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ON IT
Consolidated Edison’s Experience with On-line
Monitoring and Mitigation of Geomagnetic Disturbances
Gary R. Hoffman, Advanced Power TechnologiesSam Sambasivan, Consolidated Edison
Vincenzo Panuccio, Consolidated EdisonMypsicon, November 2016
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Agenda
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• Overview of GIC Activities at Con Edison
• Selecting the vulnerable transformers
• GIC Monitoring according to IEEE Std. C57-163-2015
• GIC Modeling of 345 kV Autotransformers
• Results of Analysis
• Conclusion
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Selection of Vulnerable Transformers According to IEEE Std C57.163-2015
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• Total susceptibility to effects of GIC is determined by:
– Transformer Design – Based Susceptibility
– GIC Level – Based Susceptibility
• Design – Based Susceptibility
– Category – A: Transformers not susceptible to effects of GIC
– Category – B: Transformers least susceptible to core saturation
– Category – C: Transformers susceptible to core saturation and structural parts overheating
– Category – D: Transformers susceptible to both core saturation as well as possible damaging windings and / or Structural parts overheating
• GIC – Level susceptibility divides transformers into 3 categories: Three ranges of GIC levels (High, Medium, and Low)
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Selection of Vulnerable Transformers at Con Edison
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• Which Transformers to Monitor– Conducted review of 2012 EPRI Sunburst data
– Commissioned a CEATI study to rank transformers based on GIC susceptibility
– Conducted comparison of highest observed GIC levels at Con Edison and results given by GIC calculation study conducted by CEATI
– Selected transformers based on these results
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Location Core Design CEATI Relative Ranking(GIC)
Transformer 1 Shell Form 1
Transformer 2 Shell Form 2
Transformer 3 Shell Form 2
Transformer 4 Shell Form 3
Transformer 5 Shell Form 3
Transformer 6 Shell Form 4
Transformer 7 Shell Form 4
Transformer 8 Shell Form 5
Transformer 9 Shell Form 6
Transformer 10 Shell Form 5
Transformer 11 Shell Form 5
Transformer 12 Shell Form Not modeled in CEATI study
• GIC Susceptible Transformers
Selection of Vulnerable Transformers at Con Edison
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GIC Monitoring
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• Why Monitor?– Provides the ability to see real time what is happening when GIC
events occur
– Continuous monitoring and operation response procedure is an effective and less costly alternative to both passive and active blocking schemes.
– Provides the gathering of data for post event analysis to help us better understanding system strengths and weaknesses during a GMD event
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GIC Monitoring
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• Monitoring According to IEEE Std. C57.163-2105
─ Measure GIC of neutral current
─ Measure harmonics on bushing CTs
─ Deploy GIC or part-cycle core saturation detection
─ Place fiber optic temperature sensors at strategic locations on new and re-built transformers
─ Perform DGA of transformers when there is evidence of part-cycle core saturation at elevated levels of GIC
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GIC Monitoring
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• GIC & Harmonics According to IEEE Std. C57.163-2105
─ GIC is quasi-dc that requires ultra low frequency measurement of GIC from X0, H0, Y0, or X0H0 bushing
─ Hall effect current sensors desensitized at power system frequency is recommended
─ Monitor current harmonics in three-phase transformers on the outer pahases
─ The magnitude of even current harmonics due to part-cycle core saturation dominate odd current harmonics1
1 US Patent 9,018,962 and Foreign Patents Pending
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GIC Monitoring
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• Typical GIC Waveform
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0
10
20
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GIC,
Amp
sADC
IEEE Std C57-163-2015™- Reprinted with permission from IEEE. Copyright IEEE 1983-2015. All rights reserved. Any comments or interpretations of the Material are the Author’s and do not represent the views of IEEE, its members or affiliates.
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GIC Monitoring
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• Typical GIC Waveform
IEEE Std C57-163-2015™- Reprinted with permission from IEEE. Copyright IEEE 1983-2015. All rights reserved. Any comments or interpretations of the Material are the Author’s and do not represent the views of IEEE, its members or affiliates.
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GIC Monitoring
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• Current Harmonic Order of Part-Cycle Core Saturation
IEEE Std C57-163-2015™- Reprinted with permission from IEEE. Copyright IEEE 1983-2015. All rights reserved. Any comments or interpretations of the Material are the Author’s and do not represent the views of IEEE, its members or affiliates.
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GIC Monitoring
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• Part-Cycle Core Saturation Detection on Three-phase Auto
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• How we Monitor?– Comprehensive GIC monitoring
device installed at all vulnerable transformers
– Device monitors:
– Temperature
– Load Current
– Harmonics
– DC Neutral Current
– Device collects data and generates alarms that operations uses to determine system status and take action during GIC events
GIC Monitor
GIC Monitoring
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Operation Response Procedure • Level 1 Alarm- Measured neutral GIC current
exceeds a threshold after a preset time delay– Operator action -Notify Substation operator,
monitor GIC currents and temperatures at all monitored transformer locations
– Report findings to Engineering.
• Level 2 Alarm (OOE Category 2) – Level 1 Alarm plus high level of harmonics- this indicates core saturation – Operator action - De-load the transformer,
monitor temperatures – Report findings to Engineering.
• Level 3 Alarm (OOE Category 1) - Level 2 Alarm plus transformer temperature exceeding temperature guideline – Operator action – Remove the transformer
from service – Report findings to Engineering.
