An Interharmonic Detection Method Combining AR Spectrum Estimation and Nonlinear Optimization

Abstract

An inter-harmonic detection method combining AR spectrum estimation and non-linear optimization is characterized in that the AR model spectrum estimation is utilized to calculate harmonic initial parameters so as to build a signal model: a sampled signal sequence to be analyzed is chosen and subject to AR model spectrum estimation so as to give the information of harmonic parameters (frequency, amplitude value and phase) with lower precision; and a model is than taken, a nonlinear optimization algorithm for solving the parameters of the signal model is put forward to calculate the phase value. The inter-harmonic detection method has the benefits that modeling of parameters of the nonlinear optimization algorithm is realized, the shortcoming that the AR spectrum estimation can not calculate the harmonic amplitude value and the phase is overcome, and the frequency computation accuracy is further improved; the sensitiveness of the iterative algorithm to the initial value is reduced, and the iteration stability and the computational efficiency are improved; and the inter-harmonic detection method has a certain noise-proof capability.

Description

technical field [0001] The invention relates to the field of power grid signal inter-harmonic analysis, in particular to an inter-harmonic detection method combining AR spectrum estimation and nonlinear optimization. Background technique [0002] With the wide application of nonlinear equipment such as power electronics in power systems, harmonics and inter-harmonics are increasing day by day. Therefore, analyzing harmonics and inter-harmonics is of great significance to the economic and safe operation of power systems. The current harmonic analysis is mainly realized by sampling and digitizing the power grid signal, such as fast Fourier transform (FFT) and windowed interpolation FFT methods. However, these methods will inevitably produce spectral leakage and fence effect when detecting harmonics, which will affect the detection accuracy. The effect is even worse when used for interharmonics (non-integer harmonics) detection, because interharmonics often appear in integer ha...

AI Technical Summary

Problems solved by technology

However, these methods will inevitably produce spectrum leakage and fence effects when detecting harmonics, which will affect the detection accuracy. The effect is even worse when used for inter-harmonic (non-integer harmonics) detection, because inter-harmonics often appear in integer orders The frequency point near the harmonic and the amplitude is small, and it is easy to be submerged by the side lobe of the integer harmonic, resulting in a greatly reduced frequency resolution, and the spectral line identification error caused by low resolution will further reduce the amplitude and phase detection accuracy

[0003] The disadvantages of the existing technology are: it is difficult to obtain the exact value of the frequency, amplitude and phase of each harmonic in the power line, and it is impossible to describe the circuit waveform containing harmonic interference

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