Storm Induced Failure of
400 Mega-HVAC Transformers
is Avoidable by Redundant
HVAC Transformer Arrays
- or -
A Current and Voltage Division Method to Reduce Mega-HVAC
Transformer Failures by Redundant Transformer Arrays
During severe solar storms HVAC transformers used by utilities of
dimensional size similar to a medium sized house are subject to
catastrophic failure. As these transformers have very long
commissioning and repair schedules their failure poses a
catastrophic risk. Large parts of grids that depend on their
existence of these AC transformers can be rendered non-functioning
when the mega transformers fail. This catastrophe can be avoided by
using simple voltage division and current division principals
implemented in the form of redundant arrays of smaller HVAC
Electric power is modern society's cornerstone technology
on which virtually all other infrastructures and services
depend. Yet HVAC power grids are particularly vulnerable to
space weather events.
Ground currents induced during geomagnetic storms can create
excess currents in the electrical grid. These excess unregulated
currents have the power to melt the copper windings of
electrically stressed transformers at the core of many mains
power distribution systems.
Sprawling power lines in essence act like VLF antennas. The
grid's distribution network picks up the induced currents
created by the solar storm and absorbs them [at full energy]
into the power grid.
A time-varying magnetic field external to the Earth induces
electric currents in the conducting ground.
These currents create a secondary (internal) magnetic field.
As a consequence of Faraday "Law of Induction" electric fields
aligned along the surface of the Earth are induced in
association with the time variations of the magnetic field. The
surface electric field causes electrical currents that are known
as Geomagnetically Induced Currents (GICs) to flow into any
This GIC induced electric field (typically measured in V/km)
acts as a voltage source across networks.
Examples of Geomagnetically Induced Current conducting networks
- electrical power transmission grids
- oil and gas pipelines
- undersea communication cables
- copper telephone networks
- telegraph networks used by railways
GICs are often described as being 'quasi Direct Current' (DC)
although the variation frequency of GIC is governed by the local
time variations of the Earth's electric field. Geomagnetically
Induced Currents in the systems that conduct them are more like
DC bias currents. For GICs to be a hazard to technology,
the current flows have to be of a magnitude and frequency that
makes electrical equipment susceptible to either immediate or
The size of the GIC in any network is governed by the electrical
properties and the topology of the network. The largest
(magnetospheric) ionospheric current variations, resulting in
the largest external magnetic field variations typically occur
during geomagnetic storms. Geomagnetic storms by their nature
create the largest GICs.
Significant temporal variation in GICs is known to range from
from a few seconds to about an hour.
Since the largest magnetic field variations are observed at
higher magnetic latitudes, GIC have been regularly measured in
Canadian, Finnish and Scandinavian power grids and pipelines
since the 1970s.
GICs of tens to hundreds of Amperes have been recorded outside
the Polar regions. GICs have also been recorded at mid-latitudes
during major geomagnetic storms with nearly the same magnitude
as the GICs in Polar regions. However, GICs are not a problem
exclusive to the mid-latitudes or the Arctic.
There is still a substantial GIC risk to low latitude areas (the
tropics). When a geomagnetic storm commences suddenly -- a high,
short-period rate of change of the Earth's magnetic field will
occur on the dayside of the Earth. This sudden induction event
will induce high current GICs into the tropic regions. These
events are typically short lived, but pose a threat to the power
supply systems in the tropics.
According to a study by Metatech corporation, a geomagnetic
storm with a strength comparative to that of 1921 would result
in at least 130 million people without electrical power and 350
broken HVAC transformers. The overall cost of restoring the grid
to its original functionality and the economic damage caused by
the disruption would be around 2 Trillion Dollars (2 000 000 000
Power distribution grids are not designed to absorb large scale
geomagnetically induced currents as part of their normal day to
Modern electric power transmission systems consist of generating
plants interconnected by electrical circuits that operate at
fixed transmission voltages controlled at substations. The grid
voltages employed are largely dependent on the path length
between these substations. Typically 200kV to 700kV system
voltages are common.
There is a trend towards higher voltages and lower line
resistances to reduce transmission losses over longer and longer
path lengths. Low line resistances produce a situation
favourable to the flow of GICs.
