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GIC Modeling SRWG Meeting
March 2014

Introduction
Terminology
Theory
GMD Impacts to Power System Equipment
Historic Events
Regulatory Activities
Geomagnetic Induced Current Modeling
GIC Study Tools
GIC Modeling Data
Challenges
IPCO GIC Study Experiences
SRWG Discussion Topics

Terminology
CME = Coronal Mass Ejection
GMD = Geomagnetic Disturbance
GIC = Geomagnetically Induced Current
HILF = High Impact Low Frequency Events
Coordinated Cyber, Physical, and Blended Attacks
Pandemics
Geomagnetic Disturbances
Electromagnetic Pulse (EMP)
Intentional Electromagnetic Interference (IEMI)

GMDs and the Power System
DC
Network
Grid
Model
GIC
AC
Network
Grid
Model
Powerflow Solar
Flare CME
Perturbation
of Earths
Magnetic
Field
nT/min
Planetary Science
Space
Image: 2012 NERC GMDTF Interim Report
Maxwell
Equations
and Earth
Conductivity
() Model
V/km
Physics (E&M) Power Engineering
Near Earths Surface

GMD Impact on Power System
Equipment
Transformer Half-Cycle Saturation
Harmonics
Increase Reactive Power Consumption
Increased risk of system voltage collapse
Transformer Heating
Increased risk of transformer damage
Protective Relaying Misoperation
Harmonics / DC Offset due to GIC
Electromechanical Relays
Communication System Issues

October 31 - Sun storm causes problems for Swedish
power system. The solar storm has caused technical
glitches in Sweden's power system in the past few
days and may be to blame for a blackout that affected
50,000 people on Thursday, October 30.
Information Notice No. 90-42: FAILURE OF ELECTRICAL POWER EQUIPMENT
DUE TO SOLAR MAGNETIC DISTURBANCES
Specific events occurred at the Three Mile Island Unit 1, Hope Creek Unit 1, and Salem Unit 1
nuclear power plants. inspection of the generator
step-up transformer severe overheating, melted
low
-voltage service connections in phases A and C,
and insulation discoloration in phase B. On
September 19, at Salem Unit 2 nuclear power
plant, a second solar storm damaged the generator
step-up transformer. Sep 1990
Transformer exit-lead
overheating
Transformer winding failure
Historic Events

GMD Regulatory Activities
FERC Order 779
Issued to NERC in May 16, 2013
Directed NERC to develop reliability
standards to address the potential impact of
GMD Events on the reliable operation of
the Bulk-Power System
Directed Standards Development in Two
Stages
Stage 1 Standards
Focus on GMD Operating Procedures
Must be filed by January 2014
Stage 2 Standards
Focus on initial and on-going study
assessments of benchmark GMD events
Must be filed by January 2015

NERC Project 2013-03
Geomagnetic Disturbance Mitigation
Stage 1: NERC EOP-010-1 Geomagnetic Disturbance Operations
NERC BOT adoption 11/7/2013
Filed with FERC 11/14/2013
Stage 2: NERC TPL-007-1 Transmission System Planned
Performance During Geomagnetic Disturbances
Standards Authorization Request (SAR) Completed
Status = Active Formal Development

NERC EOP-010-1
Applicable Entities
Reliability Coordinator
Transmission Operator with a Transmission Operator Area that includes a
power transformer with a high side wye-grounded winding with terminal
voltage greater than 200 kV
Effective Date Timeline
First day of the first calendar quarter that is six months after applicable
approvals (i.e. FERC, NERC BOT, etc.)
Requires TOPs to develop, maintain, and implement GMD
Operating Procedures to mitigate the effects of GMD events

NERC TPL-007-1
FERC Order 779 Requirements
Initial and on-going assessments of the risk and potential impact of
benchmark GMD events on the Bulk-Power System
Identification of benchmark GMD events
Develop and implement action plans to protect against instability,
uncontrolled separation, or cascading caused by GMD events
Proposed Effective Date Timeline
Implementation Period was not addressed in Order 779
Potential Impact to SRWG
May need to develop GIC Modeling and Data Reporting Requirements

