【作者】 武曹军；

【导师】 任振辉；

【作者基本信息】 河北农业大学 ， 农业电气化与自动化， 2012， 硕士

【摘要】 经济要发展,电力要先行。电能早已成为当代社会的重要能源之一,支撑着工业发展,保证着农业生产,保障着人民的生活质量,促进着国防科技的进步,可以说各个领域的发展都离不开电力。近年来,随着高压直流输电、电气化轨道交通乃至日常办公用电器的发展促进了新型电力电子设备的广泛应用,这些负载的非线性、冲击性和不平衡性的用电特征,致使大量谐波进入电网,给电网造成了严重污染。所以谐波已成为影响电能质量的一个主要因素,为改善电能质量,有效地测量并抑制谐波已显得非常重要。谐波检测和抑制是谐波问题的两个重要方面,它们是研究分析谐波问题的出发点。本文首先介绍了电力系统谐波的基本概念、电网谐波产生的原因及危害、传统的谐波测量方法及其不足。通过比较目前谐波检测采用的主要方法,从傅里叶谐波测量方法入手,根据其无法同时实现时—频变域分析的缺点,引出小波变换理论,重点论述了小波变换原理,探讨了连续小波变换、离散小波变换、小波包变换等小波理论中几种重要的变换方法,分析了这几种小波变换的时频特性。在谐波抑制方法方面,首先分析了当前电力系统常见滤波器的特点,比较了不同类型的无源滤波器和有源滤波器,探讨了无源滤波器相关参数的设计方法和有源电力滤波器的主电路设计、电流控制方法,比较了这几类滤波器的特点,讨论了建立一种混合型电力滤波器的方法。本论文完成的工作如下:(1)讨论了小波变换的原理及其在谐波分析中的应用,比较了几种常用谐波检测方法。在给出一个基于MATLAB软件的仿真引例的基础上,通过使用MATLAB软件中的小波工具箱模块做出仿真,并确定了以db20为母函数的一维离散小波变换算法在谐波检测中的有效性。(2)分析了电力系统常用无源滤波器和有源滤波器的分类、拓扑结构和主电路参数的设计方法,比较了无源滤波器,单独使用的串联型、并联型有源电力滤波器,以及混合型电力滤波器在处理电网谐波方面的差异。深入研究了混合型电力滤波器的主电路拓扑结构、参数设计。(3)设计了一种混合型有源电力滤波器,给出了该滤波器的主要结构、无源滤波器的参数设计方法、有源滤波器的主电路,讨论了其数学模型的建立。(4)给出了基于MATLAB软件的SIMULINK模块的四组仿真实例,分别是第一组无源滤波器单独使用、第一组和第二组无源滤波器共同作用、单独使用的有源滤波器和两组无源滤波器与有源滤波器共同投入使用。仿真结果表明,电源波形中的低次和高次谐波都得到了抑制,波形总体畸变率明显降低,表明本文设计的混合型电力滤波器在处理谐波方面是有效的。更多还原

【Abstract】 Economic development, the power should take the lead. The electricity has already become one of the important energy of the contemporary society, and supporting the development of industrial, agricultural, people’s quality of life and the national defense technology, we can say that the development of various fields is inseparable from power. In recent years, with the development of high-voltage direct current transmission, electrified rail transportation and even everyday office use electrical appliances promote the wide application of new power electronic devices, these non-linear load, impact and imbalance of power consumption characteristics, resulting in a large number of harmonic wave into the power grid, causing serious pollution to the grid. Harmonic has become a major factor in the impact of power quality, and effectively measuring and suppressing harmonic has become very important to improve power quality. Harmonic detection and suppression are two important aspects of the harmonic problem, and they are the starting point of the analysis of harmonic problems.This paper first introduces the basic concepts of power system harmonics, the causes of grid harmonics and its harm, the traditional harmonic measurement method and its shortcomings. Compare the current used by the harmonic detection method, starting from the Fourier harmonics measurement method which can not localize in time-frequency field simultaneous, leads to the wavelet transform theory, with emphasis on the wavelet transform theory, explores the continuous wavelet transform, discrete wavelet transform, wavelet packet transform, wavelet theory in several important transform method, analyzing the time-frequency characteristics of these types of wavelet transform. Harmonic suppression method, the first analysis of the current power system common filter characteristics, comparing different types of passive filters and active filters to explore the parameters of the passive filter design method, the main circuit and current control methods of the active power filter, compares the types of filter characteristics, discuss the establishment of a hybrid power filter ,and then gives the simulation results based on MATLAB simulation by SIMULINK to show this method is effective.In this thesis, the work done as follows:(1) The principle of the wavelet transform and its applications in harmonic analysis, comparison of several commonly used harmonic detection method. Gives an argument based on the MATLAB simulation software use cases. Simulation made by using the wavelet toolbox in MATLAB software modules, and to determine the effectiveness of the db20 for the generating function of one-dimensional discrete wavelet transform in the harmonic detection.(2) Analysis of the classification of commonly used passive filters and active filters in power system topology and circuit parameters design method to compare the passive filter alone series and shunt active power filter, and hybrid power filter in dealing with the differences of the grid harmonics. Deep study the main circuit topology of the hybrid power filter design parameters.(3) Design of a hybrid active power filter, the structure of the filter and passive filter parameter design method and the active filter circuit, and discuss its mathematical model.(4) Four sets based on the SIMULINK module of MATLAB software simulation examples are the first group of passive filter used alone, the joint action of the first group and second group of passive filters, active filter used alone and two the group of passive filters and active filters to be put into use. The simulation results show that low power waveform and higher harmonics have been suppressed, the waveform overall aberration rate was significantly lower, show that the design of hybrid power filter is effective to deal with harmonic.更多还原