Mostly, the grid is reliant on the inertia behind it to resist this particular problem. Old school coal and nuke generators had lots of inertia. Gas and Windmills have some. Solar and interconnectors have none.
You can routinely see the effects of the problem you describe between 11PM-1AM, while lots of street lights and/or domestic devices are being shut down at similar times. "See" in the sense that you can almost set your clock to when the lights start flickering. It isn't bad enough to be outside of the statutory frequency ranges the Grid is meant to operate. The increase in electrical noise is particularly noticeable to audio-geeks such as myself; and I ended up getting a UPS/rectifier to get a clean 50Hz signal. The UPS functionality is a nice-to-have extra.
In Germany, some of their closed-down nuke plants were reverse engineered into Flywheels; spun up to provide additional inertia. Britain doesn't need these "today" but there is a engineering case for installing some IMO. FInancially, flywheels are unpopular because they won't make anyone any money to operate.
Looking at the (totally predictable) response to the ESO's recent announcements of what the 2050 grid might look like I fear government-level intervention will be necessary to force through the relevant planning permission to build what we need.
The East Anglia GREEN project and objections are particularly amusing, as they all insist on looking at Offshore as an option. I'm sorry, but the power has to come onshore somewhere to go to, you know, the demand. Bit bloody useless landing it on the shoreline and then not being able to move it inland because the capacity of the existing system is inadequate for the amount of generation expected to connect in those areas.
A/C as I'm an employee in the sector.
The plans of the networks to do what is necessary are about right; but the ability to execute in the face of NIMBYism is a massive risk to the rest of us.
I am of the long term opinion the network is screwed; and you need to plan to be able to run off-grid because Britain can't do long-term infrastructure right any more.
Biting the hand that feeds IT
