VAr planning for power system security

A method is presented for identifying a dispersed reactive power (VAr) supply that can enhance power systems´ pre- and post-contingency voltage security, subject to technical and economic constraints. The problem is formulated in two stages. The first stage involves a nonlinear optimization problem which minimizes the amount of reactive supply. The second stage uses a mixed-integer linear program which optimizes the number of candidates buses for VAr support. Results of application of the method to an example system are presented