VSAT™ is a highly automated analysis tool designed for a comprehensive voltage security assessment using powerflow-based steady-state methods. VSAT includes flexible specification of voltage security criteria and computational features required to assess the voltage performance of power systems. Like TSAT and SSAT, VSAT can be used to calculate security limits under specified criteria, contingencies, and transfer conditions.


  • Planning and operational studies
  • Contingency analysis
  • Reactive power planning studies
  • Determination of voltage security limits
  • Determination of remedial actions
  • On-line voltage security assessment


  • Computation of 1-dimensional and 2-dimensional voltage security limits
  • Flexible security criteria, including thermal loading, high/low voltage limits, voltage rise/decline limits, reactive power reserve, and voltage stability margin
  • Support for wide range of models
  • Choice of solution methods, including PV, QV, continuation powerflow, modal analysis, and sensitivity analysis
  • Extensive and flexible transfer specification options
  • Efficient and robust screening of large number of contingencies for voltage stability
  • Capabilities for processing multiple contingencies, transfers, and study scenarios in single analysis session
  • Modal analysis for determination of location and mode of voltage instability
  • Determination of remedial actions for preventative and corrective controls
  • Comprehensive and summary result reports
  • Distributed computation for processing large number of contingencies and transfers
  • Easy-to-use graphical interface for data setup, program operation, and output analysis
  • Compatibility with major third-party input data formats