Electric power
is down intermittently
in more than half
of Venezuela.
Schools, industry and state buildings
are closed when they lose power.
The Russians have sent in troops.
The U.S. has told them to get out.
Societies can melt down quickly
without electric power, water, food,
transportation, communication, etc.
It could take many weeks to repair
and restart the electric grid,
to completely restore electric power
to everyone, as the weather
gets colder south of the equator.
If substations and alternators
are blown out, it could take
one year or more !
I'm assuming no power-generating
turbines were damaged.
Substation transformers
are custom made to order.
They do not exist in inventory,
at the power levels needed
on a national grid scale.
Unit substations
might be available
in small sizes
-- 50 to 100 MW.
But high voltage
and higher power
switchgear,
and transformers,
can be a
one to two year
lead time item
even if you have
the cash
to pay for them.
Grid startups
face wild variations
in load, and
sometimes fail:
Every induction motor takes
six times the normal running
current to start up.
So generation
must provide
much more power
than it was providing
when the grid failed,
and that reserve
doesn’t exist
in Venezuela.
The safe way
to restart the grid
is to isolate
all of the loads
except
residential loads
and bring up
the lower voltage
substations (10 kV)
gradually in a
controlled fashion.
The residential load
has resistive components
( water heaters,
clothes dryers,
cooking ovens, etc )
that help
reduce the
inductive component
of the electric load.
Only after the
lower voltage grid
is stabilized,
can the
higher voltage
transmission lines
and substations
be re-energized.
When the generator
is connected to the load,
it “sees” a reflected wave
coming back
to the generator
that trips
the overload safeties,
and causes the
turbine / alternator
to disconnect
if the apparent power
exceeds safe limits.
If those safeties
aren’t functional,
the risk is an
exploding substation,
or alternator, or sheared
turbine shaft.
This is why
keeping a
stable grid
operational
is a lot smarter
than trying to
roll the dice
with intermittent
generation,
and sudden
changes in loads.