Decentralized Load Frequency Control Using Servo-Type Optimal Control Theory for Interconnected Power Systems Consisting of Hydro and Thermal Plants

Abstract

This paper describes a method of designing decentralized load frequency regulators considering the generation rate constraints for interconnected power systems. An interconnected power system is composed of a number of areas. Each area is controlled separately by a decentralized regulator. The background theory in this paper is based on servo-type optimal control theory. The design of the proposed method is consisted of the following two stages.
The first stage is to get the optimal feedback gains for the decomposed area using servo-type optimal control theory. Depending on the decomposed areas, the subsystem has a possibility of uncontrollability. Then, it is necessary to decompose the power system not so as to loose the controllability.
The second stage is to add the obtained optimal feedback gains to the interconnected power system. Then, the adjacent area's observed data are neglected. Because, the feedback gains belonging to the adjacent areas are generally small compared with its own area's those.
The effectiveness of this proposed method is illustrated by the numerical simulations. The results on a 3-area power system show that the method is encouraging for random load disturbances.