共查询到20条相似文献，搜索用时 15 毫秒
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Murat Silsüpür Belgin Emre Türkay 《IEEJ Transactions on Electrical and Electronic Engineering》2019,14(1):67-74
As a result of the integration of various new load types and generation units into electric power systems, power quality disturbances such as sag–swell, harmonics, inter‐harmonics, and flicker have come into focus in the last decades. Among these disturbances, flicker is one of the serious power quality issues for both power system operators and users. In addition to having direct effects on human life such as the discomfort caused by visual disturbance, flicker may cause incorrect operations of electrical devices. Furthermore, finding a dominant flicker source in order to mitigate it and supply high‐quality power to users are the main tasks of network operators. The measurement of the flicker level is defined in the IEC 61000‐4‐15 standard as measured by a flicker meter; however, it deals only with voltage signals and is not sufficient to understand the contribution of the load and background power systems separately. Therefore, this paper proposes new approaches to the evaluation of flicker characteristics using simulated and real signals. The novelty of this paper is that it investigates the flicker characteristics in the light of multi‐resolution wavelet analysis and information‐theory‐based wavelet energy entropy analysis together and proposes a new index to interpret flickers' responsibility in load and flicker source detection. The proposed method uses only voltage and current signals and does not require additional calculation of any network parameter such as the system impedance. The proposed method is validated by simulations as well as site measurements, and the results show the accuracy and suitability of the proposed method. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
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小波分析在高次谐波抑制上的应用研究 总被引：2，自引：0，他引：2
随着非线性负荷的不断增加,电力系统的谐波含量日益增加。多分辨分析思想作为小波分析的重要理论,在谐波治理中的发挥着重要作用。从小波分析入手,通过分析多分辨分析的特性,找到了多分辨分析与谐波治理的切入点。利用多分辨分析思想,将原始信号分解为高频信号和低频信号,并且将原始信号中的高次谐波直接滤除,实现了对某个高次谐波区间或某次谐波的直接抑制或提取。算例结果表明,该方法应用在谐波抑制中是有效的、可行的。 相似文献
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乘性噪声消除的全相位分级非下采样Contourlet算法 总被引：1，自引：0，他引：1
非下采样Contourlet变换(NSCT)是平移不变的多级定向图像表示方法,不仅克服了小波变换非一维奇异性最优基的缺点,而且其平移不变性使边缘保持能力优于Contourlet;由于APDCT(全相位DCT变换)在子带分解中表现出优异的性能,所以提出了基于全相位分级的NSCT变换方法.为了消除图像中的乘法性噪声,对噪声图像进行同态变换,将乘性噪声变为加性噪声,利用全相位分级NSCT变换的阈值方法将信噪实施分离.消噪的实验结果表明,与传统的小波同态滤波方法相比,上述方法不仅在去噪性能指标而且在边缘保持的主观视觉上都表现出了优异的性能. 相似文献
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基于小波变换的统一电能质量控制器检测方法研究 总被引：3，自引：0，他引：3
本文提出了一种基于小波变换的用于统一电能质量控制器(UPQC)的检测方法,该方法对系统中的电压暂态扰动及电流稳态谐波的检测与现存的其他检测方法相比具有快速、准确的特点,满足UPQC对系统进行实时补偿的要求,并且通过电压暂态扰动及电流稳态谐波检测的数字仿真,验证了这种方法的实用性和有效性. 相似文献
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Xingkai Yu Jianxun Li Jian Xu 《International Journal of Adaptive Control and Signal Processing》2019,33(4):586-608
This paper considers estimation algorithms for linear and nonlinear systems contaminated by non‐Gaussian multiplicative and additive noises. Based on the variational idea, in order to derive optimal estimation algorithms, we combine the multiplicative noise with states as the joint parameters to estimate. The application of variational Bayesian inference to joint estimation of the state and the multiplicative noise is established. By treating the states as unknown quantities as well as the multiplicative noise, there are now correlations between the states and multiplicative noise in the posterior distribution. There are two main goals in Bayesian learning. The