Particle Swarm Optimisation of Static VAR Compensator Deployment for Voltage Support in Transmission Grid

Abstract

Voltage stability is a persistent operational challenge in power systems, particularly in developing grids such as Nigeria’s, where rapid load growth and infrastructural limitations frequently push networks close to their stability margins. This study investigates the improvement of voltage stability in a representative transmission network through the optimal placement and sizing of Static VAR Compensators using Particle Swarm Optimisation. The IEEE 30-bus test system was adopted as a benchmark and assessed under normal (100%), light (80%), heavy (120%), and stress (140%) loading conditions. Under uncompensated operation, several buses violated the statutory voltage limits of 0.95–1.05 p.u., with overvoltages reaching 1.071 p.u. during light loading and undervoltage dropping to 0.927 p.u. under stress conditions, indicating elevated risks of voltage instability and possible voltage collapse. The PSO algorithm identified optimal buses for SVC deployment, with reactive power ratings ranging from about –49.6 MVAR (reactive absorption under light load) to +68.0 MVAR (reactive injection under stress load). After compensation, all bus voltages were restored within permissible limits, with critical buses showing average improvements of 3–5%. For instance, the most depressed voltage improved from 0.927 p.u. to 0.963 p.u., while peak overvoltage reduced to approximately 1.021–1.051 p.u. These results confirm the effectiveness of PSO-optimised SVC placement for enhancing voltage stability and operational security under varying load conditions.