Optimal sizing and placement of synchronous condensers with adaptive search-space reduction

In power systems with high inverter-based resource penetration, synchronous condensers (SynCons) have become a widely deployed solution to ensure minimum grid strength levels. The optimal sizing and placement of SynCons is a complex task, particularly in large power systems. As the number of candidate buses for the installation of SynCons increases, the search space grows exponentially, leading to high computational costs and reduced effectiveness of conventional optimization techniques. To address this issue, this paper proposes an enhanced optimization methodology based on adaptive search-space reduction. The approach combines two complementary strategies: (i) the preselection of the most impactful candidate buses for grid strength enhancement using a novel metric, the Strength Sensitivity Index, and (ii) an iterative pruning process that filters out low-impact buses based on their historical allocation in previous optimization iterations. These techniques reduce the dimensionality of the problem while preserving solution quality. Simulation results on a modified IEEE 39-bus test system demonstrate that the proposed methodology accelerates convergence and improves the reliability of identifying optimal solutions, making them well-suited for long-term planning of weak grids.