Session 2A - Initialization & parameterization

Title:	Investigating Steady State Initialization for Modelica models
Authors:	Hans Olsson and Erik Henningsson
Abstract:	This paper investigates steady-state initialization both symbolically and numerically, and in particular demonstrates new ways of adapting the symbolic methods for finding steady-state solutions for Modelica models extending ideas that were previously manually implemented in libraries. The methods are compared on realistic Modelica models in Dymola.
Keywords:	initialization, fluid models, differential algebraic equation, static simulation, steady state
Paper:	full paper
Bibtex:	@InProceedings{modelica.org:Olsson:2021, title = "{Investigating Steady State Initialization for Modelica models}", author = {Hans Olsson and Erik Henningsson}, pages = {119--127}, doi = {10.3384/ecp21181119}, booktitle = {Proceedings of the 14th International Modelica Conference}, location = {Link\"oping, Sweden}, editor = {Martin Sj\"olund and Lena Buffoni and Adrian Pop and Lennart Ochel}, isbn = {978-91-7929-027-6}, issn = {1650-3740}, month = sep, series = {Link\"oping Electronic Conference Proceedings}, number = {181}, publisher = {Modelica Association and Link\"oping University Electronic Press}, year = {2021} }

Title:	New Equation-based Method for Parameter and State Estimation
Authors:	Luis Corona Mesa-Moles, Erik Henningsson, Daniel Bouskela, Audrey Jardin and Hans Olsson
Abstract:	To get reliable simulation results from a Modelica model it is important to parametrize and initialize the model using the best estimate of the state of the system. Commonly, this state estimation is done by inverse calculation on a square system of equations requiring as many known values as states to be computed. In practice this constraint is an important limitation and, in addition, this method does not provide any information on the uncertainties or confidence level associated to the estimated state. Taking advantage of the mathematical formulation of Modelica equations, this paper presents a new method to cope with the difficulties associated to the inverse calculation method. This approach adapts and extends the framework of data assimilation to provide a fully-integrated Modelica tool, which efficiently can handle every type of state estimation problem for static models. This method has been successfully tested with simple and complex Modelica models. Finally, the Modelica implementation of this technique allows to easily extend it to further applications.
Keywords:	Modelica, parameter estimation, state estimation, model, data assimilation
Paper:	full paper
Bibtex:	@InProceedings{modelica.org:Mesa-Moles:2021, title = "{New Equation-based Method for Parameter and State Estimation}", author = {Luis Corona Mesa-Moles and Erik Henningsson and Daniel Bouskela and Audrey Jardin and Hans Olsson}, pages = {129--139}, doi = {10.3384/ecp21181129}, booktitle = {Proceedings of the 14th International Modelica Conference}, location = {Link\"oping, Sweden}, editor = {Martin Sj\"olund and Lena Buffoni and Adrian Pop and Lennart Ochel}, isbn = {978-91-7929-027-6}, issn = {1650-3740}, month = sep, series = {Link\"oping Electronic Conference Proceedings}, number = {181}, publisher = {Modelica Association and Link\"oping University Electronic Press}, year = {2021} }

Title:	Efficient Parameterization of Modelica Models
Authors:	Thomas Beutlich and Dietmar Winkler
Abstract:	This article presents the different approaches and use cases for efficient parameterization of Modelica models by means of external data resources. The main motivation is to improve the overall quality, testability and reusability of Modelica application models (both on component and system level) by a separation of the behavioral implementation from its actual design parameters. The Modelica libraries ExternData and ModelicaTableAdditions are freely available to support library developers and vendors in their ambitions to offer clean and dedicated interfaces for the parameterization of the application models and to benefit from a large variability of commonly used file types, such as CSV, Excel, HDF, JSON, MATLAB MAT, XML or even domain-specific file types such as for tire properties or weather data.
Keywords:	parameterization, external data resources, Modelica external function interface, SSP
Paper:	full paper / library
Bibtex:	@InProceedings{modelica.org:Beutlich:2021, title = "{Efficient Parameterization of Modelica Models}", author = {Thomas Beutlich and Dietmar Winkler}, pages = {141--146}, doi = {10.3384/ecp21181141}, booktitle = {Proceedings of the 14th International Modelica Conference}, location = {Link\"oping, Sweden}, editor = {Martin Sj\"olund and Lena Buffoni and Adrian Pop and Lennart Ochel}, isbn = {978-91-7929-027-6}, issn = {1650-3740}, month = sep, series = {Link\"oping Electronic Conference Proceedings}, number = {181}, publisher = {Modelica Association and Link\"oping University Electronic Press}, year = {2021} }

Title:	Power Flow Record Structures to Initialize OpenIPSL Phasor Time-Domain Simulations with Python
Authors:	Sergio A. Dorado-Rojas, Giuseppe Laera, Marcelo de Castro Fernandes, Tetiana Bogodorova and Luigi Vanfretti
Abstract:	This paper presents a tool to populate power flow results for phasor time-domain simulations with the Open Instance Power System Library (OpenIPSL). Our proposal takes advantage of the object-oriented philosophy of Modelica and introduces a data structure based on records to handle power flow data for a given network model. Such records constitute a user-friendly interface to change the guess values used to solve the initial condition of a dynamical simulation straightforwardly. Power flow calculations are carried out by the open-source Python library GridCal. We demonstrate the tool capabilities by generating power flow results for several grid models and comparing them with those obtained via proprietary tools such as PSS/E. Moreover, we provide tutorial materials to ease integrating the tool for a new/experienced OpenIPSL user.
Keywords:	GridCal, OpenIPSL, Power Flow, Python, Records
Paper:	full paper
Bibtex:	@InProceedings{modelica.org:Dorado-Rojas:2021, title = "{Power Flow Record Structures to Initialize OpenIPSL Phasor Time-Domain Simulations with Python}", author = {Sergio A. Dorado-Rojas and Giuseppe Laera and Marcelo de Castro Fernandes and Tetiana Bogodorova and Luigi Vanfretti}, pages = {147--154}, doi = {10.3384/ecp21181147}, booktitle = {Proceedings of the 14th International Modelica Conference}, location = {Link\"oping, Sweden}, editor = {Martin Sj\"olund and Lena Buffoni and Adrian Pop and Lennart Ochel}, isbn = {978-91-7929-027-6}, issn = {1650-3740}, month = sep, series = {Link\"oping Electronic Conference Proceedings}, number = {181}, publisher = {Modelica Association and Link\"oping University Electronic Press}, year = {2021} }