InterPSS underlying is a framework for developing power system simulation software using Java Language. Therefore it is not an end-user power system simulation application. Based on the InterPSS core simulation engine, a number of InterPSS applications have been developed by the InterPSS development team, mainly for demonstrating or showcasing purpose, including a Desktop edition (hosted in SourceForge), a Cloud edition (hosted in Google Cloud).
InterPSS has been extended and used to develop power system simulation applications by others over the years. The following are few examples:
1) In-memory Computing Based On-line Power System Simulation
2) Transmission/Distribution co-simulation program
http://ieeexplore.ieee.org/abstract/document/7782366/
Hopefully, the above helps to clarify InterPSS project goal and positions.
InterPSS Support