catching falling conductors in midair –detecting and ... · v2 0.5 1 before break –1 v nom = 1...

©2019 San Diego Gas & Electric Company. Trademarks are property of their respective owners. All rights reserved.

Catching Falling Conductors in Midair – Detecting and Tripping Broken Distribution Circuit Conductors at

Protection Speeds

Kirsten PetersenSan Diego Gas & Electric®

• Approximately 6,500+ miles of overhead distribution line infrastructure

• Grounded three- and four-wire systems • Nominally 12kV and 4kV• High penetration of distribution PV requires new solutions

for monitoring, protection, and control

SDG&E® Overhead Distribution System

• Falling conductor protection (patented)• Driven by high penetration of distribution PV• Voltage profile monitoring and control • Selective load shedding and restoration• Power quality monitoring • Apparatus and system condition monitoring

Advanced SCADA Project ApplicationsMore Than 60 Use Cases Defined

• Increased accuracy of voltage and current • Phase angle measurements across circuit• GPS time-stamped data• 30 synchrophasor samples per second for fast

measurement (60 samples/sec in the future)• IEC 61850 GOOSE messaging for real-time control• Remote engineering access and event reports• Advanced security features

Advanced SCADA Features

SCADA System ArchitectureTraditional

Wide-Area Network

Backup Control Center

Security IP Gateway

Local-Area

Network

Mission Control Center

SecurityIP Gateway

Local-Area

Network

The illustrations herein were jointly developed by San Diego Gas & Electric, Quanta Technology, and Schweitzer Engineering Laboratories.

SCADA System ArchitectureAdvanced

Distribution Circuit Area

PDC

Substation

Security Module

Wide-Area Network


SCADA System ArchitectureTraditional and Advanced OverlayMission Control Center

SecurityIP Gateway

Local-Area

Network

Backup Control Center

Security IP Gateway

Local-Area

NetworkWide-Area Network

Traditional

AdvancedDistribution Circuit Area

Substation

Security Module

PDC


Private Long Term Evolution (LTE) Advancing Communication

Making FCP More Secure

SDG&E Typical Feeder

R1

N.O.

R2

PV

Five-Way Switch

Capacitor Bank

CB

Line Monitor

Capacitor Bank

Capacitor Bank

Substation


Advanced SCADA Locations

To Control Centervia WAN

P P

P

P

P

P

P

P

N.O.

P

P

P

Line Monitor

VR4

R1

P

VR1VR2

PV11 MW

PV21 MW

S

DVC

Feeder Relay

69 kV/12 kV

R3

VR6

VR3

R5 VR5

R4

C3

C2

C1

P

Substation

PDC and Controller Switchyard

Fiber

LEGEND

P IED With PMU and Ethernet

R Recloser

WAN Wide-Area NetworkN.O. Normally Open

PV Photovoltaic

DVC Dynamic VAR Compensator

VR Voltage Regulator

S Multiport Circuit Switch


0

5

10

15

20

25

30

0.00 0.25 0.50 0.75 1.00 1.25

Con

duct

or H

eigh

t (ft)

Time (s)

Falling Conductor Timeline

0.5 s, 4 ft

1 s, 16 ft

Conductor hits ground at 1.37 s

Detect Broken Conductor and Trip Circuit Before Line Hits the Ground?

= → =

=

≈

2 2dg

1d gt t22(30)t32.2

time 1.37s


Sequence Components Analysis

Ic1 Ib2

Ia2Ia1

Ib1 Ic2

Ia0

Ib0

Ic0Zero Sequence

Positive Sequence

Negative Sequence

Single Phase Balanced Balanced

Ic2 = a2Ia2Ic1 = aIa1

Ib1 = a2Ia1Ia0 = Ib0 = Ic0 Ib2 = aIa2


Open-Phase Analysis

jXTG

ZL

jXTHG HZ1GHX Y

I1G I1H

Z1S

E

N1

jXTG

ZL

jXTHG HZ1GHX Y

I2G I2H

Z2S

N2

jXTG

G HZ0GHX Y

I0G I0H

N0

jXTH


Open-Phase Analysis

Z1S = Z2S

jXTG

ZL

jXTH

G H

Phase A Open

LoadZ1GH, Z0GH

V1

V2 0.5 1

Before Break

–1

VNOM = 1 p.u.

1p.u.

–1

V0 V1V2

Phase A Break

–0.5 V0p.u.

