Abstract

In multi area electric power systems, if a large load is suddenly connected (or disconnected) to the system, or if a generating unit is suddenly disconnected by the protection equipment, there will be a long-term distortion in the power balance between that delivered by the turbines and that consumed by the loads. This imbalance is initially covered from the kinetic energy of rotating rotors of turbines, generators and motors and, as a result, the frequency in the system will change. Therefore The Load Frequency Control (LFC) problem is one of the most important subjects in the electric power system operation and control. In practical systems, the conventional PI type controllers are applied for Load Frequency Control. In order to overcome the drawbacks of the conventional PI controllers, numerous techniques have been proposed in literatures. In this paper, a new Fuzzy type controller is considered for Load Frequency Control problem. In this new Fuzzy technique, the upper and lower bounds of the Fuzzy membership functions are obtained using genetic algorithms optimization method and so this Fuzzy method is called “scaled-Fuzzy”. A multi area electric power system with a wide range of parametric uncertainties is given, to illustrate proposed method. To show effectiveness of the proposed method, a classical PI type controller optimized by genetic algorithms (GA) was designed in order to make comparison with the proposed scaled Fuzzy method. The simulation results visibly show the validity of scaled Fuzzy method, in comparison with the traditional PI type method.

Key words: Multi area electric power system, Load Frequency Control, scaled fuzzy logic, genetic algorithms.