共查询到20条相似文献,搜索用时 78 毫秒
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为了准确地测量和分析电力系统中的谐波参数,在分析了常用的几种谐波测量方法的基础上,提出了一种基于FFT数字倍频整周期采样的电力系统谐波参数的测量方法.研制了以高性能ARM Context-M3内核的STM32微处理器为核心的电力系统谐波检测仪.检测仪具有测量基波和各次谐波的电压、电流绝对值的功能,并且能够测得谐波含有率、功率因数、功率和基波频率等其他参数,实现了对电力系统谐波参数的实时监控. 相似文献
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基于FFT的一种计及负频率影响的相位差测量新方法 总被引:2,自引:0,他引:2
用FFT法测量低频正弦信号相位差时,精度明显下降,甚至无法测量,其主要原因之一是模型中忽略了负频率成分的贡献.基于FFT法,提出了一种计及负频率影响的相位差测量方法,分别给出了加矩形窗和加汉宁窗对应的相位差计算公式.仿真结果表明,在无噪声背景下.具有很高的精度,尤其是加汉宁窗后,误差接近双精度运算的下限;在噪声背景下,该方法的测量精度也高于FFT法.提出的测量方案简单实用,特别适用于频率很低或接近奈奎斯特频率的正弦信号相位差测量. 相似文献
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快速傅里叶变换(Fast Fourier Transform,FFT)常用于信号频率估计,采用填零的方法可降低幅度谱频率搜索间隔的量化误差,但是会使频率估计的计算量成倍增加。本文提出了一种FFT幅相联合的快速高精度频率估计算法,首先利用信号采样的频谱序列和尾首样本差确定幅度谱及峰值位置,然后由频谱序列在幅度谱峰值位置和信号采样的尾首样本差来确定频率搜索间隔的量化误差校正值。因此,所提方法同时利用了幅度谱峰值的位置信息与相位信息。分析结果表明,与仅基于幅度谱搜索的FFT算法相比,所提方法的计算复杂度更低,且定位精度更高。 相似文献
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调频信号广泛应用于声纳、雷达、激光和新兴光学交叉研究领域,其紧致性(稀疏性)是调频信号采样、去噪、压缩等研究中面临的共性基础问题。本文致力于研究调频信号在分数傅里叶变换域的稀疏性,提出了一种最大奇异值法来估计调频信号的紧致分数傅里叶变换域。该方法利用调频信号幅度谱的最大奇异值来度量其紧致域,并应用鲸鱼优化算法来搜寻紧致域,有效改善了现有方法的不足。与MNM和MACF方法相比,本文方法给出了调频信号在分数傅里叶变换域更加稀疏的表征,具有更少的重要振幅数。最后,给出了该方法在调频信号滤波中的初步应用。 相似文献
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基于稀疏表示的人脸识别算法(SRC)识别率相当高,但是当使用l1范数求最优的稀疏表示时,大大增加了算法的计算复杂度,矩阵随着维度的增加,计算时间呈几何级别上升,该文提出利用拉格朗日算法求解矩阵的逆的推导思路,用一种简化的伪逆求解方法来代替l1范数的计算,可将运算量较高的矩阵求逆运算转变为轻量级向量矩阵运算,基于AR人脸库的实验证明,维度高的时候识别率高达97%,同时,计算复杂度和开销比SRC算法大幅度降低95%。 相似文献
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介绍一种应用于车牌图像的稀疏表示超分辨率算法,依据稀疏表示理论,自然图像在合适的过完备字典下总存在稀疏的表示,为输入的低分辨率图像寻找一个稀疏表示,用稀疏系数来生成高分辨率输出图像。通过对低分辨率和高分辨率图像补丁的联合训练生成字典,该字典提供低分辨率图像补丁的稀疏表示,用来生成高分辨率图像补丁。 相似文献
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A simple algorithm for the harmonic estimation, in a wide range of frequency changes, with benefits in a reduced complexity and computational efforts is prescribed. This implementation is based on a recently introduced common structure for recursive discrete transforms and contemplated as an implementation of finite-impulse-response (FIR) and infinite-impulse-response (MR) filter transfer functions to reduce computational efforts. This structure consists of digital resonators in a common negative feedback loop. The structure of the estimation algorithm consists of two decoupled modules: the first one for an adaptive filter of input signal with harmonic amplitude and phase calculation, the second one for an external frequency estimation. A very suitable algorithm for frequency and harmonic phasor estimations is obtained. To demonstrate the performance of the developed algorithm, computer-simulated data records are processed. Simulation results show that this algorithm is applicable to detect the harmonic amplitudes of steady-state, varying and decaying sinusoidal signals. It has been found that the proposed method really meets the needs of online applications. This technique provides accurate amplitude estimates in about one period. 相似文献
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A power system digital harmonic analyzer 总被引:1,自引:0,他引:1
Mortensen A.N. Johnson G.L. 《IEEE transactions on instrumentation and measurement》1988,37(4):537-540
The authors describe the design of a harmonic analyzer for use in studying the harmonic content of commercial electric power. This MC 68000-based instrument samples the waveform and calculates the first 63 harmonics of the 60-Hz fundamental for both a voltage and current waveform. The 64-kbyte memory is adequate for one week of hourly samples for a power-quality survey by an electrical utility. The analyzer is quickly attached to the outputs of potential and current transformers by alligator clips and a current plug. The harmonic data are retrieved from the instrument by a portable computer. A separate personal computer (PC) program is then used for data analysis. Accuracy is shown to be about 0.1%, more than adequate for power quality surveys 相似文献
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Estimation of signal parameters in the frequency domain in the presence of harmonic interference: a comparative analysis 总被引:3,自引:0,他引:3
Liguori C. Paolillo A. Pignotti A. 《IEEE transactions on instrumentation and measurement》2006,55(2):562-569
