Worst-load-increase direction method for fast identification of voltage-weakness indicators

The paper addresses the two problems of classifying the voltage vulnerability of a power-system operating point and ranking the nodes on the basis of their voltage weakness. A static approach is considered, which is based on load-flow equations and allows simultaneous computation of the global and local indices with very little computational effort. The system and node weaknesses are computed, introducing the concept of most critical load-increase direction, defined as the direction in which a load increase corresponds to the maximum request of additional reactive-power generation. Node ranking requires the solution of a linear system only and allows identification of the weakest nodes and, in some case, of the weakest areas. The method has been compared to others available in the literature, with satisfactory results in the balance between accuracy and computational burden