Voltage collapse risk assessment

Abstract Several approaches have been proposed in the literature to analyze system voltage collapse, based on indices that can efficiently evaluate the load margin for which the system remains stable. All this discussion, including possible methods of solution, is being carried out under deterministic assumptions; load, generation and transmission are defined for each operating condition. The basic idea is to obtain the maximum amount of load the system can support, and what distance it is from this condition. In this work, the voltage collapse problem is reviewed, considering the stochastic nature of the load. A probabilistic methodology is developed to provide risk indices of voltage collapse, based on a combination of the tangent vector and Monte Carlo simulation methods. It is also shown how a probabilistic load flow analysis can be adapted to evaluate the proposed risk indices. In order to illustrate the proposed approach, a modification of the IEEE reliability test system is used and the applicability of the results to operation and expansion planning is discussed.