IPSA Power is a division of UK company TNEI that develops the IPSA (Interactive Power System Analsysis) software package. IPSA was started as a PhD project in 1954 and the first commercial version was released in 1980.

Functions include load flow, short circuit, OPF, transient and dynamic stability, harmonic analysis, protection coordination. A Python-based scripting language is supported, as well as an open API for use in other applications (with Visual Basic / VBA, C/C++ and Fortran bindings).

Reference: IPSA Power