Test Cases Library of Power System Sustained Oscillations

Natural oscillation case ND_8 (Back to the homepage)

This case contains two sources, i.e. generators 36 and 45, contributing two different unstable local modes.


System model:

  • All generators are in GENCLS model.
  • Parameter D for generators 36, 45 and 159 equals -1, -2.5 and 1, respectively.
  • Parameter D for all other generators equals 4.
  • All loads are in constant MVA model.


    • Disturbance:

  • A three-phase short circuit is added at bus 159 at 0.5s and cleared after 0.05s.


    • Small signal analysis:

  • The local mode at 1.41Hz has a negative damping of -0.22%.
  • The local mode at 1.27Hz has a negative damping of -1.06%.
    • Mountain View

    Figure 1. WECC 179-bus power system