Nonlinear Disturbance Observer Based DC-Link Voltage Control for Grid-Connected VSC

The control of the DC-link voltage is necessary for the operation of a voltage source converter (VSC) integrated to grid. In this paper, a nonlinear disturbance observer (NDO) is proposed to improve the dynamic performance of the voltage source converter in the presence of dc disturbance. Installation of a feedforward term has been provided with the voltage control loop, which suppresses the dc transient variations of the DC-link voltage, improving the VSC dynamics and the system power quality. The efficacy of the proposed nonlinear disturbance observer has been validated in MATLAB/SIMULINK environment and the same has been confirmed on an NI based system for real-time analysis.