License

Component Licenses

Component	License	Repository
STEPSS GUI	Apache License 2.0	SPS-L/stepss-java-ui
stepss	Apache License 2.0	SPS-L/stepss-python-ui
URAMSES	Apache License 2.0	SPS-L/stepss-uramses
stepss-eigenanalysis	Apache License 2.0	SPS-L/stepss-eigenanalysis
CODEGEN Studio	Apache License 2.0, but its PyPI wheel bundles CODEGEN: see CODEGEN License	SPS-L/stepss-cg-studio
stepss-dyngraph	Apache License 2.0	SPS-L/stepss-dyngraph (private)
RamsesNN	MIT License	SPS-L/stepss-RamsesNN
Helios	Academic Public License (free for non-commercial use), with a commercial option	See Helios License below
RAMSES	Proprietary, free for non-commercial use	See RAMSES Solver License below
CODEGEN	Proprietary, free executables (Academic Public License)	See CODEGEN License below

Documentation License

The STEPSS documentation, this website and the PDF user guide, is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt it, including for commercial purposes, provided you give appropriate credit.

This applies to the documentation only. It grants no rights over the STEPSS software itself, which remains under the terms set out below.

RAMSES Solver License

The RAMSES dynamic simulator (the solver of differential-algebraic equations) is NOT covered by the Apache License 2.0. RAMSES is the property of the University of Liège, Belgium, and is distributed under a separate proprietary license with the following terms:

• Permission is granted to use RAMSES free of charge for any non-commercial purpose, including:

  • Teaching and research at universities, colleges, and other educational institutions
  • Research at non-profit research institutions
  • Personal non-profit purposes

• For commercial use of RAMSES (including but not restricted to consulting activities, design of commercial hardware or software products, or participation by a commercial entity in research projects), you must contact the Authors for an appropriate license.

• The free-of-charge version of RAMSES is limited to:

  • Power system models of up to 1000 buses (or nodes)
  • Execution with parallelization using no more than 2 cores

• RAMSES is provided “as is”, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose, and non-infringement.

For extensions to larger models or execution using more than two cores, contact the Authors.

Helios License

STEPSS-Helios (the modern power-flow engine, also bundled as libhelios_api in stepss) is the property of Dr. Petros Aristidou, and is distributed under the STEPSS-Helios Academic Public License:

• Permission is granted to use Helios free of charge for any non-commercial purpose, including teaching and research at universities, colleges, and other educational institutions, research at non-profit research institutions, and personal non-profit purposes.
• For commercial use, a commercial license is required: contact info@sps-lab.org.
• Helios is provided “as is”, without warranty of any kind.

CODEGEN License

CODEGEN (the model generator) is the property of Dr. Thierry Van Cutsem. It is distributed under the Academic Public License for the use of STEPSS as a compiled executable that is free to use for non-commercial purposes; commercial use requires contacting the Authors. It is not open-source: its source code is not included in any of the public STEPSS repositories.

Two things ship CODEGEN, and both are therefore mixed-licence rather than the Apache 2.0 their own source is under:

• STEPSS GUI, which carries the whole toolchain.
• CODEGEN Studio, whose PyPI wheel (pip install stepss-cg-studio) bundles the CODEGEN executables for Linux, Windows and macOS so that its Run Codegen action works on a fresh install. The licence text ships inside the wheel as cg_studio/bin/LICENSE-CODEGEN, and the two leading components of the package’s version name the CODEGEN release it carries: stepss-cg-studio 5.3.0 and 5.3.1 both run CODEGEN 5.3.

Installing either means accepting these terms for the bundled generator. The Apache 2.0 licence in each of those repositories covers the code written there, not the executables shipped alongside it.

Requesting a Commercial License

The free terms above cover teaching, academic research and personal non-profit use. Anything commercial needs a license, including consulting work, designing commercial hardware or software, and a commercial entity taking part in a research project.

Which license, and from whom, depends on which components you use. They have different owners, as the table at the top of this page sets out: RAMSES belongs to the University of Liège, Helios to Dr. Petros Aristidou, and CODEGEN to Dr. Thierry Van Cutsem. A use that involves only one of them is a narrower question than one that involves all three.

Write to stepss@sps-lab.org. A first message that covers the following can be answered without a round of questions first:

• Which components the work needs, from the table above. If you are unsure, describe what you want to do and let the answer come back.
• What the use is: consulting for a client, a product you sell, an internal tool, or a funded project with a commercial partner.
• How large the systems are. The free version of RAMSES is capped at 1000 buses, so the size you need is usually the reason for the request.
• How many cores you need to run on. The free version is capped at two.
• Your timeframe, so the reply can be useful rather than merely accurate.

Identify the organisation the license would be granted to, which is not always the one asking.

Authors

STEPSS has been developed by:

• Dr. Petros Aristidou (petros.aristidou@cut.ac.cy)
• Dr. Thierry Van Cutsem (thierry.h.van.cutsem@gmail.com)

For general inquiries, licensing questions, and commercial use, please use the default contact: stepss@sps-lab.org.

Intellectual Property Rights

STEPSS is made up of three modules: Helios (power flow computations), RAMSES (the solver of differential-algebraic equations), and CODEGEN (a tool to develop models).

Helios is the property of Dr. Petros Aristidou. CODEGEN is the property of Dr. Thierry Van Cutsem, distributed as a compiled executable free to use. RAMSES is the property of the University of Liège, Belgium, which has granted to both Authors a personal, royalty-free, limited, non-exclusive, non-transferable and non-assignable license to distribute free of charge an executable version of RAMSES.