Implementation aspects of adaptive window moving average filter applied to PLLs — Comparative study

New standards for grid connected distributed generation systems requires operation for variable grid frequency. This paper discusses implementation details for the adaptive MAV (moving average) filter, used as a low pass filter in PLLs. The implementation of the MAV filter buffer is discussed, including the linear and circular cases, with fixed and variable window size. For this last case, a buffer that avoids data loss is shown. Details on the calculation of the mean value to avoid cumulative errors are presented. Experimental results validate the proposed strategies to reduce the PLL phase error and decrease its processing time are presented.