本设计采用快速傅里叶变换（FFT）来计算配电网的各项参数。利用快速傅里

本设计采用快速傅里叶变换（FFT）来计算配电网的各项参数。利用快速傅里叶变换（FFT）进行谐波分析，得到待测电压电流的各次谐波的幅值和相角，进而计算出配电网的电压、电流、功率、功率因数等参数。因此本章首先在第一节介绍快速傅里叶变换的有关内容，然后再介绍基于傅里叶变换的配电网各项参数的计算公式。
2.1 快速傅里叶变换
作为一种重要的谐波分析方法，快速傅里叶变换的目的就是要求出待测信号的各次谐波的相角和幅值，然后根据各次谐波的幅值和相角计算出配电网的各项参数。
2.2.1 FFT算法简介
FFT，即快速傅里叶变换，其目的主要是为了进行谐波分析，以求的各次谐波的相角和幅值。早期，由于离散傅里叶变换巨大的运算量，使得傅里叶变换迟迟无法用来解决实际生活中的问题。但随着FFT算法的出现，傅利叶变换的应用领域开始变的越来越广泛。经过多年来的创新和发展，该方法在理论和实现上都已经很完备了。但在FFT的使用过程中应注意，如果波形中含有谐波，在进行FFT变换可能会产生频谱混叠现象，影响最终结果的精度。要解决这个问题，就必须使数据在采样时满足奈奎斯特采样定理的要求，即数据的采样频率大于待测信号所含最高次谐波频率的两倍。
2.2.2 基于FFT的谐波分析的实现
作为谐波分析中应用最为广泛的一种方法，使用快速傅里叶变换来计算各次谐波的幅值和相角，具有运算简单，结果准确，使用方便等优点。其具体实现如下。
（1）数据采集
在进行FFT变换前，必须将模拟信号变成离散的数字信号，这就是数据采集。按照FFT的计算要求，在数据采集时，在一个周期内采集的数据点N满足如下条件： ，其中N和M均为正整数。
（2）数据重新排序
采集得到数据必须进行逆序相加计算，将原始数据序列进行重新排序，才能进行FFT计算，。假定原数据序列是{x(i)|i=0,1,2…,N-1},新序列为{X(i)|i=0,1,2…,N-1}，则二者关系如式(2-1)给出：

結果 (英文) 1:

This design uses the fast Fourier transform (FFT) to calculate the parameters of the distribution network. Using the fast Fourier transform (FFT) harmonic analysis, get measured voltage and current harmonics amplitude and phase angle, and then calculated the distribution of voltage, current, power, power factor and other parameters. Therefore, this chapter in the first section describes the contents of the fast Fourier transform, then the parameters of distribution network based on Fourier transform formula.2.1 fast Fourier transformAs an important method of harmonic analysis, fast Fourier transform is requested of the harmonics of the signal to be measured phase angle and amplitude and harmonics amplitude and phase angle to calculate the parameters of the distribution network.2.2.1 Introduction to FFT algorithm FFT, fast Fourier transform, which is mainly designed to harmonic analysis, phase angle and amplitude of the harmonics. Early due to huge computational discrete Fourier transform, Fourier transform cannot be used to solve real-life problems. But with the emergence of FFT algorithms, Fourier transform applications are becoming more and more widely. After many years of innovation and development, in both the theory and implementation of this method is very complete. But FFT should be paid attention to in the use process, if the wave contains harmonics, FFT transform may result in aliasing phenomena affect the accuracy of the final result. To resolve this issue, you must make the data satisfies the Nyquist sampling theorem in the sampling requirements, sampling frequency is greater than that contained in the signal to be measured twice times the maximum harmonic frequency.2.2.2 implementation based on FFT of harmonic analysisAs the most widely used method of harmonic analysis, using the fast Fourier transform to compute the harmonic amplitude and phase, operation simple, accurate, easy to use and so on. Its implementation is as follows.(1) data collectionIn front of the FFT transforms, analog signal into a discrete digital signal must be, this is data acquisition. According to the FFT calculations are required, at the time of data collection, data collected in a period of n satisfies the following conditions: n, where n and m are positive integers.(2) data is reorderingThe data collected must be the reversal and addition computation, to reorder the sequence of the original data in order for FFT calculation. Assumes that the original data is {x (I) |i=0,1,2...,N-1}, new sequence is {x (I) |i=0,1,2...,N-1}, is the relationship between (2-1) gives:

結果 (英文) 2:

