OpenIPSL.UsersGuide

The Open-Instance Power System Library - OpenIPSL contains many power system component models written in Modelica language that can be used for power system dynamic analysis, such as phasor time-domain simulations.

This is a very short User's Guide that will try to help users to get familiar with the library providing general information about the OpenIPSL.

More information about the library can be found on this openipsl.org dedicated to the OpenIPSL organization.

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Package Content

Name	Description
Overview	Overview
Conventions	Conventions
GettingStarted	Getting Started
Testing	Testing and Verification
Publications	Publications
References	References
ReleaseNotes	Release notes
Contact	Contact

OpenIPSL.UsersGuide.Overview

The OpenIPSL has, basically, six packages: Examples, Electrical, Nonelectrical, Interfaces, Icons and Types. They are briefly described below:

• Examples package for demonstration of power system examples that can be assembled using the library.
• Electrical: contains many different models that represent devices that form the grid or that are part of equipment which is connected to the grid. A more detailed overview is presented below.
• NonElectrical: contains elementary blocks that can be used to model a specific dynamic behavior (a lead-lag transfer function, for example). It also contains functions that are called inside models.
• Interfaces: contains the connector interface and the generator mask. The connector is present in every model that is connected to the grid.
• Icons: contains the basic icons that are used and extended throughout the library.
• Types: contains a description of the units that are used in the library and an expected order of magnitude. This information can be used to scale differential equations and enhance code generation performance.
• Tests package for small test systems which show basic behavior of some of the many components of this library.

The Electrical package has many other subpackages that are briefly described here. It also contains one model, SystemBase, which is going to be explained later in Getting Started. Within each subpackage, the user will find models grouped into software tools from which each model design was extracted.

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OpenIPSL.UsersGuide.Conventions

The team behind OpenIPSL strives to achieve a harmonized development of the library to facilitate its usability and integration into other services.

Here are some naming conventions that we try to obey:

• Names of the parameters and variables should correspond to those found in the respective documentation.
• Subscript should be denoted in Modelica with underscore, e.g., T_r or K_1. Note: some parameter names have first upper case letters and others lower case.
• Deviation signals such as Δω, should be written as domega in Modelica.
• Parameters which are not to be entered by user and variables which are not to be seen by users should be protected.
• Parameters and variables should be declared as their specific type such as Types.ApparentPower for variables that are declared in MVA. Note: if the proper unit is not represented in Types, units available in Modelica's SI (Systeme Internationale) should be used.

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OpenIPSL.UsersGuide.GettingStarted

The OpenIPSL was developed to be a familiar alternative to traditional power system analysis tools. Tutorials on OpenIPSL have been given at many conferences, and are available under the following links. We recommend you start from there:

• Quick Start Guide: Using OpenIPSL in OpenModelica
• Tutorial/Workshop: Getting Started with Power System Modeling using Modelica and the OpenIPSL

Running Time Domain Simulations

The time domain simulations using OpenIPSL models require Modelica-compliant tools. Users of the OpenIPSL are free to choose their tool of choice. However, note that the development of OpenIPSL has been carried out using OpenModelica, Dymola, Modelon Impact and Wolfram SystemModeler. The library is, also, systematically checked using the two mentioned tools (see Library Testing). Nonetheless, it might be possible to face issues when using other Modelica Tools that we have not fully tested.

There are many examples included in the library that can be used as a starting point for the users to run time domain simulations. They are located in the Examples package.

Power flow and Initialization

When building models from scratch, the user will need to provide initial guess values for certain variables. This is a common requirement for all models in Modelica libraries, and it is not specific to OpenIPSL.

In the case of OpenIPSL, all models require initial guess values that should come from a solution of the steady state of the overall model, i.e., a power flow solution. However, there is no power flow solver associated to the library as of the present time. The users are free to choose their power flow software of choice.

