Voltage instability in interconnected power systems: a simulation approach

The authors describe a method simulating, on a substantial power system, the events leading to system voltage instability and collapse. Simulations on a 92-bus network were used to study the consequences of losing five lines simultaneously. With no countermeasures, the disturbance caused system voltage instability which culminated in its collapse. Following the same disturbance, a series of specific countermeasures was simulated. This arrangement of measures was able to restore the grid to a secure operating state, even with the five lines still out of service. The simulation studies show the effectiveness of a protection arrangement, functioning during the first postdisturbance period, with well-timed measures concentrated only in the region most affected by the disturbance. By limiting the application of measures only to this area, it also prevents any effects of the disturbance from spreading to the remainder of the power grid.>