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
Generation
Function
Transmission
Georgia
Transmission
Function
Distribution
Cooperatives - 39
Oglethorpe
Power
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.
2.
3.
Phone lines
Satellite
Radio signals
DFR (USI)
SEL Relays
SEL-551
SEL-587
SEL-351S
PMU (SEL)
SEL-351A (With
PMU)
Line Loading Device (GridSense)
Substation Transformer Monitor (GridSense)
Fault Indicator (PDP)
FALLS Lightning Study Map
SAIDI Trend
35
Minutes Of Outage Time Per Customer
Yearly SAIDI
30
5 Year Average
Trend (5 Yr Avg)
25
23.17
GOOD
19.41
20
17.29
15
15.61
15.06
13.20
13.64
11.77
10
10.15
11.37
10.57 10.26
9.490
7.506
5
0
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
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)
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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
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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)
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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
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GTC hosted server similar to DFRs
Allows access to relay data
Cyber Security considerations
Does send emails
Power Quality Program
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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
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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
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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?