Almost all of our models have been developed to provide the same response than a reference power system simulation tool, e.g., PSAT and PSS®E. You can use these tools to create a power flow solution for your network. If you do not have access to these tools or do not want to use them, there are several power flow solvers available on GitHub. Examples on how to generate Modelica records from open source and proprietary power flow solvers, specifically VeraGrid (formerly GridCal) and PSS®E can be found in this paper and in this GitHub repository.

From these values, a Modelica tool solves the initialization problem for all algebraic and differential - state variables. All models in OpenIPSL are programmed in such way that by introducing a power flow solution (from another tool), the initial guesses are computed as parameters within each model and are provided into the initial equations that are used as an initial guess to solve the overall initialization problem. See this paper for a more detailed explanation.

As we have just mentioned, the full initialization of the components' internal variables and states is achieved by a set of internal initial equations that are to be derived by the developer of the model. In a effort to harmonized the presentation of the power flow parameters, a model should extend pfComponent that will provide all the necessary parameters for data coming from power flow solutions to be used in the initialization of the model. The pfComponent also provide the support for the common SystemBase component that provides a single instance of the system's common parameters, i.e., frequency and base power.

A specific tutorial for the user's to adopt the use power flow records is included in the library and can be found in Examples.Tutorial.Example_4, along with the Python utilities to generate the records from PSS®E and VeraGrid, which are distributed with this library under Resources.utils.pf2rec.

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OpenIPSL.UsersGuide.Testing

Continuous Integration

The OpenIPSL repository uses GitHub Actions for Continuous Integration services to the repository. In the current implementation, Modelica syntax and HTML documentation checking for all classes in the OpenIPSL is implemented

Regression Testing

These tests are used to ensure the validation status of models that are based on PSSE implementations. The models undergo simulations with different events such as faults, reference changes and load variations. The main idea is to try to capture different responses from the model being verified. If a model has a very small error if compared to PSSE base result for that simulation, it passes a test. A model is considered to be verified if it passes all tests. Models that pass the verification procedure have a green dashed line around them.

The regression testing is done separately in different Modelica-compliant tools (OpenModelica and Dymola, for now) so models can be independently verified. A detailed view of all models that undergo the verification process can be found in the NYPA Model Transformation reports. The entire result verification procedure is done using CSV-Compare.

Automatic regression testing is not yet configured in our Travis CI routine.

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OpenIPSL.UsersGuide.Publications

The list of publications written about OpenIPSL library and its models can be found below.

If you use OpenIPSL in your work or research, we kindly ask you to cite (preferably), our SoftwareX paper(s):

• M. de Castro, D. Winkler, G. Laera, L. Vanfretti, S.A. Dorado-Rojas, T. Rabuzin, B. Mukherjee, M. Navarro, Version [OpenIPSL 2.0.0] - [iTesla Power Systems Library (iPSL): A Modelica library for phasor time-domain simulations], SoftwareX, Volume 21, 2023, 101277, ISSN 2352-7110, DOI: 10.1016/j.softx.2022.101277.
• M. Baudette, M. Castro, T. Rabuzin, J. Lavenius, T. Bogodorova, L. Vanfretti, OpenIPSL: Open-Instance Power System Library — Update 1.5 to "iTesla Power Systems Library (iPSL): A Modelica library for phasor time-domain simulations", SoftwareX, Volume 7, January–June 2018, Pages 34-36, ISSN 2352-7110, DOI: 10.1016/j.softx.2018.01.002.

Otherwise, you cite one of the following papers, according to a specific use of OpenIPSL:

