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Story by Capell Aris The Telegraph
Last Monday, the Iberian grid suffered a disturbance in the south-west
at 12:33. In 3.5 seconds this worsened and the interconnection to France >disconnected. All renewable generation then went off-line, followed by >disconnection of all rotating generation plant. The Iberian blackout was >complete within a few seconds.
At the time the grid was producing 28.4 GW of power, of which 79 per
cent was solar and wind. This was a problematic situation as solar and
wind plants have another, not widely known, downside – one quite apart
from their intermittency and expense.
This is the fact that they do not supply any inertia to the grid.
Thermal powerplants – coal, gas, nuclear, for example – drive large >spinning generators which are directly, synchronously connected to the
grid. If there are changes which cause a difference between demand and >supply, the generators will start to spin faster or slower: but their
inertia resists this process, meaning that the frequency of the
alternating current in the grid changes only slowly. There is time for
the grid managers to act, matching supply to demand and keeping the grid >frequency within limits.
This is vital because all grids must supply power at a steady frequency
so that electrical appliances work properly and safely. Deviations from
the standard grid frequency can cause damage to equipment and other
problems: in practice what happens quite rapidly when frequency changes >significantly is that grid machinery trips out to prevent these issues
and grids go down.
When a grid has very little inertia in it – as with the Iberian one on >Monday – a problem which a high-inertia grid would easily resist can
cause a blackout within seconds. Lack of inertia was almost certainly
the primary cause of the Iberian blackout, as Matt Oliver has opined in
these pages. A grid with more inertia would not have collapsed as
quickly, and its operators would have had time to keep it up and running.
Restoration of supplies was completed by early Tuesday morning, based on >reconnection to France, which facilitated progressive area reconnections >across Spain and Portugal.
Iberia is part of the Continental Europe Synchronous Area which
stretches to 32 countries. It is interconnected as a phase-locked, 50 Hz
grid with a generation capacity of 700 GW. To improve the stability of
this grid, the EU aim is that all partners will extract 10 per cent of
their power consumption from synchronous interconnectors – ones which >transmit grid inertia – helping to make the whole system more resilient. >France is at 10 per cent, but peninsula grids and those at the
geographical fringe are the least interconnected. Spain has just 2 per
cent from synchronous interconnectors.
But there are places where things are worse. The UK and Ireland are
island grids. They do have undersea power interconnectors to Europe but
these are non-synchronous DC links and transmit no grid inertia. There’s >little prospect that this will change.
Both the Irish and UK grid system operators had developed an array of
grid protection services that can control grid frequency, loss of load
or generation protection, grid phase angle and recovering from grid
outages. Neither country has, to date, ever experienced a total system >failure, even during WWII.
In 1974 construction started on Dinorwig Power Station. It is a pumped >storage generation plant designed specifically for the provision of all
the UK’s grid protection services. Dinorwig can make huge changes to its >output in a matter of seconds, compensating for sudden events. Operation >began in 1984. In 1990 all the UK’s generating stations could provide >inertia.
Nowadays, 55 per cent of our generation mix (wind, solar, DC imports)
cannot supply inertia to the grid. Are we approaching a system that
compares with Spain and Portugal on Monday?
It certainly looks that way. In 2012 the National Grid produced a solar >briefing note for the government which is still available online. In
that note they imagine a system that has 22 GW of solar power attached
to the grid. They demonstrate their concerns based on a sunny summer day
when demand is low. The sun rises at 5 o’clock when little or no >synchronous plant other than nuclear generation will be on line and at >midday, solar is 60 per cent of all generation. The Grid’s engineers
then considered that situation “difficult to manage” and concluded that >wind+solar power must never exceed 60 per cent of generation.
We now have 17.7 GW of grid-connected solar farms to which we must add
all rooftop solar installations. At midday on Tuesday according to
Gridwatch the UK’s asynchronous, no-inertia generation was at 66 per
cent of total generation.
In 2014 National Grid produced a System Operability Framework document.
Their objective was to outline how future scenarios of generation mixes
would impact upon protection services for the grid. As more and more >renewable generators are brought on-line, the difficulties of managing
the grid have become more and more onerous. For example, one service
titled “primary response” in 1990 called for selected generation plants >to increase generation within 10 seconds after a fault is detected: by
1,200 MW in winter and 1,500 MW in summer. In 2024 these increases are >required in 1.2 seconds!
