Comment by scythe
2 days ago
The root of the issue here is underinvestment in storage. The weather is unpredictable, but the Sun is not. It doesn't suddenly get vastly brighter. Oscillation occurs within a predictable range. But partially because storage keeps getting cheaper, countries are investing at the bare minimum right now. Why buy $100 worth of batteries today when you can get it for $80 in three years?
Batteries are also inverter based sources so they typically don't add any inertia to the grid either. It's not really about the supply of power, it's about maintaining the 50hz frequency to a 0.002% accuracy (yes really) and keeping the voltage similarly exact, otherwise things start quickly disconnecting and tripping in a chain reaction. DC sources would work much better with a HVDC grid... if we had one.
grid-scale batteries generally do add inertia, because that's the most valuable service for them to provide at a small scale. Inverters attached to batteries can do it way better than spinning generators, but they need to be set up to do that.
(And a DC grid would be much more difficult to manage: the nice thing about frequency is that it has to be pretty much the same over the whole grid, so it's a useful signal for the balance between supply and demand, while voltage is really quite sensitive to local effects)
Grid forming inverters are off the shelf technology today.
Price the ancillary services and you will be swimming in them.
> it's about maintaining the 50hz frequency to a 0.002% accuracy (yes really)
That doesn't sound right to me. In the UK the legal requirement is to be within 1% so between 49.5 to 50.5 Hz.
In operation they aim for tighter than that at +/- 0.2 Hz, so 49.8 to 50.2 Hz, or 0.4%.
I can believe that other countries might have tighter limits but not that much!