Performance of Second-Order Generalized Integrator Based Adaptive Filter Under Adverse Grid Conditions

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It is a major challenge for the grid-connected power electronic converter circuits to get synchronized with the utility grid when the grid voltage is highly unbalanced and polluted with harmonics. In this situation designing a phase lock loop (PLL) is a challenge to estimate the phase, frequency, and amplitude of the utility voltage. Phase lock loop (PLLs) is a closed-loop synchronization structure where the error signal is generated from the difference of estimated phases and the reference phase values. This paper presents a filtering technique based on adaptive filter called second-order generalized integrator (SOGI). Under transient fault condition when the three-phase grid signal is highly polluted with harmonics and sudden frequency change or voltage dip occurs, it is a critical task to extract the fundamental component of the grid signal. Here for the extraction of the fundamental component from the polluted signal, two adaptive filters using SOGI can be implemented on the stationary αβ reference frame. To analyze the disturbance rejection capability of the SOGI filter different distortions have been introduced in the three-phase grid signal and the robustness is estimated on the basis of its transient response and harmonic analysis. The simulation results will validate the excellent performance of the filter.