Electrical Power System Modelling in Modelica – Comparing Open-source Library Options

Abstract

The past modelling of electrical powers systems used to be a the domain of a few major power system modelling tools. Commercial tools1 like DIgSILENT PowerFactory [3], POWERSYS EMTP-RV [17], PSCADTM [14], Siemens PSS/E R ? [20] are just some examples. All of them very powerful but with their own proprietary format for the models created makes it hard to exchange validated mod- els of power systems. In order to disconnect the dependency of the power sys- tem model from the power system tool a project funded by the European Commission was started called “iTesla – Innovative Tools for Electrical System Security within Large Areas” [7]. One of the results of the project was the creation of a open-source modelling library called iPSL [24]. The library was created using the open-source Modelica modelling language which in turn allows to be used with several different Modelica modelling tools. The strong focus during the project was the validation of the mod- els contained in the library. Most components stem from other tools (e.g., PSAT [15], PSS/E R ? [20]). But the iPSL is by far not the first open-source power system library written in Modelica. Other libraries which have been around before are: SPOT [1], ObjectStab [11] and PowerSystems [6] (an updated subset of SPOT). In addition the iPSL library has been “forked” as OpenIPSL [21] by SmartTS Lab which is one partners of the original “iTesla” project. This paper is going to investigate the differences of the different available power system libraries. Point out their specific strength and weaknesses with respect to user- friendliness, robustness, physical representation and vali- dation.