A global frequency estimator based on a frequency-locked-loop filter

IEEE Trans. Contr. Syst. Technol.

et al. 2023

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This work describes and compares two phaselocked-loop (PLL) algorithms aimed at tracking a biased sinusoidal signal with unknown frequency, amplitude and phase, with inherent robustness to dc-offset. The proposed methods endow Quadrature PLLs, renowned for their excellent tracking performance, with frequency-adaptation capability, while providing robust global stability certificates. The large-gain global stability, proven by Lyapunov-like arguments borrowed from adaptive control theory, represents a major benefit compared to conventional PLLs, whose convergence instead can be proven only locally by small-signal analysis or small-gain assumptions. In this connection, the proposed algorithms represent the first frequency-adaptive and DC-bias rejecting PLL-type architectures with Lyapunov-certified global stability. When used for signal tracking, the proposed methods are shown to outperform the adaptive observer, especially in noisy conditions. Moreover, they provide more accurate frequency estimates than existent frequency-adaptive PLLs, showing enhanced robustness in facing both phase-noise and measurement perturbations. I. INTRODUCTIONThe power distribution network is undergoing tremendous changes due to ever increasing penetration of distributed and renewable energy resources. Such a trend poses new challenges due to the increased unpredictability of these new power sources. A microgrid incorporating the renewable distributed energy resources can be operated either in grid-connected mode or in islanded mode. During both modes of operation, monitoring and control of frequency plays a vital role for power quality assessment, for the control and protection of the power grid and also for the synchronization of the microgrid with the main grid [1]. Due to the presence of disturbances and uncertainties in the grid voltage, such as harmonics, noise, G.Pin is with Electrolux Italia S.p.A., Italy

Section: B Stability Analysis Of the R-gqpllmentioning

confidence: 99%

mentioning

confidence: 99%

Robust Frequency-Adaptive Quadrature Phase-Locked-Loops With Lyapunov-Certified Global Stability

IEEE Trans. Contr. Syst. Technol.

et al. 2023

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“…The resulting PLL schemes are commonly known as QSG-PLLs or OSG-PLLs. The Frequency Locked-Loop (FLL) of [2], [3], that uses a Second Order Generalized Integrator (SOGI) to implement the OSG, is, for instance, capable of tracking sinusoidal signals with time-varying frequency and amplitude. Other methods providing frequency-adaptation ability to a PLL can be found in [4] and [5].…”

Section: Introduction and Problem Formulationmentioning

confidence: 99%

Robust Frequency-Adaptive PLL with Lyapunov Stability Guarantees

2020 IEEE Conference on Control Technology and Applications (CCTA)

et al. 2020

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The Global Quadrature Phase-Locked-Loop (GQ-PLL) is a recently-devised PLL-type architecture (based on Quadrature Signal Generation) able to track a biased sinusoidal signal with unknown frequency and amplitude. The original GQPLL formulation resorted to a non-standard nonnormalized adaptive law, able to guarantee the global convergence of the estimates for arbitrarily large adaptation gains, thus enabling arbitrarily fast adaptation transients. On the other side, the non-conventional adaptation law used in the original formulation makes it difficult to apply robustifying modifications of adaptive control. In this connection, the present work presents a new formulation for the PLL internal dynamics in order to obtain a convenient 1st order linear-in-the parameters error model, which can be dealt with by a conventional nonnormalized adaptive law, to which a robustifying modification such as projection can be applied. The large-gain global stability of the adaptive system is proven by Lyapunov arguments. The overall adaptive PLL is named Robustified GQPLL (RGQPLL).

“…In the a G. Pin is with the Global Connectivity & Technology organization of (t.parisini@gmail.com) literature, QSG units are sometimes also referred to as Orthogonal Signal Generators (OSG). The Frequency Locked-Loop (FLL) of [2], [3] based on a Second Order Generalized Integrator (SOGI) to implement the OSG, is for instance capable of tracking sinusoids with time-varying frequency and amplitude. Other algorithms taking origin from the very same idea of providing frequency-adaptive capability to a PLL can be found in [4] and [5].…”

Section: Introductionmentioning

confidence: 99%

Globally-stable tracking and estimation for single-phase electrical signals with DC-offset rejection

IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society

et al. 2019

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The present work introduces a new algorithm, named Global Quadrature PLL (GQPLL) for tracking a sinusoidal signal and for estimating its frequency and amplitude. The proposed technique derives from the well-known PLL architecture based on Quadrature Signal Generation (QSG), that is widely used for tracking the fundamental of single-phase electrical signals. The proposed algorithm improves the existent QSG-PLL solutions from two different perspectives. First, the cancellation of the DC-bias is embedded by construction. Moreover, a Lyapunov-based stability analysis guarantees the global convergence of the estimates for arbitrarily large adaptation gains, enabling fast adaptation transients. The provided simulations show that the algorithm is able to deal with sudden variations of the fundamental frequency and of the DC-bias magnitude.