GIC Modeling
Qloss_GIC, IGIC QV
PV DC
Network
Grid
Model
GIC
AC
Network
Grid
Model
Powerflow
Qloss_GIC
Contingency
Analysis Transient
Stability
E&M DC Network Model AC Network Model
Equivalent Circuit
Substation
Transmission Line
Transformer

Transmission Lines
DC Voltage Source
Transmission Line GIC Model
LY
SUB 1
(Lat A, Long A)
SUB 2
(Lat B, Long B)
Ex
EY
Lx
System Voltage
Level
(kV)
DC Resistance
(ohm/km)
230 0.072
345 0.037
500 0.013
735 0.011

Series Capacitors
Transmission Lines with Series Capacitors
Block GIC Current from flowing
Image: Idaho Power

Caution Regarding Series Capacitors
Line Shunts can form GIC circuits

Transformers
Transformer GIC Model
Winding Configuration Winding Resistance
Core Type

Substations
Typical Network Resistance Values
Image: Advanced Grounding Concepts
Grounding Resistance Measurement
Fall of Potential Test Method
System
Voltage Level
(kV)
Grounding
Resistance of
Substation
(ohms)
230 0.563
345 0.667
500 0.125
735 0.258
Substation GIC Model
Rgnd

GIC Study Tools
General Electric Positive Sequence Load Flow (GE PSLF)
GIC add-on module available in GE PSLF V18.1_02
Latitude / Longitude in bus record table
Four New tables for Substation, secddg table, trang table, e-field table
Siemens Power System Simulator for Engineering (PSSE)
GIC add-on module available in Versions 32.2 and 33.3
Input data via auxiliary text file *.GIC file or GIC module GUI
PowerWorld Simulator V17
GIC add-on module available
Input data via auxiliary text file or GIC Add-on Analysis Dialog
Calculation Methods are based on NERC GMD Task Force
Recommendations
Default values for some GIC data if unknown

GIC Modeling Data
GIC Modeling Data on an wide area basis
Powerflow Network
Latitude / Longitude of Substations
Substation Grounding Resistance
Transformer Connections
Transformer DC Winding Resistance
Status of GIC Blocking Devices
Equipment Specific GIC Modeling Data
Transformer Core Construction
Transformer Saturation Coefficient (K-Factor)

Challenges
GMD has more impact on Northern Portion of the Interconnection
Defining GIC Data Reporting Requirements
All of WECC?
Portions of WECC?
All elements of the Bulk-Power System (BPS)?
Portions of the BPS?
Transmission Lines 200kV and above?
Transformers with HV grounded-wye windings 200 kV and above?
Additional details are needed in order to completely define new data
reporting requirements
GIC Data Conversion between Software Packages
PSLF, PSS/E, PowerWorld have different input data requirements

Needs
GIC studies should be performed using Wide Area Models
GIC Data needs to be available and shared between Entities
GIC Blocking in one Area impacts GIC currents in adjacent Areas
Whack-a-Mole

IPCO GMD Study Experiences
DC GIC Analysis
Uniform Electric Field
AC Powerflow Analysis with GIC
Wide Area
Idaho Area
N-1 Contingency Analysis with GIC
Idaho Area
Reactive Margin Analysis with GIC
Idaho Area Buses
Northwest Area Buses
Idaho Area Bus Voltage Impact with GIC
Wide Area
Idaho Area

DC GIC Study Results
Transformer GIC MVAR Loss
0
100
200
300
400
500
600
700
0 30 60 90 120 150 180
MV
AR
Compass Angle (degrees)
Idaho Area MVAR Loss due to GIC
7 V/km 4 V/km

Wide Area AC Powerflow Results
Direction Electric Field Magnitude (V/km)
where Powerflow fails to solve
0 degrees 7.4
15 degrees 7.0
30 degrees 6.6
45 degrees 5.6
60 degrees 5.2
75 degrees 5.1
90 degrees 4.0
105 degrees 4.4
120 degrees 4.8
135 degrees 4.8
150 degrees 4.8
165 degrees 8.4
180 degrees 7.4

Wide Area AC Powerflow Results
(Excluding Idaho Area)
Compass
Ang

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