【作者】 孙传奇；

【导师】 滕召胜；

【作者基本信息】 湖南大学 ， 测试计量技术及仪器， 2006， 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。谐波电能的准确计量有利于电力系统的稳定、经济运行。本文的研究目的就是实现谐波电能的准确计量,为电能的科学管理提供可靠依据。本文介绍了电力系统波形畸变与谐波的基本概念,指出了主要谐波源和谐波的各种危害,分析了供电与用电方的功率分布情况,阐述了谐波电能计量技术研究的社会意义和经济价值,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,论述了谐波电能计量的基本原理。针对目前广泛采用的基于FFT的电力系统谐波电能计量方法存在难以快速、准确对非平稳谐波进行有效处理的弊端,提出了基于小波包变换的新型谐波电能计量方法,这种分析方法具有很好的时频特性,克服了傅立叶变换无时域分析能力的缺陷,对于非平稳谐波电能信号的分析与计量具有很好的效果。仿真实验验证了该方法的有效性与准确性。遵循高性能低成本硬件设计原则,设计了一种基于小波包变换的谐波电能计量系统,可以满足基于小波包变换的谐波电能计量方法对信息处理单元运行速度的需求。给出了计量单元电路和谐波有功电能、无功电能计量流程。探讨了基于小波包变换的谐波电能计量系统的误差来源,建立了系统的误差模型,提出了谐波电能计量系统的直流偏置、比差和角差的校正方法。在深入研究小波函数对应的滤波器组频率特性的基础上,分析了采样频率对谐波电能计量准确度的影响,指出并分析了过高采样率会导致谐波电能计量准确度下降的问题。仿真实验证明,本文提出的基于小波包变换的谐波电能计量方法是可行的,它是一种具有均匀频带的可以体现时间信息的新型谐波电能计量方法。该方法不仅可以有效地实现谐波电能计量,而且可以观察各频带内的时域信号波形。更多还原

【Abstract】 With the development of modern industry, the nonlinear loads of power system are greatly increased. They absorb the non-sine current waves from power network and result in voltage aberrance. Voltage aberrance makes the power quality severely deteriorate, endangers the safe and economical running of power system and affects some users’s normal work.The accurate measuring of harmonic energy may ensure power system to run in stable and economical state.The research purpose of this thesis is to realize the accurate measuring of harmonic energy and provide reliable evidence for scientific management on harmonic energy.This thesis introduces the fundamental concept of wave aberration and harmonic, and lists the main harmonic source and the hazard of harmonic in power system. Further more, it analyzes the distributing of power between power provider and user, expounds the social and economic values of the study on the technology for measuring harmonic energy, discusses several important transform methods, such as continuous wavelet transform, discrete wavelet transform and wavelet packet transform in wavelet theory, whose characteristics are analyzed, and disserts the fundamental principle of measuring harmonic energy.Against the exiting problem in the method to measure harmonic energy on the basis of FFT, which is hard to make an efficient, quick and accurate measurement of changing harmonic, this thesis presents a method to measure harmonic energy based on wavelet packet transform. The method has a good time and frequency characteristic, and it overcomes the abuse of Fourier Transform which can not analyse the signal in the time field. The analysis and measurement based on the method to the non-steady harmony signal have very good results. The emulation experiment has verified the validity and accuracy of this method.Following the hardware design principle of high capability and low cost, this thesis designs a system to measure harmonic energy based on wavelet packet transform. It may satisfy the running speed requirement of the algorithm which employs wavelet packet transform to measure harmonic energy. This thesis provides the circuit schematic of the unit for measuring harmonic energy and the flow chart for measuring harmonic active energy and harmonic reactive energy.This thesis discusses the error origin of the system for measuring harmonic energy based on wavelet packet transform, and set up the error model, and presents the更多还原