OPTIMIZATION OF LOAD SHEDDING SYSTEM

An optimization algorithm for a load shedding system is presented. The Israeli power system is not interconnected with any neighbouring system. Being a relatively small system, an outage of a single generating unit may cause blackouts. One way of preventing this is an underfrequency load shedding system, which is composed of several stages that are tripped at preset frequencies. The paper considers the optimization of this system with respect to a cost function that includes a dynamic part, i.e. integral of the deviation from nominal frequency,and a static part which is the total load shedding. The optimization is constrained by the requirement of minimum allowed frequency and limitation on the total load of the shedding system. A projected gradient method is used for the solution where analytic expressions for the partial derivatives are used to simplify the computation. Results concerning application of the optimization to a model of the actual Israeli power system are given together with a study of the cost parameters.