Phasor compensation algorithm in fixed frequency sampling mode, and compensation system

Abstract

The invention relates to a phasor compensation algorithm in a fixed frequency sampling mode, and a compensation system. The phasor compensation algorithm comprises the steps of: calculating a corresponding recursive Fourier phasor according to data of two consecutive sampling data windows at an interval of N / 2 sampling points; and if a frequency deviation value is not less than a frequency deviation comparison threshold, expanding the calculated recursive Fourier phasor into an analytical form expressed by the frequency deviation value, so as to calculate a real Fourier phasor, wherein the frequency deviation value is a difference between a signal actual frequency and a signal preset frequency. The phasor compensation algorithm is a measurement and calculation method applied to a power system. The compensation system acquires sampled data by utilizing a fixed sampling frequency to carry out Fourier phasor calculation, adopts a correction algorithm to eliminate an inherent error becausethe sampling frequency does not track the signal frequency, and obtains the real Fourier phasor through reduction. Furthermore, the incorrectness of motion behaviors of the device caused by adoptingthe Fourier phasor containing the error for performing protection control logic judgment is avoided.

Description

technical field [0001] The invention relates to a Fourier phasor compensation algorithm and a compensation system in a fixed-frequency sampling mode. Background technique [0002] For applications such as power system measurement, protection, and control, the premise of using discrete Fourier transform to accurately obtain phasors is that the sampling frequency changes in real time following the signal frequency. let f real is the actual frequency of the signal, and the preset number of sampling points per cycle is N, then at the sampling frequency f sample =N×f real In the case of , the Fourier phasor can be calculated accurately. Set signal preset frequency i.e. f meas = f real , it means that the sampling frequency follows the signal frequency, and the calculated Fourier phasor is error-free. [0003] Power system control products may sometimes be connected to electrical quantities of multiple intervals, and the signal frequencies between these multiple intervals ...

AI Technical Summary

Problems solved by technology

The sampling frequency of the device can only be one, which cannot meet the requirement of following two signal frequencies at the same time

Assuming that the frequency of the line voltage is different from the frequency of the bus voltage, at least for one of the line and the bus, the sampling frequency of the device cannot follow it

Then, for the electrical quantities that cannot be followed by the sampling frequency, there are errors in the Fourier phasors calculated by ordinary Fourier transform. Directly using the Fourier phasors with errors for protection and control logic calculation and judgment will not guarantee the correctness of the device's action behavior.

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