【作者】 程志友；

【导师】 韦穗； 梁栋；

【作者基本信息】 安徽大学 ， 计算机应用技术， 2007， 博士

【摘要】 近几年来，由于电力电子器件和非线性装置的广泛应用，使得电网中的电压和电流波形畸变越来越严重，造成了电能质量的恶化。传统的电能质量常用傅立叶变换分析方法，是基于有效值理论，已不适合处理非平稳的暂态电能质量信号。因此采用新的分析方法，对暂态电能质量进行正确的检测、分析和评估就显得十分必要。本文从电能质量定义和国内外电能质量研究现状出发，分析了目前暂态电能质量问题引起广泛关注的原因，着重对暂态电能质量扰动定位、谐波和间谐波的动态检测、无功功率的测量、暂态扰动信号的分析以及压缩等问题进行了深入研究。主要研究成果如下：1．提出一种结合Hilberr变换和向后差分的暂态电能质量扰动快速定位方法。该方法在提取暂态电能质量扰动信号的包络的基础上，利用向后差分方法实时检测信号的畸变点来进行定位。实验表明，该方法能够准确地定位暂态电能质量扰动，运算简单，实时性高，从而为扰动信号的分析和进一步采取控制措施提供依据。2．提出采用S变换时频分析方法动态检测电网中的谐波和间谐波。通过分析表明，S变换采用了窗口宽度与频率成反比的高斯窗，具有频率相关的分辨率，在性能上明显优于小波变换。所得实验结果验证了S变换对谐波和间谐波检测的有效性。3．从Budeanu无功定义出发，提出了一种S变换与Hilbert变换相结合的非正弦电路无功功率测量方法。该方法利用了Hilbert变换的高精确度的90°相移特性和S变换的先进时频分析方法来测量无功功率。仿真和实测数据表明，该方法精确度高，具有工程的实用性。4．详细分析了暂态电能质量时变性和非平稳性的特征，提出基波畸变率、扰动畸变率两项暂态电能质量指标以及采用HHT变换对暂态电能质量扰动信号进行分析，通过仿真实验和实际数据来验证所提出的指标的科学性。5．针对大量电能质量扰动数据的存储和传输问题，提出了一种新的压缩方案。通过对暂态电能质量扰动信号进行实验，从压缩的各项指标综合来看，该方法在保证信噪比的条件下，可以获得较高的压缩比。更多还原

【Abstract】 With the pervasion of power electronics apparatus and nonlinear loads, recently the power quality problems have been more and more deteriorated by the distorted waveform of voltages and currents in power network. Traditional power quality analysis is based on virtual value theory. As a frequently used analysis tool, Fourier transform is not suitable for the non-stationary signals processing. Thus new analysis methods are required to detect, identifyand evaluate power quality disturbances accurately.In this dissertation, the recent interest in power quality is introduced from two aspects-the definition and the art of the state of study on the power quality. Several key issues, such as power quality disturbance localization, dynamic detection of harmonics and intel-harmonics, measure reactive power, transient disturbances analysis and power quality disturbance signal compression are comprehensively and thoroughly studied and analyzed in this thesis. The main contribution is given as follows:1. A fast transient power quality disturbances localization approach is presented by using Hilbert transform combined with backward difference. Based on detection of the disturbance signal envelope, the approach is implemented by using backward difference to detect signals distortion point. The experimental results demonstrate that this approach possesses the merit of simplicity, speediness and accuracy. And it provides some support for the analysis of disturbance signal and further improvement.2. For the purpose of detecting harmonics and interharmonics, a method is proposed based on the time-frequency analysis method—S-transform. The reason for the superiority of S-transform are due to the fact that the width of a modified Gaussian window is a function of inverse frequency. The experimental results show that this method can detect harmonic and interharmonics effectively.3. A novel method is proposed by using S-transform and Hilbert transform to measure reactive power based on the definition of Budeanu in nonsinusoidal conditions. It is achieved by means of S-transform and shifting 90 degree of Hilbert-transform. The results of simulation and measurement of real power system show that this method is of high accuracy and can meet the needs of practical application.4.Through analyzing the time-varying and non-stability of transient power quality, two indices of transient power quality named fundamental frequency component distortion ratio and disturbance component ratio are proposed, which adopt HHT to analyze transient power quality disturbances. Simulated and real experiments show our approach is feasible in detecting transient indices of power quality.5.For a massive of power quality disturbance data stored and transmitted, a new data compression method is proposed. The test cases indicate the validity of this new method, with which Signal-to-Noise ratio can keep well and the compression ratio is satisfied.更多还原