Geomagnetic Disturbances
Update on Project 2013-03
Frank Koza, PJM, Chair of NERC GMD SDT
IEEE/PES Transformers Committee
October 23, 2014
Potential Impacts on the Power System
Geomagneticallyinduced currents (GIC)
can cause:
• Increased reactive
power consumption
• Transformer heating
• Protection System
misoperation
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RELIABILITY | ACCOUNTABILITY
TPL-007 Deliverables
• Requires a GMD Vulnerability Assessment of the system for its
ability to withstand a Benchmark GMD Event without causing a
wide area blackout, voltage collapse, or damage to
transformers, once every 5 years.
 Applicability: Planning Coordinators (PCs),Transmission Planners (TPs)
• Requires a Transformer thermal impact assessment to ensure
that all high-side, wye grounded transformers connected at
200kV or higher will not overheat based on the Benchmark GMD
Event
 Applicability: Generator Owners (GOs), Transmission Owners (TOs)
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RELIABILITY | ACCOUNTABILITY
GMD Assessment Process Overview
Geomagnetic
Field
B(t )
Potential
Mitigation
Measures
Geoelectric
Field
Earth
E(t )
Conductivity
Model
dc
System
Model
GIC
Transformer
Model
( Electrical)
GIC(t)
4
vars
Power Flow
Analysis
Transformer
Model
( Thermal)
Bus
Voltages
Line Loading &
var Reserves
Temp(t)
Fail
Assessment
Criteria
Pass
Operating
Procedures
and
Mitigation
Measures
(if needed)
Hot Spot
. Temp
RELIABILITY | ACCOUNTABILITY
GMD Benchmark Geoelectric Field
Epeak = Ebenchmark x α x β (in V/km)
where,
Epeak =
Ebenchmark =
α =
β =
5
Benchmark geoelectric field magnitude at System
location
Benchmark geoelectric field magnitude at reference
location (60 N geomagnetic latitude, resistive
ground model)
Factor adjustment for geomagnetic latitude
Factor adjustment for regional Earth conductivity
model
RELIABILITY | ACCOUNTABILITY
Reference Geoelectric Field Amplitude
1-in-100 Year Occurrence
3-8 V/km at 60⁰ N
geomagnetic latitude
8 V/km to be conservative
Statistical occurrence of spatially averaged high-latitude geoelectric field
amplitudes from IMAGE magnetometer data (1993 – 2013)
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Transformer Thermal Assessment
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Proposed Generic Thermal Model
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Transformer Models & 75 A Exclusion
• Transformer thermal models are needed for impact
assessment
 Proposed standard gives owners latitude to select appropriate approach
o manufacturer information
o general models (in development-to be available in early 2015)
o Contracted assessment
 General models are in scope of GMD Task Force project
 Implementation Plan is extended (48 months for thermal assessment)
• If calculated GIC is 75 15 A or less, then Thermal Impact
Assessment is not required
 Draft standard provides floor of 75 A per phase effective GIC
 Data is not currently available to establish an additional screening value
for 3-phase 3 limb units
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Revised Implementation Plan
A number of entities expressed concerns with the proposed
implementation plan so it was revised as follows:
Date of
Approval
10
18 Months
48 Months
•R2
•System
Models
•R6
•Thermal
Assessment
6 Months
24 Months
60 Months
•R1
•Identify
Responsibilities
•R5
•GIC Flow
Information
•R3, R4, and R7
•GMD Assessment
•Corrective Action
Plan
RELIABILITY | ACCOUNTABILITY
Next Steps
• Formal Comment and Initial Ballot— October 1 - 10, 2014
• 66% Positive Vote Required for Approval (58% achieved)
• 3rd Ballot in November
• Seek NERC Board adoption
• Submit to FERC by January 2015 deadline
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Resources
• Project page: http://www.nerc.com/pa/Stand/Pages/Project2013-03-Geomagnetic-Disturbance-Mitigation.aspx
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EOP-010-1  GMD Operations
• Requires Reliability Coordinators (RC) to develop Operating
Plans to coordinate GMD Operating Procedures in their area
• Requires Transmission Operators (TOP) to develop GMD
Operating Procedures that include:
 Steps to receive space weather information
 System Operator actions based on predetermined conditions
• Applies to RCs and TOPs with grounded transformers >200 kV
• U.S. enforcement date April 1, 2015
 Exception: RC requirement in EOP-010 to disseminate space weather
information is contingent upon retirement of IRO-005-3.1a
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Post Script to the IEEE Presentation
• Sample of Comments from PJM Members with NO votes
 Thermal assessments will require heavy reliance on manufacturers
o Response: Threshold raised to 75 amps and thermal model provided,
means that very few transformers will need a detailed assessment
 Standard does not address the execution of the Corrective Action Plan
o Response: TPL standards do not address implementation—they are plans,
execution is addressed in other processes (eg RTEP)
 Screening models to perform thermal assessments are not available
o Response: A generic model is being provided in this draft to facilitate the
assessments
 Whitepapers are not technically accurate
o Response: SDT is working with the transformer manufacturers to develop a
set of documentation that everyone agrees to
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