Operating planning voltage security computation using stratified sampling

Currently, the voltage security assessment in the power system operating planning applies the N-1 criterion in order to evaluate the voltage security impact provoked by contingencies. This criterion could be applied in probabilistic and/or deterministic methodologies. At the same time, one of the most popular and used techniques to evaluate voltage security is the system loadability computation by means of the power flow computation (CPF). In consequence, the voltage security assessment in an operating planning scenario based on exhaustive enumeration takes much computational time. This paper proposes the utilization of statistical sampling techniques, such as stratified sampling, in order to reduce the computational time. Two sets or strata are defined based on aggregated modal analysis behavior; such as, the universe of single contingencies is separated in two sets: critical and non-critical.