A probabilistic approach to the voltage stability analysis of interconnected power systems

In planning a power system it is always necessary to assess whether a voltage collapse occurs during a prefixed system operating condition. However, present approaches to the analysis of voltage instability phenomena in interconnected power systems are deterministic and, consequently, they cannot take into account the unavoidable uncertainties associated with the bus load forecast. This is indeed an important limitation. In this case the application of probabilistic techniques is the most feasible alternative. On the basis of this observation, in this paper a probabilistic approach to the voltage stability analysis of interconnected power systems is presented; it treats loads as random uncorrelated variables with normal distributions. The method proves suitable for determining systematically, for each expected system operating condition, the statistics of all the node voltages which are critical from the voltage stability viewpoint. The capability and usefulness of the suggested approach are illustrated by carrying out simulation studies on a sample power system.