In this paper, a novel method for the estimation of the parameters of the spectral components of a signal, also in the case of harmonic interference, is characterized and compared to other methods proposed in literature. The comparison criteria include the evaluation of residual errors and uncertainties on estimated parameters for different multicomponent signals. 相似文献
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We use an analytical calculation based on the Fourier-transform method to study the transmission spectra of multilayer dielectric optical structures as a function of the relative widths of the layers that constitute the unit cell. We can select which harmonics of the fundamental design frequency are transmitted. The results of this Fourier-transform approach are compared with the exact transmission calculated by means of the transfer matrix method and provide a more intuitive understanding of the transmission spectrum. A simple phasor diagram is derived from this Fourier-transform analysis for this purpose. Inasmuch as it is difficult for us to perform experiments in the optical region, we fabricate rf analogs of these structures, using coaxial cables that have different impedances. Experimental results agree with theory. 相似文献
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Global behaviour of power system frequency in korean power system for the application of frequency monitoring network 总被引:1,自引:0,他引:1
Since the concept of building an Internet-based real-time Global Positioning System synchronised wide-area frequency monitoring network (FNET) was proposed in 2001, FNET has been implemented in the Power IT Laboratory at Virginia Polytechnic Institute and State University (Virginia Tech.), and now it is used in monitoring the power system frequency in continuous time at more than 40 locations in the United States. A global view of the power system frequency based on FNET measurements helps understand the frequency behaviour more correctly, and its various applications such as event location estimation have been also studied. The global behaviour of power system frequency in the Korean power system, which has very unique characteristics, is analysed and thereby the possibility of applying FNET is studied. Although the scale of the Korean power system is much smaller than the US power systems, its global behaviour of frequency has its own characteristics, and those findings will help us understand any correlation between system characteristics and the global frequency behaviour. What is found here could serve as the first step to the application of FNET to the Korean power system. 相似文献
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研究双稳态压电发电系统非线性振动特性。通过谐波平衡法计算获得系统幅频响应方程,分析不同非线性系数、阻抗参数与激励对系统幅值解影响,随激励频率、幅值的变化,双稳态压电发电系统幅值解存在跳跃、多解现象,调节非线性系数及阻抗参数可使不稳定区域范围最小;研究外加激励对功率影响,随非线性系数及阻抗参数的增加,输出功率先增加后减小,通过调节磁化强度与负载阻抗可使系统输出功率最大;通过实验所得频率电压响应曲线及电阻功率响应曲线,验证系统非线性分析结果。可为双稳态压电发电系统工程应用提供理论依据。 相似文献
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A z-transform signal model that when combined with a nonlinear post-filtering scheme is able to estimate the operating frequency and voltage/current phasors in a power system is developed. The signal model parameters are identified by an optimisation method in which the error between the model output and the actual signal that represents a voltage or current in the power system is minimised. The form and structure of the signal model do not require iterations in the optimisation process for parameter identification. The system operating frequency is directly evaluated from the model parameters. Noise effects and possible mismatches between the model and the actual signal are countered very effectively by applying a median post-filtering process to the time series representing the frequency estimates derived from the model. Extensive simulation studies and comparisons with existing frequency estimation techniques confirm the high performance of the proposed method in terms of accuracy and time delay. The accurate estimation of the operating frequency, achieved by the proposed method, allows voltage and/or current phasors in power systems to be measured or determined more precisely. 相似文献
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为了控制电力系统谐波电压水平,对于大、中型非线性用户负荷接入电网,IEC、IEEE和英国G5/4等标准中有不同的规定。本文在扼要介绍上列标准中相关规定的基础上,总结其特点,为谐波国标(GB/T14549-1993)的修订提出一些建议。 相似文献