矢量网络分析仪中小波变换模及在值法应用

文中利用小波变换的方法对矢量网络分析仪所测到进行检测，并对检测信号进行随机噪声滤除，检测到所关心的信号，经过小波滤皮理论分析和实验结果均表明，小波变换在滤波处理中是一种简单易行，有效的方法。     

基于中位值和小波两级滤波的气相色谱分析仪数据预处理方法

当采用气相色谱法对混合气体进行分析时,由于存在奇异噪声和高斯噪声,对色谱峰检测产生不良影响。为此,通过小波变换的方法提取噪声,对噪声进行分析,建立噪声的概率分布模型,确定色谱信号中噪声的特点。根据噪声的特点,采用中位值滤波和小波变换相结合的滤波方法,处理色谱信号。实验表明,中位值滤波和小波变换相结合的两级滤波方法能有效滤除奇异噪声和高斯噪声,且信号畸变小,为后续色谱峰检测、重叠峰分离打下良好的基础。     

结合小波变换和能量算子的电压暂降检测方法

针对电压暂降扰动的准确定位与精确测量问题,提出结合小波变换与能量算子的暂降检测新方法.该方法通过小波变换将被检测电压暂降扰动分解成近似信号和细节信号两部分.在细节信号部分精确定位扰动发生起止时刻;对近似信号运行能量算子,能快速准确测量到暂降幅值.所提方法中小波变换兼具滤波效果,减弱或去掉低频暂降信号中的高频扰动成分,从...     

一种基于小波参数滤波的音素分段算法

本文提出了一种新的基于小波变换和参数滤波的音素分段算法,称为小波参数滤波算法（WPF）,小波变换具有和人耳相似的特性,即随着频率的升高,分辨率下降,我们利用眩特性先对信号进行小波域滤波,然后利用参数滤波对信号进行分段。实验表明本文提出的算法在性能上优于常规的参数滤波方法。     

用二进小波变换分析变压器中含强载波干扰的局部放电

介绍了二进小波变换的基本原理及其滤波特征,采用二进小波函数对变压器中含强载波干扰的局放信号进行了小波变换。仿真结果表明,二进小波变换能消除强载波干扰,能准确地检测出局放脉冲信号的幅值及其发生的时刻。     

小波变换在航空发电机异常检测中的应用研究

针对飞机交流发电机日常维护中传统检测和分析方法的不足,提出一种基于小波变换的飞机交流发电机异常检测方法,其思想是先把交流发电机输出电压信号采用小波进行分解,然后对分解后的小波系数利用基于噪声标准偏差估计的阈值滤波算法进行消噪处理,最后利用小波变换对消噪之后的电压信号进行奇异值检测从而获得信号的异常变化.通过对飞机交流发电机实测数据进行处理,实验结果表明,该方法能有效地排除电压信号中的噪声干扰,及时地捕获发电机输出电压信号的异常变化,最终实现比较准确的故障检测与定位,具有一定的实用价值.     

GIS局部放电包络信号噪声抑制的小波方法

基于超高频包络检波的GIS局部放电检测系统采样得到的超高频局部放电包络信号中含有噪声。笔者分析了检测系统测量过程中可能混入的几种噪声,通过截取没有局部放电的采样信号进行频谱计算,理论与实测分析结果均表明,包络检波后信号中的噪声主要是白噪声。基于小波变换的滤波算法对白噪声有很好的抑制效果,文中在对小波变换原理进行简要分析的基础上,提出了改进阈值的小波滤波算法,仿真及实测信号的滤波结果证实了该改进算法的有效性。     

基于最小熵解卷积的轨面缺陷漏磁信号处理

钢轨表面缺陷的漏磁检测会受到巡检速度等因素的影响,导致背景噪声增大,检测灵敏度降低。为了增强缺陷信号特征,提高漏磁信号的信噪比,提出了一种基于最小熵解卷积的漏磁信号处理方法。通过目标函数法,计算得到最优的逆滤波器参数,对采集到的漏磁信号进行滤波处理。为衡量最小熵解卷积算法滤波效果,将处理得到的缺陷信号和背景噪声信号的峰峰值与小波变换法和中值滤波法进行对比。实验结果表明,最小熵解卷积算法对缺陷信号起到了明显的增强作用,且其效果优于小波变换和中值滤波。     

