Frequency adaptivity improvement in GDSC-PLL

Abstract

This paper shows a scheme for improving the detection performance of the Fundamental-Frequency Positive-Sequence (FFPS) space vector through the Generalized Delayed Signal Cancellation Phase-Locked Loop (GDSC-PLL). The performance was improved by a new scheme that reduces the phase-angle error in the frequency adaptive scheme during grid frequency variations. In the new scheme we replaced the SRF-PLL used for the frequency adaptation scheme by simple samples counters. Further, we made improvements in the circuitry that performs the frequency estimation filtering. The performances of the traditional GDSC-PLL and other usual detection schemes were compared with the proposed one through transient test cases based on IEC 61000 and typical electrical events. The new approach led to a reduction of up to 79% in the phase-angle convergence time right after disturbances and a reduction of up to 65% in the mean absolute error during frequency variation.