A robust control strategies to improve transient stability in VSC-HVDC based interconnected power systems

This paper presents a robust non linear sliding mode controller(SMC) for VSC-HVDC transmission link in parallel with an AC transmission line connecting a synchronous generator to infinite bus. A non linear sliding mode 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 flow through the HVDC link. The proposed control scheme is tested under several system disturbances like changes in short-circuit ratio, 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 PI controllers whose gains are optimized with teaching learning optimization technique. The proposed controller improves voltage stability, damping of power oscillations and transient stability.