An Observer-Based Harmonic Extraction Method with Front SOGI

Xu, Maoguang; Sang, Zhongqing; Li, Xiang; You, Yong; Dai, Dongyun

doi:10.3390/machines10020095

Cited by 3 publications

(1 citation statement)

References 25 publications

(32 reference statements)

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“…The frequency-domain methods usually refer to Fourier transform-based techniques [12][13][14][15], within which the sliding discrete Fourier transform (SDFT) has gained wide applications in recent years for its efficient iteration and easy digital implementation. In [16], the SDFT was used for harmonic detection in the three-phase grid-tie inverter system; besides, SDFT has been often used in cooperation with the phase-locked loop for the stable operation and control of the grid-connected converters [17,18]. Although the SDFT algorithm is computationally efficient, this method still might have drawbacks, e.g., a slow dynamic performance and sensitivity to the frequency, and types of measures have been researched to make improvements [19], and types of improvements have been carried out in [20].…”

Section: Introductionmentioning

confidence: 99%

Rapid Extraction of the Fundamental Components for Non-Ideal Three-Phase Grid Based on an Improved Sliding Discrete Fourier Transform

Li¹,

Nai²

2022

Electronics

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In order to make an effective extraction of the fundamental components for a non-ideal three-phase grid, an improved sliding discrete Fourier transform (ISDFT) has been proposed in this paper. Firstly, the non-ideal signal characteristics are studied in detail, which reveals that there are not only typical harmonic components, but also double frequency components, that exist in dq coordinates when the three-phase grid voltages are unbalanced. Then, the structure form of the conventional sliding discrete Fourier transform (SDFT) has been redesigned to form the ISDFT algorithm, in which a special offset link is introduced to reduce the extraction time while the effectiveness is guaranteed. The experimental results show that this proposed ISDFT is suitable for types of non-ideal signals extraction and can keep a nice dynamical and steady performance in cases of grid or load disturbance. For the average extraction time, ISDFT is saving about 44.56% more of the time than SDFT and about 65.32% more than discrete Fourier transform (DFT).

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Section: Introductionmentioning

confidence: 99%

Rapid Extraction of the Fundamental Components for Non-Ideal Three-Phase Grid Based on an Improved Sliding Discrete Fourier Transform

Li¹,

Nai²

2022

Electronics

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Rapid Harmonic Detection Scheme Based on Expanded Input Observer

Zhu

et al. 2022

Electronics

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The existence of harmonics will cause the quality of power supply in a power system to decline and will affect the normal use of the power system. Therefore, it is important to suppress harmonics in the power system, and the first step of harmonic suppression is harmonic detection. To address this phenomenon, a fast harmonic detection method is proposed in this paper. It is based on the input observer theory to construct a state space model based on the original signal and harmonic components and estimate the state variables so as to achieve harmonic extraction. The characteristic roots are used to prove the convergence of the observer. In addition, the Second-Order Generalized Integration (SOGI) frequency estimation method is chosen to cascade with it so that harmonic detection can be accomplished with unknown frequencies. The simulation results prove that the proposed method can quickly converge and accurately extract each harmonic in the case of fluctuations in the fundamental amplitude, fundamental frequency and phase of the input signal, and the whole process can be completed in 0.02 s. The possible effects of white noise on harmonic extraction are also simulated, and the results prove that the accuracy of harmonic extraction can still be guaranteed in the presence of white noise. By using the Speedgoat real-time target machine built Rapid Control Prototype (RCP) as a testbed, experiments with similar simulation conditions were performed. The results show that the method has fast and accurate harmonic detection performance.

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Harmonic Mitigation Using Meta-Heuristic Optimization for Shunt Adaptive Power Filters: A Review

Duc,

Hlavaty,

Bilik

et al. 2023

Energies

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Shunt Adaptive Power Filter (SAPF) is widely used in the performance of power quality improvement activities in the power supply industry for processing industries or civil power sources in the world today based on its simplicity, transparency, high reliability, efficiency, and reliability, and their powerful compensating current-providing nature. The PI controller integrated into the SAPF operation mechanism works with extra high efficiency in selecting the current to compensate for the lost current generated in the power supply due to harmonics generated by the parameter values. The system operates by the PWM method for bridge rectifier circuits that perform the function of selecting the appropriate compensating current, providing correct compensation for the amount of current loss in the power supply. Adjusting the parameter to reach the optimal value by different methods is a promising and popular research direction at present. The parameter serves the right purpose for the PI controller to generate enough PWM pulses to excite the bridge rectifiers to generate just the right amount of compensating current and enough current to be compensated on the power supply. The commonly used parameter adjustment methods include the Ziegler Nichols closed-loop vibration method, the P-Q theoretical method, and several other methods. This study conducts a comprehensive review of the literature on modern strategies for adjusting theparameters in the PI controller in the SAPF suite by using the meta-heuristic optimization method. This study performs classification according to the operation mode of meta-heuristic optimization methods to adjust the parameter to control the PI to select the correct PWM frequency to activate bridge rectifiers to select the most optimal compensation current to compensate for the loss of current on the power supply to meet the goal of improving power quality in accordance with IEEE 519-2022 standard, leading to the total harmonic distortion (THD) value is below 5%. The study presents in detail some meta-heuristic optimization algorithms, including applications, mathematical equations, and implementation of flow charts for SAPF and provides some open problems for future research. The main objective of this study is to provide an overview of applying meta-heuristic optimization algorithms to the parameter tuning of PI controllers.

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An Observer-Based Harmonic Extraction Method with Front SOGI

Cited by 3 publications

References 25 publications

Rapid Extraction of the Fundamental Components for Non-Ideal Three-Phase Grid Based on an Improved Sliding Discrete Fourier Transform

Rapid Extraction of the Fundamental Components for Non-Ideal Three-Phase Grid Based on an Improved Sliding Discrete Fourier Transform

Rapid Harmonic Detection Scheme Based on Expanded Input Observer

Harmonic Mitigation Using Meta-Heuristic Optimization for Shunt Adaptive Power Filters: A Review

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