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

A half-wave integral, inverse time-limited technology, applied in emergency protection circuit devices, electrical components, etc., can solve problems such as the influence of frequency f, and achieve the effect of small calculation amount, simple algorithm implementation, and clear mathematical relationship.

Active Publication Date: 2012-02-15
GUODIAN NANJING AUTOMATION
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  • Claims
  • Application Information

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

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Embodiment Construction

[0075] In said step 2), the calculation process of calculating the U / f value by integrating and superimposing the positive and negative half-cycles of the voltage waveform is:

[0076] Voltage signal expression: u = 2 U sin ( 2 πft + θ ) ;

[0077] (θ=0 positive half wave or θ=π negative half wave);

[0078] T: voltage signal period;

[0079] θ: initial phase of voltage signal;

[0080] U / f=(|U / f| 前半波 +|U / f| 后半波 ) / 2;

[0081] In practical applications such as figure 2 As shown in the wiring, the line voltage of the voltage transformer is sampled in time to obtain the instantaneous value of the line voltage, such as Figure 4 As shown, y0, y1, ... yn ... ym are the sampling point values, the positive half-cycle continuous sampling point values ​​are y1, y2, y3, ... yn-1, and the negative half-cycle cont...

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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...

Claims

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Application Information

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IPC IPC(8): H02H7/00H02H7/04H02H7/06
Inventor 刘万斌包明磊罗铭
Owner GUODIAN NANJING AUTOMATION
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