0.5


• dV/dt (change detection) • V0 and V2 magnitude• V0 and V2 angle

Detection Methods

Central Logic Controller

C37.118

GOOSEControlsPMU3

PMU2

PMU1

PMU4

PDCPMU

Devices to Trip


dV/dt MethoddV0/dt Supervision CheckConductor Break

Between PMU 1 and PMU2

Trip PMU1

and PMU2

PMU1dV/dt

PMU2dV/dt

PMU3dV/dt

OR

PMU1 PMU2 PMU3dV0/dt

Between PMU 2 and PMU3

OR

Trip PMU2

and PMU3

X = threshold

> 0

< 0

< 0 < 0

< –X

> X

< X > X

> 0 > 0 < –X

> X

< X < X > X

< –X

> X

> XdV0/dtdV0/dt


V2 and V0 Magnitude Method

Between PMU1 and PMU2 Pickup Delay

Trip PMU2 and

PMU3

Between PMU2 and PMU3

< X < X > X

PMU1V2 (or V0) Magnitude

PMU2V2 (or V0) Magnitude

PMU3 V2 (or V0) Magnitude

< X > X > X

Trip PMU1and

PMU2

Conductor Break


V2 and V0 Angle Method

PMU1 PMU2 PMU3 PMU4

θ2 θ3 θ4

θ1

PMU1 PMU2 PMU3 PMU4

θ3 θ4

θ1 θ2

FC

θ1 not aligned with the other PMUs

θ1 and θ2 aligned with each otherθ3 and θ4 aligned with each other

Source 1 Source 2

Source 1 Source 2

FC

θ is V2 or V0 angleThe illustrations herein were jointly developed by San Diego Gas & Electric,

Quanta Technology, and Schweitzer Engineering Laboratories.

CB1

R1

PV

VR

CLM

L

REC

L

PV

PV

C CapacitorCB Circuit Breaker PMULM Line Monitor PMUL LoadPV PhotovoltaicREC Recloser PMUSW Five-Way SwitchVR Voltage Regulator

SW

CB

REC

L

VR VR

VR VR VRL

L

L L

CB

PV

CB

PV

CB

PV

C

C

C LEGEND

RTDS Feeder Model

Example Lab Test ResultsPV Off, Loop Open

Load % FC1 FC2 FC3 FC4100 3 3 3 375 3 3 3 325 3 3 3 3

PV On, Loop OpenLoad % PV% FC1 FC2 FC3 FC4

100

100 3 3 3 375 3 3 4 450 3 3 3 325 3 3 3 3

25

100 3 3 3 375 3 3 3 350 3 3 3 325 3 3 3 3R1

N.O.

R2

PV

Five-Way Switch

CB

Line Monitor

Substation

FC1FC2

FC4

FC3


0

10

20

0–99 100–199 200–299 300–399 400–499

Arc Speed = 5 m/s

FC1 FC2 FC3 FC4(ms)

Arc Speed and Results ComparisonNumber of Test Cases Versus dV/dt Pickup Times

0

10

20

0–99 100–199 200–299 300–399 400–499

Arc Speed = 0 m/s

FC1 FC2 FC3 FC4(ms)

The illustrations herein were jointly developed by San Diego Gas & Electric, Quanta Technology, and Schweitzer

Engineering Laboratories.

• Capacitor bank switching• Voltage regulator tap unbalance Angle method for ≈ 4.5% voltage (6 taps)

V0 magnitude method for ≈ 10% voltage (15 taps)

• Largest single-phase load switching• PV operation• Internal / external faults

Security Testing

Location

Method

PMU Status

GOOSE Trip

ResultsDetection Screen


• Conductor break between PMU1 and PMU2

• PV inverter source ON

Inverter Response

VA, VB, VC

V2

V0

V1

PMU1 PMU2


ResultsdV/dt and Magnitude Methods

dV/dt Detects V0 Magnitude Detects

V2 MagnitudeDetects

Conductor Break

Falling Conductor

Trip Command


• First system installation in January 2015• Falling Conductor Protection (FCP) in

monitoring mode• Simulation of conductor breaks with

disconnect switch opening on recloser• 100% correct operation• Ethernet radio tuning required

Field Installation and Testing

Breaking Arc – Field Versus Lab TestsField Result RTDS Model


Falling Conductor Zones

CIRCUITBREAKER

RECLOSERRECLOSER

LINE MONITOR

TRAYER SWITCH

PV

VzVyVyVz

Vv

N.O.

