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Bob Arritt, PE
Transmission Resiliency Summit Charlotte, NC3 April 2019
EPRI GMD Research Status
Update:Furthering the Research of GMD Impacts
on the Bulk Power System
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Agenda
EPRI GMD Overview
FERC/NERC GMD Project Update
Annual Research Portfolio (ARP) –GMD Vulnerability Assessments
DOE Geomagnetic Current (GIC) Blocker Demonstration
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Geomagnetic Disturbance Overview
Credit: NASA GSFC SVS
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GMD Research Portfolio
GMD Supplemental Project -
FERC/NERC GMD Project
ARP – GMD Vulnerability Assessments
SUNBURST & Adv. Sensors
• Benchmark GMD Event
• Transformer Assessment
• GMD Harmonics Assessment
• GMD Assessment Guidelines
• Commercial Planning Tools
• Road Map for Future Assessment Methods/Tools
• GIC Monitoring (neutral and line)
• Magnetometers
• Data Analytics
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Why the GMD Supplemental Project?
Improved Earth
Conductivity
Models
Improved
Harmonic
Analysis
Capability
Harmonic
Impacts Spatial
Averaging
Transformer
Thermal
Impacts
Latitude Scaling
Factor
Geoelectric
Field Evaluation
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4
pu
flu
x
Current, pu
Per Unit Saturation Curve
FERC Order 830 addressed NERC TPL-007-1 (GMD Vulnerability Assessment)
GMD Research Work Plan
October 19th, 2017 FERC Order
Will inform future revisions of TPL-007
Hig
he
st P
rio
rity
Low
est
Priority
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Newly Released Material
Improve Harmonics Analysis Capability Tool Product ID# 3002014854
Tool Evaluation and Electric Field Estimate Benchmarking Results Product ID# 3002014853
Use of MagnetotelluricMeasurement Data to Validate/Improve Existing Earth Conductivity Models Product ID# 3002014856
Transformer Vibration Analysis Product ID# 3002014855
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How Do GMD Harmonics Threaten Grid Security?
Harmonics can take out critical grid facilities:– False tripping due to distortion– Correct tripping to protect from distortion– Possible damage and failure of grid
equipment
Reactive power sources are particularly vulnerable
Loss of facilities can allow the grid to collapse at a less severe GMD intensity than predicted using intact grid
Harmonic analysis is an essential and integral part of grid GMD impact assessment
Magnetizing
Current 0A GIC
Magnetizing
Current 40A GIC
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Transformer level analysis
conventional shell form
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System level analysis
Relevant details for buses, elements, and electric field– Buses
– Transformers
– Capacitors
– Reactors
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Earth Conductivity Research
Examining the observed differences between new and existing representations of ground response.
Improve existing earth models
FERC Order 830 P78. “… As part of the second research area identified … (i.e., further analyze
earth conductivity models by, for example, using metered GIC and magnetometer
readings to calculate earth conductivity and using 3-D readings), the GMD research work
plan should specifically investigate ...”
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Earth Conductivity Research Comparisons – Original 1D
models to new measurement data
Adding new data, some areas are underestimated
some are overestimated.
Examining the observed differences between original models to new measurement data.
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Updated 1D models
Regional boundaries are updated based
on recent 3-D measurement data
• Scaling factor recalculation is on-going
• Working with a member utility to compare model results with GIC measurements
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Localized Geoelectric Field Enhancements and Latitude Scaling
Have developed comprehensive data set to support GMD analyses.
Using historical data and MagnetohydrodynamicMHD simulations, we can interpolate magnetic field values between observatories
Using historical data and Magnetohydrodynamic(MHD) simulations to show the extent of this southward motion for extreme events.
Data Set providing Ground Truth for Modeling
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Studies on the saturation of noise and vibration with GIC currents
0
1
2
3
4
5
6
7
67
70
73
76
79
82
85
88
91
19:26 19:40 19:55 20:09 20:24
GIC
Neut
ral c
urre
nt, A
mps
Soun
d Pr
essu
re le
vel, d
B (A
)
Time
Noise, dB (A)
GIC Current, A
Validation in vibration results from
laboratory and field measurements
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Industry Engagement
2019 GMD Workshop
– August 13th
– Exelon Offices
– Chicago, IL
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ARP – GMD Vulnerability Assessments:
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Background
k-factor
0
0.05
0.1
0.15
0.2
0.25
0.3
1 2 3 4 5 6 7 8 9 10 11
Pe
ak C
urr
en
t in
P.U
. of
RM
S R
ate
Cu
rre
nt
Harmonic Order
200 A/ph dc
0
0.0005
0.001
0.0015
0.002
0.0025
0.003
0.0035
1 2 3 4 5 6 7 8 9 10 11
Pe
ak C
urr
en
t in
P.U
. of
RM
S R
ate
Cu
rre
nt
Harmonic Order
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Q-GIC characteristics of a 5-legged transformer under
changing yoke and return leg cross-section area
0 0.1 0.2 0.30
0.1
0.2
Three Phase Transformer Reactive Power verses GIC
GIC (pu per phase)
Q.e
xc(
pu)
on T
rans
form
er B
ase
0.237
0
Five_LeggedGIC( )
Five_Legged.Min GIC( )
Five_Legged.k GIC( )
0.30 GIC
Provide k-factor ranges for various
core sizes
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2019 ARP Projects
GMD Planning Software Benchmarking– Benchmarking the GIC
simulation of non-uniform electric fields To ensure accuracy and
consistency across platforms, and coordinate individually with each vendor in a confidential matter and adjust where needed.
Goal is to allow vendors to expand their capabilities and to ensure accuracy across multiple platforms
“commercially-available modeling tools now advertise
capabilities that could be used to model
localized GMD enhancements, …
these capabilities have not been used extensively by
planners, nor have the different software
tools been benchmarked for
consistency in results.” – NERC statement in
FERC 851
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2019 ARP Projects – EPRI Operations Guide
Preparation– System studies
– Modeling uncertainties
– GIC monitoring
Using the results to select the most strategic locations to monitor
2-3 day NOAA Alert ≥ k7– Assess system configuration against planning
configuration
– Safe posture
During event if still ≥ K7 for x time– Actions to take with monitored GIC
Sophisticated monitoring infrastructure
Nominal monitoring infrastructure
Minimal/non-existent monitoring infrastructure
– Monitor var reserves
Reliability issues – PT/CT calibration
State estimator
PMU issues
– Emergency operation (not n-1)
– Load shedding
– GIC redirection
– Account for ambient temperature discount on at-risk transformers.
Time of day consideration (Result of GMD supplemental work)
– Leverage DGA monitoring – primarily to assess transformer condition.
– Recognize sub-storm waveforms, etc.
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DOE Support of Executive Order 13744
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DOE GIC Blocker Pilot Program
EPRI is working with DOE to help develop the pilot program plan to protect transformers in the field as directed in Executive Order 13744.
EPRI is providing the following:
– Market Survey (Completed)
– System approach to selecting sites (Completed)
Minimal impact to adjacent substations, positive impact
– Hardware specifications (for monitoring and equipment) (Completed)
– Evaluate GIC blocking devices in the field (Phase 2)
Neutral blocking device in the field.
Courtesy of EMPRIMUS, LLC
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Phase 2 Project Overview
Task 1 - Choose utility host site
collaborator(s).
Task 2 - Mitigation Technology Selection
Task 3 - Site Requirements and
Specifications
Task 4 - Mitigation and Monitoring
Equipment Specifications
Analyze and evaluate system
performance
Task 5 - Site Acceptance Tests
(SAT)
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Together…Shaping the Future of Electricity