• F. Fachini, H. Chang, T. Bogodorova, and L. Vanfretti, "Customized open source renewable energy models validated through PHIL lab experiments," Renewable Energy, Volume 244, 2025, 122627, ISSN 0960-1481, DOI: 10.1016/j.renene.2025.122627.
• F. Fachini, T. Bogodorova, L. Vanfretti and S. Boersma, "A microgrid control scheme for islanded operation and re-synchronization utilizing Model Predictive Control," Sustainable Energy, Grids and Networks, Volume 39, 2024, 101464, ISSN 2352-4677, DOI: 10.1016/j.segan.2024.101464.
• F. Fachini, M. de Castro, T. Bogodorova, and L. Vanfretti, "Modeling of Induction Motors and Variable Speed Drives for Multi-Domain System Simulations Using Modelica and the OpenIPSL Library", Electronics, Volume 13, Issue 10, 2024, 1866, ISSN 2079-9292, DOI: 10.3390/electronics13101866.
• M. de Castro and L. Vanfretti, "OpenIWPI: Open-Instance Wave-Phasor Interface Library for Power System Simulation Studies in Modelica," 16th International Modelica & FMI Conference, Lucerne, Switzerland, September 8-10, 2025. DOI: 10.3384/ecp218.
• S. Basumallik, L. Vanfretti, M.A. Dashtaki, Z. Zhang, R. Pourramezan and H. Hooshyar, "Enhancing Large-Scale Power Systems Simulations through Functional Mockup Unit-based Grid-Forming Inverter Models," 16th International Modelica & FMI Conference, Lucerne, Switzerland, September 8-10, 2025. DOI: 10.3384/ecp218.
• S. Bhattacharjee, F. Fachini, and L. Vanfretti, "Advancing Generic Renewable Energy Models: Implementation of the REEC_D and REGC_B Models in Modelica and OpenIPSL," 16th International Modelica & FMI Conference, Lucerne, Switzerland, September 8-10, 2025. DOI: 10.3384/ecp218.
• S. Bhattacharjee, L. Vanfretti, and F. Fachini, "Building Models for Stability and Control Design Analysis using Modelica and the OpenIPSL," Proceedings of the American Modelica Conference 2024, October 14-16, 2024, Storrs, Connecticut, USA. DOI: 10.3384/ecp20763.
• L. Vanfretti and C.R. Laughman, "Power System Modeling for Identification and Control Applications using Modelica and OpenIPSL," 2024 IEEE Conference on Control Technology and Applications (CCTA), Newcastle upon Tyne, United Kingdom, 2024, pp. 525-532, DOI: 10.1109/CCTA60707.2024.10666594.
• Fachini, Fernando, Srijita Bhattacharjee, Miguel Aguilera, Luigi Vanfretti, Giuseppe Laera, Tetiana Bogodorova, Ardeshir Moftakhari, Michael Huylo, and Atila Novoselac, "Exploiting Modelica and the OpenIPSL for University Campus Microgrid Model Development", 15th International Modelica Conference 2023, October 9-11, Aachen, Germany. DOI: 10.3384/ecp21181147.
• Fachini, Fernando, Aisling Pigott, Giuseppe Laera, Tetiana Bogodorova, Luigi Vanfretti, and Kyri Baker, "Developing a Campus Microgrid Model utilizing Modelica and the OpenIPSL Library", 2023 11th Workshop on Modelling and Simulation of Cyber-Physical Energy Systems (MSCPES), pp. 1-6. IEEE, 2023. DOI:10.1109/MSCPES58582.2023.10123421
• M. de Castro, G. Laera, F. Fachini, S.A. Dorado-Rojas, L. Vanfretti, S. Ahmed, C. Mishra, K.D. Jones and R. M. Gardner, "Power System Real-Time Simulation using Modelica and the FMI", American Modelica Conference 2022, October 26-28, 2022, Dallas, Texas, US. DOI: 10.3384/ECP2118685.
• G. Laera, L. Vanfretti, M. de Castro Fernandes, S.A. Dorado-Rojas, F. Fachini, C. Mishra, K.D. Jones and R.M. Gardner, "Guidelines and Use Cases for Power System Dynamics Modeling and Model Verification using Modelica", American Modelica Conference 2022, October 26-28, 2022, Dallas, Texas, US. DOI: 10.3384/ECP21186146.
• S. Boersma, X. Bombois, L. Vanfretti, J.C. Gonzalez-Torres, and A. Benchaib, "Probing Signal Design for Enhanced Damping Estimation in Power Networks", International Journal of Electrical Power & Energy Systems, vol. 129, July 2021, 106640, ISSN 0142-0615. DOI:10.1016/j.ijepes.2020.106640.
