A multi-objective AHP framework for optimal UPFC placement to enhance voltage stability in renewable-integrated power systems

Abstract Voltage stability is critical in the reliable operation and control of power systems particularly as renewable energy sources are increasingly integrated. While the injection of renewable energy can marginally improve voltage stability it does not always guarantee a substantial enhancement due to the intermittent nature of solar and wind power. This paper proposes a novel multi-objective optimization approach to enhance voltage stability in renewable-integrated power systems by optimally placing Unified Power Flow Controllers (UPFCs). The proposed multi-objective function optimizes key system objectives including voltage profile improvement, loadability margin enhancement, and power loss minimization specifically for hybrid solar and wind power systems which is a major contribution and novelty of the work. Unlike conventional approaches that rely on trial-and-error or heuristic methods this study employs the Analytic Hierarchy Process (AHP) for optimal UPFC placement ensuring a structured multi-objective decision-making framework. The proposed methodology is validated on renewable-rich modified IEEE 30-bus and IEEE 118-bus systems under various operating scenarios including contingency cases and it is validated in the NRPG-246 practical Indian bus system. The comparative analysis demonstrates that the AHP-based UPFC placement significantly enhances system stability and reliability outperforming conventional methods by offering superior decision-making capabilities in handling renewable penetration challenges.