unable to expand existing recloser loop
schemes.
Need a new sub-sectionalizing device that
can work within existing system design
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Eversource Energy
• Recloser Loop Schemes:
• Sectionalizing Recloser (SR) – opens to
isolate downstream load from a bad supply
• Tie Reclosers (TR) 1-way & 2-way –
closes to resupply isolated customers from
alternate, good sources.
• Mid-point Reclosers (MR) – remains
closed throughout - adjusts overcurrent
settings based upon direction of supply.
• Technology upgrades
• D-SCADA on 90% of reclosers for
remote switching.
• Achieved Benefits
Typical Eversource Energy one-line diagram
Fault Hunting Using Three-Phase Reclosers
• Minimize customers affected by outage
(average <500 customer/zone)
• SAIDI (CT: 2013 storms excluded)
• 86.3 minutes (TOTAL)
• 54.7 additional SAIDI minutes avoided
by loop operations (39% reduction)
• Minimizes momentary outages
• Reduce fault location time
IEEE REPC 2015
Eversource Energy
Problem: Large customer zones in locations where additional recloser
installations are not possible. (Coordination not possible, lack of alternate supplies)
Existing Loop between 2 Supplies
Supply 1
with
Multiple upstream
protective devices
Zone 1
Zone 2
Zone 2b
Zone 2a
SR
S1
Zone 2c
Zone 2d
S3
S2
N.C.
CIRCUIT 1/ CIRCUIT 2 LOOP
Supply 2
with
Multiple upstream
protective devices
N.O. TR
Zone 1
SR
N.C.
Zone 2a
S1
Zone 2b
S2
Zone 2c
S3
Zone 2d
Zone 2
Objective: Develop a new sectionalizing device,
compatible with existing schemes which can operate
without any communications to other devices.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
New Sub-Sectionalizing Device
Considerations for Design of Smart Switch
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Must be compatible with the existing loop & radial distribution system.
Minimize impact on existing overcurrent protection & coordination.
Minimize impact on settings/operation of existing equipment.
D-SCADA capable for switching.
Communications not required for loop operation.
Compare favorably with the capabilities, cost, and complexities of a
peer-to-peer or communications-based sectionalizer/switch.
Simple & flexible design to facilitate future system changes.
Emphasis on Reliability (service restoration)…
… which can take precedence over Power Quality (fault clearing &
automatic reclosing).
Overcurrent Protection element which can be activated momentarily
during loop restoration phase.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Smart Switch Application – Key Points
Normally NO OVERCURRENT PROTECTION
• Fault Clearing & Automatic Reclosing performed by upstream
devices.
Both SECTIONALIZING & RESTORATION capabilities.
• Smart Switch operates only to SECTIONALIZE after a permanent
fault occurs on the circuit, and then CLOSES when power is
RESTORED.
MOMENTARILY active OVERCURRENT PROTECTION
• Following a restoration close, it may close into a faulted zone.
• At that time, it must have fault interrupting capability (coordinated
with upstream protective devices).
• Achieved with momentarily activated Fast/Instantaneous OverCurrent Protection used only following a loop restoration attempt.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Smart Switch Control (Form 6/LS Platform)
Original Recloser Control
New Smart Switch Control
Overcurrent
Protection
Momentary
Overcurrent
Protection
Automatic
Reclosing
No
Reclosing
Loop Scheme Logic:
Sectionalization &
Restoration
Add necessary
behavior & timing to
Loop Scheme Logic
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Smart Switch Settings
• Requires only a few settings
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Loss of Voltage OPEN timer (range: 5-90 seconds)
Return of Voltage CLOSE timer (range: 0-60 sec)
Maximum Time to Close (range: 1-300 seconds)
Protection Active Timer (range: 0-30 seconds)
Maintain Protection beyond Protection
active Time
• Close Conditions: Live-Dead, Dead-Live, Live-Live
• Temporary Phase & Ground Overcurrent
Settings
• Provide Flexibility for use in:
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Looped or Radial Systems
Can accommodate fuse-saving schemes
Can be used on backbone or side-taps/laterals
Overcurrent Settings can be adjusted to remain above expected inrush
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Demonstration of Smart Switch Operating Sequence:
B1
Zone 1
SR
Zone 2
Good 3 Phase Voltage
S1
Zone 3
S2
Zone 4
TR
B2
S1
1) Normal Condition: Switch is closed, no active protection (will
not trip on any fault). Manual and DSCADA operation possible. No
HLT possible.