• M. Podlaski, L. Vanfretti, T. Bogodorova, T. Rabuzin, and M. Baudette, "RaPId - A Parameter Estimation Toolbox for Modelica/FMI-Based Models Exploiting Global Optimization Methods", SYSID 2021 - 19th IFAC Symposium on System Identification – Learning Models for Decision and Control, Padova, Italy, 14-16 July 2021, IFAC-PapersOnLine, Volume 54, Issue 7, 2021, Pages 391-396, ISSN 2405-8963, DOI: 10.1016/j.ifacol.2021.08.391. Video of paper presentation and GitHub repository.
• L. Vanfretti, G. Laera, M. de Castro Fernandes, C. Wang, C. Mishra and K. D. Jones, "Initial steps in deploying and calibrating power system models on a sychrophasor data cloud platform using FMI ", User Presentation at the FMI User Meeting at the Modelica Conference 2021, 14th International Modelica Conference, Linköping, September 20-24, 2021. Presentation, and authors' copy of abstract.
• B. Mukherjee, M. de Castro Fernandes, and L. Vanfretti, "A PMU-Based Control Scheme for Islanded Operation and Re-synchronization of DER ", International Journal of Electrical Power & Energy Systems, Volume 133, 2021, 107217, ISSN 0142-0615, DOI: 10.1016/j.ijepes.2021.107217
• F.J. Gomez, L. Vanfretti, M. Aguilera, and Svein H. Olsen, "Software Requirements for Interoperable and Standard-Based Power System Modeling Tools ", Simulation Modelling Practice and Theory, Volume 103, 2020, 102095, ISSN 1569-190X, DOI: 10.1016/j.simpat.2020.102095
• M. de Castro Fernandes, M. Navarro Catalan, M. Baudette, and L. Vanfretti, "The Open Instance Power System Library (OpenIPSL): A Modelica Library for Phasor Time-Domain Simulations ", User Presentation at the American Modelica Conference 2020, Boulder, Colorado, USA, March 23-25, 2020. Presentation Presentation PDF, video, and authors' copy of abstract.
• S.A. Dorado-Rojas, M. Navarro Catalan, M. de Castro Fernandes, and L. Vanfretti, "Performance Benchmark of Modelica Time-Domain Power System Automated Simulations using Python ", Proceedings of the American Modelica Conference 2020, Boulder, Colorado, USA, March 23-25, 2020, DOI: 10.3384/ecp2016928
• M. Podlaski, L. Vanfretti, M. de Castro Fernandes, and J. Pesente, "Parameter Estimation of User-Defined Control System Models for Itaipu Power Plant using Modelica and OpenIPSL ", Proceedings of the American Modelica Conference 2020, Boulder, Colorado, USA, March 23-25, 2020, DOI: 10.3384/ecp20169139
• M. Podlaski, L. Vanfretti, J. Pesente and P. H. Galassi, "Automated Parameter Identification and Calibration for the Itaipu Power Generation System using Modelica, FMI, and RaPId ", 2019 7th Workshop on Modeling and Simulation of Cyber-Physical Energy Systems (MSCPES), 2019, pp. 1-5, DOI: 10.1109/MSCPES.2019.8738793.
• L. Vanfretti, B. Mukherjee, K. M. Moudgalya, and F. J. Gomez, "Automatic Re-synchronization Controller Analysis within a Multi-Domain Gas Turbine and Power System Model ", 2019 7th Workshop on Modeling and Simulation of Cyber-Physical Energy Systems (MSCPES), 2019, pp. 1-5, DOI: 10.1109/MSCPES.2019.8738797.
• E. Henningsson, H. Olsson, and L. Vanfretti, "DAE Solvers for Large-Scale Hybrid Models ", Proceedings of the 13th International Modelica Conference, Regensburg, Germany, March 4–6, 2019, DOI: 10.3384/ecp19157491
• M. de Castro Fernandes, L. Vanfretti, Janaina G. de Oliveira, and M. Baudette, "A Fundamental Time-Domain and Linearized Eigenvalue Analysis of Coalesced Power Transmission and Unbalanced Distribution Grids using Modelica and the OpenIPSL ", Proceedings of the 13th International Modelica Conference, Regensburg, Germany, March 4–6, 2019, DOI: 10.3384/ecp19157617
• B. Mukherjee, and L. Vanfretti, "Modeling of PMU-Based Automatic Re-synchronization Controls for DER Generators in Power Distribution Networks using Modelica and the OpenIPSL ", Proceedings of the 13th International Modelica Conference, Regensburg, Germany, March 4–6, 2019, DOI: 10.3384/ecp19157607
• M. de Castro Fernandes, J. G. de Oliveira, L. Vanfretti, M. Baudette, and M.A. Tomim, "Modeling and simulation of a hybrid single-phase/three-phase system in Modelica ", 2018 Simposio Brasileiro de Sistemas Eletricos (SBSE), 2018, pp. 1-7, DOI: 10.1109/SBSE.2018.8395775
