Transcript Geomagnetic Storm Effects on Transmission Elements

Geomagnetic Storm Effects
on Transmission Elements
Kenneth A. Donohoo,P.E.
Oncor Electric Delivery Co LLC
NERC Planning Committee Member
NERC GMDTF Chairperson
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Introduction
Space weather can affect the power system
Large areas and multiple facilities can be affected
Can happen at any time, not just at high sun spot
activity
Not just a northern latitude issue and can adversely
impact ERCOT
Higher voltage networks are more at risk
Potential adverse impact on transformers, SVC’s and
HVDC ties
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Objectives
At the completion of this course of
instruction you will:
identify how a geomagnetic disturbance
can impact the grid
Identify possible impacts and actions to
prevent outages
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Definitions
Coronal Mass Ejection (CME) is a massive burst
of solar wind and magnetic fields rising above
the solar corona or being released into space
Geomagnetic Disturbances (GMD) are caused
by intense solar activity that impacts the Earth’s
geomagnetic field
Changes to the geomagnetic field creates a
voltage gradient and induces a Ground Induced
Current (GIC – quasi DC) through any conductor
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The Sun
CME typically take 1 to 3 days to arrive on Earth
May not head toward Earth
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Sunspot Cycle
Large GMD
Storms can
and do
occur at
anytime in
the sunspot
cycle and
not just
around the
Sunspot
peaks
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Space Storm
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Interactions
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Possible Interactions
 If the intensity and duration of a disturbance is sufficient,
these abnormal electric currents may reduce system
voltage and in the worst case, cause a widespread
power outage.
 In the extreme, severe GIC can overheat transformer
cores and lead to equipment damage or failure.
 Transformer harmonics increase
 Consume more reactive power, voltage decrease
 Trip capacitor banks, SVC’s, HVDC, etc…
 Relay misoperation
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Some Storm History
 19th century first effects observed on compass needle
 Sept 1859, largest recorded, Carrington Event
 18 hours to reach Earth
 Telegraph wires shocked operators and caused fires
 March 1989, Hydro Quebec
 Only took 92 seconds to blackout system
 Seven SVC’s tripped within 59 seconds of each other
leading to voltage collapse 25 seconds later
 Six million people without power for nine hours
 Northern lights seen as far south as Texas
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What is a K Factor?
The K-index quantifies disturbances in the horizontal
component of earth's magnetic field with an integer in the
range 0-9 with 1 being calm and 5 or more indicating a
geomagnetic storm.
Recent Storms K Factor 7 or higher:
10/01/12
03/09/12
09/26/11
08/06/11
08/05/11
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ERCOT Procedures
ERCOT Operating Procedure Manual
Transmission and Security Desk
Section 3 Review and Analyze System Security
Section 3.5 Geo-Magnetic Disturbance Notification
Procedure Purpose: To provide notification and increase
situational awareness when a GMD storm is advancing.
WHEN:
Notified by the Shift Supervisor that a K-7 or higher GMD
storm is expected;
THEN:
Issue an Advisory by making a Hotline call to TOs
Post message on MIS Public
Notify Real-Time operator to make hotline call to QSEs
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How do I find out about a
solar storm?
Information and Indications
The following are triggers that could be used to initiate operator action:
 External to your company:
 NOAA Space Weather Prediction Center
http://www.swpc.noaa.gov/ or other organization issues:
 Geomagnetic storm Watch (1-3 day lead time)
 Geomagnetic storm Warning (as early as 15-60 minutes
before a storm, and updated as solar storm
characteristics change)
 Geomagnetic storm Alert (current geomagnetic
conditions updated as k-index thresholds are crossed)
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How do I find out about a
solar storm?
