Variable Sampling Period Filter PLL for Distorted Three-Phase Systems

• Published in: IEEE transactions on power electronics Vol. 27; no. 1; pp. 321 - 330
• Main Authors: Carugati, I., Maestri, S., Donato, P. G., Carrica, D., Benedetti, M.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2012; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Circuit properties; Circuits of signal characteristics conditioning (including delay circuits); Distortion; Disturbances; Disturbances. Regulation. Protection; Dynamics; Electric potential; Electric, optical and optoelectronic circuits; Electrical engineering. Electrical power engineering; Electrical power engineering; Electronic circuits; Electronics; Exact sciences and technology; Filters; Frequencies; Grid disturbances and variable sampling period; Harmonic analysis; Harmonics; Integrated circuits; Integrated circuits by function (including memories and processors); Mathematical model; Mathematical models; Phase locked loops; Power harmonic filters; Power networks and lines; Robust control; Sampling; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Simulation; synchronism; Synchronization; Theory. Simulation; three-phase systems; Time frequency analysis; Transforms; Voltage; Waveform; Input signal; Power system harmonics; Unbalanced conditions; Power system stability; Harmonic analysis; Implementation; Energy quality; Robustness; Harmonic distortion; Phase error; Sampling; Mathematical model; Dynamic response; three-phase systems; Dynamic characteristic; Saturation; Steady state; Phase distortion; Phase locked loop; Sampling frequency; synchronism; Harmonics suppression; Integrated circuit; Three phase circuit; System simulation; Digital signal processor; Service quality; Comparative study; Grid disturbances and variable sampling period
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2011.2149542

This paper proposes a novel variable sampling period filter phase-locked loop (VSPF-PLL) for use in the general area of three-phase systems. It is based on the concept of variable sampling period, which allows to automatically adjust the sampling frequency to be N PLL times the line frequency. Conventional three-phase PLL are based on synchronous reference frames (SRFs) to estimate the phase error between the PLL and the input signals. However, SRF transform fail when the voltage waveforms are distorted. In this paper, a sliding-Goertzel-transform- based filter is used in the loop to reject disturbances, such as unbalanced voltage and harmonics. It allows to detect the positive sequence present in the systems without errors. Characteristics of VSPF-PLL, including its mathematical model as well as steady state and dynamic responses, are discussed in this paper. The method is implemented in a DSP and tested using typical disturbances, such as frequency steps, unbalances, harmonics, saturation, and line-to-ground fault. Comparative simulations are performed between the proposed VSPF-PLL and some of the most common three-phase PLL described in the literature. Advantages of the proposed system over the methods analyzed are also discussed. Structural simplicity, robustness, and harmonics rejection are other attractive features offered by the proposed system.