• M. Aguilera, L. Vanfretti, and F. Gomez, "Experiences in power system multi-domain modeling and simulation with Modelica & FMI: The case of gas power turbines and power systems ", 2018 Workshop on Modeling and Simulation of Cyber-Physical Energy Systems (MSCPES), 2018, pp. 1-6, DOI: 10.1109/MSCPES.2018.8405397
• M. Aguilera, L. Vanfretti, T. Bogodorova, and F. Gomez, "Coalesced Gas Turbine and Power System Modeling and Simulation using Modelica ", Proceedings of The American Modelica Conference 2018, October 9-10, Samberg Conference Center, Cambridge MA, USA, Issue 154, 2019-02-26, Pages 112-120, ISSN 1650-3740. DOI: 10.3384/ecp1815493
• B. Mukherjee, and L. Vanfretti, "Modeling of PMU-Based Islanded Operation Controls for Power Distribution Networks using Modelica and OpenIPSL ", Proceedings of The American Modelica Conference 2018, October 9-10, Samberg Conference Center, Cambridge MA, USA, Issue 154, 2019-02-26, Pages 112-120, ISSN 1650-3740. DOI: 10.3384/ecp18154112
• D. Winkler, "Analysing the stability of an Islanded hydro-electric power system", Proceedings of The American Modelica Conference 2018, October 9-10, Samberg Conference Center, Cambridge MA, USA, Issue 154, 2019-02-26, Pages 112-120, ISSN 1650-3740. DOI: 10.3384/ecp18154103
• D. Winkler, "Electrical Power System Modelling in Modelica - Comparing Open-source Library Options", Proceedings of the 58th Conference on Simulation and Modelling (SIMS 58), September 25-27, Reykjavik, Iceland, Issue 188, 2017-09-27, Pages 263-270, ISSN 1650-3740. DOI: 10.3384/ecp17138263
• T. Rabuzin, M. Baudette and L. Vanfretti, "Implementation of a continuous integration workflow for a power system Modelica library," 2017 IEEE Power & Energy Society General Meeting, 2017, pp. 1-5, DOI: 10.1109/PESGM.2017.8274618.
• L. Vanfretti, T. Rabuzin, M. Baudette, and M. Murad, "iTesla Power Systems Library (iPSL): A Modelica library for phasor time-domain simulations," SoftwareX, Available online 18 May 2016, ISSN 2352-7110, DOI: 10.1016/j.softx.2016.05.001.
• M. Zhang, M. Baudette, J. Lavenius, S. Løvlund, and L. Vanfretti, "Modelica Implementation and Software-to-Software Validation of Power System Component Models Commonly used by Nordic TSOs for Dynamic Simulations", In Proceedings of the 56th Conference on Simulation and Modelling (SIMS 56), 7-9 October 2015, Linköping, Sweden. DOI: 10.3384/ecp15119105
• M. Sabate, G. Leon, M. Halat, J.B. Heyberger, F.J. Gomez and L. Vanfretti, "Aspects of Power System Modeling, Initialization and Simulation using the Modelica Language", 2015 IEEE Eindhoven PowerTech 2015, June 29 - July 02, 2015, Eindhoven, Netherlands. DOI: 10.1109/PTC.2015.7232504
• M.A. Adib Murad, F.J. Gomez, and L. Vanfretti, "Equation-Based Modeling of FACTS using Modelica", 2015 IEEE Eindhoven PowerTech 2015, June 29 - July 02, 2015, Eindhoven, Netherlands. DOI: 10.1109/PTC.2015.7232500
• M.A. Adib Murad, F.J. Gomez, and L. Vanfretti, "Equation-Based Modeling and Simulation of Three-Winding, and Regulating Transformers using Modelica", 2015 IEEE Eindhoven PowerTech 2015, June 29 - July 02, 2015, Eindhoven, Netherlands. DOI: 10.1109/PTC.2015.7232503
• L. Vanfretti, T. Bogodorova, and M. Baudette, "Power System Model Identification Exploiting the Modelica Language and FMI Technologies", 2014 IEEE International Conference on Intelligent Energy and Power Systems, June 2-6, 2014, Kyiv, Ukraine. DOI: 10.1109/IEPS.2014.6874164
• L. Vanfretti, T. Bogodorova, and M. Baudette, "A Modelica Power System Component Library for Model Validation and Parameter Identification", 10th International Modelica Conference, Mar. 10 – 12, 2014, Lund, Sweden. DOI: 10.3384/ecp140961195
• T. Bogodorova, M. Sabate, G. León, L. Vanfretti, M. Halat, J.B. Heyberger, and P. Panciatici, "A Modelica Power System Library for Phasor Time-Domain Simulation", IEEE ISGT Europe 2013, Oct. 6 – 9, 2013, Lyngby, Denmark. DOI: 10.1109/ISGTEurope.2013.6695422
• L. Vanfretti, W. Li, T. Bogodorova, and P.Panciatici, "Unambiguous Power System Modeling and Simulation using Modelica Tools", 2013 IEEE Power and Energy Society General Meeting, Jul. 21 – 25, 2013, Vancouver, Canada. DOI: 10.1109/PESMG.2013.6672476

