Method for identifying excitation surge current and internal fault of transformer

A technology for internal faults and excitation inrush currents, applied to instruments, measuring only current, measuring electrical variables, etc., can solve problems such as imperfection, misjudgment, and wrong locking of transformers

Active Publication Date: 2019-12-03
HENAN POLYTECHNIC UNIV
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

However, most of these methods only distinguish the inrush current from the internal fault current in sinusoidal form, and are less involved in the saturated fault current (especially the saturated fault current caused by CT saturation when the transformer is put into the transformer with fault no-load), which may easily cause CT saturation. The saturati...

Method used

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  • Method for identifying excitation surge current and internal fault of transformer
  • Method for identifying excitation surge current and internal fault of transformer
  • Method for identifying excitation surge current and internal fault of transformer

Examples

Experimental program
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Embodiment

[0049] Use the transformer simulation module to carry out the simulation test on the matlab simulation software. The rated capacity of the transformer is set to 50MVA, the primary and secondary voltages are set to 35kV and 110kV respectively, the connection group is selected as Yd11, and the saturated core is set. The system frequency is set to 50Hz, and the sampling frequency is set to 4000Hz. Simulate the internal short-circuit fault current, excitation inrush current, and saturation fault current, as shown in the accompanying drawings Figure 4 (a), Figure 5 (a), Figure 6 (a) shown.

[0050] According to the attached picture figure 1 The process of identifying the inrush current and internal fault shown in the figure, the specific identification steps are as follows:

[0051] Step 1: Right Figure 4 (a), Figure 5 (a), Figure 6 The three current signals shown in (a) are sampled, and after each sampling, the sampling data of the latest power frequency cycle is tak...

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Abstract

The invention discloses a method for identifying excitation surge current and internal fault of a transformer, belongs to the technical field of power system relay protection, and is to solve the technical problem of identifying the excitation surge current and internal fault of the transformer in a power system. The method comprises the following steps: sampling current in a transformer differential circuit; carrying out absolute value taking and sorting operation and the like on a sampling data sequence, and calculating an equal square ratio R; if R is less than Rset, judging that the current current is an internal fault current, and starting differential protection; or otherwise, calculating a correction factor FC and a correction equal square ratio RC, and further identifying the current current according to whether RC is greater than Rset or not. The method for identifying the excitation surge current and the internal fault has the advantages of simple steps, small calculation amount, convenient engineering implementation and the like.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for identifying transformer excitation inrush current and internal faults. Background technique [0002] Transformers are vital electrical equipment in power systems. On the one hand, transformers are responsible for the transformation and distribution of electric energy, which is indispensable in the safe operation of power systems; on the other hand, large transformers are expensive and have strong economic attributes. Therefore, the safe and stable operation of the transformer must be guaranteed. [0003] In the power system, the transformer is generally equipped with longitudinal differential protection as its main protection. The basic principle of transformer longitudinal differential protection is Kirchhoff's current law: the current flowing into the transformer is equal to the current flowing out during normal operation. However,...

Claims

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Application Information

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IPC IPC(8): G01R31/00G01R19/00H02H7/045G06F17/18
CPCG01R19/0092G01R31/00G06F17/18H02H7/0455
Inventor 刘鹏辉朱军王玉梅孙抗
Owner HENAN POLYTECHNIC UNIV
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