Size and complexity of power systems impose significant challenges for the power system analysis and control. As the power system becomes more complex there is a great need to develop improved and sophisticated tools for power system analysis and simulation. These tools should be able to accurately replicate real events that occur in electric power network and help to understand dynamics of changes. A number of software packages have been developed for power system research, analysis, planning, designing and teaching. This paper describes how to utilize an electric Power System Analyzer (PSA) as a useful instrument for power flow studies. The analyzer is designed to be user-friendly, easy-to-use, with the ability to optimize power flow and to visualize the effects of changing problem parameters. PSA can handle power system networks up to 100.000 nodes.