Information and Indications (continued)
 Internal to your company:
 System-wide:
 Reactive power reserves
 System voltage/MVAR swings/current harmonics
 Equipment-level:
 GIC measuring devices
 Abnormal temperature rise (hot-spot) and/or sudden

significant gassing (where on- line DGA available) in
transformers
System or equipment relay action (e.g., capacitor bank
tripping)
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Actions Available to Operator
The following are possible actions for Transmission Operators based on available leadtime:
Long lead-time (1-3 days in advance, storm possible)
1. Increase situational awareness
1. Assess readiness of black start generators and cranking paths
2. Notify field personnel as necessary of the potential need to report
to individual substations
2. Safe system posturing
1. Return outaged equipment to service (especially series capacitors
where installed)
2. Delay planned outages
3. Remove shunt reactors
4. Modify protective relay settings based on predetermined harmonic
data corresponding to different levels of GIC (provided by
transformer manufacturer).
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Actions Available to Operator
The following are possible actions for Transmission Operators based on available leadtime (continued):
Day-of-event (hours in advance, storm imminent):
1. Increase situational awareness
1. Monitor reactive reserve
2. Monitor for unusual voltage, MVAR swings, and/or current harmonics
3. Monitor for abnormal temperature rise/noise/dissolved gas in
transformers1
4. Monitor geomagnetically induced current (GIC2) on banks so-equipped3
5. Monitor MVAR loss of all EHV transformers as possible
6. Prepare for unplanned capacitor bank/SVC/HVDC tripping4
7. Prepare for possible false SCADA/EMS indications if telecommunications
systems are disrupted (e.g., over microwave paths)
2. Safe system posturing
1. Start off-line generation, synchronous condensers
2. Enter conservative operations with possible reduced transfer limits
3. Ensure series capacitors are in-service (where installed)
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Actions Available to Operator
The following are possible actions for Transmission Operators based on available leadtime (continued):
Real-time actions only if indicated:
1. Safe system posturing
1. Selective load shedding
2. Manually start fans/pumps on selected transformers to increase
thermal margin (check that oil temperature is above 50° C as
forced oil flow at lower temperatures may cause static
electrification)
2. Possible System reconfiguration only if needed
1. Remove transformer(s) from service if imminent damage due to
overheating
2. Remove transmission line(s) from service
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Actions Available to Operator
The following are possible actions for Transmission Operators based on available leadtime (continued):
Return to normal operation
This should occur two to four hours after the last observed
geomagnetic activity.
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Internet Links
NOAA Space Weather Center
http://www.swpc.noaa.gov/
NERC GMDTF 2013
http://www.nerc.com/comm/PC/Pages/Geomagnetic-Disturbance-TaskForce-%28GMDTF%29-2013.aspx
NERC GMDTF 2011 & 2012
http://www.nerc.com/comm/PC/Pages/Geomagnetic%20Disturbance%2
0Task%20Force%20%28GMDTF%29/Geomagnetic-Disturbance-TaskForce-GMDTF.aspx
NERC Standard Project 2013-03 Geomagnetic Disturbance Mitigation
http://www.nerc.com/pa/Stand/Pages/Project-2013-03-GeomagneticDisturbance-Mitigation.aspx
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Questions
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1. Geomagnetic storms have a potential
adverse impact on ___________,
__________ and HVDC ties.
a)
b)
c)
d)
e)
transformers
SVC’s
345kV switches
Both a and b
Both b and c
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2. Changes to the geomagnetic field
creates a __________ gradient and
induces a ground induced current
through any conductor.
a)
b)
c)
d)
ferroresonance
voltage
high
exceptional
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3. In the extreme, severe GIC can
__________ transformer cores and lead
to equipment damage or failure.
a)overheat
b)ground
c) over rate
d)increase capacity
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4. Which of the following safe system
posturing actions for long lead time
(1-3 days in advance) are possible
for transmission operators?
a)
b)
c)
d)
Return outaged equipment
Delay planned outages
Remove shunt reactors
All of the above
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5. Which of the following safe system
posturing actions for day of the event
(hours in advance) are possible for
transmission operators?
a) Start off-line generation
b) Enter conservative operations with
possible reduced transfer limits
c) Ensure series capacitors are in-service
d) All of the above
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