REPETITIVE RIPPLE ESTIMATOR FILTER BASED PHASE-LOCKED LOOP

In this paper, a novel phase-locked loop is presented based on a repetitive ripple estimator filter. The primary application of the presented phase-locked loop is in the monitoring of three-phase grid voltages and synchronization of grid connected power converters for renewable energy sources with the grid. The filter is inserted inside the loop filter of the phase-locked loop to reject oscillations that can be expected from common grid voltage disturbances. Details of the filter and phase-locked loop are presented, along with the influence of all freely adjustable parameters on overall system behaviour. In the end, the behaviour of the novel phase-locked loop is tested, validated and compared to the base phase-locked loop.