The search for a "free download" of PSSE often leads to a dead end or ethical quagmires. PSSE is proprietary, commercial software. The licensing model is complex, often involving annual fees that can range from thousands to tens of thousands of dollars, depending on the modules and capacity (number of buses) required. There is no official "freemium" or general public version of the full PSSE suite.
Instead of searching for illegal downloads, explore the open-source alternatives above or reach out to Siemens for legitimate access. Using unlicensed software puts your system at risk and may violate your institution's policies. psse software download free