Multiple grids

The base has grown: the solar fields stand in the north, workshop and habitat lie in the south. Two grids, two battery banks. If the north has a surplus and the south is in need, power should go across – but only then.

Measuring grids separately#

A cable network is a power and data network at the same time. A chip on the southern network sees nothing on the northern one. The solution is devices with a separate data port:

Lay a separate control network: a cable that only connects the data ports of the batteries of both grids, the large transformer and the chip housing. Hardly any power flows over this network, but the chip sees both battery banks by their names:

lbn north BATT HASH("AkkuNord") Ratio Average
lbn south BATT HASH("AkkuSued") Ratio Average

Important: the control network must never touch a power cable of either grid. Otherwise the grids would be connected and the whole separation gone.

Controlling the transfer#

The transformer “Kopplung” hangs with its input on the northern grid and with its output on the southern grid. Power flows only in this direction. Setting limits the transfer, On switches it:

• If the south drops below 30 %, the help starts.
• Only from 70 % in the south does it end again – a hysteresis.
• The north only gives while it is itself above 40 %. Otherwise both grids would end up empty.

sgt tmp north NORTH_MIN
and help help tmp

Island mode#

Island mode means: every grid supplies itself, the transformer is off. That is the safe state during maintenance, during a short circuit in the south – and when a reading is missing. A lever “Insel” forces it by hand.