Computation method of differential filter weighting period small amplitude value

Abstract

The invention provides a calculation method of a filter-divider plus full-cycle Morlet complex wavelet amplitude, comprising the steps: (1) supplying power on a micro-computer protection device; (2) giving an initial value to k, frequency width adjusting coefficient c and a sampling point number N to the periodic signal of electric elements in a period; (3) working out the proportion coefficient Tau according to an Morlet complex wavelet discrete expression: Psi(n) equals to Tau multiplied by exp[-(6n/N-3)<2>/c] multiplied by exp(j2pikn/N) and a formula: Tau equals to N/Sigma|Psi(n)/Tau|n; wherein, n equals to 1, 2, ellipsis, N minus 1; (4) calculating the real par of Morlet complex wavelet according to a formula: Psi<R>(n) equals to Tau multiplied by exp[-(6n/N-3)<2>/c] multiplied by cos(2pikn/N); (5) calculating the virtual part of the Morlet complex wavelet according to a formula: Psi(n) equals to Tau multiplied by exp[-(6n/N-3)<2>/c] multiplied by sin(2pikn/N); (6) taking f(s) as sampling frequency so as to obtain the discrete sequence f(n) of the periodic signal of the electric element in a period; wherein, f<s> is equal to N multiplied by f; and f is the fundamental frequency of the periodic signal; (7) obtaining the discrete sequence g(n) according to a differential filter equation: g(n) equals to f(n) minus f(n minus N/2); (8) Calculating the amplitude according to a formula: Fk(n) equals to (g(n) Psi<R>(n)<2> plus g(n) Psi<1>(n))<2>. The method provided by the invention can filter the attenuation DC component and has small calculation result error when the power network frequency fluctuates.

Description

technical field [0001] The invention relates to an amplitude calculation method, in particular to a differential filter plus full cycle complex wavelet amplitude calculation method. Background technique [0002] With the development of power electronic technology, the harmonic problems brought by power electronic devices pose a potential threat to the safety, stability and economic operation of the power system, and have a great impact on the surrounding electrical environment. Harmonics are considered to be a major public nuisance of the power grid, and at the same time hinder the development of power electronics technology. Therefore, the research on the harmonic problem of power system has been gradually paid attention to. Harmonic issues involve a wide range of aspects, including analysis methods for distorted waveforms, harmonic source analysis, power grid harmonic power flow calculations, harmonic compensation and suppression, harmonic limit standards, and harmonic me...

AI Technical Summary

Problems solved by technology

[0014] The main purpose of the present invention is to provide a differential filter plus full cycle Morlet complex wavelet amplitude calculation method, which overcomes the traditional fundamental wave and harmonic amplitude calculation method of the periodic signal of each power component in the power system, which cannot filter In addition to the attenuation of the DC component, and when the grid frequency fluctuates, the calculation results have the disadvantages of large errors

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