A Novel Phase-Locked Loop with Positive and Negative Sequence Detection Capability

This paper proposes the expansion of two phase-locked loop structures to detect positive and negative sequence components. The first structure is a positive sequence detector only and the second one is a modification of the first one where an adaptive filter is added to increase filtering capability in scenarios with interharmonic distortion. Both proposed structures were implemented in the hardware-in-the-loop (HIL) dSPACE 1103 platform together with two well known structures, the DSOGI-FLL and the DDSRF-PLL. Steady-state and dynamic response of each structure were analyzed in scenarios with either harmonic distortion only or harmonic and interharmonic distortion. Results showed that the proposed structures are highly accurate, specifically under harmonic distortion, however the structure with adaptive filter is slower. In addition, results showed that the structures are at least as precise and fast as the DSOGI-FLL and DDSRF-PLL. Lastly, under interharmonic distortion, it is also found that the PLL with adaptive filter has an overall better performance.