Power transformers typically have a magnetic circuit that is
disrupted by the quasi-DC GIC: the field produced by the GIC
offsets the operating point of the magnetic circuit and the
transformer may go into half-cycle saturation. This produces
harmonics to the AC waveform, localized heating and leads to
high reactive power demands, inefficient power transmission and
possible mis-operation of protective devices.
Balancing the electrical network in such situations requires
significant additional reactive power capacity.
The magnitude of GIC that will cause significant problems to
transformers varies with transformer type. Modern industry
practice is to specify GIC tolerance levels on new transformers.
There are some partial solutions for coping with geomagnetically
induced currents, typically involving grounding the electrical
It must be noted that most electrical utilities often fail
to fully implement these recommendations.
- 50 km intervals in the latitude [North-South] domain
- 75 km intervals in the
longitude [East-West] domain
- longer intervals than 60 km closer to the tropics
GIC risk can, to some extent, be reduced by capacitor blocking
systems, maintenance schedule changes, additional on-demand
generating capacity, and ultimately the policy of load shedding.
These options are expensive and sometimes impractical.
The continued growth of high voltage power networks results in a
higher risk for all users. This is partly due to the increase in
the interconnectedness at higher voltages; connections in terms
of power transmission to grids in the auroral zone, and grids
operating closer to capacity than in the past.
To understand the flow of GICs in power grids and to advise on
GIC risk analysis of the quasi-DC properties of the grid is
necessary. This analysis must be coupled with a geophysical
model of the Earth that provides the driving surface electric
field, determined by combining time-varying ionospheric source
fields and a conductivity model of the Earth.
This kind of analysis has been performed for North America, the
UK and in Northern Europe. The complexity of power grids, the
source ionospheric current systems and the 3D ground
conductivity make an accurate analysis difficult but not
computationally impractical. By being able to analyze major
storms and their consequences it is possible to build a picture
of the weak spots in a transmission system and run hypothetical
The perils of
From the 1990s into the present day US utilities have joined
grids together to allow long-distance transmission of low-cost
power to areas of sudden demand. Canada is also part of this
North American electrical grid network, a fact often lost in the
technical literature. Canada is even more susceptible to
coupled Winter storm + Geomagnetic storm conditions. In Canada,
substantial loss of life is possible due to a grid failure's
direct effects. In the US the secondary effects of grid failure
will lead to larger per capita loss of life than Canada via
As it were : on a hot summer day in California, for instance,
people in Los Angeles might be running their air conditioners on
power routed from Oregon. This may make short term economic
sense -- but not necessarily geomagnetic sense. Grid
interconnectedness makes the power distribution network
susceptible to wide-ranging "cascade failures."
These power grid failure problems are totally 'man made' and are
'design induced problems' with several different and notable
- State or private sector companies have been hiring
electrical engineers for decades that are barely suitable to
the task of maintaining the power grid. Of the subtle
problem solving issues and complications required in real
electrical engineering these engineers know not a jot.
- Nepotism, favouritism [coupled with a hefty dose of
outright class and race discrimination] at virtually every
electrical engineering school in North America has in effect
left this part of the electrical engineering profession
(that maintains the essential functioning of the power grid)
with poor or unsuitable replacements.
- The 'classically trained' North American electrical
engineers of the 1950s to the 1970s are far better problem
solvers than their existing counterparts today.
- It must be noted that the education system in the
US functioned adequately enough during the 1950s to 1970s
to produce suitable grid engineers capable of some
original thought and innovations.
- The exiting of these engineers via retirement will
be felt in the 2010s with a drop in overall reliability of
the US electrical power grid.
- Although the education situation in Canada may be
better than the US's, Canada has neglected this vital
profession in spite of the ongoing threats to grid
reliability that pervade Canada's geographic space.
- The finance system that oversees the funding of
utilities in North America has not encouraged innovations in
grid reliability. This finance sector neglect is a global
problem -- and probably a principal reason why the HVAC
transformer redundancy problem was not solved globally at
least 30 years ago.
- Governmental regulation at all levels in North
America has failed to address the problem of Mega-HVAC
failures directly or indirectly, effectively perpetuating
the problem by neglect.
- Computational research into the known problems of
large scale AC transformer circuit grids could have fixed
the problem by the late 1990s. It is clear that limited
power grid circuit re-design is would be needed but the
problem is not a complex one.