In addition, you can also browse a few of the thesis of the students that carried out their MSc and PhD research under Prof. Vanfretti's group in the following links:

• Joan Russinol (2013).
• Le Qi (2014).
• M.Ahsan Adib Murad (2015).
• Mengjia Zhang (2015).
• Marcelo de Castro Fernandes (2017).
• Miguel Aguilera Chavez (2017).
• Biswarup Mukherjee (2017).
• Dr. Tetiana Bogodorova (2017).

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OpenIPSL.UsersGuide.References

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OpenIPSL.UsersGuide.Contact

The OpenIPSL is developed by many people from a few different organizations. This page shows the active members and contributors.

The development of the library is organized by:

Luigi Vanfretti

Professor

Department of Electrical, Computer, and Systems Engineering

Rensselaer Polytechnic Institute

110 8th St, Troy, NY 12180

United States

email: luigi.vanfretti@gmail.com

Version 3.1.0 is organized by:

Dietmar Winkler

Assistant Professor

Department of Electrical Engineering, Information Technology and Cybernetics

University of South-Eastern Norway

Campus Porsgrunn

Norway

email: dietmar.winkler@usn.no

and

Marcelo de Castro

PhD Student and Research Assistant

Department of Electrical, Computer, and Systems Engineering

Rensselaer Polytechnic Institute

110 8th St, Troy, NY 12180

United States

email: decasm3@rpi.edu

Other contributors:

In addition to that, the library currently has the following team of developers and active contributors:

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