基于形态-复小波暂态电能质量扰动检测及定位

针对暂态电能质量扰动的实际检测过程中,存在着较强的脉冲噪声和白噪声干扰,影响暂态信息准确提取的问题,设计了有效的滤波算法以在保留信号特征的前提下最大限度地抑制噪声干扰影响,该法是将基于数学形态学的广义形态滤波器作为复数小波变换的前置滤波单元,形成的一种新型形态-复小波变换综合检测算法。仿真结果表明,基于该算法的滤波器不仅可很好地解决电能质量扰动分析中滤除随机噪声和脉冲噪声的困难,还可较好地保持扰动信号的形状和特征。另外用Daubechies实小波构造了相应的正交紧支对称复小波,由其提供的复合信息可准确地检测出扰动并进行时间定位。分别用电压暂降、暂态振荡、短时谐波畸变及微小扰动对所提方法进行了数字仿真验证,结果证实了基于形态-复小波变换综合检测方法的正确性和有效性。     

基于小波自适应阈值滤波的VMD降噪方法

本文提出了一种基于小波自适应阈值滤波的可变分模式分解（VMD）降噪方法。该方法降噪过程为：先将含噪声信号进行VMD分解,进而将VMD分解分量中含大部分噪声的高频模态分量进行小波自适应阈值滤波降噪,滤波降噪后的分量与其他模态分量重构降噪信号。三个实例表明：所提方法能有效减低信号噪声,适应性广。 关键字：可变分模式分解（VMD）;小波变换; 自适应阈值     

基于自适应特征选择的人脸图像识别算法

提出一种为不同类别待测人脸样本图像选择合适的人脸特征的方法。利用AdaBoost算法以及预先设置好的不同的图像特征训练分类器,自适应地为待测样本图像选择合适的特征及相应的分类器进行分类预测,扩展了同一人脸识别算法的使用范围。实验验证了该算法的有效性。     

An efficient algorithm for assessing reliability indexes of general distribution systems

This paper presents a practical reliability assessment algorithm for distribution systems of general network configurations. This algorithm is an extension of the analytical simulation approach for radial distribution systems. In the proposed algorithm, the meshed network is first converted to a radial network. All network elements are divided mainly into three classes according to the possibility for them to obtain power supplies from different directions. Accordingly, three different methods are employed to obtain two types of reliability topology zones for the elements. The algorithm is efficient for large-scale radial/meshed distribution systems, and can accommodate the effects of fault isolation and load restoration. The validity and effectiveness of the proposed algorithm is demonstrated by applying a computer program developed based on the proposed algorithm to a number of test systems and hundreds of real distribution networks.     

A novel out of step relaying algorithm based on wavelet transform and a deep learning machine model

Out-of-step protection of one or a group of synchronous generators is unreliable in a power system which has significant renewable power penetration. In this work, an innovative out-of-step protection algorithm using wavelet transform and deep learning is presented to protect synchronous generators and transmission lines. The specific patterns are generated from both stable and unstable power swing, and three-phase fault using the wavelet transform technique. Data containing 27,008 continuous samples of 48 different features is used to train a two-layer feed-forward network. The proposed algorithm gives an automatic, setting free and highly accurate classification for the three-phase fault, stable power swing, and unstable power swing through pattern recognition within a half cycle. The proposed algorithm uses the Kundur 2-area system and a 29-bus electric network for testing under different swing center locations and levels of renewable power penetration. Hardware-in-the-loop (HIL) tests show the hardware compatibility of the developed out-of-step algorithm. The proposed algorithm is also compared with recently reported algorithms. The comparison and test results on different large-scale systems show that the proposed algorithm is simple, fast, accurate, and HIL tested, and not affected by changes in power system parameters.     

Optimal Power Flow Using Differential Search Algorithm

—In this article, a new nature-inspired metaheuristic technique called the differential search algorithm is proposed to solve the optimal power flow problem. The proposed differential search algorithm has been developed and tested under normal and contingency power system conditions. To show the effectiveness of the proposed method, it has been demonstrated on the standard IEEE 30-bus and IEEE 118-bus test systems with different objectives that reflect performance indices of the power system. Obtained results using the proposed technique indicate that the proposed differential search algorithm provides an effective, a robust, and a high-quality solution for the optimal power flow problem. The comparisons of the proposed differential search algorithm results with those reported in the literature reveal the potential and superiority of the proposed algorithm in terms of the optimal solution quality and robustness.     

