Variable Sampling Period Filter PLL for Distorted Three-Phase Systems

Single Bin Sliding Discrete Fourier Transform

“…A variable sampling period approach, named variable sampling period technique (VSPT), was developed by the authors to design synchronization methods that maintain a coherent sampling with the input signal fundamental frequency [14]. This technique has recently been adapted to dynamically adjust the sampling frequency in a harmonic measurement method based on mSDFT [15].…”

“…This technique has proven to be efficient both in three-phase and in singlephase applications yielding a robust synchronization mechanism, whose effectiveness has been tested under different conditions and scenarios [14,17]. Figure 8(a) illustrates the basic VSPT scheme for single-phase implementation, where the input signal is sampled and the input phase ϕ u ½n is extracted by the phase detector.…”

A New Synchronization Algorithm for Grid-Connected Inverters

“…Various synchronization techniques have been proposed in literatures. The zero crossing detection methods [7,8], the space-vector filtering (SVF) method [9], the artificial neural networks (ANN) method [10], the recursive weighted least-squares estimation (WLSE) algorithm [11], the discrete Fourier transform (DFT) and its modifications [12], the method based on the concept of adaptive notch filtering (ANF) [13], the Kalman filtering technique [14], the frequency-locked loop (FLL) method [15], three-phase open-loop phase-locked method [16], and the phase-locked loop (PLL) based on algorithms [17,18,19,20,21,22,23,24,25] are among the existing synchronization techniques. This paper incorporates the merits of the three-phase open-loop and closed-loop phase-locked method, and puts forward a new closed-loop phase-locked method with frequency adaptation function for three-phase grid-connected inverters.…”

An Adaptive Control System for Three-Phase Photovoltaic Inverters Working in a Polluted and Variable Frequency Electric Grid

“…Nevertheless, the stability of the adaptive filter is not studied in those methods, so that the stability of the whole SRF-PLL cannot be assured under all circumstances. Other approaches to obtain an accurate estimation of the voltage phase can be found in the literature [10], [19], [20], [30], which cope with frequency variations. In [30], an adaptive filtering method is proposed which is based on varying the sampling frequency.…”

“…Other approaches to obtain an accurate estimation of the voltage phase can be found in the literature [10], [19], [20], [30], which cope with frequency variations. In [30], an adaptive filtering method is proposed which is based on varying the sampling frequency. However, for the sampling frequency to be varied, the switching frequency is also required to do so, which might not be a good solution.…”