Identifying voltage control areas based on the interdependence of control equipment

This paper describes how voltage control areas can be identified by analyzing two sensitivity matrices. The voltage control sensitivity matrix [VCS] consists of diagonal elements that relate the magnitude of each control variable to the respective controlled voltage. Analysis of the sign of these elements provides information about whether a particular control action is appropriate or not, i.e., whether it will have the expected effect or an opposite one. The off-diagonal elements represent the interdependence among the voltage control devices. The V-Q sensitivity matrix [J_SQV] is obtained by reducing the Jacobian matrix used to solve the load flow equations by the Newton method. Comparison of the voltage control areas identified by eigenvalue and eigenvector analysis using each of the sensitivity matrices yields consistent results. A comparison is also made of these areas with those obtained directly from the matrices by applying the concept of voltage coherency.