Design of Fuzzy Sliding Mode HVDC Supplementary Controller Based on Global Signal

This paper presents a novel approach to enhance AC/DC parallel power system stability using a fuzzy controller. The global signals of the power system are adopted as the feedback input. The fuzzy controller is based on the main concepts of sliding mode control, and it is applied to high voltage direct current transmission control system to enhance the damping to the power oscillation. The fuzzy control rules that guarantee the system stability are systematically obtained based on sliding mode control. The Lyapunov stability criterion is adopted to secure the stability of the system. The fuzzy controller ensues the consistence performance when undergo operating condition change. Small signal stability analysis and time domain simulation of a two-area, four-machine AC/DC test system is carried out. The analysis results show that the proposed fuzzy sliding mode controller is capable of damping the system's low frequency oscillation and enhancing the AC system's transfer capability over a wide range of operating conditions