129MWhr Battery Doing its Job Down Under.

but unlike Dinorwig it will do nothing for the stability of the system as it has no inertia.

I guess that depends on what you mean by grid stability. Maybe I'm getting confused by the specialised meaning of words, but I would have guessed that for a grid to be stable then supply needs to match demand (or vice versa) not only on a second-by-second basis but on a minute-by-minute and hour-by-hour basis too.  Rotational inertia is great for matching second-by-second (or faster) changes - but I'd guess is less useful much beyond that as they'll soon start slowing down and bring the grid frequency down with it. For hour-by-hour you can startup or shutdown generators - so no major problems there (providing you have enough spare capacity). The minute-by-minute changes are trickier I would have thought - traditionally requiring 'spinning reserve' - i.e. plants running and consuming fuel, but just at a tick-over rate and not producing any significant power - on the basis it's far quicker to increase the power of a running plant than start one up from stationary.


From what I can gather, the Australian system has a lot of coal fired generation (about 75%) so probably not short of inertia - but likely poor response time for reasonably rapid changes in demand (or sudden loss of generation). So it seemed the Australians were using a lot of gas and diesel as something like spinning reserves - which proved rather expensive. It sounds like they're using the Tesla system to fill these minute-by-minute gaps until the coal stations can respond - seemingly saving a reasonable amount of money in the process.


As an aside I wonder how much inertia we really need. Some small off-grid systems seem to be entirely inverter driven and seem to cope with (as a percentage of their output) very significant and rapid changes in load without major issues - indeed inverter generators seem to be sold a proving better stability than their purely mechanical counterparts. I guess issues aren't quite the same - a small system 'dropping' significantly while a fault cleared probably has a lot less impact than if an entire national grid did the same, but perhaps there may be ways of managing that sort of thing if we had to.


   - Andy.

but unlike Dinorwig it will do nothing for the stability of the system as it has no inertia.

I guess that depends on what you mean by grid stability. Maybe I'm getting confused by the specialised meaning of words, but I would have guessed that for a grid to be stable then supply needs to match demand (or vice versa) not only on a second-by-second basis but on a minute-by-minute and hour-by-hour basis too.  Rotational inertia is great for matching second-by-second (or faster) changes - but I'd guess is less useful much beyond that as they'll soon start slowing down and bring the grid frequency down with it. For hour-by-hour you can startup or shutdown generators - so no major problems there (providing you have enough spare capacity). The minute-by-minute changes are trickier I would have thought - traditionally requiring 'spinning reserve' - i.e. plants running and consuming fuel, but just at a tick-over rate and not producing any significant power - on the basis it's far quicker to increase the power of a running plant than start one up from stationary.


From what I can gather, the Australian system has a lot of coal fired generation (about 75%) so probably not short of inertia - but likely poor response time for reasonably rapid changes in demand (or sudden loss of generation). So it seemed the Australians were using a lot of gas and diesel as something like spinning reserves - which proved rather expensive. It sounds like they're using the Tesla system to fill these minute-by-minute gaps until the coal stations can respond - seemingly saving a reasonable amount of money in the process.


As an aside I wonder how much inertia we really need. Some small off-grid systems seem to be entirely inverter driven and seem to cope with (as a percentage of their output) very significant and rapid changes in load without major issues - indeed inverter generators seem to be sold a proving better stability than their purely mechanical counterparts. I guess issues aren't quite the same - a small system 'dropping' significantly while a fault cleared probably has a lot less impact than if an entire national grid did the same, but perhaps there may be ways of managing that sort of thing if we had to.


   - Andy.