Modeling Multiple Grid Power Limitations

[kjs55]

Hi, It looks like the option to apply a grid power limitation at the inverter level vs. injection point is an EITHER/OR. But, what if we have limits at both the inverter level AND the injection point? It doesn't look like we have the option to apply losses at both points (nodes) in the system (it's only EITHER/OR, not AND). I suggest adding the AND option. Thanks.

[André Mermoud]

At the inverter level, there is a first limitation, which is the nominal power of the inverter.

If the Inverter's power limitation is attained (before the grid limitation is applied), it is accounted as inverter overload loss.

When the the grid limitation occurs, in practice it is executed by  limiting the power at the output of the inverters. The corresponding power loss due to the grid limitation is accounted a grid limitation (unused energy).  This requires that the "grid power measurement"  information has to be included as input to the inverter, for adjusting its real output power.

Now applying the grid limitation "at the inverter level" means that this required  grid power limit value is evaluated  at the output of the inverters. This means that the AC  losses after the inverter are not taken into account, i.e. that the effective power at the grid level will be  (Grid limit - AC losses).

 

[dtarin]

The purpose would be to allow the inverter to be limited below nameplate power (which is not uncommon), and also allow a grid limitation to be applied at the POI. This is easily implemented in excel, and should also be able to be implemented in PVsyst.