Loss of 3 Phase Voltage
S1
LOV Timer ~ 40 sec
2) Sectionalize: Switch will ONLY respond to a 3 Phase Loss of
Voltage. If a sustained loss of 3-phase voltage occurs, the switch
will TRIP on Loop Logic.
Max Time to Close ~ 65 sec
Switch Open & Waiting
S1
3) Restoration: For a period of time the switch looks for a return
of 3 Phase Voltage on either SOURCE or LOAD.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Demonstration of Smart Switch Operating Sequence: (cont.)
B1
Zone 1
SR
Zone 2
Return of 3 Phase Voltage
S1
S1
Zone 3
S2
Zone 4
TR
B2
Max Time to Close ~ 65 sec
Ret of Volt Timer ~ 3 sec
4) Return of Voltage: If a sustained 3 Phase Voltage returns on
either source or load side, the switch will prepare to CLOSE.
FAST TRIP
Good 3 Phase
PROTECTION
ACTIVE
Voltage
2 sec
S1
5a) Close (succeed): Upon closing,
O/C protection momentarily active
(2 seconds). If successful, device
resets to Normal Condition,
remains closed, with loop enabled
Fault Hunting Using Three-Phase Reclosers
Good 3 Phase
Voltage
FAST TRIP
PROTECTION
ACTIVE
2 sec
S1
5b) Close (fail): If device closed
into a Fault, It will TRIP and
LOCKOUT, loop disabled. Manual
reset required.
IEEE REPC 2015
Smart Switch Operation - Summary
• Sequence allows “Fault Hunting” to resupply power
• Applicable for either radial or loop sectionalizing systems
• Multiple Smart Switches may be applied in series
• All Smart Switches open on loss of voltage for isolation
• Resupply power to zones by sequentially closing upon return of voltage
(ROV)
• ROV closing interval is LIMITED by a separate “Max Time to
Close” timer, which will disable all automatic operation if
voltage has not returned within the user specified time.
• Inrush/Fault concerns can be addressed by fully
configurable overcurrent settings.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Smart Switch Loop Sectionalizing Application
Permanent
Fault
Reclosing:
1st = 30 sec,
2nd = 47 sec
B1
Zone 1
SR
Zone 2a
S1
Zone 2b
LOV Timer = 40 sec
S2
Zone 2c
LOV Timer = 40 sec
S3
Loop Close Timer =
60 sec
Zone 2d
TR
B2
LOV Timer = 40 sec
• SR – Trips on fault, 1st reclose interval (30 sec) begins
• SR – Recloses (@ 30 sec); trips on fault, 2nd reclose interval
(an additional 47 sec) begins. Likely permanent mainline fault.
• S1, S2, and S3 - All Open due to sustained (40 sec into the 47
second SR’s 2nd Reclose interval) loss of 3ph source & load
voltage
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Smart Switch Loop Sectionalizing Application
Permanent
Fault
Reclosing:
1st = 30 sec,
2nd = 47 sec
B1
Zone 1
SR
Zone 2a
S1
Zone 2b
ROV Timer = 3 sec
S2
Zone 2c
ROV Timer = 3 sec
S3
Loop Close Timer =
60 sec
Zone 2d
TR
B2
ROV Timer = 3 sec
• SR – Recloses at 47 seconds energizing up to S1.
• S1 – After SR recloses, S1 senses return of 3ph source voltage and
3 seconds later (2nd SR reclose + 3 sec) closes up to open S2.
• S2 – After S1 closes, S2 senses return of 3ph source voltage and 3
seconds later (2nd SR reclose + 6 sec) closes into fault – trips and
locks out.
