Description: "Package with models for DC electrical storage"

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## Buildings.Electrical.DC.Storage

Package with models for DC electrical storage

### Information

This package contains models that represent different energy storages for DC power.

Extends from Modelica.Icons.Package (Icon for standard packages).

### Package Content

Name | Description
--- | ---
Battery | Simple model of a battery
Examples | Package with example models
BaseClasses | Base models for battery package

## Buildings.Electrical.DC.Storage.Battery

Simple model of a battery

### Information

Simple model of a battery.

This model takes as an input the power that should be stored in the battery (if P > 0) or that should be extracted from the battery. The model uses a fictitious conductance (see Buildings.Electrical.DC.Loads.Conductor) G such that P = u i and i = u G, where u is the voltage difference across the pins and i is the current at the positive pin.

The output connector `SOC` is the state of charge of the battery. This model does not enforce that the state of charge is between zero and one. However, each time the state of charge crosses zero or one, a warning will be written to the simulation log file. The model also does not limit the current through the battery. The user should provide a control so that only a reasonable amount of power is exchanged, and that the state of charge remains between zero and one.

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Real | etaCha | 0.9 | Efficiency during charging [1]
Real | etaDis | 0.9 | Efficiency during discharging [1]
Real | SOC_start | 0.1 | Initial state of charge [1]
Energy | EMax |  | Maximum available charge [J]
Voltage | V_nominal |  | Nominal voltage (V_nominal >= 0) [V]

### Connectors

Type | Name | Description
--- | --- | ---
input RealInput | P | Power stored in battery (if positive), or extracted from battery (if negative) [W]
output RealOutput | SOC | State of charge [1]
Terminal_p | terminal | Generalized terminal

### Modelica definition

model Battery "Simple model of a battery" parameter Real etaCha(min=0, max=1, unit="1") = 0.9 "Efficiency during charging"; parameter Real etaDis(min=0, max=1, unit="1") = 0.9 "Efficiency during discharging"; parameter Real SOC_start(min=0, max=1, unit="1")=0.1 "Initial state of charge"; parameter Modelica.SIunits.Energy EMax(min=0, displayUnit="kWh") "Maximum available charge"; parameter Modelica.SIunits.Voltage V_nominal "Nominal voltage (V_nominal >= 0)"; Modelica.Blocks.Interfaces.RealInput P(unit="W") "Power stored in battery (if positive), or extracted from battery (if negative)"; Modelica.Blocks.Interfaces.RealOutput SOC(min=0, max=1, unit="1") "State of charge"; Buildings.Electrical.DC.Interfaces.Terminal_p terminal "Generalized terminal"; protected Buildings.Electrical.DC.Storage.BaseClasses.Charge cha( final EMax=EMax, final SOC_start=SOC_start, final etaCha=etaCha, final etaDis=etaDis) "Charge model"; Loads.Conductor bat( final P_nominal=0, final mode=Buildings.Electrical.Types.Load.VariableZ_P_input, final V_nominal=V_nominal) "Power exchanged with battery pack"; Modelica.Blocks.Math.Gain gain(final k=-1); equation connect(cha.SOC, SOC); connect(cha.P, P); connect(bat.terminal, terminal); connect(P, gain.u); connect(gain.y, bat.Pow); end Battery;