This design uses a Fast Fourier Transform (FFT) to calculate the parameters of the distribution network. Using fast Fourier transform (FFT) harmonic analysis, the harmonic of measured voltage and current amplitude and phase angle, and then calculate the distribution voltage, current, power, power factor and other parameters of the grid. This chapter introduces the relevant contents of the fast Fourier transform in the first quarter, and then introduce the Fourier transform is calculated distribution network based on various parameters.
2.1 Fast Fourier Transform
as an important harmonic analysis, fast Fourier transform purpose is to ask the various harmonics of the test signal phase angle and amplitude, and then the amplitude of each harmonic and phase angle calculated parameters distribution network.
Introduction 2.2.1 FFT algorithm
FFT, namely fast Fourier transform, its main purpose is to harmonic analysis, in order of the harmonics of the phase angle and amplitude. Early on, due to the discrete Fourier transform enormous amount of computation, so that the delay can not be used Fourier transform to solve real-life problems. But with the advent of FFT algorithms, applications of Fourier transform began to become more and more widespread. After years of innovation and development, which in theory have been very complete and implement the. But in the process of using the FFT should be noted that if the waveform contains harmonics may be generated during the FFT spectrum aliasing phenomenon, affecting the accuracy of the final result. To solve this problem, we must make the data satisfy the requirements of the Nyquist sampling theorem in sampling, the sampling frequency of the data signal to be measured is more than twice the highest harmonic contained in frequency.
2.2.2 Harmonic analysis based on FFT
harmonic analysis as one of the most widely used method of using a fast Fourier transform to calculate the harmonic amplitude and phase angle, with a simple operation, accurate, ease of use. Its implementation is as follows.
(1) Data acquisition
before performing the FFT, the analog signal must become discrete digital signal, which is data collection. Calculated in accordance with the requirements of the FFT, during data collection, the data collection point in a cycle of N satisfies the following condition: where N and M are positive integers.
(2) Data reordering
data collected must be obtained by adding the reverse calculation, the original data series reorder FFT can be calculated. Is assumed that the original data sequence {x (i) | i = 0,1,2 ..., N-1}, a new sequence {X (i) | i = 0,1,2 ..., N-1}, the two Relations formula (2-1) is given by:

結果 (英文) 3:

The design uses the fast Fu Liye transform (FFT) to calculate the parameters of the distribution network. Using fast Fourier transform (FFT) for harmonic analysis, the amplitude and phase of the voltage and current of each harmonic can be acquired, and then calculate the parameters of the distribution network voltage, current, power, power factor, etc.. So this chapter first introduces the contents of the fast Fu Liye transformation in the first section, and then introduces the calculation formula of the distribution network parameters based on Fu Liye transform..
2.1 fast Fourier transform
as a kind of important harmonic analysis method, fast Fourier transform is the phase angle and amplitude of the signal to be measured is the harmonic.Then according to the amplitude and phase of each harmonic is calculated on the basis of the parameters of the distribution network.
2.2.1 FFT algorithm brief
FFT, fast Fourier transform, its purpose is mainly for harmonic analysis, in order to the harmonic amplitude and phase angle. In the early time, because of the huge amount of computation of the discrete Fu Liye transform, Fu Liye transform could not be used to solve the problem in real life.. However, with the appearance of FFT algorithm, the application of Fu Liye transform becomes more and more extensive.. After many years of innovation and development, the method has been well in theory and implementation.. But in the course of the use of FFT should be noted,If the waveform contains the harmonics, the FFT transformation may produce the aliasing phenomenon and affect the accuracy of the final results.. In order to solve this problem, we must satisfy the requirement of the Nyquist sampling theorem when sampling, that is, the sampling frequency of the data is two times higher than the high harmonic frequency of the signal to be measured..
2.2.2 based on FFT harmonic analysis implement
as harmonic analysis in the application of the most widely used method, using fast Fourier transform to calculate the amplitude and phase of each harmonic, with simple operation, accurate and convenient advantages. Its concrete realization is as follows.
(1) data acquisition
before the FFT transform,It is necessary to turn analog signals into discrete digital signals, which is data acquisition.. According to the calculation of FFT, the data points collected in a period of time can meet the following conditions: M and N are positive integers..
(2) data reordering
acquisition data must be the reversal and addition calculation, the original data sequence for reordering to FFT. It is assumed that the original data sequence is {x (I) |i=0,1,2... , N-1}, the new sequence is {X (I) |i=0,1,2... N-1}, then the relationship between the two (2-1) is given: