Global Geomagnetic Storm Induced Failure of 400 Mega­HVACTransformers is Avoidable by Redundant HVAC Transformer Arrays

­ or ­A Current and Voltage Division Method to Reduce Mega­HVAC

Transformer Failures by Redundant Transformer Arrays

AbstractDuring severe solar storms HVAC transformers used by utilities of dimensional size similar to a medium sized houseare subject to catastrophic failure. As these transformers have very long commissioning and repair schedules theirfailure poses a catastrophic risk. Large parts of grids that depend on their existence of these AC transformers can berendered non­functioning when the mega transformers fail. This catastrophe can be avoided by using simple voltagedivision and current division principals implemented in the form of redundant arrays of smaller HVAC transformers.

Electric power is modern society's cornerstone technology on which virtually all otherinfrastructures and services depend. Yet HVAC power grids are particularlyvulnerable to space weather events.

Ground currents induced during geomagnetic storms can create excess currents in theelectrical grid. These excess unregulated currents have the power to melt the copperwindings of electrically stressed transformers at the core of many mains powerdistribution systems.

Sprawling power lines in essence act like VLF antennas. The grid's distributionnetwork picks up the induced currents created by the solar storm and absorbs them [atfull energy] into the power grid.

MechanismsA time­varying magnetic field external to the Earth induces electric currents in theconducting ground.

These currents create a secondary (internal) magnetic field.

As a consequence of Faraday "Law of Induction" electric fields aligned along thesurface of the Earth are induced in association with the time variations of the magneticfield. The surface electric field causes electrical currents that are known asGeomagnetically Induced Currents (GICs) to flow into any conducting structure.

This GIC induced electric field (typically measured in V/km) acts as a voltage sourceacross networks.

Examples of Geomagnetically Induced Current conducting networks are

electrical power transmission gridsoil and gas pipelinesundersea communication cablescopper telephone networkstelegraph networks used by railways

GICs are often described as being 'quasi Direct Current' (DC) although the variationfrequency 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 DCbias currents. For GICs to be a hazard to technology, the current flows have to be of amagnitude and frequency that makes electrical equipment susceptible to eitherimmediate or cumulative damage.

The size of the GIC in any network is governed by the electrical properties and thetopology of the network. The largest (magnetospheric) ionospheric current variations,resulting in the largest external magnetic field variations typically occur duringgeomagnetic storms. Geomagnetic storms by their nature create the largest GICs.

Significant temporal variation in GICs is known to range from from a few seconds toabout an hour.

Since the largest magnetic field variations are observed at higher magnetic latitudes,GIC have been regularly measured in Canadian, Finnish and Scandinavian powergrids 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 mid­latitudes during major geomagnetic storms withnearly the same magnitude as the GICs in Polar regions. However, GICs are not aproblem exclusive to the mid­latitudes or the Arctic.

There is still a substantial GIC risk to low latitude areas (the tropics). When ageomagnetic storm commences suddenly ­­ a high, short­period rate of change of the

Earth's magnetic field will occur on the dayside of the Earth. This sudden inductionevent will induce high current GICs into the tropic regions. These events are typicallyshort lived, but pose a threat to the power supply systems in the tropics.

The problemAccording to a study by Metatech corporation, a geomagnetic storm with a strengthcomparative to that of 1921 would result in at least 130 million people withoutelectrical power and 350 broken HVAC transformers. The overall cost of restoring thegrid to its original functionality and the economic damage caused by the disruptionwould be around 2 Trillion Dollars (2 000 000 000 000 USD).

Power distribution grids are not designed to absorb large scale geomagneticallyinduced currents as part of their normal day to day operation.

Modern electric power transmission systems consist of generating plantsinterconnected by electrical circuits that operate at fixed transmission voltagescontrolled at substations. The grid voltages employed are largely dependent on thepath length between these substations. Typically 200kV to 700kV system voltages arecommon.

There is a trend towards higher voltages and lower line resistances to reducetransmission losses over longer and longer path lengths. Low line resistances producea situation favourable to the flow of GICs.

Power transformers typically have a magnetic circuit that is disrupted by the quasi­DCGIC: the field produced by the GIC offsets the operating point of the magnetic circuitand the transformer may go into half­cycle saturation. This produces harmonics to theAC waveform, localized heating and leads to high reactive power demands, inefficientpower transmission and possible failure or abnormal operation of protective devices.

