Constant switching frequency band controller for dynamic voltage restorer

This study presents a novel constant switching frequency band controller for dynamic voltage restorer (DVR) with a proposed filter structure. The switching operation of voltage source inverter (VSI) based on band controller, which restricts the injected voltages within a band, is explored. This control method of the VSI inherits merits such as fast dynamic response, robustness, zero magnitude/phase errors and ease of implementation. The performance of the band controller is improved using a novel filter structure. Quantitative expressions involving the dynamics of DVR and variation of switching frequency are derived. The constancy in the switching frequency is subsequently achieved by an adaptive hysteresis band controller. The proposed filter structure and the adaptive band controller for the DVR are validated by carrying out simulation studies using PSCAD. The performance of the proposed controller in both transient and steady-state conditions has been evaluated and discussed. Based on the proposed design, the performance of the controller is extensively tested with various voltage disturbances on a reduced scale DVR prototype developed in the laboratory.