OPTIMUM LOAD FREQUENCY CONTROL IN POWER SYSTEM

Abstract

Improvement to present day techniques for Automatic Load Frequency Control (ALFC) is becoming more and more intri-cate due to the practical complexity of modern interconnected systems dynamics and the multiplicity of desired control cri-teria. Considerable interest has been shown in recent years to develop new techniques of ALFC using Optimal Control Theory. In this dissertation an attempt has been made to develop one such near optimal controller for ALFC using sub-optimal control Theory. The system chosen consists of two large equal electric energy areas connected by a weak-tieli_r^ The area controllers are constrained to be non-interacting by preventing the information corresponding to the states for turbine valve/gate positional deviations and area generated power deviations from flowing from one area to the other. The area controllers, then obtained, are primarily the functions of their own area states. The system equations are framed in the state-space representation with a quadratic cost criteria chosen as the performance index. Using Suboptimal control theory, a compu-ter algorithm is developed to solve for the feed back gains which minimize the given cost criteria. The dynamic response obtained from the solution of system differential equations is plotted which is found to be stable. A comparison of this response is also made with the one obtained by Elgerd and Fosha [l],[2] for a similar system and initial conditions.