EV Charger Pool

[llucax]

Update Power Distributor, Power Manager to support EV Chargers, so that EV Charger Pool can have a consistent interface as the Battery Pool, with all control commands going through the Power Manager and Power Distributor.

[shsms]

Progress update (from PR #887):

1. EVChargerPool's interface now corresponds to that of BatteryPool. Individual EV charger control is no longer possible, unless the pool is initialized for a single component.
2. PowerManager can handle EV chargers - it sends target power for a set of EV chargers to the power distributor.
3. PowerDistributor can handle allocating power to EV chargers as soon as EVs get connected, if there's unallocated power left from the target power from the power manager.

Pending items:

1. PowerDistributor needs support for throttling EV chargers when they are consuming more power than latest target power coming from the power manager.
2. Testing/Unit tests

Notes on throttling:

But because we are dealing only in Power values and not Current, we can't do the optimizations for phase-rotation we did in the original actor, when just one phase has a breach. This will still have the stage1(min charging power ~=6A) and stage2(stop completely) throttling, but will be much simpler otherwise.

And the target power has to be calculated outside. But I'm sure a grid protection actor (like the one we already(~) have for batteries) that sets higher priority bounds through the PowerManager would be enough here too, when that's the requirement.

The PowerDistributor's distribution Algorithm for EV chargers is a modular self-contained thing now. It is a simple first-come first-serve algorithm now, but can be swapped for other strategies as well.

For your attention, @thomas-nicolai-frequenz

[shsms]

Now that we can have multiple PowerManager instances - one for each component category, some of the highest priority actors like a grid safety actor might need to set bounds on all such PowerManager instances, because each of them would affect the grid power, for example.