A power electronic converter, used in photovoltaic, wind power or HVDC application for example, has a frequency-dependent equivalent impedance, which depends on controller design and physical components. This equivalent impedance can be determined from EMT models. Once the frequency-dependent equivalent impedance is known, it can be used as input data for frequency-domain models and analysis, such as the frequency sweep function in PowerFactory.

DIgSILENT has developed a tool for determination of the frequency-dependent equivalent impedance of an EMT model (device under test, DUT). A DPL script is used to control a voltage source in order to perform the impedance scan of the DUT. The results are stored in frequency-dependent vector characteristics, which can be used for according frequency domain models in PowerFactory.

The approach of the impedance scan is briefly described in chapter 2.1 of the the publication "Impedance-based power system stability analysis based on a power quality assessment toolbox - Advantages and challenges", published at the 23rd Wind & Solar Integration Workshop, Helsinki, Finland, Oct. 2024 (https://doi.org/10.1049/icp.2024.3904 ; reprint available on https://www.digsilent.de/en/downloads.html ).

The Impedance Scan tool is available for PowerFactory users upon request. If you are interested, please raise a ticket in DIgSILENT's customer portal and mention "Impedance-based Stability Analysis (IBSA)" as keyword.