Half-wave integral accumulated-type inverse time-delay over-excitation protecting method

Abstract

The invention discloses a half-wave integral accumulation-type inverse time-delay over-excitation protecting method, which is characterized by comprising the following steps that: 1) a voltage transformer is duly sampled to obtain a voltage instantaneous value; 2) harmonic voltage signal more than 150Hz is filtered through simple low-pass filtering, and then an over-excitation characteristic quantity U / f value is duly calculated through positive and negative half-wave integral superposition algorithm; 3) real over-excitation inverse time-delay curves are dispersed, and the curve fitting is realized by utilizing a multi-broken line or a staircase curve; 4) under the condition of the multi-broken line or the staircase curve, parameter transformation for reflecting an over-excitation dynamic variation process is adopted, so the multi-broken line or the staircase curve has an identical action boundary line under the condition of different U / f values; and 5) the transformation parameter values are superposed in real time according to the varied U / f values, and then the boundary off-limit judgment is executed so as to output protection action and transmit a signal. The half-wave integral accumulation-type inverse time-delay over-excitation protecting method has a small amount of calculation, and the algorithm is easy to realize.

Description

technical field [0001] The invention relates to an overexcitation protection method in the protection of large and medium-sized generators or transformers in a power system, and belongs to the technical field of power system automatic control. Background technique [0002] In the protection of large and medium-sized generators or transformers in power systems, the inverse time overexcitation protection is a necessary protection to prevent overheating of the iron core caused by overexcitation (U / f). Conventional inverse time overexcitation protection is realized by the following methods: [0003] There are two types of conventional methods for measuring U / f values: [0004] 1) Hardware measurement method: use the RC loop to directly measure the U / f value, then rectify and filter to obtain the DC signal corresponding to the U / f value, and directly sample the DC signal to obtain the U / f value; [0005] 2) Numerical calculation method: sample TV voltage, digitally calculate vo...

AI Technical Summary

Problems solved by technology

[0061] The technical problem to be solved by the present invention is to solve the problem that the U / f value error of the RC circuit measurement or synthetic calculation is affected by the frequency f, and it is not necessary to provide a dedicated channel for measuring the U / f value, and accurately realize the U / f inverse time limit curve

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