Geomagnetically induced current

Geomagnetically induced currents (GIC), affecting the normal operation of long electrical

conductor systems, are a manifestation at ground level of space weather. During space weather

events, electric currents in the magnetosphere and ionosphere experience large variations, which

manifest also in the Earth's magnetic field. These variations induce currents (GIC) in conductors

operated on the surface of Earth. Electric transmission grids and buried pipelines are common

examples of such conductor systems. GIC can cause problems, such as increased corrosion of

pipeline steel and damaged high-voltage power transformers. GIC are one possible consequence

of geomagnetic storms, which may also affect geophysical exploration surveys and oil and gas

drilling operations.

Background

The Earth's geomagnetic field varies over a wide range of timescales. The longer-term variations,

typically occurring over decades to millennia, are predominantly the result of dynamo action in

the Earth's core. Geomagnetic variations on timescales of seconds to years also occur, due to

dynamic processes in the ionosphere, magnetosphere and heliosphere. These changes are

ultimately tied to variations associated with the solar activity (or sunspot) cycle and are

manifestations of "Space Weather".

The fact that the geomagnetic field does respond to solar conditions can be useful, for example in

investigating Earth structure using magnetotellurics, but it also creates a hazard. This

geomagnetic hazard is primarily a risk to technology, at least under the Earth's protective

atmospheric blanket.[1]

Risk to infrastructure

The basic principle for the generation of GIC: variations of the ionospheric currents (I(t))

generate an electric field (E(t)) driving GIC. Shown are also real GIC recordings from the

Finnish natural gas pipeline.

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's law of induction, an electric field at the surface of the Earth is induced associated with

time variations of the magnetic field. The surface electric field causes electrical currents, known

as geomagnetically induced currents (GIC), to flow in any conducting structure, for example, a

power or pipeline grid grounded in the Earth. This electric field, measured in V/km, acts as a

voltage source across networks.

Examples of conducting networks are electrical power transmission grids, oil and gas pipelines,

undersea communication cables, telephone and telegraph networks and railways. GIC are often

described as being quasi direct current (DC), although the variation frequency of GIC is

governed by the time variation of the electric field. For GIC to be a hazard to technology, the

current has to be of a magnitude and occurrence frequency that makes the equipment susceptible

to either immediate or cumulative damage. 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, occur during

geomagnetic storms and it is then that the largest GIC occur. Significant variation periods are

typically from seconds to about an hour, so the induction process involves the upper mantle and

lithosphere. 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. GIC of tens to hundreds of Amperes have been recorded. GIC have

also been recorded at mid-latitudes during major storms. There may even be a risk to low latitude

areas, especially during a storm commencing suddenly because of the high, short-period rate of

change of the field that occurs on the dayside of the Earth.

GIC have been known since the mid-19th century when it was noted that electrical telegraph

systems could sometimes run without power during geomagnetic storms, described at the time as

operating on the "celestial battery", while at other times they were completely inoperative.[2]

GIC in power grids

Modern electric power transmission systems consist of generating plants inter-connected 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 and

200kV-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 GIC. Power transformers 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, localised heating and leads to high reactive power

demands, inefficient power transmission and possible mis-operation of protective measures.

Balancing the network in such situations requires significant additional reactive power

capacity.[3]

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.

On 13 March 1989, a severe geomagnetic storm caused the collapse of the Hydro-Québec power

grid in a matter of seconds as equipment protective relays tripped in a cascading sequence of

events.[4]

Six million people were left without power for nine hours, with significant economic

loss. Since 1989, power companies in North America, the UK, Northern Europe, and elsewhere

have invested in evaluating the GIC risk and in developing mitigation strategies.

GIC risk can, to some extent, be reduced by capacitor blocking systems, maintenance schedule

changes, additional on-demand generating capacity, and ultimately, load shedding. These options

are expensive and sometimes impractical. The continued growth of high voltage power networks

results in higher risk. 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 GIC in power grids and to advise on GIC risk, analysis of the quasi-

DC properties of the grid is necessary.[5]

This 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. Such analyses have 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.[6]

By being able to analyze major storms and their consequences we can build a

picture of the weak spots in a transmission system and run hypothetical event scenarios.

Grid management is also aided by space weather forecasts of major geomagnetic storms. This

allows for mitigation strategies to be implemented. Solar observations provide a one- to three-

day warning of an Earthbound coronal mass ejection (CME), depending on CME speed.

Following this, detection of the solar wind shock that precedes the CME in the solar wind, by

spacecraft at the L1 Lagrangian point, gives a definite 20 to 60 minutes warning of a

geomagnetic storm (again depending on local solar wind speed). The magnitude and arrival time

of a CME after detection is unknown, although there is much research and model development

within the space weather community.

GIC hazard in pipelines

Schematic illustration of the cathodic protection system used to protect pipeline from corrosion.

Major pipeline networks exist at all latitudes and many systems are on a continental scale.

Pipeline networks are constructed from steel to contain high-pressure liquid or gas and have

corrosion resistant coatings. Weathering and other damage to the pipeline coating can result in

the steel being exposed to moist air or to the ground, causing localised corrosion problems.

Cathodic protection is used to minimise corrosion by maintaining the steel at a negative potential

with respect to the ground. The operating potential is determined from the electro-chemical

properties of the soil and Earth in the vicinity of the pipeline. The GIC hazard to pipelines is that

GIC cause swings in the pipe-to-soil potential, increasing the rate of corrosion during major

geomagnetic storms (Gummow, 2002). GIC risk is not a risk of catastrophic failure, but a

reduced service life of the pipeline.