first is approximating the marginal likelihood (PDF of multiplicative noise) to perform model comparison. The second is approximating the posterior distribution over the states (also called a system model), which can then be used for prediction. The two goals constitute the iterative algorithm. The rules for determining the loop is the Kullback‐Leibler divergence between the true distribution of state and a chosen fixed tractable distribution, which is used to approximate the true one. The iterative algorithm is deduced, which is initialized based on the idea of sampling. Meanwhile, the convergence analysis of the proposed iterative algorithm is presented. The numerical simulation results in a comparison between the proposed method and these existing classic algorithms in the context of nonlinear hidden Markov models, state‐space models, and target‐tracking models with non‐Gaussian multiplicative noise demonstrate the superiorities, not only in speed, precision, and computation load but also in the ability to process non‐Gaussian complex noise. 相似文献
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Daifeng Zha Tianshuang Qiu 《International Journal of Adaptive Control and Signal Processing》2006,20(5):213-223
We proposed neural network structures related to multilayer feed‐forward networks for performing blind source separation (BSS) based on fractional lower‐order statistics. As alpha stable distribution process has no its second‐ or higher‐order statistics, we modified conventional BSS algorithms so that their capabilities are greatly improved under both Gaussian and lower‐order alpha stable distribution noise environments. We analysed the performances of the new algorithm, including the stability and convergence performance. The analysis is based on the assumption that the additive noise can be modelled as alpha stable process. The simulation experiments and analysis show that the proposed class of networks and algorithms is more robust than second‐order‐statistics‐based algorithm. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Power systems struggle from many effects, causing over-voltages and over-currents. One of these effects is ferroresonance, which is a non-linear phenomenon that occurs when the system is unbalanced. This article focuses on a 380-kV transmission line from Turkey's electrical power network where ferroresonance occurs during a switching operation. The system is first simulated on MATLAB (The MathWorks, Natick, Massachusetts, USA) model, and voltage variations are obtained. Spectral analysis methods are applied to the signal, and the frequency components of the system are examined for ferroresonant conditions. According to the obtained frequency components, the steady-state behavior of the system is explained. 相似文献
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高精度时间在国防、科研等领域正在发挥着日益重要的作用,而要提高计算原子时的准确度,消除原子钟信号的噪声是关键的步骤之一.为此,本文利用小波包分解算法对原子钟信号进行了必要的消噪处理,这样我们得到了平稳的原子钟信号,利用这些数据重新计算国家授时中心原子时TA(NTSC),计算结果表明经过消噪处理提高了TA(NTSC)稳定度和准确度;在文中还采用了目前用的比较多的Kalman滤波算法与之进行了比较,结果显示根据滤波强度的不同,此两种算法都可以达到所需要求. 相似文献
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Simulation of device and circuit noise at low frequencies is often carried out as part of a small‐signal ac analysis. Moreover, circuit simulators with rf analysis capabilities usually specify circuit performance in terms of S parameters and model high‐frequency noise in terms of noise waves and correlation matrices. It is also unusual to find circuit simulators that extend noise simulation to the time domain. This is particularly true for software packages developed from SPICE 2g6 or 3f5. This paper introduces a simple tabular noise source technique, which adds time‐domain noise to semiconductor device models and integrated circuit macromodels. The proposed technique is suitable for use with any general purpose circuit simulator. To demonstrate the power of the suggested approach the text describes time‐domain noise extensions to the SPICE diode, BJT, JFET, MOSFET and MESFET models. These noise extensions have been implemented and tested with the ‘Quite universal circuit simulator’ (Qucs). Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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分析了分解层数不同时重构信号间的最小均方误差变化趋势并根据分析结果结合高频系数白化检验自适应确定了最佳的分解层数.讨论了提升小波变换的提升算法以及新的阈值函数,使用了基于提升小波变换的改进阈值函数的方法和选取了一种最优的阈值方法并结合最佳分解层数对电磁超声回波信号进行了去噪处理,验证了算法的有效性. 相似文献
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为了减小MEMS陀螺仪随机误差,提出了一种新的去噪算法。该算法首先通过自适应噪声完备经验模态分解(CEEMDAN)将原始数据分解为多个本征模态函数(IMF),并根据多尺度排列熵与马氏距离将IMF分为噪声IMF、混叠IMF和信号IMF;其次对噪声IMF用小波包(WP)去噪,对混叠IMF用Savitzky-Golay滤波器(SG)去噪;最后,把处理后的IMF和信号IMF进行重构,得到去噪后的信号。通过所提方法对Bumps信号进行实验分析,去噪后信号从6 dB提高至17 dB,均方误差降低71.9%;对实测陀螺仪静态数据进行分析,实验结果证明去噪后信号的角度随机游走降低31.5%,表明该方法能显著提高MEMS陀螺仪的精度。 相似文献
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针对脉搏信号非线性、非平稳,且难以去噪的问题,提出了一种基于改进的自适应噪声集合经验模态分解(ICEEMDAN)与小波包分解(WPD)相结合的联合去噪方法,对采集的脉搏信号进行去噪处理。首先对噪声信号进行ICEEMDAN模态分解,产生一系列的固有模态函数(IMF),再将这些IMF分量分别与原信号进行相关系数的计算,比较相关系数的值,然后进行信号的重组,最后对重组后的信号进行小波包分解,提取得到降噪后的脉搏信号。利用仿真数据、实际采集的脉搏信号进行实验分析,将该方法与集合经验模态分解(EEMD)进行了对比,并比较了这两种方法的信噪比(SNR)和均方根误差(RMSE)。实验结果表明：基于ICEEMDAN-WPD的联合去噪方法能更有效地去除噪声,并更好地保留脉搏信号的特征。 相似文献
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《International Journal of Circuit Theory and Applications》2017,45(12):2211-2225
In this paper, we propose a time‐to‐digital converter (TDC) with first‐order noise‐shaping. The proposed gated ring oscillator (GRO)‐TDC overcomes the limitation associated with GRO's intrinsic resolution by adopting two GROs, whose delay difference is equal to half the delay of a delay cell. The GRO is composed of 17 stages of a newly proposed delay cell, which utilizes a gate‐switched configuration to solve the charge redistribution problem. The proposed GRO‐TDC is designed using a 65‐nm process technology, with an area of 0.015 mm2 and a supply voltage of 1 V. The sampling rate and the effective resolution of the proposed GRO‐TDC are 50 MS/s and 1.22 ps, respectively. Finally, the proposed GRO‐TDC consumes a power of 9.08 and 2.41 mW in the calibration and conversion modes, respectively. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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We investigate shot noise suppression in several mesoscopic structures by means of a numerical approach based on the computation of the transmission matrix with the recursive Green's function method. We retrieve the universal values of the suppression factor obtained with random matrix theory for chaotic cavities and diffusive conductors. We then extend the investigation to more complex structures, such as multiple cascaded cavities and partially diffusive systems, and discuss the consequences on the shot noise suppression factor. Finally, we analyze the behavior of shot noise in an electron waveguide containing a large number of scatterers as the spatial position of the scatterers is changed from a regular array to a random distribution. 相似文献
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为了消除单相接地故障下配电网区段定位受系统中性点接地方式、不同过渡电阻以及线性相关法定位盲区等因素对定位准确性的影响,提出一种幅值特征下基于Hausdorff距离算法的故障区段定位方法。首先,分析了零序电流暂态分量故障特征,明确健全区段、故障区段两端零序电流暂态分量幅值特征的关系。其次,引入Hausdorff距离算法,测算馈线区段两端零序电流暂态分量幅值特征匹配度,进一步通过与设定阈值的比较,可以有效区分出故障区段。仿真验证结果表明,所提方法无定位盲区,在不同系统接地方式、不同接地过渡电阻下均能够准确定位故障区段。 相似文献