'How can it take 10 hours to restore power'?! It may take longer, I don't think a re-energisation of such a large grid with very high PV penetration has ever been done, all our plans are for black/brown start of grids via gas and coal. Why does it take 10 hours? well 1/x
1. The system is in a completely not-normal state. It will take a few hours to work out what is open, closed, on off etc. 2. Bits have to be energised in stages, which may need engineers on the ground to reset relays, close switches etc. 2/x
This all has do be done slowly in stages to keep the frequency OK - too much too quick and it will collapse. 3. With such high penetration of PV, and not as many big spinning machines as we used to have, it will be difficult to plan out. But even worse, 3/x
As we get towards 10/11 hours, the batteries within the substations will start to fail. At this stage it's a nightmare because they cannot be energised remotely, and even manually the batteries will need charged because modern systems need power for the electronics... 4/x
This will be a long, slow process which no one has ever really done before. If it goes beyond 12 hours, the trouble really starts to stack up. In the UK we had a programme to replace substation batteries for this reason a few years ago @JavierBlas #powercut #spain #engineering