After nearly 50 years of operation, Dinorwig Power Station is currently
shut down for major repairs and there has been no information on when it
will re-open. Over the next five years all of our nuclear stations, bar >Sizewell, will be closed. Over the same period our combined cycle gas >generator fleet will halve from 30 GW to 15 GW. (It takes 5 years to
build a new CCGT even using an existing site. The new ones are 66 per
cent efficient and cost less than £1 billion to build a 1 GW plant – one >third the cost of an offshore windmill.)
We will lose huge amounts of grid inertia. Low-inertia operation will
become routine. It is hard to imagine that we won’t start to suffer >complete national blackouts like the Iberian one.
One last piece of doom: the recovery of Spain’s grid in just one day is >impressive. This speed is certainly due to the assistance of a large,
stable grid reconnecting into the Iberian system thus allowing recovery
in a series of stable steps as each grid area is recovered. We will not
have that facility in the UK with our asynchronous interconnectors.
Dr Capell Aris PhD spent his career in the electricity generation
sector. He is a Fellow of the Institute of Engineering and Technology
https://www.msn.com/en-us/money/companies/a-power-engineer-on-the-iberian-grid-collapse-it-makes-me-very-afraid-for-britain/ar-AA
1DZjGo
Story by Capell Aris The Telegraph
Last Monday, the Iberian grid suffered a disturbance in the south-west
at 12:33. In 3.5 seconds this worsened and the interconnection to France
disconnected. All renewable generation then went off-line, followed by
disconnection of all rotating generation plant. The Iberian blackout was
complete within a few seconds.
At the time the grid was producing 28.4 GW of power, of which 79 per
cent was solar and wind. This was a problematic situation as solar and
wind plants have another, not widely known, downside – one quite apart >>from their intermittency and expense.
This is the fact that they do not supply any inertia to the grid.
Thermal powerplants – coal, gas, nuclear, for example – drive large
spinning generators which are directly, synchronously connected to the
grid. If there are changes which cause a difference between demand and
supply, the generators will start to spin faster or slower: but their
inertia resists this process, meaning that the frequency of the
alternating current in the grid changes only slowly. There is time for
the grid managers to act, matching supply to demand and keeping the grid
frequency within limits.
This is vital because all grids must supply power at a steady frequency
so that electrical appliances work properly and safely. Deviations from
the standard grid frequency can cause damage to equipment and other
problems: in practice what happens quite rapidly when frequency changes
significantly is that grid machinery trips out to prevent these issues
and grids go down.
When a grid has very little inertia in it – as with the Iberian one on
Monday – a problem which a high-inertia grid would easily resist can
cause a blackout within seconds. Lack of inertia was almost certainly
the primary cause of the Iberian blackout, as Matt Oliver has opined in
these pages. A grid with more inertia would not have collapsed as
quickly, and its operators would have had time to keep it up and running.
Restoration of supplies was completed by early Tuesday morning, based on
reconnection to France, which facilitated progressive area reconnections
across Spain and Portugal.
Iberia is part of the Continental Europe Synchronous Area which
stretches to 32 countries. It is interconnected as a phase-locked, 50 Hz
grid with a generation capacity of 700 GW. To improve the stability of
this grid, the EU aim is that all partners will extract 10 per cent of
their power consumption from synchronous interconnectors – ones which
transmit grid inertia – helping to make the whole system more resilient. >> France is at 10 per cent, but peninsula grids and those at the
geographical fringe are the least interconnected. Spain has just 2 per
cent from synchronous interconnectors.
But there are places where things are worse. The UK and Ireland are
island grids. They do have undersea power interconnectors to Europe but
these are non-synchronous DC links and transmit no grid inertia. There’s >> little prospect that this will change.
Both the Irish and UK grid system operators had developed an array of
grid protection services that can control grid frequency, loss of load
or generation protection, grid phase angle and recovering from grid
outages. Neither country has, to date, ever experienced a total system
failure, even during WWII.
In 1974 construction started on Dinorwig Power Station. It is a pumped
storage generation plant designed specifically for the provision of all
the UK’s grid protection services. Dinorwig can make huge changes to its >> output in a matter of seconds, compensating for sudden events. Operation
began in 1984. In 1990 all the UK’s generating stations could provide
inertia.