- There is an ongoing failure by all parties involved
to make the HVAC Transformer problem and its solutions 'open
source' so as to encourage ongoing research.
- An outright disregard for electrical engineering,
chemistry and physics knowledge by the general public in
North America as well as substantial parts of Europe.
Tentative recommendations for making power
grids survive severe solar storms
General system recommendations and practices
- Generally the transformer redundancy rule should be
- [small-odd-number-under-eleven] = Number of
- Generally the transformer redundancy rule should be
- [small-odd-number-under-eleven -1] = Number of
Redundant Transformers in Use (at any one time to backup
the Mega-HVAC transformer).
- Potentially up to 13 HVAC transformers could be used
in parallel -- but the buffering and cophasing networks as
well as safety considerations might make such a system too
- There are personnel safety system issues involved
with using an array of more than 11 transformers.
- The excess redundancy of an array of 13 HVAC
transformers is only recommended for the most northerly
locations or extreme engineering conditions.
- Each HVAC transformer must have its own accompanying
buffering and matching network to terminate and match its
- It is not fully clear exactly how this HVAC
transformer network should be designed. There are at least
400 different Mega-HVAC transformer installations -- and
each may be locally unique. Let it be said that the required
AC (matching / cophasing) networks are not design
impossibilities for this kind of application.
- In principal as well as in practice: It is not
recommended risking going below 5 redundant HVAC
transformers, with 7 being the nominal recommendation.
- The ultimate number of redundant transformers must
ultimately depend on the static and dynamic load factors for
the Mega-HVAC transformer.
- Overall recommendations on redundancy : an array of
11 to 7 transformers is nominal.
Specific system recommendations and practices, typical
transformer redundancy mode of 7
- Each Mega-HVAC transformer must have [as a backup
system] an array of at least 7 HVAC transformers (6 in use
at any one time) that can be switched on as a backup system
at any time.
- At least one redundant HVAC transformer array
element must always be in 'repair or maintenance mode' or
'storm buffering mode set aside'.
- Each redundant HVAC transformer must be rated at
1/6th the combined Mega-HVAC (input/output) parameters,
where an array of 7 transformers exist.
- The individual HVAC redundant transformer array
ratings should be 133% to 166% of the [(1/6th) x
(Mega-HVAC-ratings)]. A solar storm may happen when a
redundant transformer is set aside for repair, thus the
1/6th not 1/7th constant.
- This technology will have [by necessity] at least 3
to 5 common operating modes.
- A (single input, two output) variable potentiometer
must proceed the Mega-HVAC Transformer and its backup
redundant array of transformers that splitting the input
- A variable potentiometer to split the voltage and
current between the original HVAC mega transformer and the
redundant array must under normal conditions be balancing
the loads at (50%, 50%).
- The variable potentiometer must [under stressful
solar storm conditions] reduce the load going into the Mega
HVAC transformer by at least 25% (75%, 25%) but also be able
to do so by up to 45% (95%, 5%).
Array State Machine Operating Modes
- Mode # (Input into Array, Input into Mega
- Mode 1 : (50%, 50%) : nominal operations
- Mode 2 : (75%, 25%) : the redundant HVAC array is
made backup to keep the HVAC from failing
- Mode 3 : (100%, 0%) : this
is a maintenance mode not a normal operations mode.
- Mode 4 : (0%, 100%) : this is a maintenance mode
not a normal operations mode.
- Mode 5 : (90%, 10%) : in the long term, the Mega
Transformer should be used as a secondary backup until it
is time for it to be decommissioned.
Operation Modes (Notes)
- Mode switching time must be kept at 1 hour during
the Winter and 3 hours during the Summer, with most repairs
to the redundant arrays being made during the Fall and
- A cophasing and buffering network after the
[redundant array] or after the [redundant array + mega HVAC
transformer] is needed to restore the required target output
voltages and amperages to the mains grid.
- It is not recommended to operate in INPUT-OUTPUT
SYMMETRY MODE where 1 HVAC = 1 HVAC (input, output symmetry)
unless there is an absolute engineering necessity -- except
in the form of 1 HVAC input = 2 HVAC outputs.
