At the slack bus, there is a generator that can change his output instantly. I was wondering if exists in the grid this generator. We use it to study power flow problems but I don't think that there is a generator in the grid (that of the slack) which is able to change his output instantly. Can you give a physical representation of the slack bus?

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    \$\begingroup\$ I have no idea what or where a slack bus is but if you're looking for instant generation capacity have you considered a battery inverter system? \$\endgroup\$ – Transistor Nov 1 '20 at 17:19
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    \$\begingroup\$ gridwatch.templar.co.uk ... at the moment demand is 36.36GW and frequency is 50.021Hz. Add some load and you'll see the frequency fall slightly as all the spinning generators work a little harder. If it falls far enough someone will turn the pumped storage generators up a bit; they are providing about 1.1GW out of 2.5GW capacity. Then the CCGT gas turbines will be the next to react. And so on. \$\endgroup\$ – user_1818839 Nov 1 '20 at 17:48
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    \$\begingroup\$ The “slack bus” I am referring to is 1 machine in the system (for which a load flow is being solved) that is used to make up all of the losses not accounted for in the system - to allow a numerical solution. \$\endgroup\$ – relayman357 Nov 1 '20 at 18:09
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    \$\begingroup\$ There is not a real machine or even a battery system that can change real power output instantly. However there as a wide range of response times for real machines. It may be possible to assign the slack bus role to a real machine with some limitation on what "instantaneous" really means. It would be better to search the technical literature of find a handbook that discusses the subject in depth. \$\endgroup\$ – Charles Cowie Nov 1 '20 at 18:15
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    \$\begingroup\$ You don’t need the slack bus if you are measuring real flows in the system - which is how the system operator gets their data (real transducers). \$\endgroup\$ – relayman357 Nov 1 '20 at 18:23

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