Transformer excitation inrush current identification method based on improved symbolic sequence entropy method

A technology of symbol sequence and excitation inrush current, which is applied in the direction of transformer testing, emergency protection circuit devices, electrical components, etc., can solve the problem of magnetic saturation point reduction, achieve the effect of less number, prevent malfunction, and ensure reliability

CN113049990BActive Publication Date: 2022-03-15CHINA YANGTZE POWER
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2022-03-15

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Abstract

The transformer excitation inrush current identification method based on the improved symbol sequence entropy method collects the secondary current of the current transformers on both sides of the differential protection of the transformer at a certain sampling frequency, forms a differential current signal sequence, and judges the amplitude of the differential current sequence at the same time Whether it exceeds the setting value of the differential protection starting element, if it exceeds, the starting criterion is used to judge the fault differential current and the excitation inrush current. First, normalize the initial signal sequence of the differential flow to form a normalized differential current signal sequence, compare the direction of size change between two adjacent sampling points in a cycle data window, and form a new symbol sequence. The window constructs a vector symbol sequence with a width of 2. Only three modes of 00, 11 and 22 are reserved to calculate the symbol entropy value and compare it with the set threshold value. If it is lower than the threshold value, it will be judged as an internal fault and a protection action will be taken; If it is higher than the threshold value, it will be judged as excitation inrush current or non-internal fault, and the protection will be blocked.
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Description

technical field

[0001] The invention belongs to the technical field of transformer differential protection, in particular to a transformer excitation inrush current identification method based on an improved symbol sequence entropy method. Background technique

[0002] In recent years, the power industry has made great progress. With the continuous production of ultra-high voltage, ultra-high voltage and large-capacity power transformers in my country, more and more long-distance power transmission systems are built and operated, so the requirements for the safety, stability and reliability of power systems are getting higher and higher. The power transformer is one of the most critical power equipment in the power system, especially the large power transformer is not only expensive, but also has serious failure losses, and its normal operation will affect the safe and stable operation of the entire power system.

[0003] In the field work, most of the transformers in opera...

Examples

Embodiment Construction

[0057] The transformer excitation inrush current identification method based on the improved symbolic sequence entropy method includes the following steps:

[0058] Step 1: At a certain sampling frequency, according to N points per cycle, collect the secondary current of the current transformers on both sides of the differential protection of the transformer, and form a differential current signal sequence I 1 ={I 1 (1), I 1 (2),...,I 1 (k),...I 1 (N)}, k=1,2,...,N;

[0059] Step 2: Identify the differential current signal sequence I in step 1 1 Whether the value exceeds the setting value of the differential protection starting element, if it exceeds, the starting criterion is used to judge the fault differential current and the excitation inrush current;

[0060] Step 3: Initial signal sequence I for differential flow 1 Perform normalization processing so that all sampling points fall within the [0,1] interval, and obtain the differential flow signal sequence I 2 ={I ...