In article , The Other Mike
scribeth thus
On Thu, 22 Aug 2019 10:04:24 +0100, Martin Brown
wrote:


Looking again at that map and noting her observation that the north
south transmission lines would be absolutely saturated at that peak
usage time

It's not even remotely close to being overloaded with the loss of one
circuit, 28GW national demand with depleted generation in the Midlands
and North being quite normal this time of year. Loading is such that
the loss of a double circuit, twice what happened, is well within the
short term (at least 30 mins even in the highest ambient conditions)
capabilities of the other circuits. The overhead line circuit was
only lost for 20 seconds until auto reclosing.

Isn't the 400 kV grid carrying around half a GW per circuit or is it
more now Mike?..



it struck me that transmission line effects might actually
rebound at the Hornsea windfarm when one of the four main N-S circuits
was broken to clear the fault and the instantaneous power in the grid
had to be split across the remaining three main circuits.

Hornsea might have seen some minor disturbance but the generator /
power park module protection should never be set such that it is
reaching or sensitive to a line fault over 100 miles, two/three lines
and at least three/four HV substations away.

A scenario of two near simultaneous lightning strikes should not be
discounted.


I think it may have been sat on a hair trigger and gave up too easily.
There is a hint in the official report that they "adjusted" things after
the incident to make it more robust wrt transient ms line glitches. I
find it depressing that the executive summary carefully ignored the
timeline and frequency graph evidence in favour of anodyne prose.

The timestamps are accurate within the limitations of MSF or if it
were free running the crystal in an oven in the site radioclock


They must have worked very hard on the form of words they use several
times in the report. Do they think repeating it will make it true?

It's an interim report, it's the best you and OFGEM get to see at the
moment.

It does seem that this DC to AC inverter software circuitry needs some
further though it's not that stable seemingly?

Come to think of it how does the inverter right out in the North see or
know what the grids running at, or does it just ramp up frequency and
see what currents flowing back to blighty?..

Anyone know?..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.