• TR – Following sustained (60 sec) loss of 3ph voltage, TR closes
and back feeds up to S3.
• S3 – After TR closes, S3 senses return of 3ph load voltage and 3
seconds later (TR close + 3 sec) closes into fault – trips and locks
out.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Smart Switch Radial System Application
Reclosing:
1st = 2 sec,
2nd = 5 sec,
3rd = 15 sec
ROV Timer = 3 sec
Permanent
Fault
O/C Active Timer = 2 sec
B
R
Zone 1
S1
Zone 2
LOV Timer = 10 sec
Zone 3
• B – Substation Breaker does not trip, coordinated with line Recloser R.
• R – Initial trip on fault, 1st trip (fast curve – fuse saving scheme), 1st reclose
interval (2 sec) begins.
• R - 1st reclose: trips on fault, 2nd trip (slow curve), 2nd reclose interval (5 sec)
begins, (fault is on the mainline, not on a lateral).
• R - 2nd reclose: trips on fault, 3rd trip (slow curve), 3rd reclose interval (15 sec)
begins. (Likely permanent mainline fault – need to sectionalize).
• S1 – Opens due to sustained loss of three-phase voltage (10 seconds).
• R - 3rd reclose at 15 seconds energizing up to S1.
• S1 – After R recloses, senses return of 3ph source voltage and 3 seconds
later closes into fault – trips and locks out.
In a radial application, the smart switch will only be a benefit for load side faults.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Conclusions
• New option to sectionalize a circuit where a recloser is
not feasible.
• Stand-alone autonomous operation does not require
communications to work.
• Easily engineered into existing systems.
• Easily accommodates future circuit design changes.
• Future application: Introduces the concept of using a
fast/instantaneous overcurrent element, momentarily
activated, for automatic-reclosing & loop restoration
closing. Potential means of managing let-thru fault
energy to circuit segments that are likely faulted.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Thank You!
Fault Hunting Using ThreePhase Reclosers
Michael S. Costa
Eversource Energy
Jerome V. Josken
UC Synergetic
IEEE Rural Electric Power Conference
Ashville, North Carolina
April 19-21, 2015
Dennis A. Walder
Eaton
Feeder Sectionalizing StagesDELETE SLIDE #7
Stages of Distribution Feeder Sectionalizing by Equipment Type
Loop Scheme
Peer to Peer Remote
Traditional
Loop Scheme Traditional
Sectionalizing
Sectionalizer/ Operated
Recloser
Tie Recloser Sectionalizer
Recloser
Switch
Switch
Isolation
X
X
X
Verification
X
X
X
Sectionalization
X
Restoration
Optimization
X
X
*
*
*
*
Smart
Switch
X
X
X
X
*
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*
* With addition of communications via DSCADA or DMS system
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Smart Switch Application
OLD SLIDE #8
Replaced with current slide #7
• Fault Isolation and Verification remains with
existing reclosers.
• New Smart Switch design focuses on
Sectionalization and Restoration of circuit.
• Eliminates the impact on overcurrent coordination
• Operating sequence occurs only for a permanent fault
- working after fault isolation & verification (reclosing
sequence) phases are complete.
• Fast/Instantaneous Protection used only momentarily
during restoration.
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015
Selected Smart Switch DesignDELETE SLIDE #9
• New Smart Switch Mode for Recloser/Control
• Using Form 6/LS Recloser Control as the base platform.
• Modified Firmware, and Programing Logic for recloser control.
• Sectionalization:
• Sub-sectionalize zone for permanent fault,
• Switch opens on configurable loss of voltage timing
• Restoration:
• Switch closes upon return of 3-phase voltage (either source or load side)
• Resupplies power to isolated, unfaulted zones
• Isolates outage in faulted zones (Momentary fault overcurrent trip/lockout)
• Minimal control panel modifications to support existing
operating procedures
Fault Hunting Using Three-Phase Reclosers
IEEE REPC 2015