Almost all of the methods developed thus far to calculate the post outage quantities in an electric power system use linear models for the sake of computational efficiency. Linear models, however, may cause relatively large computational errors especially for reactive power flows. This paper presents a new line outage simulation method for reactive power flows that minimizes the errors resulting from the use of linear system models. The proposed method formulates a line outage as a local nonlinear constrained optimization problem. Optimization is used as a feedback to correct the errors resulting from linearized equations. The method provides more accurate calculation of post-outage load bus voltage magnitudes with less computational effort. The method is applied to IEEE test systems and the results are compared with those obtained using the full power flow.
