Sensitivity Vectors and Contingency Ranking using Linearised AC Load Flow

Abstract

In this paper, sensitivity vector using linearised AC load flow are proposed. Change in bus voltages and line flows in the event of a line outage are found from this sensitivity vector. After evaluating post contingency flows using this vector, performance indices are used to rank contingencies. Conventional sensitivity vectors like line outage distribution factors (LODF) and power transfer distribution factors (PTDF) are usually evaluated using DC load flow. Hence, evaluation of voltage limits in the event of a contingency is not possible. AC load flow can be used to calculate the change in both voltage and active flow but it is time consuming. Hence sensitivity vectors using linearised ac load flow have been derived. These sensitivity vectors are used to find change in voltages and voltage angles in the event of a contingency. Post contingency active flows and voltages obtained from these vectors are then used to evaluate performance indices and contingencies are ranked. Simulations on the IEEE 14 bus system show that the results obtained using the proposed method are comparable to the results obtained using AC load flow.