A Fast Detection Method of Power System Harmonics Based on Differential Equations

Abstract

The invention discloses a differential equation-based rapid detection method for harmonious waves in a power system and particularly provides a method for rapidly detecting the phases and the amplitudes of signals different in frequency in the power system. The method comprises the following steps of (1) collecting sampling points at a sampling rate higher than two times a highest frequency multiplication, wherein the number of sampling points is one less than at least four times the harmonic quantity; (2) constructing a homogeneous linear differential equation of a harmonic and fitting an equation coefficient with two times the highest frequency multiplication as an order; (3) calculating the complex root of the differential equation by adopting the above equation coefficient, and calculating the frequency, the amplitude and the phase of the harmonic according to the complex root. Based on the above manner, the required amount of data is small and a result can be calculated only based on data much less than that of a cycle length of a fundamental frequency compared with the prior art. Compared with the fast Fourier transform method, the problem of frequency leakage is avoided. Meanwhile, the method can be used for calculating the frequency of each actual waveform in harmonic signals in the self-adaptive manner, and is strong in anti-jamming capability and anti-noise capacity.

Description

technical field [0001] The invention relates to the field of digital signal processing, in particular to a fast detection method for power system harmonics based on differential equations. Background technique [0002] In recent years, people's requirements for power quality have become higher and higher, and the factors causing power quality problems are also increasing. One of the influencing factors is mainly manifested as harmonics and interharmonics in the power system. Harmonic problems have a great impact on power System safety, stability, and economic operation pose potential threats, especially to power equipment. Therefore, research on power system harmonics is particularly important, and the detection of power system harmonics is the primary task of these studies. [0003] Fast Fourier transform (FFT) is the most commonly used harmonic detection method, and this method needs to collect all data within at least one complete period of the fundamental frequency to ob...

AI Technical Summary

Problems solved by technology

[0003] Fast Fourier transform (FFT) is the most commonly used harmonic detection method, and this method needs to collect all data within at least one complete period of the fundamental frequency to obtain correct results, and the FFT algorithm has the problem of energy leakage, resulting in The calculated harmonic amplitude of each frequency is quite different from the actual amplitude. In addition, the calculation process of the FFT algorithm is complicated, and real-time analysis cannot be realized.

And taking the mains as an example, the frequency of the actual power supply line is often only close to 50Hz, and cannot reach 50Hz accurately. It is necessary for the algorithm to self-adaptively calculate the frequency of the actual waveforms in the harmonic signal

Images