SUBSTATION

Zone 1 Zone 2Zone 3Zone 4

LEGEND

PMU

VOLTAGE REG

VOLTAGE REG


Synchrophasors show detailed circuit behavior Capacitive voltage sensor discoveries

11 kV

6.8 kV

2.8 kV/s

–1.7 kV/s

0

577 V/s

– 400 V/s

0

Pha

seA

Vol

t age

dVA

/ dt

dV0/

dt

Load Side

Source SideNominal

6.9 kV

Time

Time

Time

dVA /dt > 1000 V/s

dV0/dt > 400 V/s


dV/dt spikes at 1045R and 1048RZone 1 break detected

Zone 1 dV/dt Operation

• Field Event – 28th Feb 2016• FC detected by dV/dt between CB and R1


Phase-C current spikes at CB PMU

Phase-C current spikes at VR1

No current spikes observed at VR2

Zone 1 Current Spikes

• Current spikes observed at CB and VR1, but not at VR2

• Indicates temporary fault between VR1 and VR2


RTDS Simulation

CIRCUITBREAKER

RECLOSERRECLOSER

LINE MONITOR

TRAYER SWITCH

PV

VzVyVyVz

Vv

N.O.

SUBSTATION

Zone 1 Zone 2Zone 3Zone 4

LEGEND

PMU

VOLTAGE REG

VOLTAGE REG

Simulated Disturbance in RTDS - Phase C- SLG Fault (High Resistance)- 0.01 seconds duration- Speculated High Impedance Fault


• Threshold based on RTDS testing results• dI0/dt spikes at CB PMU used to block falling

conductor detection algorithms• Temporary faults can be blocked using this

supervision

dI0/dt Supervision

OR

System Fault

dI0/dt > Threshold*

Block FCP Schemes for 1 second


Algorithm picks up

Lab Simulation – Before dI0/dt

• Zone-1 mis-operation confirmed in lab

• dI0/dt block not implemented

• Mis-operation similar to field eventThe illustrations herein were jointly

developed by San Diego Gas & Electric, Quanta Technology, and Schweitzer


Mis-operations blocked by dI0/dt

Lab Simulation – After dI0/dt

• Zone-1 mis-operation simulated in lab

• dI0/dt blocks Falling Conductor scheme

• System abnormal alarm conditionThe illustrations herein were jointly

developed by San Diego Gas & Electric, Quanta Technology, and Schweitzer


System Protection is a Balancing Act

• SPEED• SENSITIVITY

• SELECTIVITY• SECURITY

FAST TO MINIMIZE DAMAGE

RELAY SEES FAULT

DO NOT TRIP FALSELY

REMOVE FAULTED ELEMENT ONLY

• SIMPLICITY SIMPLE CONTROL SCHEMES

FCP Compliments Existing Layers of Protection• FCP – Falling Conductor Protection detects break in conductor Fastest – trips before the fault Coordination – FCP should be first

• Overcurrent – Time and Instantaneous Simple coordination

• SGF – Sensitive Ground Fault detects high-impedance ground fault Slow – 3.5 to 5.5 seconds

• Advanced SGF - More sensitive than SGF using adaptive set point, spike counting, and/or harmonics Slower – > 5 seconds

• Does not detect wire down without break• Needs fast, secure, and available communication path to

circuit PMUs• Uses voltage from each protected circuit path end – a

journey of years for coverage • Learning features of new technology

FCP Limitations

Ease of Application

• Key requirement achieved – no circuit-dependent application settings

• FCP logic only needs topology of circuit and PMU IEDs

To Control Centervia WAN

P P

P

P

P

P

P

P

N.O.

P

P

P

Line Monitor

VR4

R1

P

VR1VR2

PV11 MW

PV21 MW

S

DVC

Feeder Relay

69 kV/12 kV

R3

VR6

VR3

R5 VR5

R4

C3

C2

C1

P

Substation

PDC and Controller Switchyard

Fiber

PMU1 PMU2 PMU3 PMU4

θ2 θ3 θ4

θ1

PMU1 PMU2 PMU3 PMU4

θ3 θ4

θ1 θ2

FC

θ1 not aligned with the other PMUs

θ1 and θ2 aligned with each otherθ3 and θ4 aligned with each other

Source 1 Source 2

Source 1 Source 2

FC


• Advanced SCADA has 60 use cases including FCP• FCP isolates broken conductors in 0.2 – 0.5 s (half the

distance to the ground) preventing the fault• FCP is dependable in lab test including high PV penetration• FCP mitigates HILP events – fire and hazard reduction • Confidence built from secure and reliable field performance• Compliments existing protection• Scalable design needs only circuit layout information

Summary

• FCP of first equipped circuit commissioned on 11/18/2016• Additional circuits equipped and commissioned in 2017• Pursuing ongoing work to reduce fire risk and enhance

public safety• Installing new IEDs with PMU capable devices with

moderate additional cost• SDG&E will be well positioned for future PV penetration• Overall goal of enabling FCP on 100% of HFTD circuits

Next Steps

Questions?

catching falling conductors in midair –detecting and ... · v2 0.5 1 before break –1 v nom = 1...

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