In the evolving power systems, loading margin (LM) enhancement has a significant effect on the mitigation of the risk of cascading line outages and thereby the occurrence of large blackouts. On the other hand, flexible alternating current transmission system (FACTS) devices, especially thyristor-controlled series compensated (TCSC) devices, are more effective than other mitigation strategies such as constructing new lines because of environmental and economic reasons. In this paper, a multi-objective framework is presented to maximize the LM with a minimum installation cost of TCSCs. The optimization problem is solved by using the ɛ-constraint method. The benefit of each Pareto solution is calculated by the probabilistic risk assessment, and the most preferred one is selected by a benefit/cost analysis. The proposed method is developed based on a modified alternating current (AC) version of the ORNL–Pserc–Alaska (OPA) model inspired by the self-organized criticality (SOC) theory in complex power grids. Using the benefit/cost criterion, it is revealed that by the proposed approach, a larger value for the most preferred Pareto solution is obtained in comparison with the defined transmission expansion planning (TEP) scenarios. It confirms the suitability of the proposed method to suppress the cascading outages instead of expensive and time-consuming policies such as building new lines.
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