VOLTAGE INSTABILITY IN INTERCONNECTED POWER-SYSTEMS - A SIMULATION APPROACH

Increasingly throughout the world, interconnected power systems are collapsing following severe disturbances that have produced system voltage instability. In tackling this problem, simulations on a 92 bus network have studied 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. By adopting an approach similar to underfrequency protection, measures, including load shedding, could be adopted to counter disturbances mom severe than those considered by planning criteria. This would considerably improve the resilience of interconnected power systems and by raising levels of operational security, they would be able to withstand disturbances which presently cause their collapse.