scholarly journals A Real-Time Harmonic Extraction Approach for Distorted Grid

Mathematics ◽  
2021 ◽  
Vol 9 (18) ◽  
pp. 2245
Author(s):  
Po Li ◽  
Xiang Li ◽  
Jinghui Li ◽  
Yimin You ◽  
Zhongqing Sang
Keyword(s):  
Power System ◽  
Real Time ◽  
Frequency Estimation ◽  
Harmonic Component ◽  
Estimation Algorithm ◽  
Phase Variable ◽  
Current Frequency ◽  
Zero Crossing ◽  
Grid Current ◽  
Harmonic Extraction

Harmonic interference is a major hazard in the current power system that affects power quality. How to extract harmonics quickly and accurately is the premise to ensure the sustainable operation of power system, which is particularly important in the field of new energy power generation. In this paper, a harmonic extraction method based on a time-varying observer is proposed. Firstly, a frequency estimation algorithm is used to estimate the power grid current frequency, which can estimate the frequency in real time. Then, applying the zero-crossing detection method to convert the frequency into a phase variable. Finally, using the phase variable and integral current signal as input, a observer is modeled to extract each order harmonic component. The proposed method is evaluated on a FGPA test platform, which shows that the method can extract the harmonic components of the grid current and converge within 80 ms even in the presence of grid distortions. In the verification case, the relative errors of the 1st, 5th, 7th and 11th harmonics are 0.005%, −0.003%, 0.251% and 0.620%, respectively, which are sufficiently small.

scholarly journals Harmonic Frequency Estimation Algorithm Based on MSWF in Power System

2015 ◽  
Vol 9 (1) ◽  
pp. 524-529
Author(s):  
Cao Zhe ◽  
Sun Xiangwen ◽  
Niu Xinwen
Keyword(s):  
Computational Complexity ◽  
Power System ◽  
Frequency Estimation ◽  
Recursive Algorithm ◽  
Wiener Filter ◽  
Estimation Algorithm ◽  
Music Algorithm ◽  
Harmonic Frequency ◽  
Multi Stage ◽  
Data Volume

This paper pointed out the disadvantage of harmonic frequency estimation algorithm in current power system, presented the MUSIC (multiple signal classification)-based harmonic frequency estimation algorithm in power system, and analyzed the computational complexity of the MUSIC algorithm. In order to reduce the computational complexity of conventional MUSIC algorithm and to increase the real-time characteristic of harmonic frequency estimation algorithm, we combined the multi-stage wiener filter (MSWF) recursive algorithm and MUSIC algorithm so as to avoid the subspace decomposition process of the conventional MUSIC algorithm, thus realizing the purpose of significantly reducing the computational complexity of the MUSIC algorithm. Through theoretical analysis and simulation experiments, we find that the algorithm proposed in this paper is of excellent resolution characteristic, and less dependent on data volume.

Harmonic Estimation Algorithm for Power System Based on Improved MUISC and Linear Neural Networks

2015 ◽  
Vol 9 (1) ◽  
pp. 445-451 ◽  
Author(s):  
Sun Ligong Ligong ◽  
Sun Xiangwen ◽  
Xiang Fei
Keyword(s):  
Neural Network ◽  
Power System ◽  
Frequency Estimation ◽  
Wiener Filter ◽  
Estimation Algorithm ◽  
Estimation Accuracy ◽  
Music Algorithm ◽  
Multiple Signal Classification ◽  
Harmonic Phase ◽  
Linear Neural Network

The paper proposes harmonic estimation algorithm for power system based on Multiple Signal Classification (MUSIC) and linear neural network because of the insufficiency of harmonic frequency estimation algorithm. The conventional MUSIC algorithm has the advantage of higher estimation accuracy, while the disadvantage is that the computational complexity is high and it cannot estimate the harmonic phase and amplitude. In the paper, a new harmonic estimation algorithm for power system is constructed with combining the MUSIC algorithm, the multistage Wiener filter (MSWF) and linear neural network. Theoretic analysis and simulation experiments show that the requirement to data is relatively low, and has good harmonic estimation accuracy and reliability.

