Current transformer saturation detecting technology based on phase comparing method

Abstract

The current transformer saturation detecting technology based on phase comparison method includes: 1. the sampling step of synchronously sampling the phase currents in the principal side and the opposite side of the current transformer in the set rate and transmitting the phase current of the opposite side to the principal side for storing; 2. the calculation step of calculating the instantaneous value, Fourier conversion amplitude, integrated various, etc of the phase current to obtain one phase comparison coefficient; and 3. the comparison and judgment step of comparing the obtained phase comparison coefficient with one set threshold and judging as outside fault saturation in condition of the phase comparison coefficient smaller than the set threshold or inside fault in other conditions. The technology performs phase comparison judgment with cycle data window, and is simple, reliable and fast.

Description

technical field [0001] The invention relates to a technology for detecting the working state of an electric appliance, and more precisely, the invention relates to a technology for detecting the saturation of a current transformer based on a phase comparison 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 technologies include: the time difference method based on the d...

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Problems solved by technology

[0004] However, the above-mentioned TA saturation detection technologies have their own shortcomings: 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 method of differential current harmonic ratio, 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.