Optimal load shedding to prevent voltage instability based on multi-objective optimization using modal analysis and PSO

This paper presents an optimal load shedding approach to enhance voltage stability employing a combination of modal analysis and particle swarm optimization (PSO). At first as a preventive control action the best transformers tap setting is indicated by PSO optimization to get the most possible voltage stability margin then as a corrective control action after contingencies the proposed approach is organized as a multi-objective optimization problem which reveals the best location and the lowest level of load shedding for special protection systems (SPS) in the direction of improving the voltage stability margin as well as the voltage profile. The proposed approach is applied to Gharb and Bakhtar areas of the Iranian transmission network for its annual peak load at 2009. Simulation results verify the effectiveness of the proposed scheme in comparison with the current scheme.