Static and Transient Electric Power Systems Simulation

STEPSS is the Java (Swing) desktop GUI for the RAMSES dynamic power system simulator — part of the STEPSS power system simulation platform. It bundles the complete simulation toolchain (RAMSES, PFC, CODEGEN, DYNGRAPH, gnuplot) into a single application, so users can load a network, run static and dynamic simulations, and analyse the results without touching the command line.

Current release: 3.40.

• Complete workflow in tabs — System Data, Observables, Initialization, Dynamic Simulation, Analysis, and Codegen
• Dynamic simulation — runs the bundled RAMSES engine on the loaded data and disturbance files
• Power flow — drives the bundled PFC (Power Flow Computation) executable
• Real-time plotting — live curves during simulation via gnuplot (bus voltages, machine speeds, branch flows, wall time, and more)
• Result extraction — "Extract Curves" launches the bundled DYNGRAPH viewer on saved output trajectories
• Analysis tools — Jacobian matrix extraction and small-signal stability analysis
• User models — the Codegen tab compiles user-written models with CODEGEN and saves a custom simulator executable
• Observable wizard — dialog for selecting buses, machines, shunts, branches, and injectors to record
• Integrated editing — opens data and disturbance files in the bundled Notepad++ (via Wine on Linux)
• Built-in help — embedded user guide PDF, online changelog viewer, and update checker
• Cross-platform — 64-bit Windows and Linux

Requirements: 64-bit Java 11 or later (JRE to run, JDK to build), Apache Ant to build. A prebuilt dist/stepss.jar ships in the repository, so building is only needed if you change the source.

git clone https://github.com/SPS-L/stepss-java-ui.git
cd stepss-java-ui
ant jar

The build (a NetBeans/Ant project) produces dist/stepss.jar — a self-contained jar with the Commons Exec and Commons IO libraries merged in.

java -jar dist/stepss.jar

Then, in the GUI:

1. Load the System data files (.dat) in the System Data tab
2. Load the Disturbance file (.dst)
3. Select observables to record (Observables tab or the Observable dialog)
4. Run the simulation from the Dynamic Simulation tab
5. Plot results with Extract Curves (DYNGRAPH) or watch the real-time gnuplot curves

The jar embeds the toolchain executables (Windows and Linux) and extracts them at runtime:

The bundled RAMSES is the free Limited build (up to 1000 buses, 2 cores) — see NOTICE.

In addition, the application distributes the following third-party Java libraries (merged into stepss.jar and shipped in dist/lib/): Apache Commons Exec, Apache Commons IO (both Apache License 2.0), and NetBeans AbsoluteLayout.

• PyRAMSES — Python interface for RAMSES
• URAMSES — user models for PyRAMSES

• Installation guide — GUI and Java setup
• Quick start — running simulations from the GUI
• STEPSS documentation site — user guide, file formats, model reference
• In-app: Help → User Guide (bundled PDF) and Help → Changelog

STEPSS is distributed under the Apache License 2.0 — see LICENSE. Copyright © Petros Aristidou.

The Apache license covers the Java source code in this repository only. The bundled RAMSES, PFC, CODEGEN, and DYNGRAPH executables are proprietary components under their own terms, and the bundled third-party tools and libraries (gnuplot, Notepad++, vswhere, KLU, Apache Commons Exec/IO, NetBeans AbsoluteLayout) remain under their respective licenses — see NOTICE for the complete list. The license texts of the bundled tools are also embedded in the application.

Developed and maintained by the Sustainable Power Systems Laboratory (SPS-L) at the Cyprus University of Technology, under the direction of Dr. Petros Aristidou.

STEPSS was created by Dr. Petros Aristidou and Dr. Thierry Van Cutsem.