Controlled island ng scheme for power systems

System islanding is often considered as the final stage of power system defense plans. The goal is to preserve stable areas of the faulted power systems. The islanding scheme plays an important role in the power system restoration phase as it can make the power system restoration less complex and reduce the overall restoration time. The basis for islanding is not standard but rather depends upon the nature of the utility. Even though the formation of islands is dominated by geographical proximity of the synchronous generators to maintain generation-load balance, there are some factors which can assist in designing a better islanding scheme. These factors are the type and location of the fault and the dynamic performance of every island on the system against the fault. This paper presents an optimization technique to obtain the optimal formation of islands taking into consideration the geographical distribution of the synchronous generators and the dynamic performance of every island in the system against the extreme and credible faults that lead to full system breakdown. In order to show the validity of this algorithm, the Algorithm is applied to IEEE 118 Bus System and a comparison between the proposed islanding scheme and an islanding scheme based on the geographical distribution of the synchronous generators is presented. The results presented in this paper show that taking into the account the type and location of the extreme and credible faults helps to preserve more stable area than that of the traditional islanding scheme.