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Monitored Metrics
Neutral Current and Temperature are analog values.
Harmonics point is a digital point. If total harmonic distortion goes above threshold, the point will switch from Normal to Alarm Up.
Alarms
Alarms are digital points. If thresholds are exceeded the point will switch from Normal to Alarm Up.
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GIC Monitoring
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LOCATION NEUTRAL CURRENT TEMPERATURE HARMONICS ALARMS
Minor Major Critical
Transformer 1 2.02 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 2 -1.20 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 3 -2.04 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 4 -3.30 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 5 2.02 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 6 -1.70 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 7 2.02 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 8 20 A 98.99 DEG C NORMAL ALARM UP NORMAL NORMAL
Transformer 9 1.32 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 10 -3.43 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 11 2.88 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 12 -3.00 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 13 2.04 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 14 -3.10 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
Transformer 15 1.45 A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL
GEO-MAGNETIC DISTURBANCE DISPLAY
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• High voltage transmission system
• Substation Model: Longitude & latitude & ground grid resistance
• Transmission line DC resistance
• Transformer, shunt reactor and phase angle regulator winding DC resistances
GIC Flows, Power Flow, Thermal Analysis of Transformers
GIC Modeling
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• Software Validation– GIC analysis & load flow software
– IEEE Benchmark test case (GIC Flow)
• DC Model of High Voltage Transmission System (GIC Network Model)
• Model Validation – Rotate E-Field from 0o to 180o
– Compare simulated neutral currents to measurements
GIC Modeling
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PT-1 max E-field estimated by year
Max
E-fi
eld
by y
ear f
or v
ario
us re
gion
s (m
V/km
)
• Study Database– NYISO planning model, load flow base case modified for Con Edison peak
load– Geographic Long.=74W, Geographic Lat.=41N (Mag. Lat=48) corresponds to
Piedmont (PT-1) region from US Geological Survey (USGS) – Conductivity High for PT-1 Region– Geo-electric fields (E-field) since 1985 less than 2V/km (USGS)
GIC Modeling
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• Transmission Perf. During GMD Draft TPL-007-1 standard:
Epeak =8 × 𝛼 × 𝛽 (V/km)
Epeak =8 × 0.3 × 1.17 V/km= 2.28 V/km
8 V/km is a reference peak geoelectric field amplitude derived from
statistical analysis of historical magnetometer data
𝛼 scaling factors to account for local geomagnetic latitude
𝛽 scaling factors to account for local earth conductivity
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GIC Modeling
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• GIC Flows Analysis– Simulation done at 1 V/m electric field
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TransformerNeutral GIC Flows in Ampere for Different Electric Field
Orientation0o 15o 30o 45o 60o 75o
TR1 0.92 0.83 0.68 0.48 0.26 0.01TR2 1.5 2.18 2.71 3.05 3.19 3.11TR3 2.05 2.37 2.53 2.51 2.33 1.98TR4 1.87 2.26 2.49 2.56 2.45 2.17TR5 0.31 0.2 0.08 0.05 0.17 0.29TR6 7.91 9.68 10.8 11.2 10.8 9.68TR7 5.21 5.18 4.8 4.1 3.11 1.91TR8 5.21 5 4.44 3.59 2.48 1.22
*No peak losses observed between 90o and 135o, thus was not reported in table
Results of Analysis
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• Measured GICs For Some 345 kV Transformers– Example neutral current readings for July 14, 2013 disturbance
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K5 reported by NOAA
Results of Analysis
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• Measured GICs For Some 345 kV Transformers– Neutral current readings
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TransformerTransformers neutral current readings
July 14, 2013 8:50PMApprox. K5
July 14, 2013 9:03AMApprox. K5
TR1 3.4 -4.701TR2 0.8 -0.2TR3 0.8 -0.3TR4 0 -0.3TR5 3.7 -6.401TR6 -- --TR7 6.581 -5.221TR8 -0.1 5.801TR9 8.27 -6.623TR10 13.051 -14.852TR11 0 -0.7TR12 -3.998 4.853TR13 -1.2 -0.2TR14 -- --
Results of Analysis
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• Simulated vs. Measured GICs For Some 345 kV Transformers– Stronger correlation for E-field pointing Eastward (around 90o)
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Results of Analysis
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•US Geological Survey (USGS) E-field estimations –USGS E-field estimations show no prevalent direction
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Ey (North) in mV/km
Ex (East) in mV/km
E-Field Direction at Each Minute from July 14, 2013 Event
Results of Analysis
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• Simulated vs. Measured GICs For Some 345 kV Transformers– USGS E-field estimations show no prevalent direction (provided
direction may be VERY off, but consistently off according to USGS)
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0
2
4
6
8
10
12
14
16
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0 1 2 3 4 5 6 7 8
Ey (N
orth
) in
mV
/km
Ex (East) in mV/km
E-Field Orientations
July 14, 2013 at 9:03PMJuly 14, 2013 at 8:50PM
Results of Analysis
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Conclusion
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• Completed transformer vulnerability assessments
• Completed GIC capability evaluations
• Completed installation of GIC part-cycle core saturation detection monitors at 14 locations
• Implemented system operation response to GIC
• Completed GIC network model and flows for the 345 kV transmission system including autotransformers, PARs and shunt reactors
• Further work needs to be done with gathering more detailed event data and correlating it to model results.
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Thank you!