Batt2DCInverter

Use

The Batt2DCInverter is necessary to couple an electrical storage with electrical DC-voltage consumers or the DC-grid of a building. It combines the models of a DC converter and a DC control to convert electrical power between two different DC voltage levels.

Parameters and Connectors

As connector, the Batt2DCInverter requires a specified target power ▶PRef where positive power values are an energy input into the storage and negative values represent the extraction from the storage. The reference charge (and discharge) power ▶PRef must be controlled by external controllers and is dependent on the inner building energy system or consumer states (e.g. renewable energy availability or simulated electricity prizes).

The relevant battery parameters are transmitted from the battery via the ▶ControlBus connector. These parameters are the state of charge SoC and the minimum and maximum battery voltage. Furthermore, the Battery is connected via the ▶DCBatt connector and the DC Grid via ▶DCGrid.

The parameters under the Control group contain the parameters for setting the PI controller of the Batt2DCInverter TPI and kPI, which sets the behavior of the DC converter. The battery converter acts as a PI-controller which controls charge and discharge power via a intermediate-circuit voltage at the DC-side, dependent on the reference power ▶PRef. If no precise details are known for the PI controller of the Batt2DCInverter, the set standard parameters can be used.

Furthermore, the maximum charging/discharging power of the battery or the inverter on the Batt2DCInverter model is PMax, the maximum SoC up to which charging is to take place SOCMax and the minimum SoC up to which discharging is to take place SOCMin. To set the Efficiency parameters, change inverter efficiency of a charging and discharging cycle eta in your model.

Model Background

Reference Power Calculation

Positive values for ▶PRef are ignored if the storage is already filled (SOC = SOCMax) and negative values are ignored in case of an empty storage (SOC = SOCMin). For stable operation, the model includes an internal hysteresis of 5% for the SoCs SOCMin and SOCMax, i.e. when the storage tank has reached its maximum SoC SOCMax of 90%, it is no longer charged until the SOC falls below 85%. The model behaves in the same way when the minimum SoC SOCMin is reached.

How to avoid numerical problems?

Ensure that the input parameters for the Batt2DCInverter correspond to the parameters of the coupled battery model.