Balancing the electrical network in such situations requires significant additionalreactive power capacity.

The magnitude of GIC that will cause significant problems to transformers varies withtransformer type. Modern industry practice is to specify GIC tolerance levels on newtransformers.

There are some partial solutions for coping with geomagnetically induced currents,

typically involving grounding the electrical grid at

50 km intervals in the latitude [North­South] domain75 km intervals in the longitude [East­West] domainlonger intervals than 60 km closer to the tropics

It must be noted that most electrical utilities often fail to fully implement theserecommendations.

GIC risk can, to some extent, be reduced by capacitor blocking systems, maintenanceschedule changes, additional on­demand generating capacity, and ultimately thepolicy of load shedding.

These options are expensive and sometimes impractical.

The continued growth of high voltage power networks results in a higher risk for allusers. 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 gridsoperating closer to capacity than in the past.

To understand the flow of GICs in power grids and to advise on GIC risk analysis ofthe quasi­DC properties of the grid is necessary. This analysis must be coupled with ageophysical model of the Earth that provides the driving surface electric field,determined by combining time­varying ionospheric source fields and a conductivitymodel of the Earth.

This kind of analysis has been performed for North America, the UK and in NorthernEurope. The complexity of power grids, the source ionospheric current systems andthe 3D ground conductivity make an accurate analysis difficult but notcomputationally impractical. By being able to analyze major storms and theirconsequences it is possible to build a picture of the weak spots in a transmissionsystem and run hypothetical event scenarios.

The perils of interconnectionFrom the 1990s into the present day US utilities have joined grids together to allowlong­distance transmission of low­cost power to areas of sudden demand. Canada isalso part of this North American electrical grid network, a fact often lost in thetechnical 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 tolarger per capita loss of life than Canada via primary effects.

As it were : on a hot summer day in California, for instance, people in Los Angelesmight be running their air conditioners on power routed from Oregon. This may makeshort term economic sense ­­ but not necessarily geomagnetic sense. Gridinterconnectedness makes the power distribution network susceptible to wide­ranging"cascade failures."

The problem

These power grid failure problems are totally 'man made' and are 'design inducedproblems' with several different and notable causes

State or private sector companies have been hiring electrical engineers fordecades that are barely suitable to the task of maintaining the power grid. Of thesubtle problem solving issues and complications required in real electricalengineering these engineers know not a jot.Nepotism, favoritism [coupled with a hefty dose of outright class and racediscrimination] at virtually every electrical engineering school in North Americahas in effect left this part of the electrical engineering profession (that maintainsthe essential functioning of the power grid) with poor or unsuitable replacements.The 'classically trained' North American electrical engineers of the 1950s to the1970s are far better problem solvers than their existing counterparts today.

It must be noted that the education system in the US functioned adequatelyenough during the 1950s to 1970s to produce suitable grid engineers capableof some original thought and innovations.The exiting of these engineers via retirement will be felt in the 2010s with adrop 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 togrid reliability that pervade Canada's geographic space.

The finance system that oversees the funding of utilities in North America has notencouraged innovations in grid reliability. This finance sector neglect is a globalproblem ­­ and probably a principal reason why the HVAC transformerredundancy problem was not solved globally at least 30 years ago.Governmental regulation at all levels in North America has failed to address theproblem of Mega­HVAC failures directly or indirectly, effectively perpetuating

the problem by neglect. Computational research into the known problems of large scale AC transformercircuit grids could have fixed the problem by the late 1990s. It is clear thatlimited power grid circuit re­design is would be needed but the problem is not acomplex one.There is an ongoing failure by all parties involved to make the HVACTransformer problem and its solutions 'open source' so as to encourage ongoingresearch. An outright disregard for electrical engineering, chemistry and physicsknowledge by the general public in North America as well as substantial parts ofEurope.

Tentative recommendations for making power grids survive severe solar storms

General system recommendations and practices

Generally the transformer redundancy rule should be[small­odd­number­under­eleven] = Number of Redundant Transformers.

Generally the transformer redundancy rule should be[small­odd­number­under­eleven ­1] = Number of Redundant Transformersin Use (at any one time to backup the Mega­HVAC transformer).

