Design of the Optimal Self-tuning Fuzzy-PI Controller for Rectifier Current Control in HVDC System

In this paper, we study an approach to design a self-tuning fuzzy-PI controller in HVDC (high voltage direct current) system. In the rectifier of conversional HVDC system, turning on, turning off, triggering and protections of thyristors have lots of problems that can make the dynamic instability and cannot damp the dynamic disturbance efficiently. The above problems are solved by adapting fuzzy-PI controller for the fire angle control of rectifier. The performance of the fuzzy-PI controller is sensitive to the variety of scaling factors. The design procedure dwells on the use of evolutionary computing (genetic algorithms, GAs). Then we can obtain the optimal scaling factors of the fuzzy-PI controller by genetic algorithms. In order to improve fuzzy-PI controller, we adopt FIS to tune the scaling factors of the fuzzy-PI controller on line. A comparative study has been performed between fuzzy-PI and self-tuning fuzzy-PI controller, to prove the superiority of the proposed scheme.