Nowadays, 55 per cent of our generation mix (wind, solar, DC imports)
cannot supply inertia to the grid. Are we approaching a system that
compares with Spain and Portugal on Monday?
It certainly looks that way. In 2012 the National Grid produced a solar
briefing note for the government which is still available online. In
that note they imagine a system that has 22 GW of solar power attached
to the grid. They demonstrate their concerns based on a sunny summer day
when demand is low. The sun rises at 5 o’clock when little or no
synchronous plant other than nuclear generation will be on line and at
midday, solar is 60 per cent of all generation. The Grid’s engineers
then considered that situation “difficult to manage” and concluded that >> wind+solar power must never exceed 60 per cent of generation.
We now have 17.7 GW of grid-connected solar farms to which we must add
all rooftop solar installations. At midday on Tuesday according to
Gridwatch the UK’s asynchronous, no-inertia generation was at 66 per
cent of total generation.
In 2014 National Grid produced a System Operability Framework document.
Their objective was to outline how future scenarios of generation mixes
would impact upon protection services for the grid. As more and more
renewable generators are brought on-line, the difficulties of managing
the grid have become more and more onerous. For example, one service
titled “primary response” in 1990 called for selected generation plants >> to increase generation within 10 seconds after a fault is detected: by
1,200 MW in winter and 1,500 MW in summer. In 2024 these increases are
required in 1.2 seconds!
After nearly 50 years of operation, Dinorwig Power Station is currently
shut down for major repairs and there has been no information on when it
will re-open. Over the next five years all of our nuclear stations, bar
Sizewell, will be closed. Over the same period our combined cycle gas
generator fleet will halve from 30 GW to 15 GW. (It takes 5 years to
build a new CCGT even using an existing site. The new ones are 66 per
cent efficient and cost less than £1 billion to build a 1 GW plant – one >> third the cost of an offshore windmill.)
We will lose huge amounts of grid inertia. Low-inertia operation will
become routine. It is hard to imagine that we won’t start to suffer
complete national blackouts like the Iberian one.
One last piece of doom: the recovery of Spain’s grid in just one day is
impressive. This speed is certainly due to the assistance of a large,
stable grid reconnecting into the Iberian system thus allowing recovery
in a series of stable steps as each grid area is recovered. We will not
have that facility in the UK with our asynchronous interconnectors.
Dr Capell Aris PhD spent his career in the electricity generation
sector. He is a Fellow of the Institute of Engineering and Technology
https://www.msn.com/en-us/money/companies/a-power-engineer-on-the-iberian-grid-collapse-it-makes-me-very-afraid-for-britain/ar-AA
1DZjGo
DC is already used for long distances power transfer.
These days with electronics it is easy to convert that to AC locally, synchronized if need be.
But you could drop the 50 Hz or 60 Hz net altogether and do local conversion to AC, and / or to a lower DC voltage
even for for each household.
Using high frequency switching converters reduces the amount of huge transformers.
Local batteries and solar cells... I have a 250 Ah battery pack and solar cells and a 2 kW DC to AC pure sinewave inverter here.
Will at least run the fridge and microwave if the net goes down.
On 5/1/2025 11:34 PM, Jan Panteltje wrote:
Story by Capell Aris The Telegraph
Last Monday, the Iberian grid suffered a disturbance in the south-west
at 12:33. In 3.5 seconds this worsened and the interconnection to France >>> disconnected. All renewable generation then went off-line, followed by
disconnection of all rotating generation plant. The Iberian blackout was >>> complete within a few seconds.
At the time the grid was producing 28.4 GW of power, of which 79 per
cent was solar and wind. This was a problematic situation as solar and
wind plants have another, not widely known, downside – one quite apart >>>from their intermittency and expense.
This is the fact that they do not supply any inertia to the grid.
Thermal powerplants – coal, gas, nuclear, for example – drive large
spinning generators which are directly, synchronously connected to the
grid. If there are changes which cause a difference between demand and
supply, the generators will start to spin faster or slower: but their
inertia resists this process, meaning that the frequency of the
alternating current in the grid changes only slowly. There is time for
the grid managers to act, matching supply to demand and keeping the grid >>> frequency within limits.
This is vital because all grids must supply power at a steady frequency
so that electrical appliances work properly and safely. Deviations from
the standard grid frequency can cause damage to equipment and other
problems: in practice what happens quite rapidly when frequency changes
significantly is that grid machinery trips out to prevent these issues
and grids go down.
