fault hunting using three-phase reclosers michael s. costajerome v. joskendennis a. walder...
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Fault Hunting Using Three-Phase Reclosers
Michael S. Costa Jerome V. Josken Dennis A. WalderEversource Energy UC Synergetic Eaton
IEEE Rural Electric Power ConferenceAshville, North CarolinaApril 19-21, 2015
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
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:• 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 EnergyHistory: Reliability Improvements – Distribution Automation
Need a new sub-sectionalizing device that can work within existing system design
• 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 addedretrofit 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.
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
Eversource Energy
Typical Eversource Energy one-line diagram
• 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• 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
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
Eversource Energy
Objective: Develop a new sectionalizing device, compatible with existing schemes which can operate
without any communications to other devices.
S1SRZone 1
TR
S1SR
S2
S2
S3
S3
Zone 2
Zone 1
Zone 2a Zone 2b Zone 2c Zone 2d
Zone 2a Zone 2b Zone 2c Zone 2d
Supply 1 with Multiple upstream protective devices
Problem: Large customer zones in locations where additional recloser installations are not possible. (Coordination not possible, lack of alternate supplies)
Supply 2 with Multiple upstream protective devices
Existing Loop between 2 Supplies
N.C.
N.C.
N.O.CIRCUIT 1/ CIRCUIT 2 LOOP
Zone 2
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
New Sub-Sectionalizing DeviceConsiderations for Design of Smart Switch
• 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.
Considerations for Design of Smart Switch• 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 PointsNormally 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 Over-
Current Protection used only following a loop restoration attempt.
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
Smart Switch Control (Form 6/LS Platform)
Automatic Reclosing
Loop Scheme Logic:Sectionalization &
Restoration
Overcurrent Protection
Momentary Overcurrent Protection
NoReclosing
Original Recloser Control New Smart Switch Control
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
• 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: • 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
S11) Normal Condition: Switch is closed, no active protection (will not trip on any fault). Manual and DSCADA operation possible. No HLT possible.
Good 3 Phase Voltage
S12) 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.
Loss of 3 Phase Voltage LOV Timer ~ 40 sec
S13) Restoration: For a period of time the switch looks for a return of 3 Phase Voltage on either SOURCE or LOAD.
Switch Open & Waiting Max Time to Close ~ 65 sec
S1B1 B2SR TRZone 1 Zone 2 Zone 3 Zone 4 S2
Demonstration of Smart Switch Operating Sequence:
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
S1
4) Return of Voltage: If a sustained 3 Phase Voltage returns on either source or load side, the switch will prepare to CLOSE.
Return of 3 Phase Voltage Max Time to Close ~ 65 sec
Ret of Volt Timer ~ 3 sec
S15a) Close (succeed): Upon closing, O/C protection momentarily active (2 seconds). If successful, device resets to Normal Condition, remains closed, with loop enabled
Good 3 Phase Voltage
FAST TRIPPROTECTION ACTIVE 2 sec
Good 3 Phase Voltage
S15b) Close (fail): If device closed into a Fault, It will TRIP and LOCKOUT, loop disabled. Manual reset required.
FAST TRIPPROTECTION ACTIVE
2 sec
B1 B2SR TRZone 1 Zone 2 Zone 3 Zone 4 S2S1
Demonstration of Smart Switch Operating Sequence: (cont.)
Fault Hunting Using Three-Phase Reclosers 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
• 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
Smart Switch Loop Sectionalizing Application
S1B1 B2SR TRS2 S3SR S1 S2 S3 Zone 1 Zone 2a Zone 2b Zone 2c Zone 2d
SRSR
PermanentFault
Reclosing:1st = 30 sec,2nd = 47 sec
LOV Timer = 40 sec LOV Timer = 40 sec LOV Timer = 40 sec
Reclosing:1st = 30 sec,2nd = 47 sec
Reclosing:1st = 30 sec,2nd = 47 sec
Loop Close Timer = 60 sec
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
TRTR
• 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.
Smart Switch Loop Sectionalizing Application
S1SR S2 S3SR S1 S2 S3S2 S3 Zone 1 Zone 2a Zone 2b Zone 2c Zone 2d
B1 B2
PermanentFault Loop Close Timer =
60 sec
ROV Timer = 3 sec ROV Timer = 3 sec ROV Timer = 3 sec
Reclosing:1st = 30 sec,2nd = 47 sec
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
R
Smart Switch Radial System Application
• 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.
B S1Zone 1 Zone 2 Zone 3
S1RRRRRR S1S1
PermanentFault
LOV Timer = 10 sec
Reclosing:1st = 2 sec,2nd = 5 sec,3rd = 15 sec
Reclosing:1st = 2 sec,2nd = 5 sec,3rd = 15 sec
Reclosing:1st = 2 sec,2nd = 5 sec,3rd = 15 sec
Reclosing:1st = 2 sec,2nd = 5 sec,3rd = 15 sec
LOV Timer = 10 sec
ROV Timer = 3 sec
O/C Active Timer = 2 sec
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.
Thank You!
Fault Hunting Using Three-Phase Reclosers
Michael S. Costa Jerome V. Josken Dennis A. WalderEversource Energy UC Synergetic Eaton
IEEE Rural Electric Power ConferenceAshville, North CarolinaApril 19-21, 2015
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
Stages of Distribution Feeder Sectionalizing by Equipment Type
Traditional
Recloser
Loop Scheme
Sectionalizing
Recloser
Loop Scheme
Tie Recloser
Traditional Sectionali
zer
Peer to Peer
Sectionalizer/ Switch
Remote Operate
d Switch
SmartSwitch
Isolation X X X
Verification X X X
Sectionalization
X X X X
Restoration
X X X
Optimization
* * * * * * *
Stages of Distribution Feeder Sectionalizing by Equipment Type
Traditional
Recloser
Loop Scheme
Sectionalizing
Recloser
Loop Scheme
Tie Recloser
Traditional Sectionali
zer
Peer to Peer
Sectionalizer/ Switch
Remote Operate
d Switch
Isolation X X X
Verification X X X
Sectionalization
X X X
Restoration
X X
Optimization
* * * * * *
* With addition of communications via DSCADA or DMS system
Feeder Sectionalizing StagesDELETE SLIDE #7
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
Smart Switch Application
• 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.
OLD SLIDE #8Replaced with current slide
#7
Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015
Selected Smart Switch Design• 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
DELETE SLIDE #9
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