- Arbitrarily engaging in engineering practices that
force more Mega-HVAC transformers into existence in the
existing electrical grids [except to increase the
reliability of those already deployed] has engineering and
- Many Mega-HVAC transformers that are currently
deployed may not have any actual engineering necessity, with
respect to alternate grid designs that could be put into
place that would alleviate their existence entirely.
- It is assumed that the Mega HVAC transformers will
eventually be phased out by redundant arrays of cheaper HVAC
transformers so as to totally eliminate this failure mode.
- High power diodes to keep the AC currents
unidirectional will be requried in any HVAC redundant array
design. Redundant arrays of analogue devices must be
designed so as to avoid current feedback and reflection
- Circuit breakers to separate out the transformers
from the array and grid must be 4x redundant so as to make
accidental energizing of the transformer nearly impossible.
Why the above recommendations will work, or the electrical
engineering laws we know so well
- The current entering any junction is equal to the
current leaving that junction : aka Kirchhoff's current law
- The directed sum of the electrical potential
differences around any closed circuit must be zero. (Note
that geomagnetic storms tend to disturb this difference to
destructive effect within the innards of transformers.)
- In electrical circuit theory, Thévenin's theorem for
linear electrical networks states that any combination of
voltage sources, current sources and resistors with two
terminals is electrically equivalent to a single voltage
source V and a single series resistor R. For single
frequency AC systems the theorem can also be applied to
general impedances, not just resistors. This simple
principal can simplify the conceptual and practical problems
that will be encountered along the way.
- Norton's theorem for linear electrical networks
states that any collection of voltage sources, current
sources, and resistors with two terminals is electrically
equivalent to an ideal current source, I, in parallel with a
single resistor, R. For single-frequency AC systems [like
power grids] the theorem can also be applied to general
impedances, not just resistors.
- The Norton Equivalent is used to represent any
network of linear sources and impedances, at a given
frequency. The circuit consists of an ideal current source
in parallel with an ideal impedance (or resistor for
Recommendations for Australia, Canada & New Zealand
- Australia should make the necessary changes in its
AC grids in the next 5 years, as the budgets permit at the
electrical utilities. Australia has a lot of isolated AC
power grids, so most of the Australian AC power grid may not
be affected by the induced currents problem to any extent.
Australia may have less than 4 Mega-HVAC transformers that
may be affected by the geomagnetic storm problem, so time
and care can be taken to fix the problem. Local HVAC grid
Solar and Wind power production must be increased to provide
a safety margin. There is no reason the induced currents
problem cannot be fixed by 2013 at the latest, to cope with
the expected solar activity uptick.
- Canada needs to demand that all US based mega
transformers that send power into Canada be redundant as
part of any electricity sales to the US. Domestically, a
similar assessment to the US is needed and a 7 year
replacement programme needs to be started with particular
emphasis on Ontario, Quebec and British Columbia.
- New Zealand needs to statutorily make 14 days per
year (in 4 separate months) when the North-South HVDC-HVDC
grids run totally independent of each other. Transpower [or
any entity involved in power distribution] needs to
institute a redundancy programme for its suspected HVAC
transformers at risk over the next 5 years. As HVDC is used
for long distance interconnects, some experimentation may be
needed to solve the issue. However, with NZ HVDC gird -- the
induced currents problem is far simpler and NZ to fix. New
Zealand may not have any more than 3 HVAC transformers at
substantial or substantive risk.
Recommendations for the European Union
- Mega-HVAC Transformer : The rating of the 300 or so in the US
is unknown to me, so the metric of commissioning time will be
used. If a transformer takes more than 6 months (180 days) to
build (from commissioning to delivery) then it is a Mega
- Redundant HVAC Transformer : It is assumed that each one of
these must take no more than 3 months (90 days) from
commissioning to delivery. These also must be of a size where
one can be physically delivered anywhere in Europe or North
America in 30 days.
- Matching or Cophasing Network : This network is needed to take
the multiple redundant array of HVAC transformer inputs and
linearly sum these inputs into one or two outputs with properly
matched: frequency, phase, amplitude and impudence.
Specific Solar Storm Events
Power Grid Issues
circuit (power grids have or develop many non-linear
behaviours when extended beyond 100km as a general rule)
analysis (important for understanding power grid
behaviours and risk points)
(Simulation Program with Integrated Circuit Emphasis)
Power Outage Issues
|15 May 2006
|24 October 2009
|29 August 2013 (readability,