When a grid has very little inertia in it – as with the Iberian one on >>> Monday – a problem which a high-inertia grid would easily resist can
cause a blackout within seconds. Lack of inertia was almost certainly
the primary cause of the Iberian blackout, as Matt Oliver has opined in
these pages. A grid with more inertia would not have collapsed as
quickly, and its operators would have had time to keep it up and running. >>>
Restoration of supplies was completed by early Tuesday morning, based on >>> reconnection to France, which facilitated progressive area reconnections >>> across Spain and Portugal.
Iberia is part of the Continental Europe Synchronous Area which
stretches to 32 countries. It is interconnected as a phase-locked, 50 Hz >>> grid with a generation capacity of 700 GW. To improve the stability of
this grid, the EU aim is that all partners will extract 10 per cent of
their power consumption from synchronous interconnectors – ones which
transmit grid inertia – helping to make the whole system more resilient. >>> France is at 10 per cent, but peninsula grids and those at the
geographical fringe are the least interconnected. Spain has just 2 per
cent from synchronous interconnectors.
But there are places where things are worse. The UK and Ireland are
island grids. They do have undersea power interconnectors to Europe but
these are non-synchronous DC links and transmit no grid inertia. There’s >>> little prospect that this will change.
Both the Irish and UK grid system operators had developed an array of
grid protection services that can control grid frequency, loss of load
or generation protection, grid phase angle and recovering from grid
outages. Neither country has, to date, ever experienced a total system
failure, even during WWII.
In 1974 construction started on Dinorwig Power Station. It is a pumped
storage generation plant designed specifically for the provision of all
the UK’s grid protection services. Dinorwig can make huge changes to its >>> output in a matter of seconds, compensating for sudden events. Operation >>> began in 1984. In 1990 all the UK’s generating stations could provide
inertia.
Nowadays, 55 per cent of our generation mix (wind, solar, DC imports)
cannot supply inertia to the grid. Are we approaching a system that
compares with Spain and Portugal on Monday?
It certainly looks that way. In 2012 the National Grid produced a solar
briefing note for the government which is still available online. In
that note they imagine a system that has 22 GW of solar power attached
to the grid. They demonstrate their concerns based on a sunny summer day >>> when demand is low. The sun rises at 5 o’clock when little or no
synchronous plant other than nuclear generation will be on line and at
midday, solar is 60 per cent of all generation. The Grid’s engineers
then considered that situation “difficult to manage” and concluded that >>> wind+solar power must never exceed 60 per cent of generation.
We now have 17.7 GW of grid-connected solar farms to which we must add
all rooftop solar installations. At midday on Tuesday according to
Gridwatch the UK’s asynchronous, no-inertia generation was at 66 per
cent of total generation.
In 2014 National Grid produced a System Operability Framework document.
Their objective was to outline how future scenarios of generation mixes
would impact upon protection services for the grid. As more and more
renewable generators are brought on-line, the difficulties of managing
the grid have become more and more onerous. For example, one service
titled “primary response” in 1990 called for selected generation plants >>> to increase generation within 10 seconds after a fault is detected: by
1,200 MW in winter and 1,500 MW in summer. In 2024 these increases are
required in 1.2 seconds!
After nearly 50 years of operation, Dinorwig Power Station is currently
shut down for major repairs and there has been no information on when it >>> will re-open. Over the next five years all of our nuclear stations, bar
Sizewell, will be closed. Over the same period our combined cycle gas
generator fleet will halve from 30 GW to 15 GW. (It takes 5 years to
build a new CCGT even using an existing site. The new ones are 66 per
cent efficient and cost less than £1 billion to build a 1 GW plant – one >>> third the cost of an offshore windmill.)
We will lose huge amounts of grid inertia. Low-inertia operation will
become routine. It is hard to imagine that we won’t start to suffer
complete national blackouts like the Iberian one.
One last piece of doom: the recovery of Spain’s grid in just one day is >>> impressive. This speed is certainly due to the assistance of a large,
stable grid reconnecting into the Iberian system thus allowing recovery
in a series of stable steps as each grid area is recovered. We will not
have that facility in the UK with our asynchronous interconnectors.
