Description of the "BESS (avg)" component from the Residential Energy Library.
Modeling Description
The "BESS (avg)" component implements a Battery Energy Storage System (BESS) interfaced to the grid through an average inverter model. The average modeling approach can reproduce the fundamental harmonic waveform inverter behavior according to the BESS and grid conditions with no power electronics HIL core resources. The Figure 1 shows the block diagram of the "BESS (avg)" component modeling. The model is divided into two sub-circuits. The AC side represents the inverter interface to the grid. Scada Inputs set the active and reactive power references to a generic current controller in the dq-frame. As a result, the output power measured is used to define the current flowing by the DC Side.
Component Description
The "BESS (avg)" component is found under the Sources Category of the Residential Energy library. Table 1 shows the schematic symbol and properties window of the component. The "General" tab contains the inverter’s nominal parameters ratings: power, AC voltage, frequency, number of phases, and ground connection. The "Number of phases" and the "Ground-connected" properties change the number of power ports of the component. For the single-phase operation, just two terminals are available to the user to connect to either an external grounding or an external phase to the L- port within the "Nominal AC voltage" properly configured to the adopted grid connection.
Under the "Filter" tab, the user configures the DC capacitance and the AC filter (type of filter and its parameterization). The controller parameterization is done under the "Controller" tab. Four types of batteries are available to use on the "BESS (avg)" component: "Lead-Acid," "Lithium-Ion," "Nickel-Cadmium," and "Nickel-Metal-Hydrid." The choice of the battery is made under the "Battery" tab as its nominal voltage/capacity and initial SOC, as well. With the "Preview SOC Curve," it is possible to check the battery curve according to the input parameters.
A signal-processing input port "en" at the top of the component icon turns all the loads on/off. Besides that, internal Scada Inputs are created to turn each load on/off separately.
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References
[1] - Amirnaser Yazdani, Reza Iravani. (2010). Voltage-Sourced Converters in Power Systems: Modeling, Control, and Applications. Wiley-IEEE Press.