Until earlier this year the mandated setting of LoM RoCoF relays was at a rate of change of frequency of 0.125Hz/s, and that still applies to existing generators.
I think we learned from the development of the internet that having all the units on a network behave in exactly the same way can be a recipe for disaster - the classic ethernet example was two nodes on the same segment attempting to transmit at the same time, causing a collision - both would spot the problem, cease transmission, wait for a length of time and try again. If both waited for exactly the same length of time the collision would repeat in exactly the same way and the whole sorry cycle would repeat ad finitum. It seems to me we potentially have a similar problem with the grid - if all the embedded generation in the country switches on or off at the same time it becomes difficult to impossible to keep the while grid in balance as the switch on won't happen until the grid is in balance and the act of switching on is likely to throw the whole thing back out of balance immediately.
The ethernet's solution (if I understand correctly), was to introduce deliberate "randomness" into the decision making - contrary as that feels to building a stable, predictable and reliable system. So the length of time delays in the case of a collision are literally based on a local random number generator - that way it's likely that the two units won't re-transmit at the same time, but even if they do, they're (almost) certain to miss after a few more retries - and as a result the overall system works far more reliably.
It strikes me that G83/G59 (or whatever the new one is) connections could include a degree of probability of disconnecting over a range of values, rather than all trying to switch at the same single threshold. For example rather than all units tripping out at say 200.1V & below - you could define a range - e.g. 205 to 195V and say for every percentage of that range there should be that percentage probability of disconnecting - so at 205V 0% of units should disconnect, at 200V 50% and 195V 100% and similarly at all points in between. Each individual unit (not knowing what any other unit had decided to do) would simply disconnect if it's internal random number generator (as a percentage) produced a number smaller than the percentage into the range the current grid voltage was. Averaged over many such units the grid would see a very gradual, steady and predictable rate of disconnection or reconnection - giving the controllers far more time to adjust central generation to stay in balance.
I don't think the protection settings can be that accurate. Any two at nominally the same setting will actually be marginally different, either due to variations in the measurement or variations in the accuracy of the setting (though digital is minimising this latter). However this doesn't invalidate anything you have said which certainly makes sense.
Been thinking - during the last couple of weeks, there was a huge nuclear blast at a Russian missile silo which has been pretty much hushed up.
Can't recall the exact date, but it happened roughly at the time we had the power cuts, which got me thinking about electro-magnetic pulses resulting from nuclear explosions knocking out electronic equipment..............
Maybe complete bunkum, but given that an earlier post in this thread stated that not all of the information as to the cause was in the public domain.......
I very much doubt that that the Russian nuclear accident was in any way connected to our power cut, for several reasons.
Firstly the Russian accident seems to have been a large release of radioactive material, but not a nuclear explosion.
Secondly, if it was a nuclear detonation, then any EMP caused thereby would be a line of sight effect and could not affect the UK without much more dramatic effects in places nearer to the explosion than us.
Thirdly it was not at the same time. An EMP event is instantaneous, there is no such thing as a delayed EMP,
To use a nuclear explosion as an effective EMP weapon rather than just causing some unexpected trouble, requires some careful control of the circumstances, and the radio waves produced, like the heat and light, obey the inverse square law when you get out of the near field, just like any other source. Considerable study has gone into this, although most of the results are not published
Te conclusion is that a large bomb, say 1 megaton, detonated at altitude certainly can have continent wide effects.
This graph is from this weighty tome but depicts the electric fields at the earths surface, in kilovolts per metre, at various ranges from ground zero from a 1MT detonation from outside the atmosphere, at ~ 800km altitude.
To put that into scale, a few kV/m can damage electronics with exposed wiring acting as an accidental antenna, and a interference at the level of volts per metre stops much domestic electronics until the source is removed. A typical radio signal might be 1-10 micro volts per metre.
as you see, disruption to non-shieded electronics out to a few thousand km may be expected.
The introduction to EMP Engineering Practices Handbook, Nato File 1460-3, (admittedly now rather dated), has some typical numbers, for other situations.
RWE Generation, Orstead and UKPN have been obliged to "pay up" - It doesn't seem clear to me (on quick reading) whether it'sa fine or indicates any culpability?
According to the IET Engineering and Technology News, "Ofgem said each of the companies had agreed to make a voluntary payment of £4.5m into its redress fund." although the headline calls it a fine. UKPN have been made to pay £1.5M due to a "technical breach" when they began reconnecting customers back to the grid before the ESO had told them it was safe to do so.
. . . began reconnecting customers back to the grid before the ESO had told them it was safe to do so . . .
The word “safe” is probably the wrong one to use. It was not “unsafe” in the traditional use of the word, but could have unstabilised the grid, leading to additional interruptions.
