Georgia Transmission Corporation (GTC)

Reliability Initiatives

GSU Presentation

September 2012

Douglas O. Maddox

• Manager – System Reliability• Started as distribution & lighting engineer • Manages a department of six engineers and

coop student• (1) Power Quality / Digital Fault Recorder (DFR) • (2) Clearance Mitigation staff• (1) Outage investigator • (1) Benchmarking and results reporting • (1) Trending and programs

GTC Background

• Created from Oglethorpe Power Corporation (OPC) reorganization in 1997

• New smaller Board of Directors with outside directors

• Reliability is job one• Keep improving until we say stop• Continuous feedback on reliability • Measure, report, and benchmark data• Reduce frequency and duration of outages

This Presentation

• Illustrates how GTC reliability improvement is built upon the technology of remote sensing, monitoring, and control equipment

• Explains how GTC fits in to the overall utility structure in Georgia

• IS NOT about preventing widespread blackouts or new FERC/ NERC ERO standards

Functions and types of Georgia’s electric utilities

Georgia Utilities Function Function Function

Generation Transmission Distribution

Cooperatives - 39 Oglethorpe Power

Georgia Transmission

Individual EMCs

Municipals ~ 48 MEAGPower MEAGPower Individual Cities

Investor Owned -Georgia Power

GPC GPC GPC

Cooperatives - 3 TVA TVA TVA

Georgia EMC Service Areas

Remote Sensing Equipment

• First generation of sensors was end-user notification – power problem or outage

• Equipment had no remote monitoring or control• Relays were sensors but had no remote status or control• Fuses and reclosers were down line sensors – no remote

status• Outage notification via postcard, letter, phone call, visit,

etc.• SCADA – supervisory control and data acquisition • AMI – automated metering infrastructure • Outage management systems - call in and tie to

Geographic Information Systems (GIS)• Facebook, twitter, web sites

Power Circuit Breakers

Gas Oil Vacuum

Electromechanical Relays

Fuses (Southern States)

Recloser (Joslyn)

Meters

Electromechanical Meter

AMI Meter

SCADA

RTU Control Panel

Remote sensors - continued

• Electronic relays and Digital Fault Recorders (DFRs)• Fault indicators • Fault Analysis and Lightning Location (FALLS)

lightning data & weather data • Phasor measurement units (PMUs)• Line loading and monitoring• Substation monitors• Telecommunications

1. Phone lines

2. Satellite

3. Radio signals

DFR (USI)

SEL Relays

SEL-551

SEL-351S

SEL-587

PMU (SEL)

SEL-351A (With PMU)

Line Loading Device (GridSense)

Substation Transformer Monitor (GridSense)

Fault Indicator (PDP)

FALLS Lightning Study Map

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 20110

5

10

15

20

25

30

35

23.17

15.61

19.41

15.06

17.29

13.20 13.64 11.77

10.1511.37 10.57 10.26 9.49

7.51

SAIDI TrendYearly SAIDI

5 Year Average

Trend (5 Yr Avg)

Min

ute

s O

f O

uta

ge

Tim

e P

er

Cu

sto

me

r

GOOD

MAIFI

• One minute definition of sustained outage vs. momentary outage is < one minute

• Lightning normalized (Georgia Integrated Transmission System {ITS} standard)

• Found our ITS lines did not live up to stated Basic Insulation Level (BIL) levels of protection vs. stroke magnitude (older approach of 115 kV survives 30 kA strike)

• Electric Power Research Institute (EPRI) T- Flash program

• GTC standard 115 kV t/l design would have 3 momentary per year

Wins and Losses

• Results vary based on philosophy & location• Great results Metal Oxide Varistors (MOVs) for

Homeland –Macedonia Primary (3 per structure) from 8 to <1 momentary outage per year – only strikes >100 kA flashed the line

• Terrible results for Douglas – Stump Creek (Black) – distribution pattern of 3-1-1-1 did not work, nor does 3-0-0 work

• Early fault indicator success – then false alarms• Special 115 kV FI failed lab and field tests

T/L Arresters

Standard GTC 115 MOV approach

• Most structures are single poles • Most structures have vertically mounted

phases• T-Flash predicts “O” outages per year with 3

MOV per pole• T- Flash predicts 0.16 outages per year with 2

MOV per pole• GTC generally will save one MOV per pole to

stretch MOV funds• Installation Pattern is top and bottom phase

Early Benchmarking

• 2003 trip to Florida Power and Light (FPL) for Georgia Power, GTC, and our control centers

• FPL = 4 min SAIDI • GTC = 15 min SAIDI

Differences

Looped lines – two way feeds

Redundant transformers

Intelligent fault detection and location

Sustained Outage Programs

• GTC study found 75% of SAIDI is switching & restoring good loads; 25% is restoration

• Completed motorizing substation line switches• Completed grounding switch replacements• Nearly completed converting GTC’s pole

mounted manually operated switches to remote control

• Extensive DFR upgrades, installations, & minis• Replace obsolete switches• Replace Silicon Carbide lightning arresters

Sustained Outage (continued)

• Split long circuits• Modernize relaying (SEL)• Replace older breakers• Replace older transformers • Add reliability criteria to alternative selection

for capacity and voltage solving solutions• Normally Open Point analysis • Clearance mitigation efforts

Unfinished Sustained Outage Programs

• ITS grounding switches to be replaced• Convert pole switches from manual to remote control• One directional fault indicators to be installed • Bidirectional fault indicators – testing phase • Replacements for old technology arresters, first

generation MOVs• Replace older, obsolete switches• On line transformer monitoring • Carrier relaying, tuners, traps• Real time DTF from DFR and SELs• Supporting GPC (ITS) 46 kV enhancement program

Clearance Mitigation

• 2003 time frame• 25% of SAIDI and SAIFI under abnormal

conditions - clearances• Both construction & maintenance• Extended clearances• Too many clearances• Local equipment not in good condition

Clearance Mitigation (continued)

• Combine maintenance work with construction• Combine line, sub, and metering work• Combine ITS and EMC work• Send report to EMCs daily• Minimize abnormal time & mobile time• Check lines and subs before going abnormal• Contingency plans

Digital Fault Recorders (DFRs)

• Replaced old Rochester Brand Units• New USI brand units are Sequence of Events (SOE) &

DFR combination units, windows based, with data accumulator able to be connected to home office server

• New APP brand units initially bought for smaller subs and less capacity

• Allow GPC access to server & emails• Populate real time distance to fault data into SCADA• Go beyond minimal federally required locations• Tie DFRs to FALLS data server

Relay Data Server

• GTC hosted server similar to DFRs• Allows access to relay data• Cyber Security considerations• Does send emails

Power Quality Program

• Investigate transmission problems• Assist EMC customers with investigations• Temporary meters• Permanent meters• PQ data server – GTC and EMC access• Consultant on standby• AMI systems susceptible to PQ issues

Power Quality Meters

Temporary Permanent

MAIFI Improvements

• Overhead Ground Wire (OHGW) is installed on virtually all lines serving GTC loads

• Different workshops on lightning and grounding

• T/L MOVs• FALLS acquisition• ITS policy

FALLS

• Obtained our own subscription• Review momentary outages down to 46 level• Send reports to EMC• Keep up with YTD results• Keep up with MOV effectiveness• Use in T-Flash• Use for MOV pattern selection

Remote Sensor Issues

• Cost• Reliability• Ability to communicate• Battery life• Telecom path availability, capacity, and cost • Ability to install and maintain on energized

lines

Your Questions and comments?