基于改进通信算法的暂态稳定并行仿真

通过分析电力系统暂态稳定问题的特点,提出一种面向集群系统、采用隐式积分联立求解法的空间并行算法。针对电力系统分层分区的特点,对算法实现过程中的通信耗时进行了建模,提出了改进的通信算法,减少了算法的通信耗时,提高了并行效率,并且证明该通信算法具有很好的可扩展性。对实际运行的华中电网仿真计算表明,最高的仿真加速比达到了11.17,证明了所提算法的有效性。     

Improved Harmony Algorithm and Power Loss Index for optimal locations and sizing of capacitors in radial distribution systems

In this paper, an Improved Harmony Algorithm (IHA) is proposed for optimal allocations and sizing of capacitors in various distribution systems. Initially, Power Loss Index (PLI) is introduced to get the highest candidate buses for installing capacitors. Then, the proposed IHA is employed to decide the most optimal locations of capacitors and their sizing from the elected buses by PLI. The objective function is designed to reduce the total cost and losses and consequently, to increase the net saving per year. The proposed algorithm is tested on three different radial distribution systems. The obtained results via the proposed algorithm are compared with others to highlight its benefits. Moreover, the results are introduced to verify the effectiveness of the suggested algorithm under different loading conditions.     

A novel time-domain current-detection algorithm for shunt active power filters

A novel current-detection algorithm based on the time-domain approach for three-phase shunt active power filters (APFs) to eliminate harmonics, and/or correct power factor, and/or balance asymmetrical loads is analyzed in this paper. A basic overview and evaluation of the performance of existing current-detection algorithms for active power filters are presented. According to different complicated power quality issues and various compensation purposes, a novel current-detection algorithm is then proposed. Comparing with existing algorithms, this algorithm has shorter response time delay and clearer physical meaning. Different compensating current references can, thus, be accurately and easily obtained by adopting the proposed algorithm. It ensures that the shunt APF can very well achieve different compensation purposes. Moreover, it is very easy to implement this algorithm in a digital signal processor (DSP). Simulation results obtained with MATLAB and testing results on an experimental shunt APF are presented to validate the proposed algorithm.     

电力系统无功最优潮流模型及其求解——基于改进粒子群优化算法的潮流优化

提出了一种基于改进粒子群优化算法的无功最优潮流模型及求解方法,灵活处理最优潮流问题的各种约束条件。通过对IEEE-30节点系统的仿真计算,并与遗传算法、基本粒子群优化算法计算结果进行比较,验证了本文提出的模型和方法的有效性。     

基于双端电气量的同杆平行双回线单线故障测距

考虑同杆平行双回线零序互感的影响,针对同杆双回线单回线故障,提出了一种基于故障线双端电气量的故障测距算法。该算法根据同杆平行双回线单回线内部故障的等效序网图,利用相应故障类型在故障支路的电压边界条件导出其测距方程。算法利用了现有分相电流差动保护提供的单回线本端电压和两端电流工频量,原理上与过渡电阻和系统阻抗无关。通过PSCAD/EMTDC软件,仿真计算了不同过渡电阻、系统阻抗和负荷情况下不同故障点发生各种类型故障的测距情况。仿真测距结果表明,该算法应用于同杆平行双回线单回线故障测距时具有很高的精度,并与过渡电阻、系统阻抗和负荷工况无关。     

Hybrid Fuzzy-particle Swarm Optimization-simplex (F-PSO-S) Algorithm for Optimum Design of PM Drive Couplings

This paper aimed at exploring the use of the proposed hybrid Fuzzy-Particle Swarm Optimization-Simplex (F-PSO-S) algorithm to optimize the structural design of PM couplings subject to several key design constraints. The new proposed hybrid optimization algorithm is constructed based on combining three well-known techniques: fuzzy logic (FL), particle swarm optimization (PSO), and simplex method (SM). FL is used to aggregate different scaling and/or conflicting objectives in one objective function using fuzzy combination operators. On the other hand, the PSO has obvious capabilities in global search whereas the SM has exceptional advantages in local search. As a hybrid algorithm, the F-PSO-S has the outstanding feature of combining the ability of global searching and local canvassing for different scales and/or conflicting objective functions. The proposed algorithm has been applied to permanent magnet (PM) drive couplings. A standard coupling design is used as a good initial point for the conventional SM and to define the performance constraints for the proposed optimization technique. New coupling designs are developed and optimized to show the superior capabilities of the F-PSO-S algorithm as a global optimization technique. The sensitivity analysis is also performed to identify the effects of different design parameters on the coupling performance.