An Optimal Load Cut Policy with Event-Driven Design against Voltage Instability Using Theta-Particle Swarm Optimization

The requirement for minimized cost whilst preserving power system reliability necessitates the development of both efficient system security assessment approaches and appropriate emergency remedial actions. Load shedding is a type of corrective actions that is applied to save power system stability against severe disturbances. This paper proposes an optimal load shedding policy that takes into account voltage stability of power system whenever a predetermined contingency occurs. After specification of load cut candidate points by V-Q sensitivity analysis the amount of load curtailment is determined by solving a non-linear multi-objective problem. A modified Theta-PSO algorithm with the lexicographic method is used to optimize the multi-objective function that consists of load cut amount, loading margin, branches’ overload and deviation from voltage limits. In addition, dynamic simulations are performed to determine the critical time of load shedding. The proposed method is tested on Khorasan area of Iran‘s power system, which shows its better performance compared to the current load shedding scheme.