A Novel Scenario-based Reactive Power Planning Method Including Investment and Operational Costs

This paper presents a novel formulation for Reactive Power Planning (RPP), combining a simple continuous investment model with a scenario-based Optimal Reactive Power Dispatch (ORPD) problem relaxed using Second-Order Cone Programming (SOCP). The proposed framework aims to minimize both investment and operational costs associated with reactive power compensation under load uncertainty. To guide investment decisions, several network sensitivity indicators such as voltage deviation, the L-index, and the Voltage Sensitivity Index are used to prioritize nodes based on their impact on system voltage profile. The proposed formulation is tested on the IEEE 118-bus system using a set of 100 scenarios derived from realistic synthetic load profiles. Two case studies are compared: one with conventional loads and another including significant photovoltaic integration and lower power factors. Results demonstrate that considering a more comprehensive set of candidate nodes improves cost efficiency, and that investment and reactive dispatch become more critical and expensive in systems with high renewable penetration. A trade-off is observed between solution optimality and computational effort, suggesting that limiting the size of candidate set to 50 % of network nodes may offer a practical compromise. This work serves as a proof of concept of the proposed RPP formulation and lays the foundation for future extensions to Security-Constrained RPP in larger systems.