A Function Based Fuzzy Controller for VSC-HVDC System to Enhance Transient Stability of AC/DC Power System

This paper presents a robust function based optimized fuzzy controller for VSC-HVDC transmission link operating in parallel with an AC transmission line connecting a synchronous generator to infinite bus. A two input one output methodology based optimized non-linear fuzzy logic controller has been proposed to provide voltage support by means of reactive control at both ends: to damp power oscillations and improve transient stability by controlling either active or reactive power: and to control the power now through the HVDC link. An improved Teaching Learning Algorithm is applied to tune the gains of the fuzzy controller. Comprehensive computer simulations arc carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, torque change and faults on the converter and inverter buses. Based upon the time domain simulations in MATLAB/SIMULINK environment, the proposed controller is tested and its better performance is shown compare with the conventional PI controllers with respect to voltage stability, damping of power oscillations and improving of transient stability.