Real-Time Multi-Objective Optimization for Reactive Power Dispatch in Islanded Power System
Carolina M. Martín, Francisco Arredondo, Santiago Arnaltes, Jaime Alonso-Martínez, José Luis Rodríguez-Amenedo Departamento de Ingeniería Eléctrica, Universidad Carlos III de Madrid Campus de Leganés, Leganés, Madrid (Spain) 2026-06-27

Abstract

This paper proposes a real-time (RT) optimization strategy for managing reactive power reserves in islanded power systems, explicitly maintaining safe margins from voltage limits. Existing formulations, dominated by objective functions aimed at minimizing losses, are shown to systematically drive bus voltages close to their upper admissible limits, potentially reducing operational margins and increasing the risk of overvoltage tripping. This work conducts a comparative study using three alternative multi-objective functions aimed at reducing power losses and mitigating voltage saturation: one previously proposed in the literature and two new formulations presented in this paper to overcome the limitations identified in the first. The analysis is conducted within a realistic real-time hardware-in-the-loop (HIL) optimization laboratory environment (RTOLab) and assessed over a full-day operation with a 5-minute execution interval. The optimization problem computes reactive power and voltage setpoints for power plant controllers in real time and performs redispatch actions as necessary to ensure secure operation. Results demonstrate that the two multi-objective functions proposed in this paper, aimed at avoiding voltage limits or penalizing reactive power reserve utilization, have a limited impact on system losses and exhibit operational robustness in RT optimization–based applications.

Key words: Optimal reactive power management, voltage control, optimal control setpoints, real-time optimization, hardware-in-the-loop simulation.

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