Potentially up to 13 HVAC transformers could be used in parallel ­­ but thebuffering and cophasing networks as well as safety considerations might makesuch a system too complex.There are personnel safety system issues involved with using an array of morethan 11 transformers.The excess redundancy of an array of 13 HVAC transformers is onlyrecommended for the most northerly locations or extreme engineering conditions.Each HVAC transformer must have its own accompanying buffering andmatching network to terminate and match its output.It is not fully clear exactly how this HVAC transformer network should bedesigned. There are at least 400 different Mega­HVAC 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 5redundant HVAC transformers, with 7 being the nominal recommendation.The ultimate number of redundant transformers must ultimately depend on thestatic and dynamic load factors for the Mega­HVAC transformer.

Overall recommendations on redundancy : an array of 11 to 7 transformers isnominal.

Specific system recommendations and practices, typical transformer redundancymode of 7

Each Mega­HVAC transformer must have [as a backup system] an array of atleast 7 HVAC transformers (6 in use at any one time) that can be switched on as abackup 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 Mega­HVAC (input/output) parameters, where an array of 7 transformers exist. The individual HVAC redundant transformer array ratings should be 133% to166% of the [(1/6th) x (Mega­HVAC­ratings)]. A solar storm may happen whena redundant transformer is set aside for repair, thus the 1/6th not 1/7th constant.

Operation modes

This technology will have [by necessity] at least 3 to 5 common operating modes.A (single input, two output) variable potentiometer must proceed the Mega­HVAC Transformer and its backup redundant array of transformers that splittingthe input load.A variable potentiometer to split the voltage and current between the originalHVAC mega transformer and the redundant array must under normal conditionsbe balancing the loads at (50%, 50%).The variable potentiometer must [under stressful solar storm conditions] reducethe load going into the Mega HVAC transformer by at least 25% (75%, 25%) butalso be able to do so by up to 45% (95%, 5%).

Redundant Transformer Array State Machine Operating Modes

Mode # (Input into Array, Input into Mega Transformer) Mode 1 : (50%, 50%) : nominal operationsMode 2 : (75%, 25%) : the redundant HVAC array is made backup to keepthe HVAC from failingMode 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 operationsmode.Mode 5 : (90%, 10%) : in the long term, the Mega Transformer should beused 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 duringthe Summer, with most repairs to the redundant arrays being made during the Falland Spring.A cophasing and buffering network after the [redundant array] or after the[redundant array + mega HVAC transformer] is needed to restore the requiredtarget output voltages and amperages to the mains grid.It is not recommended to operate in INPUT­OUTPUT SYMMETRY MODEwhere 1 HVAC = 1 HVAC (input, output symmetry) unless there is an absoluteengineering necessity ­­ except in the form of 1 HVAC input = 2 HVAC outputs.Arbitrarily engaging in engineering practices that force more Mega­HVACtransformers into existence in the existing electrical grids [except to increase thereliability of those already deployed] has engineering and reliability limitations.Many Mega­HVAC transformers that are currently deployed may not have anyactual engineering necessity, with respect to alternate grid designs that could beput into place that would alleviate their existence entirely.It is assumed that the Mega HVAC transformers will eventually be phased out byredundant arrays of cheaper HVAC transformers so as to totally eliminate thisfailure mode.High power diodes to keep the AC currents unidirectional will be requried in anyHVAC redundant array design. Redundant arrays of analogue devices must bedesigned so as to avoid current feedback and reflection problems.Circuit breakers to separate out the transformers from the array and grid must be4x redundant so as to make accidental energizing of the transformer nearlyimpossible.

Why the above recommendations will work, or the electrical engineering laws weknow so well

The current entering any junction is equal to the current leaving that junction :aka Kirchhoff's current law (KCL).

The directed sum of the electrical potential differences around any closed circuitmust be zero. (Note that geomagnetic storms tend to disturb this difference todestructive effect within the innards of transformers.)In electrical circuit theory, Thévenin's theorem for linear electrical networksstates that any combination of voltage sources, current sources and resistors withtwo terminals is electrically equivalent to a single voltage source V and a singleseries resistor R. For single frequency AC systems the theorem can also beapplied to general impedances, not just resistors. This simple principal cansimplify the conceptual and practical problems that will be encountered along theway.Norton's theorem for linear electrical networks states that any collection ofvoltage sources, current sources, and resistors with two terminals is electricallyequivalent to an ideal current source, I, in parallel with a single resistor, R. Forsingle­frequency AC systems [like power grids] the theorem can also be appliedto general impedances, not just resistors.The Norton Equivalent is used to represent any network of linear sources andimpedances, at a given frequency. The circuit consists of an ideal current sourcein parallel with an ideal impedance (or resistor for non­reactive circuits).

