Optimal under Voltage Load Shedding to Prevent Frequency Instability with Considering Load Interruption Cost

In this study, a static method which makes best load shedding scheme to reach a maximum voltage security margin, prevent voltage instability and emendation of power system frequency during generation unit outage is developed. Minimization of total load interruption cost with considering frequency emendation constraint, Voltage security margin, and alleviating transmission line over loadings have great significance in fitness function to reach a coordinated load shedding pattern. In this paper, Load interruption cost has been modeled as a quadratic function and frequency constraint modeled based on extra load must be shed caused by generator outage contingencies in under study power system. HGAPSO and PSO are used as optimization tools for solving mentioned problem during contingency conditions. The proposed approach is carried out on IEEE 14 and 30 bus test systems and results are discussed.