Phase difference correction method applied to self-adaptive sampling of power grid having wide range of frequency fluctuation

Abstract

The invention discloses a phase difference correction method applied to self-adaptive sampling of a power grid having a wide range of frequency fluctuation. The method overcomes lower measurement precision of phase difference correction methods upon dynamic variation of a fundamental frequency by increasing computing of frequency change rate, predicting real-time fundamental frequency for each measurement, correcting sample frequency so as to carry out measurement. Therefore, the method herein effectively reduce spectral frequency leakage and increases measurement precision. The method herein conducts simulation analysis on variety-frequency power grid signals by using phase difference correction method which is based on Harming window, verifies the feasibility of self-adaptive sampling methods. The method can produce high magnitude and phase measurement precision when a frequency is stable, and can also reach IEC standard requirements for magnitude measurement precision when the fundamental frequency has wide range of fluctuation, so that the method herein effectively reduce phase difference errors, can real-time reflect state of a system, and is suitable for on-line monitoring harmonic waves of a power grid which has a wide range of frequency fluctuation.

Description

technical field [0001] The invention belongs to the technical field of electric power harmonic analysis, and in particular relates to a phase difference correction method applied to self-adaptive sampling of a fluctuating power grid with a wide frequency range. Background technique [0002] Accurate and real-time online monitoring of power harmonic parameters is an important technical means in the process of developing smart grid and controlling harmonic pollution. Discrete Fourier Transform (DFT) has been widely used in power harmonic monitoring due to its advantages of fast calculation speed and easy engineering implementation. In the case of synchronous sampling, the measurement error of DFT for the fundamental wave and each harmonic is extremely small, and when the fundamental frequency of the system changes dynamically resulting in a large frequency offset, the spectrum leakage caused by signal truncation under non-synchronous sampling It will have a great impact on th...

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Problems solved by technology

However, since the larger the number of sampling points, the greater the amount of calculation, it will affect the real-time performance of the algorithm; and when the sampling frequency is constant, as the number of sampling points increases, the length of the sampling window will be lengthened accordingly, and the errors caused by asynchronous sampling will continue to accumulate. Therefore, the number of sampling points N should not be too large

At the same time, the value of the point L of the second segment of signal translation should not be too small, otherwise it will affect the anti-noise ability of the phase difference method

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