Single Phase PLL for a Distorted Grid

The PLL with output phase filtration based on the variable coefficient discrete system is presented. The proposed PLL method provides relatively fast setting time and high rate of input signal phase change. An additional filter allows providing a phase reference signal with given bandwidth from noisy grids to obtain stability in the closed loop system. This method can be applied to symmetrical sequence extraction at three-phase systems, single-phase grid-tie converters and possible to use as part of the demodulation algorithm.