Extended State Observer Based Nonsingular Terminal Sliding Mode Control for Voltage Source Converter Station With Uncertain Disturbances

This paper proposes a generalized design method of extended state observer (ESO) based nonsingular terminal sliding mode (NTSM) control for voltage source converter (VSC) station. The non-linear loads and external disturbances and parameter perturbations of the converter station are considered as external disturbances which are bounded. The ESO is designed to reject the external disturbances which include not only the unmeasured system states but also the modeling uncertainties. At the same time, the non-singular terminal sliding mode control method based on ESO is proposed to solve the problems of slow dynamic response of output voltage and high waveform distortion rate in converter station. The proposed control method is validated through numerical simulation shows a closed-loop dynamics and better transient performance, and the controller can effectively suppress the differential peak values of active power, reactive power and DC voltage in the initial stage of system start-up. Under conditions of non-singularity of the controller, the influence of system disturbances in the chattering of the controller is effectively eliminated and the robust performance of the system is enhanced.