【作者】 张向程；

【导师】 滕召胜；

【作者基本信息】 湖南大学 ， 测试计量技术及仪器， 2004， 硕士

【摘要】 随着现代工业的发展，电力系统中的非线性负荷大量增加，这些非线性负荷从电网吸收非正弦电流，导致电网电压发生畸变，使电能质量严重恶化，危及电力系统安全和经济运行，影响了用户的正常工作。谐波含量已经成为衡量电能质量的重要参数，对供电系统中的谐波检测具有重要的意义。 本文介绍了电力系统谐波的基本概念、谐波产生机理、谐波危害、谐波源及传统的谐波测量方法及其不足，探讨了连续小波变换、离散小波变换和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。针对目前电力系统谐波分析方法存在的难以快速、准确对非平稳暂态谐波进行实时分析检测等问题，提出研究并实现了一种基于小波包分解系数重构算法的谐波分析、测量方法；提出了谐波变化率概念，研究、提出并建立了基于小波包分解系数重构算法的谐波变化率测量方法，据此可实现电力系统的各次谐波跟踪，为对谐波采取行之有效的实时补偿提供理论依据；提出并建立了一种基于小波包分解系数重构算法的谐波功率测量新方法，仿真试验证明了这种新方法的可行性与正确性；探索利用小波变换将某一信号分解到某一频带上，根据采样频率及其小波包分解尺度确定频带范围，实现该频带所包含的谐波含量分析，获得频带内所有整数次和非整数次谐波量值，克服传统谐波测量因频谱泄漏、栅栏效应造成的信息遗漏，提高测量的可靠性与准确性。 依据本文研究的基于小波包分解系数重构算法的谐波分析、测量方法已成功应用于XDZ-1虚拟化电能参数自动测试系统，用户使用和系统检验证明了该方法的先进性和实用性。系统已于2004年1月通过广西电力公司组织的专家鉴定。更多还原

【Abstract】 With the development of modern industry, nonlinear loads of power system are greatly increased. They absorb non-sine current waves form power network and result in voltage aberrance. Voltage aberrance makes power quality severely worsen, endangers power system safely and economically running and affects some users working normally. Harmonic content has become an important symbol of power quality. So, harmonic measurement in power system is of important significance.This paper introduces the concept of harmonic, harmonic mechanism of production, hazard of harmonic, harmonic source and deficiency of traditional harmonic measurement method. Moreover, it discusses several transform methods, such as continuous wavelet transform, discrete wavelet transform and wavelet packet transform of which characteristics are analyzed. Against the exiting question about which is hard to real-time analyze and measure speedy and exactly measurement of changing harmonic, this paper studys and realizes a harmonic analysis and measurement method based on reconstruction of wavelet packet decomposed coefficients. This paper puts forward a new concept of harmonic change rate. What’s more, this paper studys, put forwards and builds a measurement method of harmonic change rate based on reconstruction of wavelet packet decomposed coefficients. According to this method, power system harmonic track can be realized. This method provides theory basis for taking an effective method for harmonic real-time compensate. This paper puts forward and builds a new measurement method based on reconstruction of wavelet packet decomposed coefficients. Emulator test shows the feasibility and correctness of this method. Using wavelet transform can make one voltage process decompose to a frequency band. According to sample frequency and decompose scale, frequency band can be confirmed. Harmonic content analysis is realized. All integral and non-integral harmonics are obtained. This method overcomes information missing resulting from spectrum leak, fence effect in traditional harmonic measurement. Reliability and accuracy of harmonic are improved.The method based on this paper has been successfully applied in XDZ-1 Virtual PowerParameter Measurement and Electric Measuring Instrument Meter Automatic Verification.The users and system verification have proved the advance and practicability of this method. The system has passed the expert authentication organized by Guangxi Power Company in January of 2004.更多还原