Power System Frequency Estimation Algorithm for Electric Energy Metering of Nonlinear Loads

2012 ◽  
Vol 19 (2) ◽  
pp. 307-320
Author(s):  
Zhang Peng ◽  
Li Hong-Bin
Keyword(s):  
Power System ◽  
Frequency Estimation ◽  
Electric Energy ◽  
Estimation Algorithm ◽  
Discrete Wavelet ◽  
Monitoring And Control ◽  
Nonlinear Loads ◽  
Nonlinear Load ◽  
Energy Metering ◽  
System Frequency

Power System Frequency Estimation Algorithm for Electric Energy Metering of Nonlinear LoadsIn this paper, a discrete wavelet transform (DWT) based approach is proposed for power system frequency estimation. Unlike the existing frequency estimators mainly used for power system monitoring and control, the proposed approach is developed for fundamental frequency estimation in the field of energy metering of nonlinear loads. The characteristics of a nonlinear load is that the power signal is heavily distorted, composed of harmonics, inter-harmonics and corrupted by noise. The main idea is to predetermine a series of frequency points, and the mean value of two frequency points nearest to the power system frequency is accepted as the approximate solution. Firstly the input signal is modulated with a series of modulating signals, whose frequencies are those frequency points. Then the modulated signals are decomposed into individual frequency bands using DWT, and differences between the maximum and minimum wavelet coefficients in the lowest frequency band are calculated. Similarities among power system frequency and those frequency points are judged by the differences. Simulation results have proven high immunity to noise, harmonic and inter-harmonic interferences. The proposed method is applicable for real-time power system frequency estimation for electric energy measurement of nonlinear loads.

scholarly journals Harmonic Frequency Estimation Algorithm based on ESPRIT and MSWF in Power System

2015 ◽  
Vol 9 (1) ◽  
pp. 518-523 ◽  
Author(s):  
Sun Xiangwen ◽  
Cao Zhe ◽  
Tian Wei
Keyword(s):  
Power System ◽  
Simulation Experiment ◽  
Frequency Estimation ◽  
Wiener Filter ◽  
Estimation Algorithm ◽  
Frequency Resolution ◽  
Harmonic Frequency ◽  
Fast Estimation ◽  
Multistage Wiener Filter ◽  
Esprit Algorithm

This paper points out the deficiency in the current harmonic frequency estimation algorithm in power system. In order to improve the accuracy of detection and reduce the computational complexity, the study combined the ESPRIT algorithm with multistage Wiener filter (MSWF) recurrence to achieve fast estimation of harmonic frequency. Theoretical analysis and simulation experiment show that the algorithm had relatively low requirement for the amount of data, and demonstrated good frequency resolution characteristics and anti-jamming capability, which made it ideally suitable for harmonic analysis in power system.

Development of Adaptive Feed-Forward Cancellation With Frequency Estimation Algorithm for Compensation of Periodic Disturbance at Arbitrary Frequency

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Shota Yabui ◽  
Tsuyoshi Inoue
Keyword(s):  
Real Time ◽  
Frequency Estimation ◽  
Estimation Algorithm ◽  
Open Loop ◽  
Fixed Frequency ◽  
Nyquist Diagram ◽  
Feed Forward ◽  
Periodic Disturbance ◽  
Arbitrary Frequency ◽  
The Stability

Abstract In this study, an adaptive feed-forward cancellation (AFC) with frequency estimation algorithm has been developed to compensate for periodic disturbance at an arbitrary frequency. Conventional AFC was developed to compensate for periodic disturbance at a fixed frequency and cannot compensate for the disturbance in which the frequency varies in real-time. The proposed method can estimate the frequency of the disturbance in real-time by using the input and output signals of the AFC. It can compensate for the periodic disturbance at an arbitrary frequency. In addition, the stability of the feedback control system with the proposed AFC can be optimized at any frequency based on the vector locus of the open-loop characteristic on the Nyquist diagram. The effectiveness of the proposed AFC was confirmed in experiments compensating for whirling vibration, whose frequency varies in real-time in rotating machinery. The proposed AFC can estimate the frequency of the disturbance automatically and compensate for this adequately.

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