Extended State Observer Based Super Twisting Sliding Mode Control of SMES-DVR For Sensitive Load Protection

Dynamic voltage restorer with superconducting magnet energy storage reduces the coupling between the DVR and the power grid, offering greater toughness and a wider voltage compensation range. For SMES, the DVR grid-connected inverter part can be regarded as the power electronic load. SMES-DVR compensates for voltage dips with transient energy exchanges between the SMES and the grid. The nonlinearity, parameter uncertainty, and load disturbance of the DVR system will make it difficult to track the reference signal and keep DC-link voltage at the desired value. Hence, an efficient controller must be designed to compensate the intricate correlation related to the SMES-DVR. A novel sliding mode controller is proposed for SMES-DVR based on the super-twisting sliding mode controller (STSMC) and extended state observer (ESO). The proposed controller not only can regulate the DC-link voltage tending to target value with a shorter transition time and smaller overshoot, but also has a strong anti-interference ability because of the disturbance estimation of the extended state observer. Finally, the simulation results based on MATLAB/Simulink indicate that SMES-DVR with the proposed SMC controller can promptly compensate for the voltage sags/swells of the sensitive loads and effectively reduce the total harmonic distortion.