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Discriminated method of generator terminal voltage mutual inductor once-off-line

A technology of terminal voltage and discrimination method, which is applied in the direction of instruments, measuring electricity, measuring electrical variables, etc., to prevent misoperation of protection, easy to implement, and simple to judge.

Active Publication Date: 2013-05-08
NR ELECTRIC CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for some units, such as nuclear power, large-scale hydropower or gas turbine units, often only one set of conventional voltage transformers can be connected, and other related electrical quantities must be used for a disconnection judgment.

Method used

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  • Discriminated method of generator terminal voltage mutual inductor once-off-line
  • Discriminated method of generator terminal voltage mutual inductor once-off-line
  • Discriminated method of generator terminal voltage mutual inductor once-off-line

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Embodiment Construction

[0035] The protective device simultaneously samples the TV voltage of the voltage transformer at the generator terminal and the zero-sequence voltage or zero-sequence current of the neutral point. The protection device performs full-cycle Fourier filtering and calculation on the sampled voltage and current, and obtains the negative sequence voltage 3U2 of the machine terminal TV, the fundamental wave zero sequence voltage 3U0 of the open triangle, and the zero sequence voltage Un0 or zero sequence current of the neutral point In0; pre-set the fixed value U0.set1 or I0.set1, U2.set2 and U0.set2 in the protection device, and judge according to the following inequality:

[0036] Un0

[0037] 3U2>U2.set2 Formula 2

[0038] 3U0>U0.set2 Formula 3

[0039] Among them, U0.set1, U2.set2, and U0.set2 are voltage fixed values, and I0.set1 is current fixed value.

[0040] When the conditions of formulas 1, 2, and 3 are satisfied at the same time, after ...

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Abstract

Disclosed is a discriminated method of generator terminal voltage mutual inductor once-off-line. A protector detects negative sequence voltage of a generator terminal voltage mutual inductor, open-mouth triangle fundamental wave zero sequence voltage and zero sequence voltage or a zero sequence current of a neutral point of a generator. According to the following formula, the detectable quantities are respectively compared with corresponding constant values, namely, when the conditions that the terminal voltage (TV) negative sequence voltage is larger than a constant value or the TV open-mouth triangle fundamental wave zero sequence voltage is larger than a constant value, and meanwhile the zero sequence voltage or the zero sequence current of the neutral point of the generator is smaller than a constant value are satisfied, once-off-line of the TV appears and alarm signals are sent, third harmonic voltage-type stator grounding protection and harmonic voltage-type stator grounding protection of a generator are locked, and protection mal-operations are avoided.

Description

technical field [0001] The present invention relates to the field of electric power system relay protection, and more specifically to a method for judging a disconnection of a terminal voltage transformer used for stator grounding protection of a generator, and to a relay protection device and a safety automatic device applying the method. It is used to prevent malfunction of generator stator grounding protection. Background technique [0002] When the generator is running normally, the three-phase voltage is symmetrical, the zero-sequence voltage of the TV open triangle at the machine terminal mainly includes the third harmonic voltage component, and the fundamental zero-sequence voltage is basically zero. When the stator single-phase grounding fault occurs inside the generator stator winding, the symmetry of the three-phase voltage of the generator is destroyed, and the open triangle of the machine terminal TV will appear the fundamental zero-sequence voltage, and the 3rd ...

Claims

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Application Information

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IPC IPC(8): G01R31/02G01R31/06
Inventor 陈佳胜陈俊张琦雪郭自刚严伟沈全荣
Owner NR ELECTRIC CO LTD
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