Security constrained AC transmission network expansion planning

Abstract

Modern transmission network expansion planning (TNEP) is carried out with AC network model, which is able to handle voltage and voltage stability constraints. However, such a model requires optimization with iterative AC power flow model, which is computationally so demanding that most of the researchers have ignored the vital (N-1) security constraints. Therefore, the objective of this research work is to develop an efficient, two-stage optimization methodology for security constrained AC TNEP. As single-stage, rigorous methods cannot be considered for solving this problem for even a moderately sized system due to extreme computational burden involved, the proposed two-stage methodology provides an attractive alternative. By this methodology, in the first stage, a DC expansion planning problem is solved which provides an initial guess as well as some very intelligent strategies to reduce the number of power flow solutions required for the second stage of AC transmission and reactive expansion planning. A modified artificial bee colony (MABC) algorithm is used to solve the resulting optimization problem. Static AC TNEP results for Garver 6 bus, IEEE 24 bus, IEEE 118 bus and IEEE 300 bus test systems have been obtained with the proposed approach. Wherever possible, the results are compared with that obtained by the rigorous method and with similar results reported in literature, to demonstrate the substantial benefits of the proposed method. Also, multi-stage dynamic AC TNEP for the Garver 6 bus system is solved to show the applicability of the methodology to such problems.