Enhanced frequency-adaptive self-tuning filter-based continuous terminal sliding mode control of single-phase dynamic voltage restorer

This paper presents a continuous terminal sliding mode controller (CTSMC) for single-phase dynamic voltage restorers (DVRs). The presented controller can substantially eliminate the chattering compared to the first-order sliding mode counterpart while achieving faster convergence speed compared to the super twisting counterpart. Moreover, the continuous control signal enables the voltage source inverter to operate at constant switching frequency. As the reference compensation voltage generator, an enhanced single-phase self-tuning (SP-STF) filter is also proposed. The SP-STF has excellent band-pass filtering property, can completely attenuate DC offset and has fast dynamic response. The SP-STF has been made frequency-adaptive through unknown grid frequency estimation under a delayed-based linear regression framework. Comprehensive stability analysis of the controller and filter are presented. Experimental studies are performed to demonstrate the effectiveness of the proposed comprehensive control solution. Comparative simulation studies are also provided to highlight the advantages of the proposed approach. Results show that the proposed technique can quickly detect and compensate for any grid voltage fluctuations and helps to maintain constant voltage at the load side despite voltage sag/swell and distortions.