like MATPOWER to see which fits your needs.
Once logged in, request the University Edition. Siemens will send a download link and activation instructions to your registered email address. Step 4: Download the Installer
The free version is strictly limited to networks with a maximum of 50 buses .
: While specific to the version, older versions like PSS/E-30 required roughly of disk space with documentation and a minimum of 512 MB RAM Learning Resources PSS E Xplore Trial for Academic Users - Siemens
Academic institutions and engineering firms can face massive fines and legal audits for utilizing pirated Siemens software.