Pipeline networks are modelled in a similar manner to power grids, for example through

distributed source transmission line models that provide the pipe-to-soil potential at any point

along the pipe (Boteler, 1997; Pulkkinen et al., 2001). These models need to consider

complicated pipeline topologies, including bends and branches, as well as electrical insulators (or

flanges) that electrically isolate different sections. From a detailed knowledge of the pipeline

response to GIC, pipeline engineers can understand the behaviour of the cathodic protection

system even during a geomagnetic storm, when pipeline surveying and maintenance may be

suspended.

Further reading

Bolduc, L., GIC observations and studies in the Hydro-Québec power system. J. Atmos.

Sol. Terr. Phys., 64(16), 1793–1802, 2002.

Boteler, D. H., Distributed source transmission line theory for electromagnetic induction

studies. In Supplement of the Proceedings of the 12th International Zurich Symposium

and Technical Exhibition on Electromagnetic Compatibility. pp. 401–408, 1997.

Boteler, D. H., Pirjola, R. J. and Nevanlinna, H., The effects of geomagnetic disturbances

on electrical systems at the Earth's surface. Adv. Space. Res., 22(1), 17-27, 1998.

Erinmez, I. A., Kappenman, J. G. and Radasky, W. A., Management of the

geomagnetically induced current risks on the national grid company's electric power

transmission system. J. Atmos. Sol. Terr. Phys., 64(5-6), 743-756, 2002.

Gummow, R. A., GIC effects on pipeline corrosion and corrosion-control systems. J.

Atmos. Sol. Terr. Phys., 64(16), 1755–1764, 2002.

Lanzerotti, L. J., Space weather effects on technologies. In Song, P., Singer, H. J., Siscoe,

G. L. (eds.), Space Weather. American Geophysical Union, Geophysical Monograph,

125, pp. 11–22, 2001.

Lehtinen, M., and R. Pirjola, Currents produced in earthed conductor networks by

geomagnetically-induced electric fields, Annales Geophysicae, 3, 4, 479-484, 1985.

Pirjola, R., Fundamentals about the flow of geomagnetically induced currents in a power

system applicable to estimating space weather risks and designing remedies. J. Atmos.

Sol. Terr. Phys., 64(18), 1967-1972, 2002.

Pirjola, R., Kauristie, K., Lappalainen, H. and Viljanen, A. and Pulkkinen A., Space

weather risk. AGU Space Weather, 3, S02A02, doi:10.1029/2004SW000112, 2005.

Thomson, A. W. P., A. J. McKay, E. Clarke, and S. J. Reay, Surface electric fields and

geomagnetically induced currents in the Scottish Power grid during the 30 October 2003

geomagnetic storm, AGU Space Weather, 3, S11002, doi:10.1029/2005SW000156, 2005.

Pulkkinen, A., R. Pirjola, D. Boteler, A. Viljanen, and I. Yegorov, Modelling of space

weather effects on pipelines, Journal of Applied Geophysics, 48, 233-256, 2001.

Pulkkinen, A. Geomagnetic Induction During Highly Disturbed Space Weather

Conditions: Studies of Ground Effects, PhD thesis, University of Helsinki, 2003.

(available at eThesis)

External GIC links

Solar Shield — experimental GIC forecasting system

Solar Terrestrial Dispatch — GIC warning distribution center

GICnow! Service by Finnish Meteorological Institute

Ground Effects Topical Group of ESA Space Weather Working Team

Article by J. Kappenman on GIC in power grids

Metatech Corporation's GIC site

Space Weather

Power grid related links

Geomagnetic Storm Induced HVAC Transformer Failure is Avoidable

NOAA Economics -- Geomagnetic Storm datasets and Economic Research

Geomagnetic Storms Can Threaten Electric Power Grid

Global Geomagnetic 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

Abstract

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

transformers.

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.

Mechanisms

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's Law of Induction, an electric field at the surface of the Earth is 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 conducting structure.

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

Examples of GIC conducting networks are: electrical power transmission grids, oil and gas pipelines, undersea

communication cables, telephone and telegraph networks and 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. 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

cumulative damage.

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.

The problem

According to a study by Metatech Corporation, a geomagnetic storm with 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, 000 USD).

Power distribution grids are not designed to absorb large scale geomagnetically induced currents as part of their

normal day to day operation.

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 favorable 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 grid at

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

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

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 event scenarios.

The perils of interconnection

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 primary effects.

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."

The problem

These power grid failure problems are totally 'man made' and are 'design induced problems' with several different

and notable causes

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, favoritism [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.

o 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.

o 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.

o 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

o [small-odd-number-under-eleven] = Number of Redundant Transformers.

Generally the transformer redundancy rule should be

o [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 complex.

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 output.

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.

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 Mega-HVAC Transformer and its

backup redundant array of transformers that splitting the input load.

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%).

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 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 Spring.

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.

I do not recommend 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 reliability limitations.

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 analog devices must be designed so as to avoid current feedback and reflection

problems.

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

(KCL).

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

non-reactive 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 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

TBA

TBA

TBA

Definitions

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 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 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.

Technical references

Physics

Template:Magnetospherics ()

Geomagnetic_storm ()

Geomagnetically_induced_current (The Source of the variant DC currents in AC power grids that cause

problems.)

Specific Solar Storm Events

March_1989_geomagnetic_storm (It caused substantial damage to the HVAC grid in North Eastern North

America)

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)

Faraday's_law_of_induction ()

Faraday_paradox ()

Voltage_divider ()

Current_divider ()

Kirchhoff's circuit laws ()

Thevenin's_theorem ()

Norton's_theorem ()

Circuit Analysis

Linear_circuit ()

Mesh_analysis ()

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")

Grid-tied_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, 1965-Present)

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 : Max Power / Original idea : 15 May 2006 / Created : 24 October 2009 / Last Modified : 22 August

2010