Current transformer saturation detecting technology based on correlation coefficient process

Abstract

The current transformer saturation detecting process based on correlation coefficient method includes: 1. the sampling step of sampling the phase currents in the principal side of the current transformer in the set rate and storing the sampled result in the memory; 2. the calculation step of calculating the real part, the imaginary part of the phase current in cycle Fourier conversion algorithm and DC component average value in the cycle, and calculating the correlation coefficient of the phase current sampling value in one cycle; and 3. the comparison and judgment step of comparing the obtained correlation coefficient with one set threshold and judging as the current phase TA saturation in condition of the calculated correlation coefficient smaller than the set threshold. The technology may be applied in high voltage line protecting system.

Description

technical field [0001] The invention relates to a method for detecting the working state of an electrical appliance, and more precisely, the invention relates to a current transformer saturation detection technology based on a correlation coefficient method. It belongs to the technical field of power system automation. Background technique [0002] At present, high-voltage and ultra-high-voltage equipment are used in many places in the power system, but when the high-voltage, ultra-high-voltage equipment and transmission lines of the power system fail outside the area, when the current transformer (TA) is saturated, it may cause differential protection malfunction. By detecting the degree of TA saturation when faults occur outside the zone, corresponding countermeasures can be taken, which can effectively prevent the misoperation of differential protection. [0003] Some existing TA saturation detection methods include: the time difference method based on the differential c...

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Problems solved by technology

[0004] However, the above-mentioned TA saturation detection methods have their own disadvantages: although the time difference method is simple, it cannot accurately detect the time difference between the differential current and the braking current when the TA is extremely saturated; and for the differential current harmonic ratio method, due to the difference When the current is extremely saturated, the harmonics are relatively small, so it cannot be accurately judged; for the segmented waveform identification method and the multi-order difference method, it is more sensitive to the waveform and is greatly affected by the harmonic content and DC component of the line

None of the above TA saturation detection methods can accurately detect TA saturation, and cannot effectively ensure that the differential protection does not malfunction when an external fault occurs.