Calculation Method of Dominant Interharmonic Spectrum Distribution

Abstract

The invention discloses a dominant interharmonic spectrum distribution calculation method. The method comprises steps: a digital quantity for three-phase voltage and current signals of an M-frequencytime window is taken for discrete Fourier transform (DFT) analysis, and a rough interharmonic signal spectrum distribution diagram is acquired; according to the rough interharmonic signal spectrum distribution diagram, a harmonic singlet effective value and a harmonic cluster effective value are calculated, and the ratio of the harmonic cluster effective value to the harmonic singlet effective value is further calculated; according to the size relationship between the ratio and a threshold, whether interharmonics exist near the harmonics is judged; and if yes, the existence range of dominant interharmonics is determined, data in a certain time window are selected for DFT analysis, and the dominant interharmonic spectrum distribution is determined. Due to the method of the invention, the dominant interharmonic spectrum distribution can be simply and quickly; a help is provided for interharmonic control; influences on a power grid by the interharmonics are reduced; and safe and stable operation of power supply equipment and power consumption equipment.

Description

technical field [0001] The present invention relates to a method for calculating the frequency spectrum distribution of dominant interharmonics, in particular to a method for measuring interharmonics in the fields of impact loads, fluctuating loads, new energy photovoltaic power generation and wind power generation in electric power systems, belonging to Technical field of power quality monitoring. Background technique [0002] In recent years, with the extensive use of various power electronic devices, interharmonic pollution exists widely in power systems and is becoming more and more serious. Inter-harmonics will endanger the safe and stable operation of the power supply system and affect the normal and stable operation of electrical equipment. For example, inter-harmonics will cause voltage and current waveform distortion, reduce the power factor of the load, and increase energy loss; Harmonics will interfere with the normal operation of audio equipment; frequencies clo...

AI Technical Summary

Problems solved by technology

Wavelet transform can well reflect the time domain and frequency domain characteristics of the signal in the time-frequency diagram, but there are serious defects: frequency band aliasing, leakage and other problems

However, the inter-harmonic measurement results are represented by a set, and only the center frequency of the set can not obtain the accurate amplitude, frequency, and phase information of each dominant inter-harmonic component

Moreover, there may be spectral leakage and fence effects in the harmonic measurement in between

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