Current transformer saturation identifying method and device

Abstract

The invention provides a current transformer saturation identifying method and device. According to the method, a peak point before a zero crossing point, the zero crossing point and a peak point after crossing point in sampling data are determined, data between the peak point before the zero crossing point and the zero crossing point and data between the peak point after the zero crossing point and the zero crossing point are subjected to normalization processing respectively, then a deviation value through a data sequence obtained after combined data processing, and if the deviation value is larger than zero, it is judged that a current transformer is saturated. Since whether the deviation value is larger than zero or not depends on the overall distribution characteristics of the sampling data, the current signal of the current transformer can be distorted when the current transformer is saturated, and the deviation value obtained by means of the distribution characteristics of the data obtained after the current signal distortion can be larger than zero so that it can be accurately judged that the current transformer is distorted. The method has the advantages of that the capacity of resisting disturbance is high, the method is little affected by noise, the requirement for the sampling frequency is low, the calculation is simple, the requirement for the operational capability of a protective device is low, and on-line real-time monitoring is easily achieved.

Description

technical field [0001] The invention relates to the field of relay protection of power systems, and more specifically, to a method and device for identifying saturation of a current transformer. Background technique [0002] When the current transformer (Current Transformer, CT) is saturated, the primary current is transferred to the secondary, and the current waveform will be distorted, which may cause differential protection malfunction. Relevant misoperation events occur from time to time, resulting in a decrease in the correct rate of protection actions and causing adverse effects. [0003] The root cause of differential protection misoperation caused by faults outside the protection zone of differential protection is that one of the CTs on both sides of the differential protection is saturated, or the degree of saturation of the two CTs on both sides is inconsistent. When the protection CT is mixed with the measurement CT, the electromagnetic CT is mixed with the elect...

AI Technical Summary

Problems solved by technology

Among them, the correct rate of harmonic braking method to identify saturation is not satisfactory; the difference method has poor anti-interference ability and is easily affected by noise; the adaptability of mathematical morphology method is poor; support vector machine and artificial neural network identification The method requires a lot of training in advance, and requires high computing power of the protection device

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