Get an insight to geomagnetic induced current and its mitigation strategy.

1. PROTECTING
POWERGRIDS FROM GIC
BY..
ANIRUDH VINOD
ARUNKUMAR.C

2. Mitigation
strategies
conclusions
Risk analysis of
geomagnetic
induced current
in power lines

3. Part 1 –Risk analysis
 Risk analysis involves considering the
causes and sources of risk, their
consequences and the likelihood of
occurrence.
 The risk analysis effectively tells us about
the root cause ,likelihood and
consequence I.e. understanding the risk
and evaluating it .
Risk
analysis
likelihood of
solar storms
root cause –
solar storm and
threat level
consequences
at various levels

4. 1.1 Root cause
 Sun is the source of most terrestrial space weather
,it is the only natural source of GIC.
 Solar activity is measured in terms of the number
of sun spot . sunspots are the site of origin for the
solar storms , They are perceived as dark areas on
the surface of the Sun and they are in the same
size range as Earth. The reason for their apparent
darkness is that they have about 2000K lower
temperature compared to the surrounding area
and thus they emit less light. The lower
temperature is due to the strong magnetic fields
that counteract the convection of hotter material
moving towards the surface.

5. 1.1.2 Delving deeper into flares and cme
 Solar flares are bursts of high energy electromagnetic radiation, ranging from gamma
rays to extreme ultraviolet, and are seldom visible to the naked eye.
 A coronal mass ejection is essentially a magnetic explosion inside the Sun that propels
a massive cloud of charged particles out into interplanetary space. These plasma
clouds can contain in the order of billions of tons of matter and can be accelerated to
several millions of meter per second, and will typically reach Earth in the order of 20
hours to several days. During solar maxima the Sun produces 3 CME s per day on
average while only producing 1 every 5 days during a minimum .CME are the main
source of geomagnetic storms and gic .

6.  The charged particles of solar winds are provided a way to enter
the near earth regions through the cusps of earth’s magnetic
field .
 As the solar wind interacts with the magnetosphere it causes a
current to flow in the ionosphere. This current can reach several
millions of Amperes and is known as an electro jet.
 Changes In the current of the electro jet causes fluctuations in
the geomagnetic field which, in accordance with Faraday’s Law
of induction induces an electric field in the ground.
 These geomagnetic fields in its turn will drive within conducting
structures such as power lines this is known as geomagntically
induced currents.
1.1.3 Effect on earth’s atmosphere

7. 1.2.0 Component level consequence
 TRANSFORMER CONSEQUENCES
When GIC starts to flow through a transformer winding it will DC bias the transformer
and cause the core to start to saturate. This saturation will cause: (a) production of both
even and odd harmonics, (b) a substantial increase in reactive power consumption and (c)
increased heat production and an increase of transformer losses (efficiency declines). The
severity of these effects depends on the strength of the geomagnetic disturbance
when the transformer core reaches saturation is that the permeability of the core drops
drastically, which means that the inductance and thus the impedance of the transformer
also will drop. As the impedance drops, the magnetization current increases inversely
proportional to the drop according to Ohm’s law This will lead to a deformation of the AC
current sine

8. Delving deeper
 The deformation of the sinusoidal current
caused by the increased magnetization current
has consequences to the power system-
1)harmonic generation
2)reactive power consumption
3)heating and catastrophic failure
4)increase in transformer loss

10. PROTECTIVE RELAY CONSEQUENCES
 A protective relay is a device meant to disconnect any element of a
power system that experiences a fault or operates in an abnormal
manner.
 During geomagnetic storms there is a likelihood of protective relays
misinterpreting the harmonics content in the AC and sense false
fault conditions. protective relays are sensitive to the harmonic
content in the current and particularly to the third harmonics of the
fundamental frequency. During geomagnetic storms transformers
can produce large amounts of harmonics as described above; if this
harmonic content is high enough it can cause the protective relay
to erroneously sense a fault and trip

11. 1.2.1 consequence at system level
 Depending on the severity of a geomagnetic disturbance, the consequences at power
systems component level, can have a series of consequences at the system level,
ranging from no system impact at all to widespread voltage collapse significantly
disrupting critical infrastructure.
1) local power outage
2)loss of production
3)voltage collapse
4)supply risk

12. 1.3.0 Likelihood of
solar storm
The GIC related incidents are
plotted over a sunspot activity
graph.
The likelihood of solar storms
does not follow a uniform curve
rather it varies with solar cycle
.the CME’s mainly occur during
solar maxima .the likelihood of
cme is linear to the number of
sunspots.