Dr Capell Aris PhD spent his career in the electricity generation
sector. He is a Fellow of the Institute of Engineering and Technology
https://www.msn.com/en-us/money/companies/a-power-engineer-on-the-iberian-grid-collapse-it-makes-me-very-afraid-for-britain/ar-AA
1DZjGo
DC is already used for long distances power transfer.
I was taught (in electronics classes) that the problem with DC is that
it suffers significant power loss over distances due to the resistance
in copper, aluminum or steel wire.
OHM's law applies to wire as anyone
who studies electronics knows. Alternating current overcame the
resistance in wire due to the "skin effect" where the collapsing
magnetic field around the wire during the negative phase of alternating >current cycle replenishes the flow of electrons in the wire.
to College Avenue in Fort Collins, CO in the 20th century (and may still
be running) that had DC motors. The voltage at the source of the power
for the street cars was 800 volts DC at City Park. The voltage two
miles away at the end of the line on College Avenue was reduced by 200
volts due to the resistance in the copper wire to 500 volts. Unless a
way has been devised to overcome OHM's law, I don't see how high voltage
can be transmitted across Europe using direct current. Perhaps you can >explain.
On 5/1/2025 11:34 PM, Jan Panteltje wrote:
Story by Capell Aris The Telegraph
Last Monday, the Iberian grid suffered a disturbance in the south-west >>>> at 12:33. In 3.5 seconds this worsened and the interconnection to France >>>> disconnected. All renewable generation then went off-line, followed by >>>> disconnection of all rotating generation plant. The Iberian blackout was >>>> complete within a few seconds.
At the time the grid was producing 28.4 GW of power, of which 79 per
cent was solar and wind. This was a problematic situation as solar and >>>> wind plants have another, not widely known, downside – one quite apart >>> >from their intermittency and expense.
This is the fact that they do not supply any inertia to the grid.
Thermal powerplants – coal, gas, nuclear, for example – drive large >>>> spinning generators which are directly, synchronously connected to the >>>> grid. If there are changes which cause a difference between demand and >>>> supply, the generators will start to spin faster or slower: but their
inertia resists this process, meaning that the frequency of the
alternating current in the grid changes only slowly. There is time for >>>> the grid managers to act, matching supply to demand and keeping the grid >>>> frequency within limits.
This is vital because all grids must supply power at a steady frequency >>>> so that electrical appliances work properly and safely. Deviations from >>>> the standard grid frequency can cause damage to equipment and other
problems: in practice what happens quite rapidly when frequency changes >>>> significantly is that grid machinery trips out to prevent these issues >>>> and grids go down.
When a grid has very little inertia in it – as with the Iberian one on >>>> Monday – a problem which a high-inertia grid would easily resist can >>>> cause a blackout within seconds. Lack of inertia was almost certainly
the primary cause of the Iberian blackout, as Matt Oliver has opined in >>>> these pages. A grid with more inertia would not have collapsed as
quickly, and its operators would have had time to keep it up and running. >>>>
Restoration of supplies was completed by early Tuesday morning, based on >>>> reconnection to France, which facilitated progressive area reconnections >>>> across Spain and Portugal.
Iberia is part of the Continental Europe Synchronous Area which
stretches to 32 countries. It is interconnected as a phase-locked, 50 Hz >>>> grid with a generation capacity of 700 GW. To improve the stability of >>>> this grid, the EU aim is that all partners will extract 10 per cent of >>>> their power consumption from synchronous interconnectors – ones which >>>> transmit grid inertia – helping to make the whole system more resilient. >>>> France is at 10 per cent, but peninsula grids and those at the
geographical fringe are the least interconnected. Spain has just 2 per >>>> cent from synchronous interconnectors.
But there are places where things are worse. The UK and Ireland are
island grids. They do have undersea power interconnectors to Europe but >>>> these are non-synchronous DC links and transmit no grid inertia. There’s >>>> little prospect that this will change.
Both the Irish and UK grid system operators had developed an array of
grid protection services that can control grid frequency, loss of load >>>> or generation protection, grid phase angle and recovering from grid
outages. Neither country has, to date, ever experienced a total system >>>> failure, even during WWII.
In 1974 construction started on Dinorwig Power Station. It is a pumped >>>> storage generation plant designed specifically for the provision of all >>>> the UK’s grid protection services. Dinorwig can make huge changes to its >>>> output in a matter of seconds, compensating for sudden events. Operation >>>> began in 1984. In 1990 all the UK’s generating stations could provide >>>> inertia.
