Real-time identification method for current transformer entering and exiting magnetic saturation state

Abstract

The invention discloses a real-time identification method for a current transformer entering and exiting a magnetic saturation state, which comprises acquiring the real-time sampling value of the secondary current of the current transformer and transforming it to obtain a saturation judging value; judging according to the saturation judging value and completing the identification of the current transformer The state of entering and exiting magnetic saturation is identified. The present invention judges TA saturation through linear operation of 5 continuous sampling points, and only needs 4 addition and subtraction and 1 multiplication operation for each judgment, with small amount of computation, fast detection speed, and easy implementation; and during the saturation period, the conversion value The reverse change of D effectively isolates the saturated input signal and the exit signal, and solves the problem that the slightly saturated input and output signals are easy to overlap; finally, the method of the present invention is applicable to different short circuit levels, different DC offset degrees, different residual magnetism, different nature load and noise conditions. Therefore, the method of the invention has high reliability, good real-time performance, fast operation speed and easy implementation.

Description

technical field [0001] The invention specifically relates to a real-time identification method for a current transformer entering and exiting a magnetic saturation state. Background technique [0002] With the development of economy and technology and the improvement of people's living standards, electric energy has become an indispensable secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, the stable and reliable operation of the power system has become one of the most important tasks of the power system. [0003] A current transformer (Current Transformer, TA) is essentially a magnetic component, which is an important part of a power system and is widely used in current sampling occasions. The saturation of the current transformer will distort the secondary current waveform, which may cause malfunction, delayed action or refusal of the relay protection device. Therefore, it is of great signific...

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Problems solved by technology

Among them, the differential method has low anti-interference ability, and cannot accurately judge the mild saturation of TA; the derivative method is susceptible to noise interference, and the threshold setting is difficult; the harmonic braking method cannot determine the time when TA enters and exits saturation in real time, and is easily affected by harmonics and transient DC components. The impact of the impedance calculation method is limited by the resistance and inductance model and the line voltage signal, and the amount of calculation is large; the wavelet analysis method has poor real-time performance and is susceptible to noise interference; the adaptability of the mathematical morphology method needs to be strengthened, and it is easily affected by harmonics; Hill Unexplained negative frequencies and apparent endpoint effects with Burt-Huang transformation law

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