基于小波包变换的非线性负荷的电能计量算法研究

发布时间：2018-04-10 21:37

本文选题：小波包变换 + 非线性负荷　；参考：《华北电力大学》2017年硕士论文

【摘要】：随着社会的进步、工业的发展,电网的容量迅速扩展,电气化铁路、轧钢机、光伏发电、电力电子产品等非线性负荷日益增多,已经成为电网负荷中十分重要的一部分。由于大量非线性负荷的接入、现场负荷的频繁波动,用电负载电流呈现出随时间变化,甚至出现短时间的剧烈波动的情况。这些非线性负荷还会引入谐波,使得电压、电流的波形发生畸变,尤其是电流畸变更为严重,从而导致电网中电能质量日趋下降。智能电能表是国家法定计量器具之一,而现有的电能表都是基于传统正弦稳态功率理论进行电能的计量的,难以满足非线性负荷条件下电能的准确计量。由于计量准确度的较少的变化,都会带来较大的经济效益,因此实现非线性负荷用电量的准确计量是不容忽视的课题。论文主要研究了小波包变换在非线性负荷电能计量中的应用。首先介绍了非线性负荷电能计量的现状,并针对电气化铁路、轧钢机、太阳能光伏发电等典型非线性负荷制定了现场电压、电流的数据采集方案,并根据现场测试采集的数据针对谐波、间谐波的存在情况进行分析。其次,对现有的电能计量算法,即点积和电能计量算法、基于FFT的电能计量算法、基于加窗插值FFT的电能计量算法作了介绍并进行Matlab仿真,在此基础上对上述方法所存在的问题进行了分析。针对非线性负荷存在大量谐波、间谐波的情况,论文提出了基于小波包变换的非线性负荷电能计量新算法。根据符合非线性负荷电能计量的计量标准IEEE1459-2000所定义的电器物理量,给出了具体的电能计量步骤与计算公式的推导过程。同样对该方法进行了Matlab仿真。并且通过Matlab仿真、现场所采集的典型非线性负荷数据所得到的计算电能值以及算法复杂度三方面与现有方法进行了比较。通过仿真和现场采集数据计算所得到的结论证明,小波包电能算法与现有的电能计量方法相比,能够更准确的计量非线性负荷的用电量,所提出的算法具有一定的参考价值。
[Abstract]:With the progress of society and the development of industry, the capacity of power grid expands rapidly. The nonlinear loads such as electrified railway, rolling mill, photovoltaic power generation and power electronic products are increasing day by day, which has become a very important part of power grid load.Because of a large number of nonlinear load access, the frequent fluctuations of the field load, the electric load current changes with time, or even a short period of violent fluctuations.These nonlinear loads will also introduce harmonics, which will make the waveform of voltage and current distorted, especially the distortion of current is more serious, resulting in the power quality in the power network declining day by day.Intelligent watt-hour meter is one of the national legal measuring instruments, but the existing watt-hour meter is based on the traditional sinusoidal steady-state power theory, so it is difficult to satisfy the accurate measurement of electric energy under the condition of nonlinear load.Because less change of metering accuracy will bring great economic benefit, it is an important task to realize accurate metering of nonlinear load electricity consumption.This paper mainly studies the application of wavelet packet transform in nonlinear load energy measurement.Firstly, the current situation of nonlinear load electric energy measurement is introduced, and the data acquisition scheme of field voltage and current is established for typical nonlinear loads such as electrified railway, steel rolling mill, solar photovoltaic power generation and so on.According to the data collected from field testing, the existence of harmonics and interharmonics is analyzed.Secondly, the existing power metering algorithms, namely dot product and power metering algorithms, the power metering algorithms based on FFT, and the power metering algorithms based on windowed interpolated FFT are introduced and simulated by Matlab.On this basis, the problems existing in the above methods are analyzed.In view of the existence of a large number of harmonics and interharmonics in nonlinear load, a new algorithm of nonlinear load energy measurement based on wavelet packet transform is proposed in this paper.According to the electrical physical quantity defined by the standard IEEE1459-2000 of nonlinear load electric energy metering, the concrete steps of electric energy metering and the derivation of calculating formula are given.The method is also simulated by Matlab.Through Matlab simulation, the computational power value and the algorithm complexity obtained from the typical nonlinear load data collected in the field are compared with the existing methods.The results of simulation and field data calculation show that the wavelet packet power algorithm can measure the power consumption of nonlinear load more accurately than the existing power metering method, and the proposed algorithm has certain reference value.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM933.4

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