A second order method for contingency severity assessment with respect to voltage collapse

The increase in power transfer among areas of interconnected systems, and the reduction of reactive power reserves, force system operators and planners to consider the contingency analysis also from the voltage/reactive point of view. In this paper, second order information derived from the singular value analysis of the Jacobian of load flow equations is used to obtain an effective ranking of contingencies with respect to the voltage collapse. Besides, a quantification of the risk associated to a contingency is provided by a procedure that calculates quasilinear indices useful both in planning and in operation. The effectiveness of the presented indices is supported by the analysis of the perturbation on the Italian power system in August 1994.