An Analytical Approach to Parameter Selection for SOGI-Based Fourth-Order Quadrature Signal Generators

Abstract

Dual quadrature signal generators (QSGs) with a positive sequence calculator (PSC) are used as a prefilter in phase-locked loops (PLLs) to extract the fundamental positive sequence voltage components under non-ideal grid conditions. The QSG's order directly impacts the dynamics and quality of the generated positive sequence component. Fourth-order QSGs have better filtering capability when compared to second-and third-order QSGs. They exhibit superior performance in the presence of harmonic distorted grid voltages. However, the dynamic response of such fourth-order QSGs are greatly affected by the choice of system parameters. In this paper, an analytical approach based on settling time is proposed for parameter selection of two existing second-order generalized integrator (SOGI) based fourth-order QSGs viz. cascaded SOGI-QSG and second-order SOGI-QSG (SO-SOGI-QSG). The proposed method predicts the settling time for a choice of parameter selection with better accuracy than the existing procedure. It also helps in choosing parameter values that lead to faster settling times. Simulation and hardware results are provided to support the proposed approach.