Fault Hunting Using Three-Phase Reclosers Michael S. CostaJerome V. JoskenDennis A. Walder...

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


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.


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


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


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.


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.


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


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


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:


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


FAST TRIPPROTECTION ACTIVE 2 sec


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.)


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.


• 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



Loop Close Timer = 60 sec


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



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




LOV Timer = 10 sec

ROV Timer = 3 sec

O/C Active Timer = 2 sec


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


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


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


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

Fault Hunting Using Three-Phase Reclosers Michael S. CostaJerome V. JoskenDennis A. Walder...

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