摘 要随着非线性设备负载应用的增加，电网中间谐波含量呈增长趋势，其危害已经引起人们的高度关注。然而间谐波的检测是对其进行分析、抑制的前提。因此，对电力系统间谐波检测算法进行研究具有较好的实际应用价值。本文以电力系统中含谐波与间谐波的电压信号模型为研究对象，采用FFT，加窗FFT 等算法检测间谐波，在MATLAB 环境下实现了间谐波的检测算法并用模型进行了仿真。本文主要完成的工作如下：（1）针对在非同步采样情况下，直接采用 FFT 算法检测间谐波精度低的问题，文中分析了窗函数特性， 选定采用hanning 窗， 推导了加窗FFT 算法插值的简化算式，并对直接 FFT 以及加窗FFT 检测间谐波的算法进行了仿真，给出了仿真结果。（2）利用小波包特性，对信号进行小波包分解完成对电压信号频率成份的检测。仿真结果表明：加窗 FFT 算法能够较好地解决间谐波检测中的非同步采样精度低的问题，小波包分解能较好估算信号中的频率成份。58948
毕业论文关键词：间谐波，傅里叶变换，窗函数，小波包
Abstract With the increase of nonlinear equipment load application and the growth trendamong power grid harmonic content, the harm has aroused people's attention.The detectionof harmonics is the premise of inhibition to analyze it.Therefore, the study of power systemharmonics detection algorithm has a good practical application value.Based on containing harmonic in power system harmonics,the voltage signal model isselected as the research object.The paper uses FFT, harmonics detection and window FFTalgorithm to analyse harmonics. the detection of harmonics in the MATLAB environmentto achieve the algorithm and the simulation with the model have been finished.In this paper,the main work is as follows:(1) The paper aims at under asynchronous sampling condition and uses FFTalgorithm directly to solve the problem of low precision of harmonics detection. this paperanalyzes the characteristics of window function and selects the hanning window to reducethe error value. Simplified formula of add window interpolation FFT algorithm has beendeduced. the direct FFT and window FFT harmonics detection algorithm are simulated, thesimulation results are given.(2) The paper uses wavelet packet characteristic to complete the detection of voltagesignal frequency components.The simulation results show that: add window FFT algorithm can well solve theharmonic detection between the non synchronous sampling in the problem of low precision,wavelet packet decomposition can estimate signal frequency of the ingredients.
Key words: harmonics, Fourier transform, window function, wavelet packet
目录
第一章绪论1
1.1研究的目的和意义.1
1.2间谐波的基本概念.2
1.3间谐波和谐波的区别3
1.4间谐波波源和它的危害..4
1.5研究现状6
1.6本文主要研究内容.7
第二章基于傅里叶变换的间谐波检测算法8
2.1傅里叶变换..8
2.1.1傅里叶变换分析法8
2.1.2离散傅里叶变换和快速傅里叶变换8
2.2电力系统中间谐波检测的fft算法.9
2.3影响间谐波检测精度的因素10
2.3.1栅栏效应..10
2.3.2频谱泄漏..10
2.4算法的仿真及其结果.11
2.5本章小结.14
第三章加窗傅里叶变换的间谐波检测算法.15
3.1常见的窗函数及其特性15
3.1.1矩形窗.15
3.1.2Hanning窗16
3.1.3Hamming窗.16
3.1.4Blackman窗.17
3.2窗函数选择原则18
3.3加hanning窗的FFT算法..18
3.4算法的仿真及其结果分析.20
3.5本章小结.21
第四章基于小波包的间谐波频率检测23
4.1小波包的研究意义..23
4.2小波包分解的优势..23 电力系统间谐波检测算法设计与仿真:http://www.youerw.com/zidonghua/lunwen_63969.html