Application of PLL based on the method of symmetrical components in SVC control

This paper proposes a phase locked loop for SVC control, i.e., symmetrical components based synchronous reference frame phase-locked loop (SCSRF-PLL). This is achieved by transforming both positive and negative-sequence components of the utility voltage into the synchronous reference frame (SRF), tracking the phase of the fundamental-frequency positive-sequence component of the utility voltage, then the phase angel of three-phase utility voltages relative to PLL can be gotten through coordinate transformation, which completely eliminates the detection errors of conventional synchronous reference frame PLL (SRF-PLL). The SCSRF-PLL conducts then to a fast, precise, and robust positive-sequence voltage tracking even under distorted grid conditions such as with harmonics, unbalance and frequency variations. The feasibility and effectiveness of the synchronization method is verified by simulation experiment results.