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 ACpower grids, so most of the Australian AC power grid may not be affected by theinduced currents problem to any extent. Australia may have less than 4 Mega­HVAC transformers that may be affected by the geomagnetic storm problem, sotime and care can be taken to fix the problem. Local HVAC grid Solar and Windpower production must be increased to provide a safety margin. There is noreason the induced currents problem cannot be fixed by 2013 at the latest, to copewith the expected solar activity uptick.Canada needs to demand that all US based mega transformers that send powerinto 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 programmeneeds to be started with particular emphasis on Ontario, Quebec and BritishColumbia.New Zealand needs to statutorily make 14 days per year (in 4 separate months)when the North­South HVDC­HVDC 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 thenext 5 years. As HVDC is used for long distance interconnects, someexperimentation may be needed to solve the issue. However, with NZ HVDCgird ­­ the induced currents problem is far simpler and NZ to fix. New Zealandmay not have any more than 3 HVAC transformers at substantial or substantiverisk.

Recommendations for the European Union

TBATBATBA

Definitions

Mega­HVAC Transformer : The rating of the 300 or so in the US is unknown to me, so the metric ofcommissioning time will be used. If a transformer takes more than 6 months (180 days) to build (fromcommissioning to delivery) then it is a Mega Transformer.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 inEurope or North America in 30 days.Matching or Cophasing Network : This network is needed to take the multiple redundant array of HVACtransformer inputs and linearly sum these inputs into one or two outputs with properly matched: frequency,phase, amplitude and impudence.

Technical references

Physics

Template:Magnetospherics ()Geomagnetic_storm ()

Geomagnetically induced current (The Source of the variant DC bias currents in AC power grids that causeproblems.)

Specific Solar Storm Events

March 1989 geomagnetic storm (It caused substantial damage to the HVAC grid in North Eastern NorthAmerica)Solar storm of 1859 (The globally famous Carrington Event)http://science.nasa.gov/headlines/y2009/21jan_severespaceweather.htm ()

Electrical Engineering

Transformer ()Transformer types (DC, AC) : Transformers generally only operate in the DC or AC domains, and fail if non­speccurrents are introduced. Faraday's Law of Induction (Induction of the Earth's magnetic field into mains power lines can create megawattlevel voltages and amperages.)Faraday paradox () OHM's LAW ESSENTIALS : Voltage divider (also known as Voltage Division) & Current divider (also known asCurrent Division); both work in the AC domain with slightly different physical interpretations from the DCdomain. Kirchhoff's circuit laws ()Thevenin's theorem ()Norton's theorem (Norton Equivalents can be used to simplify circuit analysis)

Circuit Analysis

Linear circuit (power grids have or develop many non­linear behaviours when extended beyond 100km as ageneral rule)Mesh analysis (important for understanding power grid behaviours and risk points)Source transformation ()SPICE (Simulation Program with Integrated Circuit Emphasis)

Power Grid Issues

Electricity distribution (Topic overview.)Electric power transmission (Technological overview)Electrical substation (Where HVAC is distributed)Load profile (is an area in surplus or brownout)Power system harmonics (the irregular nature of power distribution system creates internal oscillatory conditions)Dynamic demand (electric power) ()Distributed generation (a way of reducing catastrophic network failures, more viable in the developed world)Flexible AC transmission system (AC transmission systems that can adapt to a wide set of conditions)Smart Power Grid (an extended "Flexible AC transmission system")Grid­tied electrical system ()

Power Outage Issues

Power outage (when there is no power, various causes exist)List of power outages (beyond 1m hours of transmission must be lost, 1965­Present)Rolling blackout (used for technical or energy conservation reasons)Cascading failure (when a failure in point A causes failures in point B C D E, applies to entire power networks)

Created by Original Idea Created Last Modified Version Revision StateMax Power 15 May 2006 24 October 2009 22 May 2014 (readability, content) 0.87a Revisable