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A method for judging the startup of an interphase current mutation amount through a floating threshold

A technology of phase-to-phase current and sudden change, applied in the field of power system, can solve problems such as frequent start-up of protection devices, and achieve the effect of frequent start-up of protection

Active Publication Date: 2019-01-11
BEIJING SIFANG JIBAO AUTOMATION +1
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Problems solved by technology

[0006] In order to solve the problem of frequent start-up of protection devices when the error of the system frequency relative to the power frequency exceeds ±2Hz during operation, this invention proposes a method for judging the start-up of the phase-to-phase current mutation through a floating threshold

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  • A method for judging the startup of an interphase current mutation amount through a floating threshold
  • A method for judging the startup of an interphase current mutation amount through a floating threshold

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Embodiment Construction

[0045] The technical solution of the present invention will be described in further detail below in conjunction with the accompanying drawings.

[0046] figure 1 It is a schematic diagram of the protection sampling interval in the oscillogram with the AC volume of 55Hz in normal operation.

[0047] The figure shows a part of the protection recording, which is AC 55Hz. The left side of the figure shows the instantaneous values ​​of each secondary current and secondary voltage at time L (at 20ms) and time R (at 40ms), and the instantaneous values ​​of the same AC volume at 20ms and 40ms are different. At this time, the phase current at every 20ms interval during normal operation has obvious mutation characteristics.

[0048] Taking phase A current as an example, the instantaneous values ​​at 0ms, 20ms, and 40ms are -0.252, -0.369, and -0.347 respectively. There will be differences between the instantaneous values ​​at 0ms and 20ms, and between 0ms and 20ms. The greater the lo...

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Abstract

The invention discloses a method for judging the startup of an interphase current mutation amount through a floating threshold. The realization method is that the floating value is increased on the basis of the fixed value of the starting current of the sudden change amount, and the starting threshold of the sudden change amount of the current between phases is taken as the starting threshold value. When the instantaneous value of the interphase current abrupt change is greater than the threshold of the interphase current abrupt change, the interphase current abrupt change element is allowed to start. Using the method of judging the sudden change of current between phases by floating threshold, the frequent start-up of the protection device can be prevented when the error of the system frequency relative to the power frequency exceeds + / - 2 Hz during operation.

Description

technical field [0001] The invention belongs to the field of power systems, and in particular relates to a method for realizing a starting element of a relay protection device. Background technique [0002] At present, the AC sampling of the microcomputer relay protection device is mainly based on the algorithm of power frequency 50Hz. When the frequency changes more than ±2Hz, it will affect the calculation accuracy of AC current and AC voltage. [0003] During island operation, the system frequency may reach the range of 45Hz to 68Hz. During island operation, when no system failure occurs, the protection device is required to operate normally. However, the protection device is still based on the algorithm of power frequency 50Hz, which may cause the protection to start frequently and enter the interruption of fault processing. [0004] The frequent activation of the protective device during normal operation will lead to unsafe factors. During normal operation, if the s...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26H02H3/08
CPCH02H3/083H02H7/26
Inventor 杜兆强伍叶凯张月品黄少锋徐振宇赵志宏于洪雷熊军黄继伟
Owner BEIJING SIFANG JIBAO AUTOMATION
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