13. Part 2-mitigation strategies
System
hardening
Operational
mitigation
Mitigation of
risks

14. 2.1 System hardening
Hardening of the power system is optimally done
through the application of passive devices or
circuit modifications that block or reduce the flow of GIC
in a power grid.
The flow of the GIC enters and exits the single
transformer neutral-to-ground point on each
transformer and the flow splits equally in each of the
three phases of the transformers and transmission lines
Since the capacitors block the flow of all DC currents, all
GIC flow in this transmission line, and by extension the
two transformers at each end of the transmission line,
would also be blocked.

15. Reduction devices

16. 2.2GIC Blocking and AC Bypass Device
Design and Operation
In this section a Functional approach and conceptual
design for a device capable of either blocking GIC or
reducing its levels compared to the normal solidly
grounded power grid design will be provided . The GIC
blocking device for application on bulk power systems
requires a capability to block DC or GIC flows into or out of
the transformer while simultaneously allowing a path for
the flow of long-duration low-level AC currents and very
short-duration but very high magnitude AC currents due to
nearby faults on the high voltage network. The operational
aspects of the capacitor–based Neutral Blocking and
Bypass Device (NBBD) are illustrated in the next few
schematic diagrams.

18. “
”
governments has alarmingly admitted it is woefully underprepared for a major
solar storm which could cause plane crashes, train derailments, huge fires, mass
power blackouts and satellite disruption. such a black out would be catastrophic
for a technology dependent civilisation like ours ,it would take upto 10years to
fully recover from it ,this would put the entire civilisation on a backward track and
crisis would ensue.
PART3-CONCLUSION

19. The way forward…..
With the combined effort of modeling and simulation of power systems under the stress
of a geomagnetic disturbance, future disasters can be mitigated by strategically protecting
the critical/vulnerable points in power systems around the world from GIC.
Once the models have been validated and incorporated into power analysis software,
power system planning engineers can use tools to effectively reduce the impacts of GIC on
their system. Mitigation strategies will be explored: transformer bypassing, installing of GIC
blocking devices, power flow redistribution by intentional line outages, and load shedding
schemes, to name a few.

20.  The short-term and long-term mitigation strategies of GIC need to be explored. From
an operating perspective, operators must be ready to respond to a GMD event, given
information of a storms arrival in a few hours to days timeframe. Long-term mitigation
strategies become important when GIC blocking devices have been added to the
system. GIC has the potential to be redistributed in the system since it can no longer
enter/exit blocked points. How the GIC redistributes and how to appropriately plan for
the redistribution is something that will be addressed with further research

21.  THANKS TO
DR.P.KANNAN – HOD ,ECE
PEC,CH-123
DR.G.SIVAKUMAR-DEPT OF CHEMISTRY
PEC,CH-123
REFERENCE
RISK ANALYSIS OF GIC IN POWER SYSTEM-RASMUS THORBERG
Pulkkinen, A. (2003). Geomagnetic induction during highly disturbed space weather conditions: studies of
ground effects. Helsinki, Finland: Finnish Meteorological Institute
Wik, M. (2008). The Sun, Space Weather and Effects. Kiruna, Sweden: Swedish Institute of Space Physics.
Wikipedia (2012, January 03). Catastrophic failure. Retrieved January 27, 2012, from Wikipedia, the free
encyclopedia: http://en.wikipedia.org/wiki/Catastrophic_failure