Nowadays, 55 per cent of our generation mix (wind, solar, DC imports)
cannot supply inertia to the grid. Are we approaching a system that
compares with Spain and Portugal on Monday?
It certainly looks that way. In 2012 the National Grid produced a solar >>>> briefing note for the government which is still available online. In
that note they imagine a system that has 22 GW of solar power attached >>>> to the grid. They demonstrate their concerns based on a sunny summer day >>>> when demand is low. The sun rises at 5 o’clock when little or no
synchronous plant other than nuclear generation will be on line and at >>>> midday, solar is 60 per cent of all generation. The Grid’s engineers >>>> then considered that situation “difficult to manage” and concluded that
wind+solar power must never exceed 60 per cent of generation.
We now have 17.7 GW of grid-connected solar farms to which we must add >>>> all rooftop solar installations. At midday on Tuesday according to
Gridwatch the UK’s asynchronous, no-inertia generation was at 66 per >>>> cent of total generation.
In 2014 National Grid produced a System Operability Framework document. >>>> Their objective was to outline how future scenarios of generation mixes >>>> would impact upon protection services for the grid. As more and more
renewable generators are brought on-line, the difficulties of managing >>>> the grid have become more and more onerous. For example, one service
titled “primary response” in 1990 called for selected generation plants
to increase generation within 10 seconds after a fault is detected: by >>>> 1,200 MW in winter and 1,500 MW in summer. In 2024 these increases are >>>> required in 1.2 seconds!
After nearly 50 years of operation, Dinorwig Power Station is currently >>>> shut down for major repairs and there has been no information on when it >>>> will re-open. Over the next five years all of our nuclear stations, bar >>>> Sizewell, will be closed. Over the same period our combined cycle gas
generator fleet will halve from 30 GW to 15 GW. (It takes 5 years to
build a new CCGT even using an existing site. The new ones are 66 per
cent efficient and cost less than £1 billion to build a 1 GW plant – one
third the cost of an offshore windmill.)
We will lose huge amounts of grid inertia. Low-inertia operation will
become routine. It is hard to imagine that we won’t start to suffer
complete national blackouts like the Iberian one.
One last piece of doom: the recovery of Spain’s grid in just one day is >>>> impressive. This speed is certainly due to the assistance of a large,
stable grid reconnecting into the Iberian system thus allowing recovery >>>> in a series of stable steps as each grid area is recovered. We will not >>>> have that facility in the UK with our asynchronous interconnectors.
Dr Capell Aris PhD spent his career in the electricity generation
sector. He is a Fellow of the Institute of Engineering and Technology
https://www.msn.com/en-us/money/companies/a-power-engineer-on-the-iberian-grid-collapse-it-makes-me-very-afraid-for-britain/ar-AA
1DZjGo
DC is already used for long distances power transfer.
I was taught (in electronics classes) that the problem with DC is that
it suffers significant power loss over distances due to the resistance
in copper, aluminum or steel wire.
That is why long distance DC uses very high voltages, so higher voltage lower current, less Ohmic losses.
OHM's law applies to wire as anyone
who studies electronics knows. Alternating current overcame the
resistance in wire due to the "skin effect" where the collapsing
magnetic field around the wire during the negative phase of alternating
current cycle replenishes the flow of electrons in the wire.
That is not corrent
One problem with AC is _inductance_ of the wire.
Skin effect only works for AC and causes the current to flow mainly on the outside of the inductor / cable,
requiring thicker (or maybe hollow?) cables.
https://en.wikipedia.org/wiki/Skin_effect
to College Avenue in Fort Collins, CO in the 20th century (and may still
be running) that had DC motors. The voltage at the source of the power
for the street cars was 800 volts DC at City Park. The voltage two
miles away at the end of the line on College Avenue was reduced by 200
volts due to the resistance in the copper wire to 500 volts. Unless a
way has been devised to overcome OHM's law, I don't see how high voltage
can be transmitted across Europe using direct current. Perhaps you can
explain.
You are confused, or your teacher were:
https://en.wikipedia.org/wiki/High-voltage_direct_current
There are high voltage long distance links in the US too.
I stand corrected. I'm not sure, in retrospect, if I was given >misinformation at the community college I attended back in the '80s or
if I misremember what they were teaching per the topic under discussion.
Either way, thank you for correcting my lack of knowledge and setting
the record straight.