Fault Hunting Using Three-Phase Reclosers Michael S. CostaJerome V. JoskenDennis A. Walder Eversource EnergyUC SynergeticEaton IEEE Rural Electric Power Conference Ashville, North Carolina April 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 Energy History: 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) : ~ 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.

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. S1 SR Zone 1 TR S1 SR S2 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.O. CIRCUIT 1/ CIRCUIT 2 LOOP Zone 2

Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015 New Sub-Sectionalizing Device 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. 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 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 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 No Reclosing No Reclosing Original Recloser ControlNew Smart Switch Control Add necessary behavior & timing to Loop Scheme Logic

Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015 Smart Switch Settings

Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015 S1 1) 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 S1 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. Loss of 3 Phase Voltage LOV Timer ~ 40 sec S1 3) 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 S1 B1 B2 SR TR Zone 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 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 Good 3 Phase Voltage FAST TRIP PROTECTION ACTIVE 2 sec Good 3 Phase Voltage S1 5b) Close (fail): If device closed into a Fault, It will TRIP and LOCKOUT, loop disabled. Manual reset required. FAST TRIP PROTECTION ACTIVE 2 sec B1 B2 SR TR Zone 1 Zone 2 Zone 3 Zone 4 S2 S1 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, 1 st reclose interval (30 sec) begins SR – Recloses 30 sec); trips on fault, 2 nd 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 2 nd Reclose interval) loss of 3ph source & load voltage Smart Switch Loop Sectionalizing Application S1 B1 B2 SR TR S2 S3 SR S1 S2 S3 Zone 1 Zone 2a Zone 2b Zone 2c Zone 2d SR Permanent Fault Reclosing: 1 st = 30 sec, 2 nd = 47 sec LOV Timer = 40 sec Reclosing: 1 st = 30 sec, 2 nd = 47 sec Reclosing: 1 st = 30 sec, 2 nd = 47 sec Loop Close Timer = 60 sec

Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015 TR SR – Recloses at 47 seconds energizing up to S1. S1 – After SR recloses, S1 senses return of 3ph source voltage and 3 seconds later (2 nd SR reclose + 3 sec) closes up to open S2. S2 – After S1 closes, S2 senses return of 3ph source voltage and 3 seconds later (2 nd 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 S1 SR S2 S3 SR S1 S2 S3 S2 S3 Zone 1 Zone 2a Zone 2b Zone 2c Zone 2d B1 B2 Permanent Fault Loop Close Timer = 60 sec ROV Timer = 3 sec Reclosing: 1 st = 30 sec, 2 nd = 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, 1 st trip (fast curve – fuse saving scheme), 1 st reclose interval (2 sec) begins. R - 1 st reclose: trips on fault, 2 nd trip (slow curve), 2 nd reclose interval (5 sec) begins, (fault is on the mainline, not on a lateral). R - 2 nd reclose: trips on fault, 3 rd trip (slow curve), 3 rd 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 S1 Zone 1 Zone 2 Zone 3 S1 RRRRRR Permanent Fault LOV Timer = 10 sec Reclosing: 1 st = 2 sec, 2 nd = 5 sec, 3 rd = 15 sec Reclosing: 1 st = 2 sec, 2 nd = 5 sec, 3 rd = 15 sec Reclosing: 1 st = 2 sec, 2 nd = 5 sec, 3 rd = 15 sec Reclosing: 1 st = 2 sec, 2 nd = 5 sec, 3 rd = 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. CostaJerome V. JoskenDennis A. Walder Eversource EnergyUC SynergeticEaton IEEE Rural Electric Power Conference Ashville, North Carolina April 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 Sectionalizer Peer to Peer Sectionalizer/ Switch Remote Operated Switch Smart Switch Isolation XXX Verification XXX Sectionalization XXXX Restoration XXX Optimization ******* Stages of Distribution Feeder Sectionalizing by Equipment Type Traditional Recloser Loop Scheme Sectionalizing Recloser Loop Scheme Tie Recloser Traditional Sectionalizer Peer to Peer Sectionalizer/ Switch Remote Operated Switch Isolation XXX Verification XXX Sectionalization XXX Restoration XX Optimization ****** * With addition of communications via DSCADA or DMS system Feeder Sectionalizing Stages DELETE 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 #8 Replaced with current slide #7 OLD SLIDE #8 Replaced with current slide #7

Fault Hunting Using Three-Phase Reclosers IEEE REPC 2015 Selected Smart Switch Design DELETE SLIDE #9